Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

11 files changed, 4861 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
new file mode 100644
index 000000000..2d240bfa8
--- /dev/null
+++ b/drivers/misc/eeprom/Kconfig
@@ -0,0 +1,134 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menu "EEPROM support"
+
+config EEPROM_AT24
+	tristate "I2C EEPROMs / RAMs / ROMs from most vendors"
+	depends on I2C && SYSFS
+	select NVMEM
+	select NVMEM_SYSFS
+	select REGMAP
+	select REGMAP_I2C
+	help
+	  Enable this driver to get read/write support to most I2C EEPROMs
+	  and compatible devices like FRAMs, SRAMs, ROMs etc. After you
+	  configure the driver to know about each chip on your target
+	  board.  Use these generic chip names, instead of vendor-specific
+	  ones like at24c64, 24lc02 or fm24c04:
+
+	     24c00, 24c01, 24c02, spd (readonly 24c02), 24c04, 24c08,
+	     24c16, 24c32, 24c64, 24c128, 24c256, 24c512, 24c1024, 24c2048
+
+	  Unless you like data loss puzzles, always be sure that any chip
+	  you configure as a 24c32 (32 kbit) or larger is NOT really a
+	  24c16 (16 kbit) or smaller, and vice versa. Marking the chip
+	  as read-only won't help recover from this. Also, if your chip
+	  has any software write-protect mechanism you may want to review the
+	  code to make sure this driver won't turn it on by accident.
+
+	  If you use this with an SMBus adapter instead of an I2C adapter,
+	  full functionality is not available.  Only smaller devices are
+	  supported (24c16 and below, max 4 kByte).
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called at24.
+
+config EEPROM_AT25
+	tristate "SPI EEPROMs (FRAMs) from most vendors"
+	depends on SPI && SYSFS
+	select NVMEM
+	select NVMEM_SYSFS
+	help
+	  Enable this driver to get read/write support to most SPI EEPROMs
+	  and Cypress FRAMs,
+	  after you configure the board init code to know about each eeprom
+	  on your target board.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called at25.
+
+config EEPROM_LEGACY
+	tristate "Old I2C EEPROM reader (DEPRECATED)"
+	depends on I2C && SYSFS
+	help
+	  If you say yes here you get read-only access to the EEPROM data
+	  available on modern memory DIMMs and Sony Vaio laptops via I2C. Such
+	  EEPROMs could theoretically be available on other devices as well.
+
+	  This driver is deprecated and will be removed soon, please use the
+	  better at24 driver instead.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called eeprom.
+
+config EEPROM_MAX6875
+	tristate "Maxim MAX6874/5 power supply supervisor"
+	depends on I2C
+	help
+	  If you say yes here you get read-only support for the user EEPROM of
+	  the Maxim MAX6874/5 EEPROM-programmable, quad power-supply
+	  sequencer/supervisor.
+
+	  All other features of this chip should be accessed via i2c-dev.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called max6875.
+
+
+config EEPROM_93CX6
+	tristate "EEPROM 93CX6 support"
+	help
+	  This is a driver for the EEPROM chipsets 93c46 and 93c66.
+	  The driver supports both read as well as write commands.
+
+	  If unsure, say N.
+
+config EEPROM_93XX46
+	tristate "Microwire EEPROM 93XX46 support"
+	depends on SPI && SYSFS
+	select REGMAP
+	select NVMEM
+	select NVMEM_SYSFS
+	help
+	  Driver for the microwire EEPROM chipsets 93xx46x. The driver
+	  supports both read and write commands and also the command to
+	  erase the whole EEPROM.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called eeprom_93xx46.
+
+	  If unsure, say N.
+
+config EEPROM_DIGSY_MTC_CFG
+	bool "DigsyMTC display configuration EEPROMs device"
+	depends on GPIO_MPC5200 && SPI_GPIO
+	help
+	  This option enables access to display configuration EEPROMs
+	  on digsy_mtc board. You have to additionally select Microwire
+	  EEPROM 93XX46 driver. sysfs entries will be created for that
+	  EEPROM allowing to read/write the configuration data or to
+	  erase the whole EEPROM.
+
+	  If unsure, say N.
+
+config EEPROM_IDT_89HPESX
+	tristate "IDT 89HPESx PCIe-swtiches EEPROM / CSR support"
+	depends on I2C && SYSFS
+	help
+	  Enable this driver to get read/write access to EEPROM / CSRs
+	  over IDT PCIe-swtich i2c-slave interface.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called idt_89hpesx.
+
+config EEPROM_EE1004
+	tristate "SPD EEPROMs on DDR4 memory modules"
+	depends on I2C && SYSFS
+	help
+	  Enable this driver to get read support to SPD EEPROMs following
+	  the JEDEC EE1004 standard. These are typically found on DDR4
+	  SDRAM memory modules.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ee1004.
+
+endmenu
diff --git a/drivers/misc/eeprom/Makefile b/drivers/misc/eeprom/Makefile
new file mode 100644
index 000000000..a9b4b6579
--- /dev/null
+++ b/drivers/misc/eeprom/Makefile
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_EEPROM_AT24)	+= at24.o
+obj-$(CONFIG_EEPROM_AT25)	+= at25.o
+obj-$(CONFIG_EEPROM_LEGACY)	+= eeprom.o
+obj-$(CONFIG_EEPROM_MAX6875)	+= max6875.o
+obj-$(CONFIG_EEPROM_93CX6)	+= eeprom_93cx6.o
+obj-$(CONFIG_EEPROM_93XX46)	+= eeprom_93xx46.o
+obj-$(CONFIG_EEPROM_DIGSY_MTC_CFG) += digsy_mtc_eeprom.o
+obj-$(CONFIG_EEPROM_IDT_89HPESX) += idt_89hpesx.o
+obj-$(CONFIG_EEPROM_EE1004)	+= ee1004.o
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
new file mode 100644
index 000000000..938c4f41b
--- /dev/null
+++ b/drivers/misc/eeprom/at24.c
@@ -0,0 +1,861 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * at24.c - handle most I2C EEPROMs
+ *
+ * Copyright (C) 2005-2007 David Brownell
+ * Copyright (C) 2008 Wolfram Sang, Pengutronix
+ */
+
+#include <linux/acpi.h>
+#include <linux/bitops.h>
+#include <linux/capability.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+/* Address pointer is 16 bit. */
+#define AT24_FLAG_ADDR16	BIT(7)
+/* sysfs-entry will be read-only. */
+#define AT24_FLAG_READONLY	BIT(6)
+/* sysfs-entry will be world-readable. */
+#define AT24_FLAG_IRUGO		BIT(5)
+/* Take always 8 addresses (24c00). */
+#define AT24_FLAG_TAKE8ADDR	BIT(4)
+/* Factory-programmed serial number. */
+#define AT24_FLAG_SERIAL	BIT(3)
+/* Factory-programmed mac address. */
+#define AT24_FLAG_MAC		BIT(2)
+/* Does not auto-rollover reads to the next slave address. */
+#define AT24_FLAG_NO_RDROL	BIT(1)
+
+/*
+ * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
+ * Differences between different vendor product lines (like Atmel AT24C or
+ * MicroChip 24LC, etc) won't much matter for typical read/write access.
+ * There are also I2C RAM chips, likewise interchangeable. One example
+ * would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
+ *
+ * However, misconfiguration can lose data. "Set 16-bit memory address"
+ * to a part with 8-bit addressing will overwrite data. Writing with too
+ * big a page size also loses data. And it's not safe to assume that the
+ * conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
+ * uses 0x51, for just one example.
+ *
+ * Accordingly, explicit board-specific configuration data should be used
+ * in almost all cases. (One partial exception is an SMBus used to access
+ * "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
+ *
+ * So this driver uses "new style" I2C driver binding, expecting to be
+ * told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
+ * similar kernel-resident tables; or, configuration data coming from
+ * a bootloader.
+ *
+ * Other than binding model, current differences from "eeprom" driver are
+ * that this one handles write access and isn't restricted to 24c02 devices.
+ * It also handles larger devices (32 kbit and up) with two-byte addresses,
+ * which won't work on pure SMBus systems.
+ */
+
+struct at24_data {
+	/*
+	 * Lock protects against activities from other Linux tasks,
+	 * but not from changes by other I2C masters.
+	 */
+	struct mutex lock;
+
+	unsigned int write_max;
+	unsigned int num_addresses;
+	unsigned int offset_adj;
+
+	u32 byte_len;
+	u16 page_size;
+	u8 flags;
+
+	struct nvmem_device *nvmem;
+	struct regulator *vcc_reg;
+	void (*read_post)(unsigned int off, char *buf, size_t count);
+
+	/*
+	 * Some chips tie up multiple I2C addresses; dummy devices reserve
+	 * them for us.
+	 */
+	u8 bank_addr_shift;
+	struct regmap *client_regmaps[];
+};
+
+/*
+ * This parameter is to help this driver avoid blocking other drivers out
+ * of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
+ * clock, one 256 byte read takes about 1/43 second which is excessive;
+ * but the 1/170 second it takes at 400 kHz may be quite reasonable; and
+ * at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
+ *
+ * This value is forced to be a power of two so that writes align on pages.
+ */
+static unsigned int at24_io_limit = 128;
+module_param_named(io_limit, at24_io_limit, uint, 0);
+MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
+
+/*
+ * Specs often allow 5 msec for a page write, sometimes 20 msec;
+ * it's important to recover from write timeouts.
+ */
+static unsigned int at24_write_timeout = 25;
+module_param_named(write_timeout, at24_write_timeout, uint, 0);
+MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
+
+struct at24_chip_data {
+	u32 byte_len;
+	u8 flags;
+	u8 bank_addr_shift;
+	void (*read_post)(unsigned int off, char *buf, size_t count);
+};
+
+#define AT24_CHIP_DATA(_name, _len, _flags)				\
+	static const struct at24_chip_data _name = {			\
+		.byte_len = _len, .flags = _flags,			\
+	}
+
+#define AT24_CHIP_DATA_CB(_name, _len, _flags, _read_post)		\
+	static const struct at24_chip_data _name = {			\
+		.byte_len = _len, .flags = _flags,			\
+		.read_post = _read_post,				\
+	}
+
+#define AT24_CHIP_DATA_BS(_name, _len, _flags, _bank_addr_shift)	\
+	static const struct at24_chip_data _name = {			\
+		.byte_len = _len, .flags = _flags,			\
+		.bank_addr_shift = _bank_addr_shift			\
+	}
+
+static void at24_read_post_vaio(unsigned int off, char *buf, size_t count)
+{
+	int i;
+
+	if (capable(CAP_SYS_ADMIN))
+		return;
+
+	/*
+	 * Hide VAIO private settings to regular users:
+	 * - BIOS passwords: bytes 0x00 to 0x0f
+	 * - UUID: bytes 0x10 to 0x1f
+	 * - Serial number: 0xc0 to 0xdf
+	 */
+	for (i = 0; i < count; i++) {
+		if ((off + i <= 0x1f) ||
+		    (off + i >= 0xc0 && off + i <= 0xdf))
+			buf[i] = 0;
+	}
+}
+
+/* needs 8 addresses as A0-A2 are ignored */
+AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
+/* old variants can't be handled with this generic entry! */
+AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs01, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs02, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
+	AT24_FLAG_MAC | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
+	AT24_FLAG_MAC | AT24_FLAG_READONLY);
+/* spd is a 24c02 in memory DIMMs */
+AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
+	AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
+/* 24c02_vaio is a 24c02 on some Sony laptops */
+AT24_CHIP_DATA_CB(at24_data_24c02_vaio, 2048 / 8,
+	AT24_FLAG_READONLY | AT24_FLAG_IRUGO,
+	at24_read_post_vaio);
+AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs04, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+/* 24rf08 quirk is handled at i2c-core */
+AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs08, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs16, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24cs32, 16,
+	AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24cs64, 16,
+	AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA_BS(at24_data_24c1025, 1048576 / 8, AT24_FLAG_ADDR16, 2);
+AT24_CHIP_DATA(at24_data_24c2048, 2097152 / 8, AT24_FLAG_ADDR16);
+/* identical to 24c08 ? */
+AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
+
+static const struct i2c_device_id at24_ids[] = {
+	{ "24c00",	(kernel_ulong_t)&at24_data_24c00 },
+	{ "24c01",	(kernel_ulong_t)&at24_data_24c01 },
+	{ "24cs01",	(kernel_ulong_t)&at24_data_24cs01 },
+	{ "24c02",	(kernel_ulong_t)&at24_data_24c02 },
+	{ "24cs02",	(kernel_ulong_t)&at24_data_24cs02 },
+	{ "24mac402",	(kernel_ulong_t)&at24_data_24mac402 },
+	{ "24mac602",	(kernel_ulong_t)&at24_data_24mac602 },
+	{ "spd",	(kernel_ulong_t)&at24_data_spd },
+	{ "24c02-vaio",	(kernel_ulong_t)&at24_data_24c02_vaio },
+	{ "24c04",	(kernel_ulong_t)&at24_data_24c04 },
+	{ "24cs04",	(kernel_ulong_t)&at24_data_24cs04 },
+	{ "24c08",	(kernel_ulong_t)&at24_data_24c08 },
+	{ "24cs08",	(kernel_ulong_t)&at24_data_24cs08 },
+	{ "24c16",	(kernel_ulong_t)&at24_data_24c16 },
+	{ "24cs16",	(kernel_ulong_t)&at24_data_24cs16 },
+	{ "24c32",	(kernel_ulong_t)&at24_data_24c32 },
+	{ "24cs32",	(kernel_ulong_t)&at24_data_24cs32 },
+	{ "24c64",	(kernel_ulong_t)&at24_data_24c64 },
+	{ "24cs64",	(kernel_ulong_t)&at24_data_24cs64 },
+	{ "24c128",	(kernel_ulong_t)&at24_data_24c128 },
+	{ "24c256",	(kernel_ulong_t)&at24_data_24c256 },
+	{ "24c512",	(kernel_ulong_t)&at24_data_24c512 },
+	{ "24c1024",	(kernel_ulong_t)&at24_data_24c1024 },
+	{ "24c1025",	(kernel_ulong_t)&at24_data_24c1025 },
+	{ "24c2048",    (kernel_ulong_t)&at24_data_24c2048 },
+	{ "at24",	0 },
+	{ /* END OF LIST */ }
+};
+MODULE_DEVICE_TABLE(i2c, at24_ids);
+
+static const struct of_device_id at24_of_match[] = {
+	{ .compatible = "atmel,24c00",		.data = &at24_data_24c00 },
+	{ .compatible = "atmel,24c01",		.data = &at24_data_24c01 },
+	{ .compatible = "atmel,24cs01",		.data = &at24_data_24cs01 },
+	{ .compatible = "atmel,24c02",		.data = &at24_data_24c02 },
+	{ .compatible = "atmel,24cs02",		.data = &at24_data_24cs02 },
+	{ .compatible = "atmel,24mac402",	.data = &at24_data_24mac402 },
+	{ .compatible = "atmel,24mac602",	.data = &at24_data_24mac602 },
+	{ .compatible = "atmel,spd",		.data = &at24_data_spd },
+	{ .compatible = "atmel,24c04",		.data = &at24_data_24c04 },
+	{ .compatible = "atmel,24cs04",		.data = &at24_data_24cs04 },
+	{ .compatible = "atmel,24c08",		.data = &at24_data_24c08 },
+	{ .compatible = "atmel,24cs08",		.data = &at24_data_24cs08 },
+	{ .compatible = "atmel,24c16",		.data = &at24_data_24c16 },
+	{ .compatible = "atmel,24cs16",		.data = &at24_data_24cs16 },
+	{ .compatible = "atmel,24c32",		.data = &at24_data_24c32 },
+	{ .compatible = "atmel,24cs32",		.data = &at24_data_24cs32 },
+	{ .compatible = "atmel,24c64",		.data = &at24_data_24c64 },
+	{ .compatible = "atmel,24cs64",		.data = &at24_data_24cs64 },
+	{ .compatible = "atmel,24c128",		.data = &at24_data_24c128 },
+	{ .compatible = "atmel,24c256",		.data = &at24_data_24c256 },
+	{ .compatible = "atmel,24c512",		.data = &at24_data_24c512 },
+	{ .compatible = "atmel,24c1024",	.data = &at24_data_24c1024 },
+	{ .compatible = "atmel,24c1025",	.data = &at24_data_24c1025 },
+	{ .compatible = "atmel,24c2048",	.data = &at24_data_24c2048 },
+	{ /* END OF LIST */ },
+};
+MODULE_DEVICE_TABLE(of, at24_of_match);
+
+static const struct acpi_device_id __maybe_unused at24_acpi_ids[] = {
+	{ "INT3499",	(kernel_ulong_t)&at24_data_INT3499 },
+	{ "TPF0001",	(kernel_ulong_t)&at24_data_24c1024 },
+	{ /* END OF LIST */ }
+};
+MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
+
+/*
+ * This routine supports chips which consume multiple I2C addresses. It
+ * computes the addressing information to be used for a given r/w request.
+ * Assumes that sanity checks for offset happened at sysfs-layer.
+ *
+ * Slave address and byte offset derive from the offset. Always
+ * set the byte address; on a multi-master board, another master
+ * may have changed the chip's "current" address pointer.
+ */
+static struct regmap *at24_translate_offset(struct at24_data *at24,
+					    unsigned int *offset)
+{
+	unsigned int i;
+
+	if (at24->flags & AT24_FLAG_ADDR16) {
+		i = *offset >> 16;
+		*offset &= 0xffff;
+	} else {
+		i = *offset >> 8;
+		*offset &= 0xff;
+	}
+
+	return at24->client_regmaps[i];
+}
+
+static struct device *at24_base_client_dev(struct at24_data *at24)
+{
+	return regmap_get_device(at24->client_regmaps[0]);
+}
+
+static size_t at24_adjust_read_count(struct at24_data *at24,
+				      unsigned int offset, size_t count)
+{
+	unsigned int bits;
+	size_t remainder;
+
+	/*
+	 * In case of multi-address chips that don't rollover reads to
+	 * the next slave address: truncate the count to the slave boundary,
+	 * so that the read never straddles slaves.
+	 */
+	if (at24->flags & AT24_FLAG_NO_RDROL) {
+		bits = (at24->flags & AT24_FLAG_ADDR16) ? 16 : 8;
+		remainder = BIT(bits) - offset;
+		if (count > remainder)
+			count = remainder;
+	}
+
+	if (count > at24_io_limit)
+		count = at24_io_limit;
+
+	return count;
+}
+
+static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
+				unsigned int offset, size_t count)
+{
+	unsigned long timeout, read_time;
+	struct regmap *regmap;
+	int ret;
+
+	regmap = at24_translate_offset(at24, &offset);
+	count = at24_adjust_read_count(at24, offset, count);
+
+	/* adjust offset for mac and serial read ops */
+	offset += at24->offset_adj;
+
+	timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
+	do {
+		/*
+		 * The timestamp shall be taken before the actual operation
+		 * to avoid a premature timeout in case of high CPU load.
+		 */
+		read_time = jiffies;
+
+		ret = regmap_bulk_read(regmap, offset, buf, count);
+		dev_dbg(regmap_get_device(regmap), "read %zu@%d --> %d (%ld)\n",
+			count, offset, ret, jiffies);
+		if (!ret)
+			return count;
+
+		usleep_range(1000, 1500);
+	} while (time_before(read_time, timeout));
+
+	return -ETIMEDOUT;
+}
+
+/*
+ * Note that if the hardware write-protect pin is pulled high, the whole
+ * chip is normally write protected. But there are plenty of product
+ * variants here, including OTP fuses and partial chip protect.
+ *
+ * We only use page mode writes; the alternative is sloooow. These routines
+ * write at most one page.
+ */
+
+static size_t at24_adjust_write_count(struct at24_data *at24,
+				      unsigned int offset, size_t count)
+{
+	unsigned int next_page;
+
+	/* write_max is at most a page */
+	if (count > at24->write_max)
+		count = at24->write_max;
+
+	/* Never roll over backwards, to the start of this page */
+	next_page = roundup(offset + 1, at24->page_size);
+	if (offset + count > next_page)
+		count = next_page - offset;
+
+	return count;
+}
+
+static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
+				 unsigned int offset, size_t count)
+{
+	unsigned long timeout, write_time;
+	struct regmap *regmap;
+	int ret;
+
+	regmap = at24_translate_offset(at24, &offset);
+	count = at24_adjust_write_count(at24, offset, count);
+	timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
+
+	do {
+		/*
+		 * The timestamp shall be taken before the actual operation
+		 * to avoid a premature timeout in case of high CPU load.
+		 */
+		write_time = jiffies;
+
+		ret = regmap_bulk_write(regmap, offset, buf, count);
+		dev_dbg(regmap_get_device(regmap), "write %zu@%d --> %d (%ld)\n",
+			count, offset, ret, jiffies);
+		if (!ret)
+			return count;
+
+		usleep_range(1000, 1500);
+	} while (time_before(write_time, timeout));
+
+	return -ETIMEDOUT;
+}
+
+static int at24_read(void *priv, unsigned int off, void *val, size_t count)
+{
+	struct at24_data *at24;
+	struct device *dev;
+	char *buf = val;
+	int i, ret;
+
+	at24 = priv;
+	dev = at24_base_client_dev(at24);
+
+	if (unlikely(!count))
+		return count;
+
+	if (off + count > at24->byte_len)
+		return -EINVAL;
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(dev);
+		return ret;
+	}
+
+	/*
+	 * Read data from chip, protecting against concurrent updates
+	 * from this host, but not from other I2C masters.
+	 */
+	mutex_lock(&at24->lock);
+
+	for (i = 0; count; i += ret, count -= ret) {
+		ret = at24_regmap_read(at24, buf + i, off + i, count);
+		if (ret < 0) {
+			mutex_unlock(&at24->lock);
+			pm_runtime_put(dev);
+			return ret;
+		}
+	}
+
+	mutex_unlock(&at24->lock);
+
+	pm_runtime_put(dev);
+
+	if (unlikely(at24->read_post))
+		at24->read_post(off, buf, i);
+
+	return 0;
+}
+
+static int at24_write(void *priv, unsigned int off, void *val, size_t count)
+{
+	struct at24_data *at24;
+	struct device *dev;
+	char *buf = val;
+	int ret;
+
+	at24 = priv;
+	dev = at24_base_client_dev(at24);
+
+	if (unlikely(!count))
+		return -EINVAL;
+
+	if (off + count > at24->byte_len)
+		return -EINVAL;
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(dev);
+		return ret;
+	}
+
+	/*
+	 * Write data to chip, protecting against concurrent updates
+	 * from this host, but not from other I2C masters.
+	 */
+	mutex_lock(&at24->lock);
+
+	while (count) {
+		ret = at24_regmap_write(at24, buf, off, count);
+		if (ret < 0) {
+			mutex_unlock(&at24->lock);
+			pm_runtime_put(dev);
+			return ret;
+		}
+		buf += ret;
+		off += ret;
+		count -= ret;
+	}
+
+	mutex_unlock(&at24->lock);
+
+	pm_runtime_put(dev);
+
+	return 0;
+}
+
+static const struct at24_chip_data *at24_get_chip_data(struct device *dev)
+{
+	struct device_node *of_node = dev->of_node;
+	const struct at24_chip_data *cdata;
+	const struct i2c_device_id *id;
+
+	id = i2c_match_id(at24_ids, to_i2c_client(dev));
+
+	/*
+	 * The I2C core allows OF nodes compatibles to match against the
+	 * I2C device ID table as a fallback, so check not only if an OF
+	 * node is present but also if it matches an OF device ID entry.
+	 */
+	if (of_node && of_match_device(at24_of_match, dev))
+		cdata = of_device_get_match_data(dev);
+	else if (id)
+		cdata = (void *)id->driver_data;
+	else
+		cdata = acpi_device_get_match_data(dev);
+
+	if (!cdata)
+		return ERR_PTR(-ENODEV);
+
+	return cdata;
+}
+
+static int at24_make_dummy_client(struct at24_data *at24, unsigned int index,
+				  struct i2c_client *base_client,
+				  struct regmap_config *regmap_config)
+{
+	struct i2c_client *dummy_client;
+	struct regmap *regmap;
+
+	dummy_client = devm_i2c_new_dummy_device(&base_client->dev,
+						 base_client->adapter,
+						 base_client->addr +
+						 (index << at24->bank_addr_shift));
+	if (IS_ERR(dummy_client))
+		return PTR_ERR(dummy_client);
+
+	regmap = devm_regmap_init_i2c(dummy_client, regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	at24->client_regmaps[index] = regmap;
+
+	return 0;
+}
+
+static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
+{
+	if (flags & AT24_FLAG_MAC) {
+		/* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
+		return 0xa0 - byte_len;
+	} else if (flags & AT24_FLAG_SERIAL && flags & AT24_FLAG_ADDR16) {
+		/*
+		 * For 16 bit address pointers, the word address must contain
+		 * a '10' sequence in bits 11 and 10 regardless of the
+		 * intended position of the address pointer.
+		 */
+		return 0x0800;
+	} else if (flags & AT24_FLAG_SERIAL) {
+		/*
+		 * Otherwise the word address must begin with a '10' sequence,
+		 * regardless of the intended address.
+		 */
+		return 0x0080;
+	} else {
+		return 0;
+	}
+}
+
+static int at24_probe(struct i2c_client *client)
+{
+	struct regmap_config regmap_config = { };
+	struct nvmem_config nvmem_config = { };
+	u32 byte_len, page_size, flags, addrw;
+	const struct at24_chip_data *cdata;
+	struct device *dev = &client->dev;
+	bool i2c_fn_i2c, i2c_fn_block;
+	unsigned int i, num_addresses;
+	struct at24_data *at24;
+	bool full_power;
+	struct regmap *regmap;
+	bool writable;
+	u8 test_byte;
+	int err;
+
+	i2c_fn_i2c = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
+	i2c_fn_block = i2c_check_functionality(client->adapter,
+					       I2C_FUNC_SMBUS_WRITE_I2C_BLOCK);
+
+	cdata = at24_get_chip_data(dev);
+	if (IS_ERR(cdata))
+		return PTR_ERR(cdata);
+
+	err = device_property_read_u32(dev, "pagesize", &page_size);
+	if (err)
+		/*
+		 * This is slow, but we can't know all eeproms, so we better
+		 * play safe. Specifying custom eeprom-types via device tree
+		 * or properties is recommended anyhow.
+		 */
+		page_size = 1;
+
+	flags = cdata->flags;
+	if (device_property_present(dev, "read-only"))
+		flags |= AT24_FLAG_READONLY;
+	if (device_property_present(dev, "no-read-rollover"))
+		flags |= AT24_FLAG_NO_RDROL;
+
+	err = device_property_read_u32(dev, "address-width", &addrw);
+	if (!err) {
+		switch (addrw) {
+		case 8:
+			if (flags & AT24_FLAG_ADDR16)
+				dev_warn(dev,
+					 "Override address width to be 8, while default is 16\n");
+			flags &= ~AT24_FLAG_ADDR16;
+			break;
+		case 16:
+			flags |= AT24_FLAG_ADDR16;
+			break;
+		default:
+			dev_warn(dev, "Bad \"address-width\" property: %u\n",
+				 addrw);
+		}
+	}
+
+	err = device_property_read_u32(dev, "size", &byte_len);
+	if (err)
+		byte_len = cdata->byte_len;
+
+	if (!i2c_fn_i2c && !i2c_fn_block)
+		page_size = 1;
+
+	if (!page_size) {
+		dev_err(dev, "page_size must not be 0!\n");
+		return -EINVAL;
+	}
+
+	if (!is_power_of_2(page_size))
+		dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
+
+	err = device_property_read_u32(dev, "num-addresses", &num_addresses);
+	if (err) {
+		if (flags & AT24_FLAG_TAKE8ADDR)
+			num_addresses = 8;
+		else
+			num_addresses =	DIV_ROUND_UP(byte_len,
+				(flags & AT24_FLAG_ADDR16) ? 65536 : 256);
+	}
+
+	if ((flags & AT24_FLAG_SERIAL) && (flags & AT24_FLAG_MAC)) {
+		dev_err(dev,
+			"invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
+		return -EINVAL;
+	}
+
+	regmap_config.val_bits = 8;
+	regmap_config.reg_bits = (flags & AT24_FLAG_ADDR16) ? 16 : 8;
+	regmap_config.disable_locking = true;
+
+	regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	at24 = devm_kzalloc(dev, struct_size(at24, client_regmaps, num_addresses),
+			    GFP_KERNEL);
+	if (!at24)
+		return -ENOMEM;
+
+	mutex_init(&at24->lock);
+	at24->byte_len = byte_len;
+	at24->page_size = page_size;
+	at24->flags = flags;
+	at24->read_post = cdata->read_post;
+	at24->bank_addr_shift = cdata->bank_addr_shift;
+	at24->num_addresses = num_addresses;
+	at24->offset_adj = at24_get_offset_adj(flags, byte_len);
+	at24->client_regmaps[0] = regmap;
+
+	at24->vcc_reg = devm_regulator_get(dev, "vcc");
+	if (IS_ERR(at24->vcc_reg))
+		return PTR_ERR(at24->vcc_reg);
+
+	writable = !(flags & AT24_FLAG_READONLY);
+	if (writable) {
+		at24->write_max = min_t(unsigned int,
+					page_size, at24_io_limit);
+		if (!i2c_fn_i2c && at24->write_max > I2C_SMBUS_BLOCK_MAX)
+			at24->write_max = I2C_SMBUS_BLOCK_MAX;
+	}
+
+	/* use dummy devices for multiple-address chips */
+	for (i = 1; i < num_addresses; i++) {
+		err = at24_make_dummy_client(at24, i, client, &regmap_config);
+		if (err)
+			return err;
+	}
+
+	/*
+	 * We initialize nvmem_config.id to NVMEM_DEVID_AUTO even if the
+	 * label property is set as some platform can have multiple eeproms
+	 * with same label and we can not register each of those with same
+	 * label. Failing to register those eeproms trigger cascade failure
+	 * on such platform.
+	 */
+	nvmem_config.id = NVMEM_DEVID_AUTO;
+
+	if (device_property_present(dev, "label")) {
+		err = device_property_read_string(dev, "label",
+						  &nvmem_config.name);
+		if (err)
+			return err;
+	} else {
+		nvmem_config.name = dev_name(dev);
+	}
+
+	nvmem_config.type = NVMEM_TYPE_EEPROM;
+	nvmem_config.dev = dev;
+	nvmem_config.read_only = !writable;
+	nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO);
+	nvmem_config.owner = THIS_MODULE;
+	nvmem_config.compat = true;
+	nvmem_config.base_dev = dev;
+	nvmem_config.reg_read = at24_read;
+	nvmem_config.reg_write = at24_write;
+	nvmem_config.priv = at24;
+	nvmem_config.stride = 1;
+	nvmem_config.word_size = 1;
+	nvmem_config.size = byte_len;
+
+	i2c_set_clientdata(client, at24);
+
+	full_power = acpi_dev_state_d0(&client->dev);
+	if (full_power) {
+		err = regulator_enable(at24->vcc_reg);
+		if (err) {
+			dev_err(dev, "Failed to enable vcc regulator\n");
+			return err;
+		}
+
+		pm_runtime_set_active(dev);
+	}
+	pm_runtime_enable(dev);
+
+	at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
+	if (IS_ERR(at24->nvmem)) {
+		pm_runtime_disable(dev);
+		if (!pm_runtime_status_suspended(dev))
+			regulator_disable(at24->vcc_reg);
+		return PTR_ERR(at24->nvmem);
+	}
+
+	/*
+	 * Perform a one-byte test read to verify that the chip is functional,
+	 * unless powering on the device is to be avoided during probe (i.e.
+	 * it's powered off right now).
+	 */
+	if (full_power) {
+		err = at24_read(at24, 0, &test_byte, 1);
+		if (err) {
+			pm_runtime_disable(dev);
+			if (!pm_runtime_status_suspended(dev))
+				regulator_disable(at24->vcc_reg);
+			return -ENODEV;
+		}
+	}
+
+	pm_runtime_idle(dev);
+
+	if (writable)
+		dev_info(dev, "%u byte %s EEPROM, writable, %u bytes/write\n",
+			 byte_len, client->name, at24->write_max);
+	else
+		dev_info(dev, "%u byte %s EEPROM, read-only\n",
+			 byte_len, client->name);
+
+	return 0;
+}
+
+static void at24_remove(struct i2c_client *client)
+{
+	struct at24_data *at24 = i2c_get_clientdata(client);
+
+	pm_runtime_disable(&client->dev);
+	if (acpi_dev_state_d0(&client->dev)) {
+		if (!pm_runtime_status_suspended(&client->dev))
+			regulator_disable(at24->vcc_reg);
+		pm_runtime_set_suspended(&client->dev);
+	}
+}
+
+static int __maybe_unused at24_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct at24_data *at24 = i2c_get_clientdata(client);
+
+	return regulator_disable(at24->vcc_reg);
+}
+
+static int __maybe_unused at24_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct at24_data *at24 = i2c_get_clientdata(client);
+
+	return regulator_enable(at24->vcc_reg);
+}
+
+static const struct dev_pm_ops at24_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(at24_suspend, at24_resume, NULL)
+};
+
+static struct i2c_driver at24_driver = {
+	.driver = {
+		.name = "at24",
+		.pm = &at24_pm_ops,
+		.of_match_table = at24_of_match,
+		.acpi_match_table = ACPI_PTR(at24_acpi_ids),
+	},
+	.probe_new = at24_probe,
+	.remove = at24_remove,
+	.id_table = at24_ids,
+	.flags = I2C_DRV_ACPI_WAIVE_D0_PROBE,
+};
+
+static int __init at24_init(void)
+{
+	if (!at24_io_limit) {
+		pr_err("at24: at24_io_limit must not be 0!\n");
+		return -EINVAL;
+	}
+
+	at24_io_limit = rounddown_pow_of_two(at24_io_limit);
+	return i2c_add_driver(&at24_driver);
+}
+module_init(at24_init);
+
+static void __exit at24_exit(void)
+{
+	i2c_del_driver(&at24_driver);
+}
+module_exit(at24_exit);
+
+MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
+MODULE_AUTHOR("David Brownell and Wolfram Sang");
+MODULE_LICENSE("GPL");
diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
new file mode 100644
index 000000000..bdffc6543
--- /dev/null
+++ b/drivers/misc/eeprom/at25.c
@@ -0,0 +1,536 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for most of the SPI EEPROMs, such as Atmel AT25 models
+ * and Cypress FRAMs FM25 models.
+ *
+ * Copyright (C) 2006 David Brownell
+ */
+
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <linux/spi/eeprom.h>
+#include <linux/spi/spi.h>
+
+#include <linux/nvmem-provider.h>
+
+/*
+ * NOTE: this is an *EEPROM* driver. The vagaries of product naming
+ * mean that some AT25 products are EEPROMs, and others are FLASH.
+ * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver,
+ * not this one!
+ *
+ * EEPROMs that can be used with this driver include, for example:
+ *   AT25M02, AT25128B
+ */
+
+#define	FM25_SN_LEN	8		/* serial number length */
+#define EE_MAXADDRLEN	3		/* 24 bit addresses, up to 2 MBytes */
+
+struct at25_data {
+	struct spi_eeprom	chip;
+	struct spi_device	*spi;
+	struct mutex		lock;
+	unsigned		addrlen;
+	struct nvmem_config	nvmem_config;
+	struct nvmem_device	*nvmem;
+	u8 sernum[FM25_SN_LEN];
+	u8 command[EE_MAXADDRLEN + 1];
+};
+
+#define	AT25_WREN	0x06		/* latch the write enable */
+#define	AT25_WRDI	0x04		/* reset the write enable */
+#define	AT25_RDSR	0x05		/* read status register */
+#define	AT25_WRSR	0x01		/* write status register */
+#define	AT25_READ	0x03		/* read byte(s) */
+#define	AT25_WRITE	0x02		/* write byte(s)/sector */
+#define	FM25_SLEEP	0xb9		/* enter sleep mode */
+#define	FM25_RDID	0x9f		/* read device ID */
+#define	FM25_RDSN	0xc3		/* read S/N */
+
+#define	AT25_SR_nRDY	0x01		/* nRDY = write-in-progress */
+#define	AT25_SR_WEN	0x02		/* write enable (latched) */
+#define	AT25_SR_BP0	0x04		/* BP for software writeprotect */
+#define	AT25_SR_BP1	0x08
+#define	AT25_SR_WPEN	0x80		/* writeprotect enable */
+
+#define	AT25_INSTR_BIT3	0x08		/* additional address bit in instr */
+
+#define	FM25_ID_LEN	9		/* ID length */
+
+/*
+ * Specs often allow 5ms for a page write, sometimes 20ms;
+ * it's important to recover from write timeouts.
+ */
+#define	EE_TIMEOUT	25
+
+/*-------------------------------------------------------------------------*/
+
+#define	io_limit	PAGE_SIZE	/* bytes */
+
+static int at25_ee_read(void *priv, unsigned int offset,
+			void *val, size_t count)
+{
+	struct at25_data *at25 = priv;
+	char *buf = val;
+	size_t max_chunk = spi_max_transfer_size(at25->spi);
+	unsigned int msg_offset = offset;
+	size_t bytes_left = count;
+	size_t segment;
+	u8			*cp;
+	ssize_t			status;
+	struct spi_transfer	t[2];
+	struct spi_message	m;
+	u8			instr;
+
+	if (unlikely(offset >= at25->chip.byte_len))
+		return -EINVAL;
+	if ((offset + count) > at25->chip.byte_len)
+		count = at25->chip.byte_len - offset;
+	if (unlikely(!count))
+		return -EINVAL;
+
+	do {
+		segment = min(bytes_left, max_chunk);
+		cp = at25->command;
+
+		instr = AT25_READ;
+		if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
+			if (msg_offset >= BIT(at25->addrlen * 8))
+				instr |= AT25_INSTR_BIT3;
+
+		mutex_lock(&at25->lock);
+
+		*cp++ = instr;
+
+		/* 8/16/24-bit address is written MSB first */
+		switch (at25->addrlen) {
+		default:	/* case 3 */
+			*cp++ = msg_offset >> 16;
+			fallthrough;
+		case 2:
+			*cp++ = msg_offset >> 8;
+			fallthrough;
+		case 1:
+		case 0:	/* can't happen: for better code generation */
+			*cp++ = msg_offset >> 0;
+		}
+
+		spi_message_init(&m);
+		memset(t, 0, sizeof(t));
+
+		t[0].tx_buf = at25->command;
+		t[0].len = at25->addrlen + 1;
+		spi_message_add_tail(&t[0], &m);
+
+		t[1].rx_buf = buf;
+		t[1].len = segment;
+		spi_message_add_tail(&t[1], &m);
+
+		status = spi_sync(at25->spi, &m);
+
+		mutex_unlock(&at25->lock);
+
+		if (status)
+			return status;
+
+		msg_offset += segment;
+		buf += segment;
+		bytes_left -= segment;
+	} while (bytes_left > 0);
+
+	dev_dbg(&at25->spi->dev, "read %zu bytes at %d\n",
+		count, offset);
+	return 0;
+}
+
+/* Read extra registers as ID or serial number */
+static int fm25_aux_read(struct at25_data *at25, u8 *buf, uint8_t command,
+			 int len)
+{
+	int status;
+	struct spi_transfer t[2];
+	struct spi_message m;
+
+	spi_message_init(&m);
+	memset(t, 0, sizeof(t));
+
+	t[0].tx_buf = at25->command;
+	t[0].len = 1;
+	spi_message_add_tail(&t[0], &m);
+
+	t[1].rx_buf = buf;
+	t[1].len = len;
+	spi_message_add_tail(&t[1], &m);
+
+	mutex_lock(&at25->lock);
+
+	at25->command[0] = command;
+
+	status = spi_sync(at25->spi, &m);
+	dev_dbg(&at25->spi->dev, "read %d aux bytes --> %d\n", len, status);
+
+	mutex_unlock(&at25->lock);
+	return status;
+}
+
+static ssize_t sernum_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct at25_data *at25;
+
+	at25 = dev_get_drvdata(dev);
+	return sysfs_emit(buf, "%*ph\n", (int)sizeof(at25->sernum), at25->sernum);
+}
+static DEVICE_ATTR_RO(sernum);
+
+static struct attribute *sernum_attrs[] = {
+	&dev_attr_sernum.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(sernum);
+
+static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
+{
+	struct at25_data *at25 = priv;
+	size_t maxsz = spi_max_transfer_size(at25->spi);
+	const char *buf = val;
+	int			status = 0;
+	unsigned		buf_size;
+	u8			*bounce;
+
+	if (unlikely(off >= at25->chip.byte_len))
+		return -EFBIG;
+	if ((off + count) > at25->chip.byte_len)
+		count = at25->chip.byte_len - off;
+	if (unlikely(!count))
+		return -EINVAL;
+
+	/* Temp buffer starts with command and address */
+	buf_size = at25->chip.page_size;
+	if (buf_size > io_limit)
+		buf_size = io_limit;
+	bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL);
+	if (!bounce)
+		return -ENOMEM;
+
+	/*
+	 * For write, rollover is within the page ... so we write at
+	 * most one page, then manually roll over to the next page.
+	 */
+	mutex_lock(&at25->lock);
+	do {
+		unsigned long	timeout, retries;
+		unsigned	segment;
+		unsigned	offset = off;
+		u8		*cp = bounce;
+		int		sr;
+		u8		instr;
+
+		*cp = AT25_WREN;
+		status = spi_write(at25->spi, cp, 1);
+		if (status < 0) {
+			dev_dbg(&at25->spi->dev, "WREN --> %d\n", status);
+			break;
+		}
+
+		instr = AT25_WRITE;
+		if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
+			if (offset >= BIT(at25->addrlen * 8))
+				instr |= AT25_INSTR_BIT3;
+		*cp++ = instr;
+
+		/* 8/16/24-bit address is written MSB first */
+		switch (at25->addrlen) {
+		default:	/* case 3 */
+			*cp++ = offset >> 16;
+			fallthrough;
+		case 2:
+			*cp++ = offset >> 8;
+			fallthrough;
+		case 1:
+		case 0:	/* can't happen: for better code generation */
+			*cp++ = offset >> 0;
+		}
+
+		/* Write as much of a page as we can */
+		segment = buf_size - (offset % buf_size);
+		if (segment > count)
+			segment = count;
+		if (segment > maxsz)
+			segment = maxsz;
+		memcpy(cp, buf, segment);
+		status = spi_write(at25->spi, bounce,
+				segment + at25->addrlen + 1);
+		dev_dbg(&at25->spi->dev, "write %u bytes at %u --> %d\n",
+			segment, offset, status);
+		if (status < 0)
+			break;
+
+		/*
+		 * REVISIT this should detect (or prevent) failed writes
+		 * to read-only sections of the EEPROM...
+		 */
+
+		/* Wait for non-busy status */
+		timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT);
+		retries = 0;
+		do {
+
+			sr = spi_w8r8(at25->spi, AT25_RDSR);
+			if (sr < 0 || (sr & AT25_SR_nRDY)) {
+				dev_dbg(&at25->spi->dev,
+					"rdsr --> %d (%02x)\n", sr, sr);
+				/* at HZ=100, this is sloooow */
+				msleep(1);
+				continue;
+			}
+			if (!(sr & AT25_SR_nRDY))
+				break;
+		} while (retries++ < 3 || time_before_eq(jiffies, timeout));
+
+		if ((sr < 0) || (sr & AT25_SR_nRDY)) {
+			dev_err(&at25->spi->dev,
+				"write %u bytes offset %u, timeout after %u msecs\n",
+				segment, offset,
+				jiffies_to_msecs(jiffies -
+					(timeout - EE_TIMEOUT)));
+			status = -ETIMEDOUT;
+			break;
+		}
+
+		off += segment;
+		buf += segment;
+		count -= segment;
+
+	} while (count > 0);
+
+	mutex_unlock(&at25->lock);
+
+	kfree(bounce);
+	return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
+{
+	u32 val;
+	int err;
+
+	strscpy(chip->name, "at25", sizeof(chip->name));
+
+	err = device_property_read_u32(dev, "size", &val);
+	if (err)
+		err = device_property_read_u32(dev, "at25,byte-len", &val);
+	if (err) {
+		dev_err(dev, "Error: missing \"size\" property\n");
+		return err;
+	}
+	chip->byte_len = val;
+
+	err = device_property_read_u32(dev, "pagesize", &val);
+	if (err)
+		err = device_property_read_u32(dev, "at25,page-size", &val);
+	if (err) {
+		dev_err(dev, "Error: missing \"pagesize\" property\n");
+		return err;
+	}
+	chip->page_size = val;
+
+	err = device_property_read_u32(dev, "address-width", &val);
+	if (err) {
+		err = device_property_read_u32(dev, "at25,addr-mode", &val);
+		if (err) {
+			dev_err(dev, "Error: missing \"address-width\" property\n");
+			return err;
+		}
+		chip->flags = (u16)val;
+	} else {
+		switch (val) {
+		case 9:
+			chip->flags |= EE_INSTR_BIT3_IS_ADDR;
+			fallthrough;
+		case 8:
+			chip->flags |= EE_ADDR1;
+			break;
+		case 16:
+			chip->flags |= EE_ADDR2;
+			break;
+		case 24:
+			chip->flags |= EE_ADDR3;
+			break;
+		default:
+			dev_err(dev,
+				"Error: bad \"address-width\" property: %u\n",
+				val);
+			return -ENODEV;
+		}
+		if (device_property_present(dev, "read-only"))
+			chip->flags |= EE_READONLY;
+	}
+	return 0;
+}
+
+static int at25_fram_to_chip(struct device *dev, struct spi_eeprom *chip)
+{
+	struct at25_data *at25 = container_of(chip, struct at25_data, chip);
+	u8 sernum[FM25_SN_LEN];
+	u8 id[FM25_ID_LEN];
+	int i;
+
+	strscpy(chip->name, "fm25", sizeof(chip->name));
+
+	/* Get ID of chip */
+	fm25_aux_read(at25, id, FM25_RDID, FM25_ID_LEN);
+	if (id[6] != 0xc2) {
+		dev_err(dev, "Error: no Cypress FRAM (id %02x)\n", id[6]);
+		return -ENODEV;
+	}
+	/* Set size found in ID */
+	if (id[7] < 0x21 || id[7] > 0x26) {
+		dev_err(dev, "Error: unsupported size (id %02x)\n", id[7]);
+		return -ENODEV;
+	}
+
+	chip->byte_len = BIT(id[7] - 0x21 + 4) * 1024;
+	if (chip->byte_len > 64 * 1024)
+		chip->flags |= EE_ADDR3;
+	else
+		chip->flags |= EE_ADDR2;
+
+	if (id[8]) {
+		fm25_aux_read(at25, sernum, FM25_RDSN, FM25_SN_LEN);
+		/* Swap byte order */
+		for (i = 0; i < FM25_SN_LEN; i++)
+			at25->sernum[i] = sernum[FM25_SN_LEN - 1 - i];
+	}
+
+	chip->page_size = PAGE_SIZE;
+	return 0;
+}
+
+static const struct of_device_id at25_of_match[] = {
+	{ .compatible = "atmel,at25" },
+	{ .compatible = "cypress,fm25" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, at25_of_match);
+
+static const struct spi_device_id at25_spi_ids[] = {
+	{ .name = "at25" },
+	{ .name = "fm25" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, at25_spi_ids);
+
+static int at25_probe(struct spi_device *spi)
+{
+	struct at25_data	*at25 = NULL;
+	int			err;
+	int			sr;
+	struct spi_eeprom *pdata;
+	bool is_fram;
+
+	err = device_property_match_string(&spi->dev, "compatible", "cypress,fm25");
+	if (err >= 0)
+		is_fram = true;
+	else
+		is_fram = false;
+
+	/*
+	 * Ping the chip ... the status register is pretty portable,
+	 * unlike probing manufacturer IDs. We do expect that system
+	 * firmware didn't write it in the past few milliseconds!
+	 */
+	sr = spi_w8r8(spi, AT25_RDSR);
+	if (sr < 0 || sr & AT25_SR_nRDY) {
+		dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
+		return -ENXIO;
+	}
+
+	at25 = devm_kzalloc(&spi->dev, sizeof(*at25), GFP_KERNEL);
+	if (!at25)
+		return -ENOMEM;
+
+	mutex_init(&at25->lock);
+	at25->spi = spi;
+	spi_set_drvdata(spi, at25);
+
+	/* Chip description */
+	pdata = dev_get_platdata(&spi->dev);
+	if (pdata) {
+		at25->chip = *pdata;
+	} else {
+		if (is_fram)
+			err = at25_fram_to_chip(&spi->dev, &at25->chip);
+		else
+			err = at25_fw_to_chip(&spi->dev, &at25->chip);
+		if (err)
+			return err;
+	}
+
+	/* For now we only support 8/16/24 bit addressing */
+	if (at25->chip.flags & EE_ADDR1)
+		at25->addrlen = 1;
+	else if (at25->chip.flags & EE_ADDR2)
+		at25->addrlen = 2;
+	else if (at25->chip.flags & EE_ADDR3)
+		at25->addrlen = 3;
+	else {
+		dev_dbg(&spi->dev, "unsupported address type\n");
+		return -EINVAL;
+	}
+
+	at25->nvmem_config.type = is_fram ? NVMEM_TYPE_FRAM : NVMEM_TYPE_EEPROM;
+	at25->nvmem_config.name = dev_name(&spi->dev);
+	at25->nvmem_config.dev = &spi->dev;
+	at25->nvmem_config.read_only = at25->chip.flags & EE_READONLY;
+	at25->nvmem_config.root_only = true;
+	at25->nvmem_config.owner = THIS_MODULE;
+	at25->nvmem_config.compat = true;
+	at25->nvmem_config.base_dev = &spi->dev;
+	at25->nvmem_config.reg_read = at25_ee_read;
+	at25->nvmem_config.reg_write = at25_ee_write;
+	at25->nvmem_config.priv = at25;
+	at25->nvmem_config.stride = 1;
+	at25->nvmem_config.word_size = 1;
+	at25->nvmem_config.size = at25->chip.byte_len;
+
+	at25->nvmem = devm_nvmem_register(&spi->dev, &at25->nvmem_config);
+	if (IS_ERR(at25->nvmem))
+		return PTR_ERR(at25->nvmem);
+
+	dev_info(&spi->dev, "%d %s %s %s%s, pagesize %u\n",
+		 (at25->chip.byte_len < 1024) ?
+			at25->chip.byte_len : (at25->chip.byte_len / 1024),
+		 (at25->chip.byte_len < 1024) ? "Byte" : "KByte",
+		 at25->chip.name, is_fram ? "fram" : "eeprom",
+		 (at25->chip.flags & EE_READONLY) ? " (readonly)" : "",
+		 at25->chip.page_size);
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static struct spi_driver at25_driver = {
+	.driver = {
+		.name		= "at25",
+		.of_match_table = at25_of_match,
+		.dev_groups	= sernum_groups,
+	},
+	.probe		= at25_probe,
+	.id_table	= at25_spi_ids,
+};
+
+module_spi_driver(at25_driver);
+
+MODULE_DESCRIPTION("Driver for most SPI EEPROMs");
+MODULE_AUTHOR("David Brownell");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:at25");
diff --git a/drivers/misc/eeprom/digsy_mtc_eeprom.c b/drivers/misc/eeprom/digsy_mtc_eeprom.c
new file mode 100644
index 000000000..f1f766b70
--- /dev/null
+++ b/drivers/misc/eeprom/digsy_mtc_eeprom.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * EEPROMs access control driver for display configuration EEPROMs
+ * on DigsyMTC board.
+ *
+ * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@denx.de>
+ *
+ * FIXME: this driver is used on a device-tree probed platform: it
+ * should be defined as a bit-banged SPI device and probed from the device
+ * tree and not like this with static grabbing of a few numbered GPIO
+ * lines at random.
+ *
+ * Add proper SPI and EEPROM in arch/powerpc/boot/dts/digsy_mtc.dts
+ * and delete this driver.
+ */
+
+#include <linux/gpio.h>
+#include <linux/gpio/machine.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_gpio.h>
+#include <linux/eeprom_93xx46.h>
+
+#define GPIO_EEPROM_CLK		216
+#define GPIO_EEPROM_CS		210
+#define GPIO_EEPROM_DI		217
+#define GPIO_EEPROM_DO		249
+#define GPIO_EEPROM_OE		255
+#define EE_SPI_BUS_NUM	1
+
+static void digsy_mtc_op_prepare(void *p)
+{
+	/* enable */
+	gpio_set_value(GPIO_EEPROM_OE, 0);
+}
+
+static void digsy_mtc_op_finish(void *p)
+{
+	/* disable */
+	gpio_set_value(GPIO_EEPROM_OE, 1);
+}
+
+struct eeprom_93xx46_platform_data digsy_mtc_eeprom_data = {
+	.flags		= EE_ADDR8,
+	.prepare	= digsy_mtc_op_prepare,
+	.finish		= digsy_mtc_op_finish,
+};
+
+static struct spi_gpio_platform_data eeprom_spi_gpio_data = {
+	.num_chipselect	= 1,
+};
+
+static struct platform_device digsy_mtc_eeprom = {
+	.name	= "spi_gpio",
+	.id	= EE_SPI_BUS_NUM,
+	.dev	= {
+		.platform_data	= &eeprom_spi_gpio_data,
+	},
+};
+
+static struct gpiod_lookup_table eeprom_spi_gpiod_table = {
+	.dev_id         = "spi_gpio",
+	.table          = {
+		GPIO_LOOKUP("gpio@b00", GPIO_EEPROM_CLK,
+			    "sck", GPIO_ACTIVE_HIGH),
+		GPIO_LOOKUP("gpio@b00", GPIO_EEPROM_DI,
+			    "mosi", GPIO_ACTIVE_HIGH),
+		GPIO_LOOKUP("gpio@b00", GPIO_EEPROM_DO,
+			    "miso", GPIO_ACTIVE_HIGH),
+		GPIO_LOOKUP("gpio@b00", GPIO_EEPROM_CS,
+			    "cs", GPIO_ACTIVE_HIGH),
+		{ },
+	},
+};
+
+static struct spi_board_info digsy_mtc_eeprom_info[] __initdata = {
+	{
+		.modalias		= "93xx46",
+		.max_speed_hz		= 1000000,
+		.bus_num		= EE_SPI_BUS_NUM,
+		.chip_select		= 0,
+		.mode			= SPI_MODE_0,
+		.platform_data		= &digsy_mtc_eeprom_data,
+	},
+};
+
+static int __init digsy_mtc_eeprom_devices_init(void)
+{
+	int ret;
+
+	ret = gpio_request_one(GPIO_EEPROM_OE, GPIOF_OUT_INIT_HIGH,
+				"93xx46 EEPROMs OE");
+	if (ret) {
+		pr_err("can't request gpio %d\n", GPIO_EEPROM_OE);
+		return ret;
+	}
+	gpiod_add_lookup_table(&eeprom_spi_gpiod_table);
+	spi_register_board_info(digsy_mtc_eeprom_info,
+				ARRAY_SIZE(digsy_mtc_eeprom_info));
+	return platform_device_register(&digsy_mtc_eeprom);
+}
+device_initcall(digsy_mtc_eeprom_devices_init);
diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c
new file mode 100644
index 000000000..c8c6deb7e
--- /dev/null
+++ b/drivers/misc/eeprom/ee1004.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ee1004 - driver for DDR4 SPD EEPROMs
+ *
+ * Copyright (C) 2017-2019 Jean Delvare
+ *
+ * Based on the at24 driver:
+ * Copyright (C) 2005-2007 David Brownell
+ * Copyright (C) 2008 Wolfram Sang, Pengutronix
+ */
+
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+
+/*
+ * DDR4 memory modules use special EEPROMs following the Jedec EE1004
+ * specification. These are 512-byte EEPROMs using a single I2C address
+ * in the 0x50-0x57 range for data. One of two 256-byte page is selected
+ * by writing a command to I2C address 0x36 or 0x37 on the same I2C bus.
+ *
+ * Therefore we need to request these 2 additional addresses, and serialize
+ * access to all such EEPROMs with a single mutex.
+ *
+ * We assume it is safe to read up to 32 bytes at once from these EEPROMs.
+ * We use SMBus access even if I2C is available, these EEPROMs are small
+ * enough, and reading from them infrequent enough, that we favor simplicity
+ * over performance.
+ */
+
+#define EE1004_ADDR_SET_PAGE		0x36
+#define EE1004_NUM_PAGES		2
+#define EE1004_PAGE_SIZE		256
+#define EE1004_PAGE_SHIFT		8
+#define EE1004_EEPROM_SIZE		(EE1004_PAGE_SIZE * EE1004_NUM_PAGES)
+
+/*
+ * Mutex protects ee1004_set_page and ee1004_dev_count, and must be held
+ * from page selection to end of read.
+ */
+static DEFINE_MUTEX(ee1004_bus_lock);
+static struct i2c_client *ee1004_set_page[EE1004_NUM_PAGES];
+static unsigned int ee1004_dev_count;
+static int ee1004_current_page;
+
+static const struct i2c_device_id ee1004_ids[] = {
+	{ "ee1004", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ee1004_ids);
+
+/*-------------------------------------------------------------------------*/
+
+static int ee1004_get_current_page(void)
+{
+	int err;
+
+	err = i2c_smbus_read_byte(ee1004_set_page[0]);
+	if (err == -ENXIO) {
+		/* Nack means page 1 is selected */
+		return 1;
+	}
+	if (err < 0) {
+		/* Anything else is a real error, bail out */
+		return err;
+	}
+
+	/* Ack means page 0 is selected, returned value meaningless */
+	return 0;
+}
+
+static int ee1004_set_current_page(struct device *dev, int page)
+{
+	int ret;
+
+	if (page == ee1004_current_page)
+		return 0;
+
+	/* Data is ignored */
+	ret = i2c_smbus_write_byte(ee1004_set_page[page], 0x00);
+	/*
+	 * Don't give up just yet. Some memory modules will select the page
+	 * but not ack the command. Check which page is selected now.
+	 */
+	if (ret == -ENXIO && ee1004_get_current_page() == page)
+		ret = 0;
+	if (ret < 0) {
+		dev_err(dev, "Failed to select page %d (%d)\n", page, ret);
+		return ret;
+	}
+
+	dev_dbg(dev, "Selected page %d\n", page);
+	ee1004_current_page = page;
+
+	return 0;
+}
+
+static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf,
+				  unsigned int offset, size_t count)
+{
+	int status, page;
+
+	page = offset >> EE1004_PAGE_SHIFT;
+	offset &= (1 << EE1004_PAGE_SHIFT) - 1;
+
+	status = ee1004_set_current_page(&client->dev, page);
+	if (status)
+		return status;
+
+	/* Can't cross page boundaries */
+	if (offset + count > EE1004_PAGE_SIZE)
+		count = EE1004_PAGE_SIZE - offset;
+
+	if (count > I2C_SMBUS_BLOCK_MAX)
+		count = I2C_SMBUS_BLOCK_MAX;
+
+	return i2c_smbus_read_i2c_block_data_or_emulated(client, offset, count, buf);
+}
+
+static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
+			   struct bin_attribute *bin_attr,
+			   char *buf, loff_t off, size_t count)
+{
+	struct i2c_client *client = kobj_to_i2c_client(kobj);
+	size_t requested = count;
+	int ret = 0;
+
+	/*
+	 * Read data from chip, protecting against concurrent access to
+	 * other EE1004 SPD EEPROMs on the same adapter.
+	 */
+	mutex_lock(&ee1004_bus_lock);
+
+	while (count) {
+		ret = ee1004_eeprom_read(client, buf, off, count);
+		if (ret < 0)
+			goto out;
+
+		buf += ret;
+		off += ret;
+		count -= ret;
+	}
+out:
+	mutex_unlock(&ee1004_bus_lock);
+
+	return ret < 0 ? ret : requested;
+}
+
+static BIN_ATTR_RO(eeprom, EE1004_EEPROM_SIZE);
+
+static struct bin_attribute *ee1004_attrs[] = {
+	&bin_attr_eeprom,
+	NULL
+};
+
+BIN_ATTRIBUTE_GROUPS(ee1004);
+
+static void ee1004_cleanup(int idx)
+{
+	if (--ee1004_dev_count == 0)
+		while (--idx >= 0) {
+			i2c_unregister_device(ee1004_set_page[idx]);
+			ee1004_set_page[idx] = NULL;
+		}
+}
+
+static int ee1004_probe(struct i2c_client *client)
+{
+	int err, cnr = 0;
+
+	/* Make sure we can operate on this adapter */
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_READ_I2C_BLOCK) &&
+	    !i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_READ_BYTE_DATA))
+		return -EPFNOSUPPORT;
+
+	/* Use 2 dummy devices for page select command */
+	mutex_lock(&ee1004_bus_lock);
+	if (++ee1004_dev_count == 1) {
+		for (cnr = 0; cnr < EE1004_NUM_PAGES; cnr++) {
+			struct i2c_client *cl;
+
+			cl = i2c_new_dummy_device(client->adapter, EE1004_ADDR_SET_PAGE + cnr);
+			if (IS_ERR(cl)) {
+				err = PTR_ERR(cl);
+				goto err_clients;
+			}
+			ee1004_set_page[cnr] = cl;
+		}
+
+		/* Remember current page to avoid unneeded page select */
+		err = ee1004_get_current_page();
+		if (err < 0)
+			goto err_clients;
+		dev_dbg(&client->dev, "Currently selected page: %d\n", err);
+		ee1004_current_page = err;
+	} else if (client->adapter != ee1004_set_page[0]->adapter) {
+		dev_err(&client->dev,
+			"Driver only supports devices on a single I2C bus\n");
+		err = -EOPNOTSUPP;
+		goto err_clients;
+	}
+	mutex_unlock(&ee1004_bus_lock);
+
+	dev_info(&client->dev,
+		 "%u byte EE1004-compliant SPD EEPROM, read-only\n",
+		 EE1004_EEPROM_SIZE);
+
+	return 0;
+
+ err_clients:
+	ee1004_cleanup(cnr);
+	mutex_unlock(&ee1004_bus_lock);
+
+	return err;
+}
+
+static void ee1004_remove(struct i2c_client *client)
+{
+	/* Remove page select clients if this is the last device */
+	mutex_lock(&ee1004_bus_lock);
+	ee1004_cleanup(EE1004_NUM_PAGES);
+	mutex_unlock(&ee1004_bus_lock);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static struct i2c_driver ee1004_driver = {
+	.driver = {
+		.name = "ee1004",
+		.dev_groups = ee1004_groups,
+	},
+	.probe_new = ee1004_probe,
+	.remove = ee1004_remove,
+	.id_table = ee1004_ids,
+};
+module_i2c_driver(ee1004_driver);
+
+MODULE_DESCRIPTION("Driver for EE1004-compliant DDR4 SPD EEPROMs");
+MODULE_AUTHOR("Jean Delvare");
+MODULE_LICENSE("GPL");
diff --git a/drivers/misc/eeprom/eeprom.c b/drivers/misc/eeprom/eeprom.c
new file mode 100644
index 000000000..8a841a75d
--- /dev/null
+++ b/drivers/misc/eeprom/eeprom.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
+ *                           Philip Edelbrock <phil@netroedge.com>
+ * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
+ * Copyright (C) 2003 IBM Corp.
+ * Copyright (C) 2004 Jean Delvare <jdelvare@suse.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/capability.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
+					0x55, 0x56, 0x57, I2C_CLIENT_END };
+
+
+/* Size of EEPROM in bytes */
+#define EEPROM_SIZE		256
+
+/* possible types of eeprom devices */
+enum eeprom_nature {
+	UNKNOWN,
+	VAIO,
+};
+
+/* Each client has this additional data */
+struct eeprom_data {
+	struct mutex update_lock;
+	u8 valid;			/* bitfield, bit!=0 if slice is valid */
+	unsigned long last_updated[8];	/* In jiffies, 8 slices */
+	u8 data[EEPROM_SIZE];		/* Register values */
+	enum eeprom_nature nature;
+};
+
+
+static void eeprom_update_client(struct i2c_client *client, u8 slice)
+{
+	struct eeprom_data *data = i2c_get_clientdata(client);
+	int i;
+
+	mutex_lock(&data->update_lock);
+
+	if (!(data->valid & (1 << slice)) ||
+	    time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
+		dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
+
+		if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+			for (i = slice << 5; i < (slice + 1) << 5; i += 32)
+				if (i2c_smbus_read_i2c_block_data(client, i,
+							32, data->data + i)
+							!= 32)
+					goto exit;
+		} else {
+			for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
+				int word = i2c_smbus_read_word_data(client, i);
+				if (word < 0)
+					goto exit;
+				data->data[i] = word & 0xff;
+				data->data[i + 1] = word >> 8;
+			}
+		}
+		data->last_updated[slice] = jiffies;
+		data->valid |= (1 << slice);
+	}
+exit:
+	mutex_unlock(&data->update_lock);
+}
+
+static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
+			   struct bin_attribute *bin_attr,
+			   char *buf, loff_t off, size_t count)
+{
+	struct i2c_client *client = kobj_to_i2c_client(kobj);
+	struct eeprom_data *data = i2c_get_clientdata(client);
+	u8 slice;
+
+	/* Only refresh slices which contain requested bytes */
+	for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
+		eeprom_update_client(client, slice);
+
+	/* Hide Vaio private settings to regular users:
+	   - BIOS passwords: bytes 0x00 to 0x0f
+	   - UUID: bytes 0x10 to 0x1f
+	   - Serial number: 0xc0 to 0xdf */
+	if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
+		int i;
+
+		for (i = 0; i < count; i++) {
+			if ((off + i <= 0x1f) ||
+			    (off + i >= 0xc0 && off + i <= 0xdf))
+				buf[i] = 0;
+			else
+				buf[i] = data->data[off + i];
+		}
+	} else {
+		memcpy(buf, &data->data[off], count);
+	}
+
+	return count;
+}
+
+static const struct bin_attribute eeprom_attr = {
+	.attr = {
+		.name = "eeprom",
+		.mode = S_IRUGO,
+	},
+	.size = EEPROM_SIZE,
+	.read = eeprom_read,
+};
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = client->adapter;
+
+	/* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
+	   addresses 0x50-0x57, but we only care about 0x50. So decline
+	   attaching to addresses >= 0x51 on DDC buses */
+	if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
+		return -ENODEV;
+
+	/* There are four ways we can read the EEPROM data:
+	   (1) I2C block reads (faster, but unsupported by most adapters)
+	   (2) Word reads (128% overhead)
+	   (3) Consecutive byte reads (88% overhead, unsafe)
+	   (4) Regular byte data reads (265% overhead)
+	   The third and fourth methods are not implemented by this driver
+	   because all known adapters support one of the first two. */
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
+	 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
+		return -ENODEV;
+
+	strscpy(info->type, "eeprom", I2C_NAME_SIZE);
+
+	return 0;
+}
+
+static int eeprom_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct eeprom_data *data;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	memset(data->data, 0xff, EEPROM_SIZE);
+	i2c_set_clientdata(client, data);
+	mutex_init(&data->update_lock);
+	data->nature = UNKNOWN;
+
+	/* Detect the Vaio nature of EEPROMs.
+	   We use the "PCG-" or "VGN-" prefix as the signature. */
+	if (client->addr == 0x57
+	 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+		char name[4];
+
+		name[0] = i2c_smbus_read_byte_data(client, 0x80);
+		name[1] = i2c_smbus_read_byte_data(client, 0x81);
+		name[2] = i2c_smbus_read_byte_data(client, 0x82);
+		name[3] = i2c_smbus_read_byte_data(client, 0x83);
+
+		if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
+			dev_info(&client->dev, "Vaio EEPROM detected, "
+				 "enabling privacy protection\n");
+			data->nature = VAIO;
+		}
+	}
+
+	/* Let the users know they are using deprecated driver */
+	dev_notice(&client->dev,
+		   "eeprom driver is deprecated, please use at24 instead\n");
+
+	/* create the sysfs eeprom file */
+	return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
+}
+
+static void eeprom_remove(struct i2c_client *client)
+{
+	sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
+}
+
+static const struct i2c_device_id eeprom_id[] = {
+	{ "eeprom", 0 },
+	{ }
+};
+
+static struct i2c_driver eeprom_driver = {
+	.driver = {
+		.name	= "eeprom",
+	},
+	.probe		= eeprom_probe,
+	.remove		= eeprom_remove,
+	.id_table	= eeprom_id,
+
+	.class		= I2C_CLASS_DDC | I2C_CLASS_SPD,
+	.detect		= eeprom_detect,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(eeprom_driver);
+
+MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
+		"Philip Edelbrock <phil@netroedge.com> and "
+		"Greg Kroah-Hartman <greg@kroah.com>");
+MODULE_DESCRIPTION("I2C EEPROM driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/misc/eeprom/eeprom_93cx6.c b/drivers/misc/eeprom/eeprom_93cx6.c
new file mode 100644
index 000000000..9627294fe
--- /dev/null
+++ b/drivers/misc/eeprom/eeprom_93cx6.c
@@ -0,0 +1,372 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2004 - 2006 rt2x00 SourceForge Project
+ * <http://rt2x00.serialmonkey.com>
+ *
+ * Module: eeprom_93cx6
+ * Abstract: EEPROM reader routines for 93cx6 chipsets.
+ * Supported chipsets: 93c46 & 93c66.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/eeprom_93cx6.h>
+
+MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
+MODULE_VERSION("1.0");
+MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
+MODULE_LICENSE("GPL");
+
+static inline void eeprom_93cx6_pulse_high(struct eeprom_93cx6 *eeprom)
+{
+	eeprom->reg_data_clock = 1;
+	eeprom->register_write(eeprom);
+
+	/*
+	 * Add a short delay for the pulse to work.
+	 * According to the specifications the "maximum minimum"
+	 * time should be 450ns.
+	 */
+	ndelay(450);
+}
+
+static inline void eeprom_93cx6_pulse_low(struct eeprom_93cx6 *eeprom)
+{
+	eeprom->reg_data_clock = 0;
+	eeprom->register_write(eeprom);
+
+	/*
+	 * Add a short delay for the pulse to work.
+	 * According to the specifications the "maximum minimum"
+	 * time should be 450ns.
+	 */
+	ndelay(450);
+}
+
+static void eeprom_93cx6_startup(struct eeprom_93cx6 *eeprom)
+{
+	/*
+	 * Clear all flags, and enable chip select.
+	 */
+	eeprom->register_read(eeprom);
+	eeprom->reg_data_in = 0;
+	eeprom->reg_data_out = 0;
+	eeprom->reg_data_clock = 0;
+	eeprom->reg_chip_select = 1;
+	eeprom->drive_data = 1;
+	eeprom->register_write(eeprom);
+
+	/*
+	 * kick a pulse.
+	 */
+	eeprom_93cx6_pulse_high(eeprom);
+	eeprom_93cx6_pulse_low(eeprom);
+}
+
+static void eeprom_93cx6_cleanup(struct eeprom_93cx6 *eeprom)
+{
+	/*
+	 * Clear chip_select and data_in flags.
+	 */
+	eeprom->register_read(eeprom);
+	eeprom->reg_data_in = 0;
+	eeprom->reg_chip_select = 0;
+	eeprom->register_write(eeprom);
+
+	/*
+	 * kick a pulse.
+	 */
+	eeprom_93cx6_pulse_high(eeprom);
+	eeprom_93cx6_pulse_low(eeprom);
+}
+
+static void eeprom_93cx6_write_bits(struct eeprom_93cx6 *eeprom,
+	const u16 data, const u16 count)
+{
+	unsigned int i;
+
+	eeprom->register_read(eeprom);
+
+	/*
+	 * Clear data flags.
+	 */
+	eeprom->reg_data_in = 0;
+	eeprom->reg_data_out = 0;
+	eeprom->drive_data = 1;
+
+	/*
+	 * Start writing all bits.
+	 */
+	for (i = count; i > 0; i--) {
+		/*
+		 * Check if this bit needs to be set.
+		 */
+		eeprom->reg_data_in = !!(data & (1 << (i - 1)));
+
+		/*
+		 * Write the bit to the eeprom register.
+		 */
+		eeprom->register_write(eeprom);
+
+		/*
+		 * Kick a pulse.
+		 */
+		eeprom_93cx6_pulse_high(eeprom);
+		eeprom_93cx6_pulse_low(eeprom);
+	}
+
+	eeprom->reg_data_in = 0;
+	eeprom->register_write(eeprom);
+}
+
+static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
+	u16 *data, const u16 count)
+{
+	unsigned int i;
+	u16 buf = 0;
+
+	eeprom->register_read(eeprom);
+
+	/*
+	 * Clear data flags.
+	 */
+	eeprom->reg_data_in = 0;
+	eeprom->reg_data_out = 0;
+	eeprom->drive_data = 0;
+
+	/*
+	 * Start reading all bits.
+	 */
+	for (i = count; i > 0; i--) {
+		eeprom_93cx6_pulse_high(eeprom);
+
+		eeprom->register_read(eeprom);
+
+		/*
+		 * Clear data_in flag.
+		 */
+		eeprom->reg_data_in = 0;
+
+		/*
+		 * Read if the bit has been set.
+		 */
+		if (eeprom->reg_data_out)
+			buf |= (1 << (i - 1));
+
+		eeprom_93cx6_pulse_low(eeprom);
+	}
+
+	*data = buf;
+}
+
+/**
+ * eeprom_93cx6_read - Read a word from eeprom
+ * @eeprom: Pointer to eeprom structure
+ * @word: Word index from where we should start reading
+ * @data: target pointer where the information will have to be stored
+ *
+ * This function will read the eeprom data as host-endian word
+ * into the given data pointer.
+ */
+void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom, const u8 word,
+	u16 *data)
+{
+	u16 command;
+
+	/*
+	 * Initialize the eeprom register
+	 */
+	eeprom_93cx6_startup(eeprom);
+
+	/*
+	 * Select the read opcode and the word to be read.
+	 */
+	command = (PCI_EEPROM_READ_OPCODE << eeprom->width) | word;
+	eeprom_93cx6_write_bits(eeprom, command,
+		PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
+
+	/*
+	 * Read the requested 16 bits.
+	 */
+	eeprom_93cx6_read_bits(eeprom, data, 16);
+
+	/*
+	 * Cleanup eeprom register.
+	 */
+	eeprom_93cx6_cleanup(eeprom);
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_read);
+
+/**
+ * eeprom_93cx6_multiread - Read multiple words from eeprom
+ * @eeprom: Pointer to eeprom structure
+ * @word: Word index from where we should start reading
+ * @data: target pointer where the information will have to be stored
+ * @words: Number of words that should be read.
+ *
+ * This function will read all requested words from the eeprom,
+ * this is done by calling eeprom_93cx6_read() multiple times.
+ * But with the additional change that while the eeprom_93cx6_read
+ * will return host ordered bytes, this method will return little
+ * endian words.
+ */
+void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
+	__le16 *data, const u16 words)
+{
+	unsigned int i;
+	u16 tmp;
+
+	for (i = 0; i < words; i++) {
+		tmp = 0;
+		eeprom_93cx6_read(eeprom, word + i, &tmp);
+		data[i] = cpu_to_le16(tmp);
+	}
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
+
+/**
+ * eeprom_93cx6_readb - Read a byte from eeprom
+ * @eeprom: Pointer to eeprom structure
+ * @byte: Byte index from where we should start reading
+ * @data: target pointer where the information will have to be stored
+ *
+ * This function will read a byte of the eeprom data
+ * into the given data pointer.
+ */
+void eeprom_93cx6_readb(struct eeprom_93cx6 *eeprom, const u8 byte,
+	u8 *data)
+{
+	u16 command;
+	u16 tmp;
+
+	/*
+	 * Initialize the eeprom register
+	 */
+	eeprom_93cx6_startup(eeprom);
+
+	/*
+	 * Select the read opcode and the byte to be read.
+	 */
+	command = (PCI_EEPROM_READ_OPCODE << (eeprom->width + 1)) | byte;
+	eeprom_93cx6_write_bits(eeprom, command,
+		PCI_EEPROM_WIDTH_OPCODE + eeprom->width + 1);
+
+	/*
+	 * Read the requested 8 bits.
+	 */
+	eeprom_93cx6_read_bits(eeprom, &tmp, 8);
+	*data = tmp & 0xff;
+
+	/*
+	 * Cleanup eeprom register.
+	 */
+	eeprom_93cx6_cleanup(eeprom);
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_readb);
+
+/**
+ * eeprom_93cx6_multireadb - Read multiple bytes from eeprom
+ * @eeprom: Pointer to eeprom structure
+ * @byte: Index from where we should start reading
+ * @data: target pointer where the information will have to be stored
+ * @bytes: Number of bytes that should be read.
+ *
+ * This function will read all requested bytes from the eeprom,
+ * this is done by calling eeprom_93cx6_readb() multiple times.
+ */
+void eeprom_93cx6_multireadb(struct eeprom_93cx6 *eeprom, const u8 byte,
+	u8 *data, const u16 bytes)
+{
+	unsigned int i;
+
+	for (i = 0; i < bytes; i++)
+		eeprom_93cx6_readb(eeprom, byte + i, &data[i]);
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_multireadb);
+
+/**
+ * eeprom_93cx6_wren - set the write enable state
+ * @eeprom: Pointer to eeprom structure
+ * @enable: true to enable writes, otherwise disable writes
+ *
+ * Set the EEPROM write enable state to either allow or deny
+ * writes depending on the @enable value.
+ */
+void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable)
+{
+	u16 command;
+
+	/* start the command */
+	eeprom_93cx6_startup(eeprom);
+
+	/* create command to enable/disable */
+
+	command = enable ? PCI_EEPROM_EWEN_OPCODE : PCI_EEPROM_EWDS_OPCODE;
+	command <<= (eeprom->width - 2);
+
+	eeprom_93cx6_write_bits(eeprom, command,
+				PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
+
+	eeprom_93cx6_cleanup(eeprom);
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_wren);
+
+/**
+ * eeprom_93cx6_write - write data to the EEPROM
+ * @eeprom: Pointer to eeprom structure
+ * @addr: Address to write data to.
+ * @data: The data to write to address @addr.
+ *
+ * Write the @data to the specified @addr in the EEPROM and
+ * waiting for the device to finish writing.
+ *
+ * Note, since we do not expect large number of write operations
+ * we delay in between parts of the operation to avoid using excessive
+ * amounts of CPU time busy waiting.
+ */
+void eeprom_93cx6_write(struct eeprom_93cx6 *eeprom, u8 addr, u16 data)
+{
+	int timeout = 100;
+	u16 command;
+
+	/* start the command */
+	eeprom_93cx6_startup(eeprom);
+
+	command = PCI_EEPROM_WRITE_OPCODE << eeprom->width;
+	command |= addr;
+
+	/* send write command */
+	eeprom_93cx6_write_bits(eeprom, command,
+				PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
+
+	/* send data */
+	eeprom_93cx6_write_bits(eeprom, data, 16);
+
+	/* get ready to check for busy */
+	eeprom->drive_data = 0;
+	eeprom->reg_chip_select = 1;
+	eeprom->register_write(eeprom);
+
+	/* wait at-least 250ns to get DO to be the busy signal */
+	usleep_range(1000, 2000);
+
+	/* wait for DO to go high to signify finish */
+
+	while (true) {
+		eeprom->register_read(eeprom);
+
+		if (eeprom->reg_data_out)
+			break;
+
+		usleep_range(1000, 2000);
+
+		if (--timeout <= 0) {
+			printk(KERN_ERR "%s: timeout\n", __func__);
+			break;
+		}
+	}
+
+	eeprom_93cx6_cleanup(eeprom);
+}
+EXPORT_SYMBOL_GPL(eeprom_93cx6_write);
diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
new file mode 100644
index 000000000..b630625b3
--- /dev/null
+++ b/drivers/misc/eeprom/eeprom_93xx46.c
@@ -0,0 +1,583 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for 93xx46 EEPROMs
+ *
+ * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@denx.de>
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/nvmem-provider.h>
+#include <linux/eeprom_93xx46.h>
+
+#define OP_START	0x4
+#define OP_WRITE	(OP_START | 0x1)
+#define OP_READ		(OP_START | 0x2)
+#define ADDR_EWDS	0x00
+#define ADDR_ERAL	0x20
+#define ADDR_EWEN	0x30
+
+struct eeprom_93xx46_devtype_data {
+	unsigned int quirks;
+	unsigned char flags;
+};
+
+static const struct eeprom_93xx46_devtype_data at93c46_data = {
+	.flags = EE_SIZE1K,
+};
+
+static const struct eeprom_93xx46_devtype_data at93c56_data = {
+	.flags = EE_SIZE2K,
+};
+
+static const struct eeprom_93xx46_devtype_data at93c66_data = {
+	.flags = EE_SIZE4K,
+};
+
+static const struct eeprom_93xx46_devtype_data atmel_at93c46d_data = {
+	.flags = EE_SIZE1K,
+	.quirks = EEPROM_93XX46_QUIRK_SINGLE_WORD_READ |
+		  EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH,
+};
+
+static const struct eeprom_93xx46_devtype_data microchip_93lc46b_data = {
+	.flags = EE_SIZE1K,
+	.quirks = EEPROM_93XX46_QUIRK_EXTRA_READ_CYCLE,
+};
+
+struct eeprom_93xx46_dev {
+	struct spi_device *spi;
+	struct eeprom_93xx46_platform_data *pdata;
+	struct mutex lock;
+	struct nvmem_config nvmem_config;
+	struct nvmem_device *nvmem;
+	int addrlen;
+	int size;
+};
+
+static inline bool has_quirk_single_word_read(struct eeprom_93xx46_dev *edev)
+{
+	return edev->pdata->quirks & EEPROM_93XX46_QUIRK_SINGLE_WORD_READ;
+}
+
+static inline bool has_quirk_instruction_length(struct eeprom_93xx46_dev *edev)
+{
+	return edev->pdata->quirks & EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH;
+}
+
+static inline bool has_quirk_extra_read_cycle(struct eeprom_93xx46_dev *edev)
+{
+	return edev->pdata->quirks & EEPROM_93XX46_QUIRK_EXTRA_READ_CYCLE;
+}
+
+static int eeprom_93xx46_read(void *priv, unsigned int off,
+			      void *val, size_t count)
+{
+	struct eeprom_93xx46_dev *edev = priv;
+	char *buf = val;
+	int err = 0;
+	int bits;
+
+	if (unlikely(off >= edev->size))
+		return 0;
+	if ((off + count) > edev->size)
+		count = edev->size - off;
+	if (unlikely(!count))
+		return count;
+
+	mutex_lock(&edev->lock);
+
+	if (edev->pdata->prepare)
+		edev->pdata->prepare(edev);
+
+	/* The opcode in front of the address is three bits. */
+	bits = edev->addrlen + 3;
+
+	while (count) {
+		struct spi_message m;
+		struct spi_transfer t[2] = { { 0 } };
+		u16 cmd_addr = OP_READ << edev->addrlen;
+		size_t nbytes = count;
+
+		if (edev->pdata->flags & EE_ADDR8) {
+			cmd_addr |= off;
+			if (has_quirk_single_word_read(edev))
+				nbytes = 1;
+		} else {
+			cmd_addr |= (off >> 1);
+			if (has_quirk_single_word_read(edev))
+				nbytes = 2;
+		}
+
+		dev_dbg(&edev->spi->dev, "read cmd 0x%x, %d Hz\n",
+			cmd_addr, edev->spi->max_speed_hz);
+
+		if (has_quirk_extra_read_cycle(edev)) {
+			cmd_addr <<= 1;
+			bits += 1;
+		}
+
+		spi_message_init(&m);
+
+		t[0].tx_buf = (char *)&cmd_addr;
+		t[0].len = 2;
+		t[0].bits_per_word = bits;
+		spi_message_add_tail(&t[0], &m);
+
+		t[1].rx_buf = buf;
+		t[1].len = count;
+		t[1].bits_per_word = 8;
+		spi_message_add_tail(&t[1], &m);
+
+		err = spi_sync(edev->spi, &m);
+		/* have to wait at least Tcsl ns */
+		ndelay(250);
+
+		if (err) {
+			dev_err(&edev->spi->dev, "read %zu bytes at %d: err. %d\n",
+				nbytes, (int)off, err);
+			break;
+		}
+
+		buf += nbytes;
+		off += nbytes;
+		count -= nbytes;
+	}
+
+	if (edev->pdata->finish)
+		edev->pdata->finish(edev);
+
+	mutex_unlock(&edev->lock);
+
+	return err;
+}
+
+static int eeprom_93xx46_ew(struct eeprom_93xx46_dev *edev, int is_on)
+{
+	struct spi_message m;
+	struct spi_transfer t;
+	int bits, ret;
+	u16 cmd_addr;
+
+	/* The opcode in front of the address is three bits. */
+	bits = edev->addrlen + 3;
+
+	cmd_addr = OP_START << edev->addrlen;
+	if (edev->pdata->flags & EE_ADDR8)
+		cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS) << 1;
+	else
+		cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS);
+
+	if (has_quirk_instruction_length(edev)) {
+		cmd_addr <<= 2;
+		bits += 2;
+	}
+
+	dev_dbg(&edev->spi->dev, "ew%s cmd 0x%04x, %d bits\n",
+			is_on ? "en" : "ds", cmd_addr, bits);
+
+	spi_message_init(&m);
+	memset(&t, 0, sizeof(t));
+
+	t.tx_buf = &cmd_addr;
+	t.len = 2;
+	t.bits_per_word = bits;
+	spi_message_add_tail(&t, &m);
+
+	mutex_lock(&edev->lock);
+
+	if (edev->pdata->prepare)
+		edev->pdata->prepare(edev);
+
+	ret = spi_sync(edev->spi, &m);
+	/* have to wait at least Tcsl ns */
+	ndelay(250);
+	if (ret)
+		dev_err(&edev->spi->dev, "erase/write %sable error %d\n",
+			is_on ? "en" : "dis", ret);
+
+	if (edev->pdata->finish)
+		edev->pdata->finish(edev);
+
+	mutex_unlock(&edev->lock);
+	return ret;
+}
+
+static ssize_t
+eeprom_93xx46_write_word(struct eeprom_93xx46_dev *edev,
+			 const char *buf, unsigned off)
+{
+	struct spi_message m;
+	struct spi_transfer t[2];
+	int bits, data_len, ret;
+	u16 cmd_addr;
+
+	if (unlikely(off >= edev->size))
+		return -EINVAL;
+
+	/* The opcode in front of the address is three bits. */
+	bits = edev->addrlen + 3;
+
+	cmd_addr = OP_WRITE << edev->addrlen;
+
+	if (edev->pdata->flags & EE_ADDR8) {
+		cmd_addr |= off;
+		data_len = 1;
+	} else {
+		cmd_addr |= (off >> 1);
+		data_len = 2;
+	}
+
+	dev_dbg(&edev->spi->dev, "write cmd 0x%x\n", cmd_addr);
+
+	spi_message_init(&m);
+	memset(t, 0, sizeof(t));
+
+	t[0].tx_buf = (char *)&cmd_addr;
+	t[0].len = 2;
+	t[0].bits_per_word = bits;
+	spi_message_add_tail(&t[0], &m);
+
+	t[1].tx_buf = buf;
+	t[1].len = data_len;
+	t[1].bits_per_word = 8;
+	spi_message_add_tail(&t[1], &m);
+
+	ret = spi_sync(edev->spi, &m);
+	/* have to wait program cycle time Twc ms */
+	mdelay(6);
+	return ret;
+}
+
+static int eeprom_93xx46_write(void *priv, unsigned int off,
+				   void *val, size_t count)
+{
+	struct eeprom_93xx46_dev *edev = priv;
+	char *buf = val;
+	int i, ret, step = 1;
+
+	if (unlikely(off >= edev->size))
+		return -EFBIG;
+	if ((off + count) > edev->size)
+		count = edev->size - off;
+	if (unlikely(!count))
+		return count;
+
+	/* only write even number of bytes on 16-bit devices */
+	if (edev->pdata->flags & EE_ADDR16) {
+		step = 2;
+		count &= ~1;
+	}
+
+	/* erase/write enable */
+	ret = eeprom_93xx46_ew(edev, 1);
+	if (ret)
+		return ret;
+
+	mutex_lock(&edev->lock);
+
+	if (edev->pdata->prepare)
+		edev->pdata->prepare(edev);
+
+	for (i = 0; i < count; i += step) {
+		ret = eeprom_93xx46_write_word(edev, &buf[i], off + i);
+		if (ret) {
+			dev_err(&edev->spi->dev, "write failed at %d: %d\n",
+				(int)off + i, ret);
+			break;
+		}
+	}
+
+	if (edev->pdata->finish)
+		edev->pdata->finish(edev);
+
+	mutex_unlock(&edev->lock);
+
+	/* erase/write disable */
+	eeprom_93xx46_ew(edev, 0);
+	return ret;
+}
+
+static int eeprom_93xx46_eral(struct eeprom_93xx46_dev *edev)
+{
+	struct eeprom_93xx46_platform_data *pd = edev->pdata;
+	struct spi_message m;
+	struct spi_transfer t;
+	int bits, ret;
+	u16 cmd_addr;
+
+	/* The opcode in front of the address is three bits. */
+	bits = edev->addrlen + 3;
+
+	cmd_addr = OP_START << edev->addrlen;
+	if (edev->pdata->flags & EE_ADDR8)
+		cmd_addr |= ADDR_ERAL << 1;
+	else
+		cmd_addr |= ADDR_ERAL;
+
+	if (has_quirk_instruction_length(edev)) {
+		cmd_addr <<= 2;
+		bits += 2;
+	}
+
+	dev_dbg(&edev->spi->dev, "eral cmd 0x%04x, %d bits\n", cmd_addr, bits);
+
+	spi_message_init(&m);
+	memset(&t, 0, sizeof(t));
+
+	t.tx_buf = &cmd_addr;
+	t.len = 2;
+	t.bits_per_word = bits;
+	spi_message_add_tail(&t, &m);
+
+	mutex_lock(&edev->lock);
+
+	if (edev->pdata->prepare)
+		edev->pdata->prepare(edev);
+
+	ret = spi_sync(edev->spi, &m);
+	if (ret)
+		dev_err(&edev->spi->dev, "erase error %d\n", ret);
+	/* have to wait erase cycle time Tec ms */
+	mdelay(6);
+
+	if (pd->finish)
+		pd->finish(edev);
+
+	mutex_unlock(&edev->lock);
+	return ret;
+}
+
+static ssize_t eeprom_93xx46_store_erase(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct eeprom_93xx46_dev *edev = dev_get_drvdata(dev);
+	int erase = 0, ret;
+
+	sscanf(buf, "%d", &erase);
+	if (erase) {
+		ret = eeprom_93xx46_ew(edev, 1);
+		if (ret)
+			return ret;
+		ret = eeprom_93xx46_eral(edev);
+		if (ret)
+			return ret;
+		ret = eeprom_93xx46_ew(edev, 0);
+		if (ret)
+			return ret;
+	}
+	return count;
+}
+static DEVICE_ATTR(erase, S_IWUSR, NULL, eeprom_93xx46_store_erase);
+
+static void select_assert(void *context)
+{
+	struct eeprom_93xx46_dev *edev = context;
+
+	gpiod_set_value_cansleep(edev->pdata->select, 1);
+}
+
+static void select_deassert(void *context)
+{
+	struct eeprom_93xx46_dev *edev = context;
+
+	gpiod_set_value_cansleep(edev->pdata->select, 0);
+}
+
+static const struct of_device_id eeprom_93xx46_of_table[] = {
+	{ .compatible = "eeprom-93xx46", .data = &at93c46_data, },
+	{ .compatible = "atmel,at93c46", .data = &at93c46_data, },
+	{ .compatible = "atmel,at93c46d", .data = &atmel_at93c46d_data, },
+	{ .compatible = "atmel,at93c56", .data = &at93c56_data, },
+	{ .compatible = "atmel,at93c66", .data = &at93c66_data, },
+	{ .compatible = "microchip,93lc46b", .data = &microchip_93lc46b_data, },
+	{}
+};
+MODULE_DEVICE_TABLE(of, eeprom_93xx46_of_table);
+
+static const struct spi_device_id eeprom_93xx46_spi_ids[] = {
+	{ .name = "eeprom-93xx46",
+	  .driver_data = (kernel_ulong_t)&at93c46_data, },
+	{ .name = "at93c46",
+	  .driver_data = (kernel_ulong_t)&at93c46_data, },
+	{ .name = "at93c46d",
+	  .driver_data = (kernel_ulong_t)&atmel_at93c46d_data, },
+	{ .name = "at93c56",
+	  .driver_data = (kernel_ulong_t)&at93c56_data, },
+	{ .name = "at93c66",
+	  .driver_data = (kernel_ulong_t)&at93c66_data, },
+	{ .name = "93lc46b",
+	  .driver_data = (kernel_ulong_t)&microchip_93lc46b_data, },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, eeprom_93xx46_spi_ids);
+
+static int eeprom_93xx46_probe_dt(struct spi_device *spi)
+{
+	const struct of_device_id *of_id =
+		of_match_device(eeprom_93xx46_of_table, &spi->dev);
+	struct device_node *np = spi->dev.of_node;
+	struct eeprom_93xx46_platform_data *pd;
+	u32 tmp;
+	int ret;
+
+	pd = devm_kzalloc(&spi->dev, sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		return -ENOMEM;
+
+	ret = of_property_read_u32(np, "data-size", &tmp);
+	if (ret < 0) {
+		dev_err(&spi->dev, "data-size property not found\n");
+		return ret;
+	}
+
+	if (tmp == 8) {
+		pd->flags |= EE_ADDR8;
+	} else if (tmp == 16) {
+		pd->flags |= EE_ADDR16;
+	} else {
+		dev_err(&spi->dev, "invalid data-size (%d)\n", tmp);
+		return -EINVAL;
+	}
+
+	if (of_property_read_bool(np, "read-only"))
+		pd->flags |= EE_READONLY;
+
+	pd->select = devm_gpiod_get_optional(&spi->dev, "select",
+					     GPIOD_OUT_LOW);
+	if (IS_ERR(pd->select))
+		return PTR_ERR(pd->select);
+
+	pd->prepare = select_assert;
+	pd->finish = select_deassert;
+	gpiod_direction_output(pd->select, 0);
+
+	if (of_id->data) {
+		const struct eeprom_93xx46_devtype_data *data = of_id->data;
+
+		pd->quirks = data->quirks;
+		pd->flags |= data->flags;
+	}
+
+	spi->dev.platform_data = pd;
+
+	return 0;
+}
+
+static int eeprom_93xx46_probe(struct spi_device *spi)
+{
+	struct eeprom_93xx46_platform_data *pd;
+	struct eeprom_93xx46_dev *edev;
+	int err;
+
+	if (spi->dev.of_node) {
+		err = eeprom_93xx46_probe_dt(spi);
+		if (err < 0)
+			return err;
+	}
+
+	pd = spi->dev.platform_data;
+	if (!pd) {
+		dev_err(&spi->dev, "missing platform data\n");
+		return -ENODEV;
+	}
+
+	edev = devm_kzalloc(&spi->dev, sizeof(*edev), GFP_KERNEL);
+	if (!edev)
+		return -ENOMEM;
+
+	if (pd->flags & EE_SIZE1K)
+		edev->size = 128;
+	else if (pd->flags & EE_SIZE2K)
+		edev->size = 256;
+	else if (pd->flags & EE_SIZE4K)
+		edev->size = 512;
+	else {
+		dev_err(&spi->dev, "unspecified size\n");
+		return -EINVAL;
+	}
+
+	if (pd->flags & EE_ADDR8)
+		edev->addrlen = ilog2(edev->size);
+	else if (pd->flags & EE_ADDR16)
+		edev->addrlen = ilog2(edev->size) - 1;
+	else {
+		dev_err(&spi->dev, "unspecified address type\n");
+		return -EINVAL;
+	}
+
+	mutex_init(&edev->lock);
+
+	edev->spi = spi;
+	edev->pdata = pd;
+
+	edev->nvmem_config.type = NVMEM_TYPE_EEPROM;
+	edev->nvmem_config.name = dev_name(&spi->dev);
+	edev->nvmem_config.dev = &spi->dev;
+	edev->nvmem_config.read_only = pd->flags & EE_READONLY;
+	edev->nvmem_config.root_only = true;
+	edev->nvmem_config.owner = THIS_MODULE;
+	edev->nvmem_config.compat = true;
+	edev->nvmem_config.base_dev = &spi->dev;
+	edev->nvmem_config.reg_read = eeprom_93xx46_read;
+	edev->nvmem_config.reg_write = eeprom_93xx46_write;
+	edev->nvmem_config.priv = edev;
+	edev->nvmem_config.stride = 4;
+	edev->nvmem_config.word_size = 1;
+	edev->nvmem_config.size = edev->size;
+
+	edev->nvmem = devm_nvmem_register(&spi->dev, &edev->nvmem_config);
+	if (IS_ERR(edev->nvmem))
+		return PTR_ERR(edev->nvmem);
+
+	dev_info(&spi->dev, "%d-bit eeprom containing %d bytes %s\n",
+		(pd->flags & EE_ADDR8) ? 8 : 16,
+		edev->size,
+		(pd->flags & EE_READONLY) ? "(readonly)" : "");
+
+	if (!(pd->flags & EE_READONLY)) {
+		if (device_create_file(&spi->dev, &dev_attr_erase))
+			dev_err(&spi->dev, "can't create erase interface\n");
+	}
+
+	spi_set_drvdata(spi, edev);
+	return 0;
+}
+
+static void eeprom_93xx46_remove(struct spi_device *spi)
+{
+	struct eeprom_93xx46_dev *edev = spi_get_drvdata(spi);
+
+	if (!(edev->pdata->flags & EE_READONLY))
+		device_remove_file(&spi->dev, &dev_attr_erase);
+}
+
+static struct spi_driver eeprom_93xx46_driver = {
+	.driver = {
+		.name	= "93xx46",
+		.of_match_table = of_match_ptr(eeprom_93xx46_of_table),
+	},
+	.probe		= eeprom_93xx46_probe,
+	.remove		= eeprom_93xx46_remove,
+	.id_table	= eeprom_93xx46_spi_ids,
+};
+
+module_spi_driver(eeprom_93xx46_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Driver for 93xx46 EEPROMs");
+MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
+MODULE_ALIAS("spi:93xx46");
+MODULE_ALIAS("spi:eeprom-93xx46");
+MODULE_ALIAS("spi:93lc46b");
diff --git a/drivers/misc/eeprom/idt_89hpesx.c b/drivers/misc/eeprom/idt_89hpesx.c
new file mode 100644
index 000000000..367054e0c
--- /dev/null
+++ b/drivers/misc/eeprom/idt_89hpesx.c
@@ -0,0 +1,1597 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *   Copyright (C) 2016 T-Platforms. All Rights Reserved.
+ *
+ * IDT PCIe-switch NTB Linux driver
+ *
+ * Contact Information:
+ * Serge Semin <fancer.lancer@gmail.com>, <Sergey.Semin@t-platforms.ru>
+ */
+/*
+ *           NOTE of the IDT 89HPESx SMBus-slave interface driver
+ *    This driver primarily is developed to have an access to EEPROM device of
+ * IDT PCIe-switches. IDT provides a simple SMBus interface to perform IO-
+ * operations from/to EEPROM, which is located at private (so called Master)
+ * SMBus of switches. Using that interface this the driver creates a simple
+ * binary sysfs-file in the device directory:
+ * /sys/bus/i2c/devices/<bus>-<devaddr>/eeprom
+ * In case if read-only flag is specified in the dts-node of device desription,
+ * User-space applications won't be able to write to the EEPROM sysfs-node.
+ *    Additionally IDT 89HPESx SMBus interface has an ability to write/read
+ * data of device CSRs. This driver exposes debugf-file to perform simple IO
+ * operations using that ability for just basic debug purpose. Particularly
+ * next file is created in the specific debugfs-directory:
+ * /sys/kernel/debug/idt_csr/
+ * Format of the debugfs-node is:
+ * $ cat /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
+ * <CSR address>:<CSR value>
+ * So reading the content of the file gives current CSR address and it value.
+ * If User-space application wishes to change current CSR address,
+ * it can just write a proper value to the sysfs-file:
+ * $ echo "<CSR address>" > /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>
+ * If it wants to change the CSR value as well, the format of the write
+ * operation is:
+ * $ echo "<CSR address>:<CSR value>" > \
+ *        /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
+ * CSR address and value can be any of hexadecimal, decimal or octal format.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/sysfs.h>
+#include <linux/debugfs.h>
+#include <linux/mod_devicetable.h>
+#include <linux/property.h>
+#include <linux/i2c.h>
+#include <linux/pci_ids.h>
+#include <linux/delay.h>
+
+#define IDT_NAME		"89hpesx"
+#define IDT_89HPESX_DESC	"IDT 89HPESx SMBus-slave interface driver"
+#define IDT_89HPESX_VER		"1.0"
+
+MODULE_DESCRIPTION(IDT_89HPESX_DESC);
+MODULE_VERSION(IDT_89HPESX_VER);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("T-platforms");
+
+/*
+ * csr_dbgdir - CSR read/write operations Debugfs directory
+ */
+static struct dentry *csr_dbgdir;
+
+/*
+ * struct idt_89hpesx_dev - IDT 89HPESx device data structure
+ * @eesize:	Size of EEPROM in bytes (calculated from "idt,eecompatible")
+ * @eero:	EEPROM Read-only flag
+ * @eeaddr:	EEPROM custom address
+ *
+ * @inieecmd:	Initial cmd value for EEPROM read/write operations
+ * @inicsrcmd:	Initial cmd value for CSR read/write operations
+ * @iniccode:	Initialial command code value for IO-operations
+ *
+ * @csr:	CSR address to perform read operation
+ *
+ * @smb_write:	SMBus write method
+ * @smb_read:	SMBus read method
+ * @smb_mtx:	SMBus mutex
+ *
+ * @client:	i2c client used to perform IO operations
+ *
+ * @ee_file:	EEPROM read/write sysfs-file
+ */
+struct idt_smb_seq;
+struct idt_89hpesx_dev {
+	u32 eesize;
+	bool eero;
+	u8 eeaddr;
+
+	u8 inieecmd;
+	u8 inicsrcmd;
+	u8 iniccode;
+
+	u16 csr;
+
+	int (*smb_write)(struct idt_89hpesx_dev *, const struct idt_smb_seq *);
+	int (*smb_read)(struct idt_89hpesx_dev *, struct idt_smb_seq *);
+	struct mutex smb_mtx;
+
+	struct i2c_client *client;
+
+	struct bin_attribute *ee_file;
+	struct dentry *csr_dir;
+};
+
+/*
+ * struct idt_smb_seq - sequence of data to be read/written from/to IDT 89HPESx
+ * @ccode:	SMBus command code
+ * @bytecnt:	Byte count of operation
+ * @data:	Data to by written
+ */
+struct idt_smb_seq {
+	u8 ccode;
+	u8 bytecnt;
+	u8 *data;
+};
+
+/*
+ * struct idt_eeprom_seq - sequence of data to be read/written from/to EEPROM
+ * @cmd:	Transaction CMD
+ * @eeaddr:	EEPROM custom address
+ * @memaddr:	Internal memory address of EEPROM
+ * @data:	Data to be written at the memory address
+ */
+struct idt_eeprom_seq {
+	u8 cmd;
+	u8 eeaddr;
+	u16 memaddr;
+	u8 data;
+} __packed;
+
+/*
+ * struct idt_csr_seq - sequence of data to be read/written from/to CSR
+ * @cmd:	Transaction CMD
+ * @csraddr:	Internal IDT device CSR address
+ * @data:	Data to be read/written from/to the CSR address
+ */
+struct idt_csr_seq {
+	u8 cmd;
+	u16 csraddr;
+	u32 data;
+} __packed;
+
+/*
+ * SMBus command code macros
+ * @CCODE_END:		Indicates the end of transaction
+ * @CCODE_START:	Indicates the start of transaction
+ * @CCODE_CSR:		CSR read/write transaction
+ * @CCODE_EEPROM:	EEPROM read/write transaction
+ * @CCODE_BYTE:		Supplied data has BYTE length
+ * @CCODE_WORD:		Supplied data has WORD length
+ * @CCODE_BLOCK:	Supplied data has variable length passed in bytecnt
+ *			byte right following CCODE byte
+ */
+#define CCODE_END	((u8)0x01)
+#define CCODE_START	((u8)0x02)
+#define CCODE_CSR	((u8)0x00)
+#define CCODE_EEPROM	((u8)0x04)
+#define CCODE_BYTE	((u8)0x00)
+#define CCODE_WORD	((u8)0x20)
+#define CCODE_BLOCK	((u8)0x40)
+#define CCODE_PEC	((u8)0x80)
+
+/*
+ * EEPROM command macros
+ * @EEPROM_OP_WRITE:	EEPROM write operation
+ * @EEPROM_OP_READ:	EEPROM read operation
+ * @EEPROM_USA:		Use specified address of EEPROM
+ * @EEPROM_NAERR:	EEPROM device is not ready to respond
+ * @EEPROM_LAERR:	EEPROM arbitration loss error
+ * @EEPROM_MSS:		EEPROM misplace start & stop bits error
+ * @EEPROM_WR_CNT:	Bytes count to perform write operation
+ * @EEPROM_WRRD_CNT:	Bytes count to write before reading
+ * @EEPROM_RD_CNT:	Bytes count to perform read operation
+ * @EEPROM_DEF_SIZE:	Fall back size of EEPROM
+ * @EEPROM_DEF_ADDR:	Defatul EEPROM address
+ * @EEPROM_TOUT:	Timeout before retry read operation if eeprom is busy
+ */
+#define EEPROM_OP_WRITE	((u8)0x00)
+#define EEPROM_OP_READ	((u8)0x01)
+#define EEPROM_USA	((u8)0x02)
+#define EEPROM_NAERR	((u8)0x08)
+#define EEPROM_LAERR    ((u8)0x10)
+#define EEPROM_MSS	((u8)0x20)
+#define EEPROM_WR_CNT	((u8)5)
+#define EEPROM_WRRD_CNT	((u8)4)
+#define EEPROM_RD_CNT	((u8)5)
+#define EEPROM_DEF_SIZE	((u16)4096)
+#define EEPROM_DEF_ADDR	((u8)0x50)
+#define EEPROM_TOUT	(100)
+
+/*
+ * CSR command macros
+ * @CSR_DWE:		Enable all four bytes of the operation
+ * @CSR_OP_WRITE:	CSR write operation
+ * @CSR_OP_READ:	CSR read operation
+ * @CSR_RERR:		Read operation error
+ * @CSR_WERR:		Write operation error
+ * @CSR_WR_CNT:		Bytes count to perform write operation
+ * @CSR_WRRD_CNT:	Bytes count to write before reading
+ * @CSR_RD_CNT:		Bytes count to perform read operation
+ * @CSR_MAX:		Maximum CSR address
+ * @CSR_DEF:		Default CSR address
+ * @CSR_REAL_ADDR:	CSR real unshifted address
+ */
+#define CSR_DWE			((u8)0x0F)
+#define CSR_OP_WRITE		((u8)0x00)
+#define CSR_OP_READ		((u8)0x10)
+#define CSR_RERR		((u8)0x40)
+#define CSR_WERR		((u8)0x80)
+#define CSR_WR_CNT		((u8)7)
+#define CSR_WRRD_CNT		((u8)3)
+#define CSR_RD_CNT		((u8)7)
+#define CSR_MAX			((u32)0x3FFFF)
+#define CSR_DEF			((u16)0x0000)
+#define CSR_REAL_ADDR(val)	((unsigned int)val << 2)
+
+/*
+ * IDT 89HPESx basic register
+ * @IDT_VIDDID_CSR:	PCIe VID and DID of IDT 89HPESx
+ * @IDT_VID_MASK:	Mask of VID
+ */
+#define IDT_VIDDID_CSR	((u32)0x0000)
+#define IDT_VID_MASK	((u32)0xFFFF)
+
+/*
+ * IDT 89HPESx can send NACK when new command is sent before previous one
+ * fininshed execution. In this case driver retries operation
+ * certain times.
+ * @RETRY_CNT:		Number of retries before giving up and fail
+ * @idt_smb_safe:	Generate a retry loop on corresponding SMBus method
+ */
+#define RETRY_CNT (128)
+#define idt_smb_safe(ops, args...) ({ \
+	int __retry = RETRY_CNT; \
+	s32 __sts; \
+	do { \
+		__sts = i2c_smbus_ ## ops ## _data(args); \
+	} while (__retry-- && __sts < 0); \
+	__sts; \
+})
+
+/*===========================================================================
+ *                         i2c bus level IO-operations
+ *===========================================================================
+ */
+
+/*
+ * idt_smb_write_byte() - SMBus write method when I2C_SMBUS_BYTE_DATA operation
+ *                        is only available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ */
+static int idt_smb_write_byte(struct idt_89hpesx_dev *pdev,
+			      const struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx;
+
+	/* Loop over the supplied data sending byte one-by-one */
+	for (idx = 0; idx < seq->bytecnt; idx++) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == seq->bytecnt - 1)
+			ccode |= CCODE_END;
+
+		/* Send data to the device */
+		sts = idt_smb_safe(write_byte, pdev->client, ccode,
+			seq->data[idx]);
+		if (sts != 0)
+			return (int)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_read_byte() - SMBus read method when I2C_SMBUS_BYTE_DATA operation
+ *                        is only available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ */
+static int idt_smb_read_byte(struct idt_89hpesx_dev *pdev,
+			     struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx;
+
+	/* Loop over the supplied buffer receiving byte one-by-one */
+	for (idx = 0; idx < seq->bytecnt; idx++) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == seq->bytecnt - 1)
+			ccode |= CCODE_END;
+
+		/* Read data from the device */
+		sts = idt_smb_safe(read_byte, pdev->client, ccode);
+		if (sts < 0)
+			return (int)sts;
+
+		seq->data[idx] = (u8)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_write_word() - SMBus write method when I2C_SMBUS_BYTE_DATA and
+ *                        I2C_FUNC_SMBUS_WORD_DATA operations are available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ */
+static int idt_smb_write_word(struct idt_89hpesx_dev *pdev,
+			      const struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx, evencnt;
+
+	/* Calculate the even count of data to send */
+	evencnt = seq->bytecnt - (seq->bytecnt % 2);
+
+	/* Loop over the supplied data sending two bytes at a time */
+	for (idx = 0; idx < evencnt; idx += 2) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_WORD;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == evencnt - 2)
+			ccode |= CCODE_END;
+
+		/* Send word data to the device */
+		sts = idt_smb_safe(write_word, pdev->client, ccode,
+			*(u16 *)&seq->data[idx]);
+		if (sts != 0)
+			return (int)sts;
+	}
+
+	/* If there is odd number of bytes then send just one last byte */
+	if (seq->bytecnt != evencnt) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE | CCODE_END;
+		if (idx == 0)
+			ccode |= CCODE_START;
+
+		/* Send byte data to the device */
+		sts = idt_smb_safe(write_byte, pdev->client, ccode,
+			seq->data[idx]);
+		if (sts != 0)
+			return (int)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_read_word() - SMBus read method when I2C_SMBUS_BYTE_DATA and
+ *                       I2C_FUNC_SMBUS_WORD_DATA operations are available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ */
+static int idt_smb_read_word(struct idt_89hpesx_dev *pdev,
+			     struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx, evencnt;
+
+	/* Calculate the even count of data to send */
+	evencnt = seq->bytecnt - (seq->bytecnt % 2);
+
+	/* Loop over the supplied data reading two bytes at a time */
+	for (idx = 0; idx < evencnt; idx += 2) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_WORD;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == evencnt - 2)
+			ccode |= CCODE_END;
+
+		/* Read word data from the device */
+		sts = idt_smb_safe(read_word, pdev->client, ccode);
+		if (sts < 0)
+			return (int)sts;
+
+		*(u16 *)&seq->data[idx] = (u16)sts;
+	}
+
+	/* If there is odd number of bytes then receive just one last byte */
+	if (seq->bytecnt != evencnt) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE | CCODE_END;
+		if (idx == 0)
+			ccode |= CCODE_START;
+
+		/* Read last data byte from the device */
+		sts = idt_smb_safe(read_byte, pdev->client, ccode);
+		if (sts < 0)
+			return (int)sts;
+
+		seq->data[idx] = (u8)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_write_block() - SMBus write method when I2C_SMBUS_BLOCK_DATA
+ *                         operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ */
+static int idt_smb_write_block(struct idt_89hpesx_dev *pdev,
+			       const struct idt_smb_seq *seq)
+{
+	u8 ccode;
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Send block of data to the device */
+	return idt_smb_safe(write_block, pdev->client, ccode, seq->bytecnt,
+		seq->data);
+}
+
+/*
+ * idt_smb_read_block() - SMBus read method when I2C_SMBUS_BLOCK_DATA
+ *                        operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ */
+static int idt_smb_read_block(struct idt_89hpesx_dev *pdev,
+			      struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Read block of data from the device */
+	sts = idt_smb_safe(read_block, pdev->client, ccode, seq->data);
+	if (sts != seq->bytecnt)
+		return (sts < 0 ? sts : -ENODATA);
+
+	return 0;
+}
+
+/*
+ * idt_smb_write_i2c_block() - SMBus write method when I2C_SMBUS_I2C_BLOCK_DATA
+ *                             operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ *
+ * NOTE It's usual SMBus write block operation, except the actual data length is
+ * sent as first byte of data
+ */
+static int idt_smb_write_i2c_block(struct idt_89hpesx_dev *pdev,
+				   const struct idt_smb_seq *seq)
+{
+	u8 ccode, buf[I2C_SMBUS_BLOCK_MAX + 1];
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the data to send. Length byte must be added prior the data */
+	buf[0] = seq->bytecnt;
+	memcpy(&buf[1], seq->data, seq->bytecnt);
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Send length and block of data to the device */
+	return idt_smb_safe(write_i2c_block, pdev->client, ccode,
+		seq->bytecnt + 1, buf);
+}
+
+/*
+ * idt_smb_read_i2c_block() - SMBus read method when I2C_SMBUS_I2C_BLOCK_DATA
+ *                            operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ *
+ * NOTE It's usual SMBus read block operation, except the actual data length is
+ * retrieved as first byte of data
+ */
+static int idt_smb_read_i2c_block(struct idt_89hpesx_dev *pdev,
+				  struct idt_smb_seq *seq)
+{
+	u8 ccode, buf[I2C_SMBUS_BLOCK_MAX + 1];
+	s32 sts;
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Read length and block of data from the device */
+	sts = idt_smb_safe(read_i2c_block, pdev->client, ccode,
+		seq->bytecnt + 1, buf);
+	if (sts != seq->bytecnt + 1)
+		return (sts < 0 ? sts : -ENODATA);
+	if (buf[0] != seq->bytecnt)
+		return -ENODATA;
+
+	/* Copy retrieved data to the output data buffer */
+	memcpy(seq->data, &buf[1], seq->bytecnt);
+
+	return 0;
+}
+
+/*===========================================================================
+ *                          EEPROM IO-operations
+ *===========================================================================
+ */
+
+/*
+ * idt_eeprom_read_byte() - read just one byte from EEPROM
+ * @pdev:	Pointer to the driver data
+ * @memaddr:	Start EEPROM memory address
+ * @data:	Data to be written to EEPROM
+ */
+static int idt_eeprom_read_byte(struct idt_89hpesx_dev *pdev, u16 memaddr,
+				u8 *data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_eeprom_seq eeseq;
+	struct idt_smb_seq smbseq;
+	int ret, retry;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_EEPROM;
+	smbseq.data = (u8 *)&eeseq;
+
+	/*
+	 * Sometimes EEPROM may respond with NACK if it's busy with previous
+	 * operation, so we need to perform a few attempts of read cycle
+	 */
+	retry = RETRY_CNT;
+	do {
+		/* Send EEPROM memory address to read data from */
+		smbseq.bytecnt = EEPROM_WRRD_CNT;
+		eeseq.cmd = pdev->inieecmd | EEPROM_OP_READ;
+		eeseq.eeaddr = pdev->eeaddr;
+		eeseq.memaddr = cpu_to_le16(memaddr);
+		ret = pdev->smb_write(pdev, &smbseq);
+		if (ret != 0) {
+			dev_err(dev, "Failed to init eeprom addr 0x%02x",
+				memaddr);
+			break;
+		}
+
+		/* Perform read operation */
+		smbseq.bytecnt = EEPROM_RD_CNT;
+		ret = pdev->smb_read(pdev, &smbseq);
+		if (ret != 0) {
+			dev_err(dev, "Failed to read eeprom data 0x%02x",
+				memaddr);
+			break;
+		}
+
+		/* Restart read operation if the device is busy */
+		if (retry && (eeseq.cmd & EEPROM_NAERR)) {
+			dev_dbg(dev, "EEPROM busy, retry reading after %d ms",
+				EEPROM_TOUT);
+			msleep(EEPROM_TOUT);
+			continue;
+		}
+
+		/* Check whether IDT successfully read data from EEPROM */
+		if (eeseq.cmd & (EEPROM_NAERR | EEPROM_LAERR | EEPROM_MSS)) {
+			dev_err(dev,
+				"Communication with eeprom failed, cmd 0x%hhx",
+				eeseq.cmd);
+			ret = -EREMOTEIO;
+			break;
+		}
+
+		/* Save retrieved data and exit the loop */
+		*data = eeseq.data;
+		break;
+	} while (retry--);
+
+	/* Return the status of operation */
+	return ret;
+}
+
+/*
+ * idt_eeprom_write() - EEPROM write operation
+ * @pdev:	Pointer to the driver data
+ * @memaddr:	Start EEPROM memory address
+ * @len:	Length of data to be written
+ * @data:	Data to be written to EEPROM
+ */
+static int idt_eeprom_write(struct idt_89hpesx_dev *pdev, u16 memaddr, u16 len,
+			    const u8 *data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_eeprom_seq eeseq;
+	struct idt_smb_seq smbseq;
+	int ret;
+	u16 idx;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_EEPROM;
+	smbseq.data = (u8 *)&eeseq;
+
+	/* Send data byte-by-byte, checking if it is successfully written */
+	for (idx = 0; idx < len; idx++, memaddr++) {
+		/* Lock IDT SMBus device */
+		mutex_lock(&pdev->smb_mtx);
+
+		/* Perform write operation */
+		smbseq.bytecnt = EEPROM_WR_CNT;
+		eeseq.cmd = pdev->inieecmd | EEPROM_OP_WRITE;
+		eeseq.eeaddr = pdev->eeaddr;
+		eeseq.memaddr = cpu_to_le16(memaddr);
+		eeseq.data = data[idx];
+		ret = pdev->smb_write(pdev, &smbseq);
+		if (ret != 0) {
+			dev_err(dev,
+				"Failed to write 0x%04hx:0x%02hhx to eeprom",
+				memaddr, data[idx]);
+			goto err_mutex_unlock;
+		}
+
+		/*
+		 * Check whether the data is successfully written by reading
+		 * from the same EEPROM memory address.
+		 */
+		eeseq.data = ~data[idx];
+		ret = idt_eeprom_read_byte(pdev, memaddr, &eeseq.data);
+		if (ret != 0)
+			goto err_mutex_unlock;
+
+		/* Check whether the read byte is the same as written one */
+		if (eeseq.data != data[idx]) {
+			dev_err(dev, "Values don't match 0x%02hhx != 0x%02hhx",
+				eeseq.data, data[idx]);
+			ret = -EREMOTEIO;
+			goto err_mutex_unlock;
+		}
+
+		/* Unlock IDT SMBus device */
+err_mutex_unlock:
+		mutex_unlock(&pdev->smb_mtx);
+		if (ret != 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_eeprom_read() - EEPROM read operation
+ * @pdev:	Pointer to the driver data
+ * @memaddr:	Start EEPROM memory address
+ * @len:	Length of data to read
+ * @buf:	Buffer to read data to
+ */
+static int idt_eeprom_read(struct idt_89hpesx_dev *pdev, u16 memaddr, u16 len,
+			   u8 *buf)
+{
+	int ret;
+	u16 idx;
+
+	/* Read data byte-by-byte, retrying if it wasn't successful */
+	for (idx = 0; idx < len; idx++, memaddr++) {
+		/* Lock IDT SMBus device */
+		mutex_lock(&pdev->smb_mtx);
+
+		/* Just read the byte to the buffer */
+		ret = idt_eeprom_read_byte(pdev, memaddr, &buf[idx]);
+
+		/* Unlock IDT SMBus device */
+		mutex_unlock(&pdev->smb_mtx);
+
+		/* Return error if read operation failed */
+		if (ret != 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*===========================================================================
+ *                          CSR IO-operations
+ *===========================================================================
+ */
+
+/*
+ * idt_csr_write() - CSR write operation
+ * @pdev:	Pointer to the driver data
+ * @csraddr:	CSR address (with no two LS bits)
+ * @data:	Data to be written to CSR
+ */
+static int idt_csr_write(struct idt_89hpesx_dev *pdev, u16 csraddr,
+			 const u32 data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_csr_seq csrseq;
+	struct idt_smb_seq smbseq;
+	int ret;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_CSR;
+	smbseq.data = (u8 *)&csrseq;
+
+	/* Lock IDT SMBus device */
+	mutex_lock(&pdev->smb_mtx);
+
+	/* Perform write operation */
+	smbseq.bytecnt = CSR_WR_CNT;
+	csrseq.cmd = pdev->inicsrcmd | CSR_OP_WRITE;
+	csrseq.csraddr = cpu_to_le16(csraddr);
+	csrseq.data = cpu_to_le32(data);
+	ret = pdev->smb_write(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to write 0x%04x: 0x%04x to csr",
+			CSR_REAL_ADDR(csraddr), data);
+		goto err_mutex_unlock;
+	}
+
+	/* Send CSR address to read data from */
+	smbseq.bytecnt = CSR_WRRD_CNT;
+	csrseq.cmd = pdev->inicsrcmd | CSR_OP_READ;
+	ret = pdev->smb_write(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to init csr address 0x%04x",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Perform read operation */
+	smbseq.bytecnt = CSR_RD_CNT;
+	ret = pdev->smb_read(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to read csr 0x%04x",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Check whether IDT successfully retrieved CSR data */
+	if (csrseq.cmd & (CSR_RERR | CSR_WERR)) {
+		dev_err(dev, "IDT failed to perform CSR r/w");
+		ret = -EREMOTEIO;
+		goto err_mutex_unlock;
+	}
+
+	/* Unlock IDT SMBus device */
+err_mutex_unlock:
+	mutex_unlock(&pdev->smb_mtx);
+
+	return ret;
+}
+
+/*
+ * idt_csr_read() - CSR read operation
+ * @pdev:	Pointer to the driver data
+ * @csraddr:	CSR address (with no two LS bits)
+ * @data:	Data to be written to CSR
+ */
+static int idt_csr_read(struct idt_89hpesx_dev *pdev, u16 csraddr, u32 *data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_csr_seq csrseq;
+	struct idt_smb_seq smbseq;
+	int ret;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_CSR;
+	smbseq.data = (u8 *)&csrseq;
+
+	/* Lock IDT SMBus device */
+	mutex_lock(&pdev->smb_mtx);
+
+	/* Send CSR register address before reading it */
+	smbseq.bytecnt = CSR_WRRD_CNT;
+	csrseq.cmd = pdev->inicsrcmd | CSR_OP_READ;
+	csrseq.csraddr = cpu_to_le16(csraddr);
+	ret = pdev->smb_write(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to init csr address 0x%04x",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Perform read operation */
+	smbseq.bytecnt = CSR_RD_CNT;
+	ret = pdev->smb_read(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to read csr 0x%04x",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Check whether IDT successfully retrieved CSR data */
+	if (csrseq.cmd & (CSR_RERR | CSR_WERR)) {
+		dev_err(dev, "IDT failed to perform CSR r/w");
+		ret = -EREMOTEIO;
+		goto err_mutex_unlock;
+	}
+
+	/* Save data retrieved from IDT */
+	*data = le32_to_cpu(csrseq.data);
+
+	/* Unlock IDT SMBus device */
+err_mutex_unlock:
+	mutex_unlock(&pdev->smb_mtx);
+
+	return ret;
+}
+
+/*===========================================================================
+ *                          Sysfs/debugfs-nodes IO-operations
+ *===========================================================================
+ */
+
+/*
+ * eeprom_write() - EEPROM sysfs-node write callback
+ * @filep:	Pointer to the file system node
+ * @kobj:	Pointer to the kernel object related to the sysfs-node
+ * @attr:	Attributes of the file
+ * @buf:	Buffer to write data to
+ * @off:	Offset at which data should be written to
+ * @count:	Number of bytes to write
+ */
+static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
+			    struct bin_attribute *attr,
+			    char *buf, loff_t off, size_t count)
+{
+	struct idt_89hpesx_dev *pdev;
+	int ret;
+
+	/* Retrieve driver data */
+	pdev = dev_get_drvdata(kobj_to_dev(kobj));
+
+	/* Perform EEPROM write operation */
+	ret = idt_eeprom_write(pdev, (u16)off, (u16)count, (u8 *)buf);
+	return (ret != 0 ? ret : count);
+}
+
+/*
+ * eeprom_read() - EEPROM sysfs-node read callback
+ * @filep:	Pointer to the file system node
+ * @kobj:	Pointer to the kernel object related to the sysfs-node
+ * @attr:	Attributes of the file
+ * @buf:	Buffer to write data to
+ * @off:	Offset at which data should be written to
+ * @count:	Number of bytes to write
+ */
+static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
+			   struct bin_attribute *attr,
+			   char *buf, loff_t off, size_t count)
+{
+	struct idt_89hpesx_dev *pdev;
+	int ret;
+
+	/* Retrieve driver data */
+	pdev = dev_get_drvdata(kobj_to_dev(kobj));
+
+	/* Perform EEPROM read operation */
+	ret = idt_eeprom_read(pdev, (u16)off, (u16)count, (u8 *)buf);
+	return (ret != 0 ? ret : count);
+}
+
+/*
+ * idt_dbgfs_csr_write() - CSR debugfs-node write callback
+ * @filep:	Pointer to the file system file descriptor
+ * @buf:	Buffer to read data from
+ * @count:	Size of the buffer
+ * @offp:	Offset within the file
+ *
+ * It accepts either "0x<reg addr>:0x<value>" for saving register address
+ * and writing value to specified DWORD register or "0x<reg addr>" for
+ * just saving register address in order to perform next read operation.
+ *
+ * WARNING No spaces are allowed. Incoming string must be strictly formated as:
+ * "<reg addr>:<value>". Register address must be aligned within 4 bytes
+ * (one DWORD).
+ */
+static ssize_t idt_dbgfs_csr_write(struct file *filep, const char __user *ubuf,
+				   size_t count, loff_t *offp)
+{
+	struct idt_89hpesx_dev *pdev = filep->private_data;
+	char *colon_ch, *csraddr_str, *csrval_str;
+	int ret, csraddr_len;
+	u32 csraddr, csrval;
+	char *buf;
+
+	if (*offp)
+		return 0;
+
+	/* Copy data from User-space */
+	buf = kmalloc(count + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, ubuf, count)) {
+		ret = -EFAULT;
+		goto free_buf;
+	}
+	buf[count] = 0;
+
+	/* Find position of colon in the buffer */
+	colon_ch = strnchr(buf, count, ':');
+
+	/*
+	 * If there is colon passed then new CSR value should be parsed as
+	 * well, so allocate buffer for CSR address substring.
+	 * If no colon is found, then string must have just one number with
+	 * no new CSR value
+	 */
+	if (colon_ch != NULL) {
+		csraddr_len = colon_ch - buf;
+		csraddr_str =
+			kmalloc(csraddr_len + 1, GFP_KERNEL);
+		if (csraddr_str == NULL) {
+			ret = -ENOMEM;
+			goto free_buf;
+		}
+		/* Copy the register address to the substring buffer */
+		strncpy(csraddr_str, buf, csraddr_len);
+		csraddr_str[csraddr_len] = '\0';
+		/* Register value must follow the colon */
+		csrval_str = colon_ch + 1;
+	} else /* if (str_colon == NULL) */ {
+		csraddr_str = (char *)buf; /* Just to shut warning up */
+		csraddr_len = strnlen(csraddr_str, count);
+		csrval_str = NULL;
+	}
+
+	/* Convert CSR address to u32 value */
+	ret = kstrtou32(csraddr_str, 0, &csraddr);
+	if (ret != 0)
+		goto free_csraddr_str;
+
+	/* Check whether passed register address is valid */
+	if (csraddr > CSR_MAX || !IS_ALIGNED(csraddr, SZ_4)) {
+		ret = -EINVAL;
+		goto free_csraddr_str;
+	}
+
+	/* Shift register address to the right so to have u16 address */
+	pdev->csr = (csraddr >> 2);
+
+	/* Parse new CSR value and send it to IDT, if colon has been found */
+	if (colon_ch != NULL) {
+		ret = kstrtou32(csrval_str, 0, &csrval);
+		if (ret != 0)
+			goto free_csraddr_str;
+
+		ret = idt_csr_write(pdev, pdev->csr, csrval);
+		if (ret != 0)
+			goto free_csraddr_str;
+	}
+
+	/* Free memory only if colon has been found */
+free_csraddr_str:
+	if (colon_ch != NULL)
+		kfree(csraddr_str);
+
+	/* Free buffer allocated for data retrieved from User-space */
+free_buf:
+	kfree(buf);
+
+	return (ret != 0 ? ret : count);
+}
+
+/*
+ * idt_dbgfs_csr_read() - CSR debugfs-node read callback
+ * @filep:	Pointer to the file system file descriptor
+ * @buf:	Buffer to write data to
+ * @count:	Size of the buffer
+ * @offp:	Offset within the file
+ *
+ * It just prints the pair "0x<reg addr>:0x<value>" to passed buffer.
+ */
+#define CSRBUF_SIZE	((size_t)32)
+static ssize_t idt_dbgfs_csr_read(struct file *filep, char __user *ubuf,
+				  size_t count, loff_t *offp)
+{
+	struct idt_89hpesx_dev *pdev = filep->private_data;
+	u32 csraddr, csrval;
+	char buf[CSRBUF_SIZE];
+	int ret, size;
+
+	/* Perform CSR read operation */
+	ret = idt_csr_read(pdev, pdev->csr, &csrval);
+	if (ret != 0)
+		return ret;
+
+	/* Shift register address to the left so to have real address */
+	csraddr = ((u32)pdev->csr << 2);
+
+	/* Print the "0x<reg addr>:0x<value>" to buffer */
+	size = snprintf(buf, CSRBUF_SIZE, "0x%05x:0x%08x\n",
+		(unsigned int)csraddr, (unsigned int)csrval);
+
+	/* Copy data to User-space */
+	return simple_read_from_buffer(ubuf, count, offp, buf, size);
+}
+
+/*
+ * eeprom_attribute - EEPROM sysfs-node attributes
+ *
+ * NOTE Size will be changed in compliance with OF node. EEPROM attribute will
+ * be read-only as well if the corresponding flag is specified in OF node.
+ */
+static BIN_ATTR_RW(eeprom, EEPROM_DEF_SIZE);
+
+/*
+ * csr_dbgfs_ops - CSR debugfs-node read/write operations
+ */
+static const struct file_operations csr_dbgfs_ops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.write = idt_dbgfs_csr_write,
+	.read = idt_dbgfs_csr_read
+};
+
+/*===========================================================================
+ *                       Driver init/deinit methods
+ *===========================================================================
+ */
+
+/*
+ * idt_set_defval() - disable EEPROM access by default
+ * @pdev:	Pointer to the driver data
+ */
+static void idt_set_defval(struct idt_89hpesx_dev *pdev)
+{
+	/* If OF info is missing then use next values */
+	pdev->eesize = 0;
+	pdev->eero = true;
+	pdev->inieecmd = 0;
+	pdev->eeaddr = 0;
+}
+
+static const struct i2c_device_id ee_ids[];
+
+/*
+ * idt_ee_match_id() - check whether the node belongs to compatible EEPROMs
+ */
+static const struct i2c_device_id *idt_ee_match_id(struct fwnode_handle *fwnode)
+{
+	const struct i2c_device_id *id = ee_ids;
+	const char *compatible, *p;
+	char devname[I2C_NAME_SIZE];
+	int ret;
+
+	ret = fwnode_property_read_string(fwnode, "compatible", &compatible);
+	if (ret)
+		return NULL;
+
+	p = strchr(compatible, ',');
+	strscpy(devname, p ? p + 1 : compatible, sizeof(devname));
+	/* Search through the device name */
+	while (id->name[0]) {
+		if (strcmp(devname, id->name) == 0)
+			return id;
+		id++;
+	}
+	return NULL;
+}
+
+/*
+ * idt_get_fw_data() - get IDT i2c-device parameters from device tree
+ * @pdev:	Pointer to the driver data
+ */
+static void idt_get_fw_data(struct idt_89hpesx_dev *pdev)
+{
+	struct device *dev = &pdev->client->dev;
+	struct fwnode_handle *fwnode;
+	const struct i2c_device_id *ee_id = NULL;
+	u32 eeprom_addr;
+	int ret;
+
+	device_for_each_child_node(dev, fwnode) {
+		ee_id = idt_ee_match_id(fwnode);
+		if (ee_id)
+			break;
+
+		dev_warn(dev, "Skip unsupported EEPROM device %pfw\n", fwnode);
+	}
+
+	/* If there is no fwnode EEPROM device, then set zero size */
+	if (!ee_id) {
+		dev_warn(dev, "No fwnode, EEPROM access disabled");
+		idt_set_defval(pdev);
+		return;
+	}
+
+	/* Retrieve EEPROM size */
+	pdev->eesize = (u32)ee_id->driver_data;
+
+	/* Get custom EEPROM address from 'reg' attribute */
+	ret = fwnode_property_read_u32(fwnode, "reg", &eeprom_addr);
+	if (ret || (eeprom_addr == 0)) {
+		dev_warn(dev, "No EEPROM reg found, use default address 0x%x",
+			 EEPROM_DEF_ADDR);
+		pdev->inieecmd = 0;
+		pdev->eeaddr = EEPROM_DEF_ADDR << 1;
+	} else {
+		pdev->inieecmd = EEPROM_USA;
+		pdev->eeaddr = eeprom_addr << 1;
+	}
+
+	/* Check EEPROM 'read-only' flag */
+	if (fwnode_property_read_bool(fwnode, "read-only"))
+		pdev->eero = true;
+	else /* if (!fwnode_property_read_bool(node, "read-only")) */
+		pdev->eero = false;
+
+	fwnode_handle_put(fwnode);
+	dev_info(dev, "EEPROM of %d bytes found by 0x%x",
+		pdev->eesize, pdev->eeaddr);
+}
+
+/*
+ * idt_create_pdev() - create and init data structure of the driver
+ * @client:	i2c client of IDT PCIe-switch device
+ */
+static struct idt_89hpesx_dev *idt_create_pdev(struct i2c_client *client)
+{
+	struct idt_89hpesx_dev *pdev;
+
+	/* Allocate memory for driver data */
+	pdev = devm_kmalloc(&client->dev, sizeof(struct idt_89hpesx_dev),
+		GFP_KERNEL);
+	if (pdev == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	/* Initialize basic fields of the data */
+	pdev->client = client;
+	i2c_set_clientdata(client, pdev);
+
+	/* Read firmware nodes information */
+	idt_get_fw_data(pdev);
+
+	/* Initialize basic CSR CMD field - use full DWORD-sized r/w ops */
+	pdev->inicsrcmd = CSR_DWE;
+	pdev->csr = CSR_DEF;
+
+	/* Enable Packet Error Checking if it's supported by adapter */
+	if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC)) {
+		pdev->iniccode = CCODE_PEC;
+		client->flags |= I2C_CLIENT_PEC;
+	} else /* PEC is unsupported */ {
+		pdev->iniccode = 0;
+	}
+
+	return pdev;
+}
+
+/*
+ * idt_free_pdev() - free data structure of the driver
+ * @pdev:	Pointer to the driver data
+ */
+static void idt_free_pdev(struct idt_89hpesx_dev *pdev)
+{
+	/* Clear driver data from device private field */
+	i2c_set_clientdata(pdev->client, NULL);
+}
+
+/*
+ * idt_set_smbus_ops() - set supported SMBus operations
+ * @pdev:	Pointer to the driver data
+ * Return status of smbus check operations
+ */
+static int idt_set_smbus_ops(struct idt_89hpesx_dev *pdev)
+{
+	struct i2c_adapter *adapter = pdev->client->adapter;
+	struct device *dev = &pdev->client->dev;
+
+	/* Check i2c adapter read functionality */
+	if (i2c_check_functionality(adapter,
+				    I2C_FUNC_SMBUS_READ_BLOCK_DATA)) {
+		pdev->smb_read = idt_smb_read_block;
+		dev_dbg(dev, "SMBus block-read op chosen");
+	} else if (i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+		pdev->smb_read = idt_smb_read_i2c_block;
+		dev_dbg(dev, "SMBus i2c-block-read op chosen");
+	} else if (i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_READ_WORD_DATA) &&
+		   i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+		pdev->smb_read = idt_smb_read_word;
+		dev_warn(dev, "Use slow word/byte SMBus read ops");
+	} else if (i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+		pdev->smb_read = idt_smb_read_byte;
+		dev_warn(dev, "Use slow byte SMBus read op");
+	} else /* no supported smbus read operations */ {
+		dev_err(dev, "No supported SMBus read op");
+		return -EPFNOSUPPORT;
+	}
+
+	/* Check i2c adapter write functionality */
+	if (i2c_check_functionality(adapter,
+				    I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)) {
+		pdev->smb_write = idt_smb_write_block;
+		dev_dbg(dev, "SMBus block-write op chosen");
+	} else if (i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
+		pdev->smb_write = idt_smb_write_i2c_block;
+		dev_dbg(dev, "SMBus i2c-block-write op chosen");
+	} else if (i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_WRITE_WORD_DATA) &&
+		   i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
+		pdev->smb_write = idt_smb_write_word;
+		dev_warn(dev, "Use slow word/byte SMBus write op");
+	} else if (i2c_check_functionality(adapter,
+					   I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
+		pdev->smb_write = idt_smb_write_byte;
+		dev_warn(dev, "Use slow byte SMBus write op");
+	} else /* no supported smbus write operations */ {
+		dev_err(dev, "No supported SMBus write op");
+		return -EPFNOSUPPORT;
+	}
+
+	/* Initialize IDT SMBus slave interface mutex */
+	mutex_init(&pdev->smb_mtx);
+
+	return 0;
+}
+
+/*
+ * idt_check_dev() - check whether it's really IDT 89HPESx device
+ * @pdev:	Pointer to the driver data
+ * Return status of i2c adapter check operation
+ */
+static int idt_check_dev(struct idt_89hpesx_dev *pdev)
+{
+	struct device *dev = &pdev->client->dev;
+	u32 viddid;
+	int ret;
+
+	/* Read VID and DID directly from IDT memory space */
+	ret = idt_csr_read(pdev, IDT_VIDDID_CSR, &viddid);
+	if (ret != 0) {
+		dev_err(dev, "Failed to read VID/DID");
+		return ret;
+	}
+
+	/* Check whether it's IDT device */
+	if ((viddid & IDT_VID_MASK) != PCI_VENDOR_ID_IDT) {
+		dev_err(dev, "Got unsupported VID/DID: 0x%08x", viddid);
+		return -ENODEV;
+	}
+
+	dev_info(dev, "Found IDT 89HPES device VID:0x%04x, DID:0x%04x",
+		(viddid & IDT_VID_MASK), (viddid >> 16));
+
+	return 0;
+}
+
+/*
+ * idt_create_sysfs_files() - create sysfs attribute files
+ * @pdev:	Pointer to the driver data
+ * Return status of operation
+ */
+static int idt_create_sysfs_files(struct idt_89hpesx_dev *pdev)
+{
+	struct device *dev = &pdev->client->dev;
+	int ret;
+
+	/* Don't do anything if EEPROM isn't accessible */
+	if (pdev->eesize == 0) {
+		dev_dbg(dev, "Skip creating sysfs-files");
+		return 0;
+	}
+
+	/* Allocate memory for attribute file */
+	pdev->ee_file = devm_kmalloc(dev, sizeof(*pdev->ee_file), GFP_KERNEL);
+	if (!pdev->ee_file)
+		return -ENOMEM;
+
+	/* Copy the declared EEPROM attr structure to change some of fields */
+	memcpy(pdev->ee_file, &bin_attr_eeprom, sizeof(*pdev->ee_file));
+
+	/* In case of read-only EEPROM get rid of write ability */
+	if (pdev->eero) {
+		pdev->ee_file->attr.mode &= ~0200;
+		pdev->ee_file->write = NULL;
+	}
+	/* Create EEPROM sysfs file */
+	pdev->ee_file->size = pdev->eesize;
+	ret = sysfs_create_bin_file(&dev->kobj, pdev->ee_file);
+	if (ret != 0) {
+		dev_err(dev, "Failed to create EEPROM sysfs-node");
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_remove_sysfs_files() - remove sysfs attribute files
+ * @pdev:	Pointer to the driver data
+ */
+static void idt_remove_sysfs_files(struct idt_89hpesx_dev *pdev)
+{
+	struct device *dev = &pdev->client->dev;
+
+	/* Don't do anything if EEPROM wasn't accessible */
+	if (pdev->eesize == 0)
+		return;
+
+	/* Remove EEPROM sysfs file */
+	sysfs_remove_bin_file(&dev->kobj, pdev->ee_file);
+}
+
+/*
+ * idt_create_dbgfs_files() - create debugfs files
+ * @pdev:	Pointer to the driver data
+ */
+#define CSRNAME_LEN	((size_t)32)
+static void idt_create_dbgfs_files(struct idt_89hpesx_dev *pdev)
+{
+	struct i2c_client *cli = pdev->client;
+	char fname[CSRNAME_LEN];
+
+	/* Create Debugfs directory for CSR file */
+	snprintf(fname, CSRNAME_LEN, "%d-%04hx", cli->adapter->nr, cli->addr);
+	pdev->csr_dir = debugfs_create_dir(fname, csr_dbgdir);
+
+	/* Create Debugfs file for CSR read/write operations */
+	debugfs_create_file(cli->name, 0600, pdev->csr_dir, pdev,
+			    &csr_dbgfs_ops);
+}
+
+/*
+ * idt_remove_dbgfs_files() - remove debugfs files
+ * @pdev:	Pointer to the driver data
+ */
+static void idt_remove_dbgfs_files(struct idt_89hpesx_dev *pdev)
+{
+	/* Remove CSR directory and it sysfs-node */
+	debugfs_remove_recursive(pdev->csr_dir);
+}
+
+/*
+ * idt_probe() - IDT 89HPESx driver probe() callback method
+ */
+static int idt_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+	struct idt_89hpesx_dev *pdev;
+	int ret;
+
+	/* Create driver data */
+	pdev = idt_create_pdev(client);
+	if (IS_ERR(pdev))
+		return PTR_ERR(pdev);
+
+	/* Set SMBus operations */
+	ret = idt_set_smbus_ops(pdev);
+	if (ret != 0)
+		goto err_free_pdev;
+
+	/* Check whether it is truly IDT 89HPESx device */
+	ret = idt_check_dev(pdev);
+	if (ret != 0)
+		goto err_free_pdev;
+
+	/* Create sysfs files */
+	ret = idt_create_sysfs_files(pdev);
+	if (ret != 0)
+		goto err_free_pdev;
+
+	/* Create debugfs files */
+	idt_create_dbgfs_files(pdev);
+
+	return 0;
+
+err_free_pdev:
+	idt_free_pdev(pdev);
+
+	return ret;
+}
+
+/*
+ * idt_remove() - IDT 89HPESx driver remove() callback method
+ */
+static void idt_remove(struct i2c_client *client)
+{
+	struct idt_89hpesx_dev *pdev = i2c_get_clientdata(client);
+
+	/* Remove debugfs files first */
+	idt_remove_dbgfs_files(pdev);
+
+	/* Remove sysfs files */
+	idt_remove_sysfs_files(pdev);
+
+	/* Discard driver data structure */
+	idt_free_pdev(pdev);
+}
+
+/*
+ * ee_ids - array of supported EEPROMs
+ */
+static const struct i2c_device_id ee_ids[] = {
+	{ "24c32",  4096},
+	{ "24c64",  8192},
+	{ "24c128", 16384},
+	{ "24c256", 32768},
+	{ "24c512", 65536},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, ee_ids);
+
+/*
+ * idt_ids - supported IDT 89HPESx devices
+ */
+static const struct i2c_device_id idt_ids[] = {
+	{ "89hpes8nt2", 0 },
+	{ "89hpes12nt3", 0 },
+
+	{ "89hpes24nt6ag2", 0 },
+	{ "89hpes32nt8ag2", 0 },
+	{ "89hpes32nt8bg2", 0 },
+	{ "89hpes12nt12g2", 0 },
+	{ "89hpes16nt16g2", 0 },
+	{ "89hpes24nt24g2", 0 },
+	{ "89hpes32nt24ag2", 0 },
+	{ "89hpes32nt24bg2", 0 },
+
+	{ "89hpes12n3", 0 },
+	{ "89hpes12n3a", 0 },
+	{ "89hpes24n3", 0 },
+	{ "89hpes24n3a", 0 },
+
+	{ "89hpes32h8", 0 },
+	{ "89hpes32h8g2", 0 },
+	{ "89hpes48h12", 0 },
+	{ "89hpes48h12g2", 0 },
+	{ "89hpes48h12ag2", 0 },
+	{ "89hpes16h16", 0 },
+	{ "89hpes22h16", 0 },
+	{ "89hpes22h16g2", 0 },
+	{ "89hpes34h16", 0 },
+	{ "89hpes34h16g2", 0 },
+	{ "89hpes64h16", 0 },
+	{ "89hpes64h16g2", 0 },
+	{ "89hpes64h16ag2", 0 },
+
+	/* { "89hpes3t3", 0 }, // No SMBus-slave iface */
+	{ "89hpes12t3g2", 0 },
+	{ "89hpes24t3g2", 0 },
+	/* { "89hpes4t4", 0 }, // No SMBus-slave iface */
+	{ "89hpes16t4", 0 },
+	{ "89hpes4t4g2", 0 },
+	{ "89hpes10t4g2", 0 },
+	{ "89hpes16t4g2", 0 },
+	{ "89hpes16t4ag2", 0 },
+	{ "89hpes5t5", 0 },
+	{ "89hpes6t5", 0 },
+	{ "89hpes8t5", 0 },
+	{ "89hpes8t5a", 0 },
+	{ "89hpes24t6", 0 },
+	{ "89hpes6t6g2", 0 },
+	{ "89hpes24t6g2", 0 },
+	{ "89hpes16t7", 0 },
+	{ "89hpes32t8", 0 },
+	{ "89hpes32t8g2", 0 },
+	{ "89hpes48t12", 0 },
+	{ "89hpes48t12g2", 0 },
+	{ /* END OF LIST */ }
+};
+MODULE_DEVICE_TABLE(i2c, idt_ids);
+
+static const struct of_device_id idt_of_match[] = {
+	{ .compatible = "idt,89hpes8nt2", },
+	{ .compatible = "idt,89hpes12nt3", },
+
+	{ .compatible = "idt,89hpes24nt6ag2", },
+	{ .compatible = "idt,89hpes32nt8ag2", },
+	{ .compatible = "idt,89hpes32nt8bg2", },
+	{ .compatible = "idt,89hpes12nt12g2", },
+	{ .compatible = "idt,89hpes16nt16g2", },
+	{ .compatible = "idt,89hpes24nt24g2", },
+	{ .compatible = "idt,89hpes32nt24ag2", },
+	{ .compatible = "idt,89hpes32nt24bg2", },
+
+	{ .compatible = "idt,89hpes12n3", },
+	{ .compatible = "idt,89hpes12n3a", },
+	{ .compatible = "idt,89hpes24n3", },
+	{ .compatible = "idt,89hpes24n3a", },
+
+	{ .compatible = "idt,89hpes32h8", },
+	{ .compatible = "idt,89hpes32h8g2", },
+	{ .compatible = "idt,89hpes48h12", },
+	{ .compatible = "idt,89hpes48h12g2", },
+	{ .compatible = "idt,89hpes48h12ag2", },
+	{ .compatible = "idt,89hpes16h16", },
+	{ .compatible = "idt,89hpes22h16", },
+	{ .compatible = "idt,89hpes22h16g2", },
+	{ .compatible = "idt,89hpes34h16", },
+	{ .compatible = "idt,89hpes34h16g2", },
+	{ .compatible = "idt,89hpes64h16", },
+	{ .compatible = "idt,89hpes64h16g2", },
+	{ .compatible = "idt,89hpes64h16ag2", },
+
+	{ .compatible = "idt,89hpes12t3g2", },
+	{ .compatible = "idt,89hpes24t3g2", },
+
+	{ .compatible = "idt,89hpes16t4", },
+	{ .compatible = "idt,89hpes4t4g2", },
+	{ .compatible = "idt,89hpes10t4g2", },
+	{ .compatible = "idt,89hpes16t4g2", },
+	{ .compatible = "idt,89hpes16t4ag2", },
+	{ .compatible = "idt,89hpes5t5", },
+	{ .compatible = "idt,89hpes6t5", },
+	{ .compatible = "idt,89hpes8t5", },
+	{ .compatible = "idt,89hpes8t5a", },
+	{ .compatible = "idt,89hpes24t6", },
+	{ .compatible = "idt,89hpes6t6g2", },
+	{ .compatible = "idt,89hpes24t6g2", },
+	{ .compatible = "idt,89hpes16t7", },
+	{ .compatible = "idt,89hpes32t8", },
+	{ .compatible = "idt,89hpes32t8g2", },
+	{ .compatible = "idt,89hpes48t12", },
+	{ .compatible = "idt,89hpes48t12g2", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, idt_of_match);
+
+/*
+ * idt_driver - IDT 89HPESx driver structure
+ */
+static struct i2c_driver idt_driver = {
+	.driver = {
+		.name = IDT_NAME,
+		.of_match_table = idt_of_match,
+	},
+	.probe = idt_probe,
+	.remove = idt_remove,
+	.id_table = idt_ids,
+};
+
+/*
+ * idt_init() - IDT 89HPESx driver init() callback method
+ */
+static int __init idt_init(void)
+{
+	int ret;
+
+	/* Create Debugfs directory first */
+	if (debugfs_initialized())
+		csr_dbgdir = debugfs_create_dir("idt_csr", NULL);
+
+	/* Add new i2c-device driver */
+	ret = i2c_add_driver(&idt_driver);
+	if (ret) {
+		debugfs_remove_recursive(csr_dbgdir);
+		return ret;
+	}
+
+	return 0;
+}
+module_init(idt_init);
+
+/*
+ * idt_exit() - IDT 89HPESx driver exit() callback method
+ */
+static void __exit idt_exit(void)
+{
+	/* Discard debugfs directory and all files if any */
+	debugfs_remove_recursive(csr_dbgdir);
+
+	/* Unregister i2c-device driver */
+	i2c_del_driver(&idt_driver);
+}
+module_exit(idt_exit);
diff --git a/drivers/misc/eeprom/max6875.c b/drivers/misc/eeprom/max6875.c
new file mode 100644
index 000000000..6bd4f4339
--- /dev/null
+++ b/drivers/misc/eeprom/max6875.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * max6875.c - driver for MAX6874/MAX6875
+ *
+ * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
+ *
+ * Based on eeprom.c
+ *
+ * The MAX6875 has a bank of registers and two banks of EEPROM.
+ * Address ranges are defined as follows:
+ *  * 0x0000 - 0x0046 = configuration registers
+ *  * 0x8000 - 0x8046 = configuration EEPROM
+ *  * 0x8100 - 0x82FF = user EEPROM
+ *
+ * This driver makes the user EEPROM available for read.
+ *
+ * The registers & config EEPROM should be accessed via i2c-dev.
+ *
+ * The MAX6875 ignores the lowest address bit, so each chip responds to
+ * two addresses - 0x50/0x51 and 0x52/0x53.
+ *
+ * Note that the MAX6875 uses i2c_smbus_write_byte_data() to set the read
+ * address, so this driver is destructive if loaded for the wrong EEPROM chip.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+
+/* The MAX6875 can only read/write 16 bytes at a time */
+#define SLICE_SIZE			16
+#define SLICE_BITS			4
+
+/* USER EEPROM is at addresses 0x8100 - 0x82FF */
+#define USER_EEPROM_BASE		0x8100
+#define USER_EEPROM_SIZE		0x0200
+#define USER_EEPROM_SLICES		32
+
+/* MAX6875 commands */
+#define MAX6875_CMD_BLK_READ		0x84
+
+/* Each client has this additional data */
+struct max6875_data {
+	struct i2c_client	*fake_client;
+	struct mutex		update_lock;
+
+	u32			valid;
+	u8			data[USER_EEPROM_SIZE];
+	unsigned long		last_updated[USER_EEPROM_SLICES];
+};
+
+static void max6875_update_slice(struct i2c_client *client, int slice)
+{
+	struct max6875_data *data = i2c_get_clientdata(client);
+	int i, j, addr;
+	u8 *buf;
+
+	if (slice >= USER_EEPROM_SLICES)
+		return;
+
+	mutex_lock(&data->update_lock);
+
+	buf = &data->data[slice << SLICE_BITS];
+
+	if (!(data->valid & (1 << slice)) ||
+	    time_after(jiffies, data->last_updated[slice])) {
+
+		dev_dbg(&client->dev, "Starting update of slice %u\n", slice);
+
+		data->valid &= ~(1 << slice);
+
+		addr = USER_EEPROM_BASE + (slice << SLICE_BITS);
+
+		/* select the eeprom address */
+		if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
+			dev_err(&client->dev, "address set failed\n");
+			goto exit_up;
+		}
+
+		if (i2c_check_functionality(client->adapter,
+					    I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+			if (i2c_smbus_read_i2c_block_data(client,
+							  MAX6875_CMD_BLK_READ,
+							  SLICE_SIZE,
+							  buf) != SLICE_SIZE) {
+				goto exit_up;
+			}
+		} else {
+			for (i = 0; i < SLICE_SIZE; i++) {
+				j = i2c_smbus_read_byte(client);
+				if (j < 0) {
+					goto exit_up;
+				}
+				buf[i] = j;
+			}
+		}
+		data->last_updated[slice] = jiffies;
+		data->valid |= (1 << slice);
+	}
+exit_up:
+	mutex_unlock(&data->update_lock);
+}
+
+static ssize_t max6875_read(struct file *filp, struct kobject *kobj,
+			    struct bin_attribute *bin_attr,
+			    char *buf, loff_t off, size_t count)
+{
+	struct i2c_client *client = kobj_to_i2c_client(kobj);
+	struct max6875_data *data = i2c_get_clientdata(client);
+	int slice, max_slice;
+
+	/* refresh slices which contain requested bytes */
+	max_slice = (off + count - 1) >> SLICE_BITS;
+	for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++)
+		max6875_update_slice(client, slice);
+
+	memcpy(buf, &data->data[off], count);
+
+	return count;
+}
+
+static const struct bin_attribute user_eeprom_attr = {
+	.attr = {
+		.name = "eeprom",
+		.mode = S_IRUGO,
+	},
+	.size = USER_EEPROM_SIZE,
+	.read = max6875_read,
+};
+
+static int max6875_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct max6875_data *data;
+	int err;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
+				     | I2C_FUNC_SMBUS_READ_BYTE))
+		return -ENODEV;
+
+	/* Only bind to even addresses */
+	if (client->addr & 1)
+		return -ENODEV;
+
+	data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	/* A fake client is created on the odd address */
+	data->fake_client = i2c_new_dummy_device(client->adapter, client->addr + 1);
+	if (IS_ERR(data->fake_client)) {
+		err = PTR_ERR(data->fake_client);
+		goto exit_kfree;
+	}
+
+	/* Init real i2c_client */
+	i2c_set_clientdata(client, data);
+	mutex_init(&data->update_lock);
+
+	err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr);
+	if (err)
+		goto exit_remove_fake;
+
+	return 0;
+
+exit_remove_fake:
+	i2c_unregister_device(data->fake_client);
+exit_kfree:
+	kfree(data);
+	return err;
+}
+
+static void max6875_remove(struct i2c_client *client)
+{
+	struct max6875_data *data = i2c_get_clientdata(client);
+
+	i2c_unregister_device(data->fake_client);
+
+	sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr);
+	kfree(data);
+}
+
+static const struct i2c_device_id max6875_id[] = {
+	{ "max6875", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max6875_id);
+
+static struct i2c_driver max6875_driver = {
+	.driver = {
+		.name	= "max6875",
+	},
+	.probe		= max6875_probe,
+	.remove		= max6875_remove,
+	.id_table	= max6875_id,
+};
+
+module_i2c_driver(max6875_driver);
+
+MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
+MODULE_DESCRIPTION("MAX6875 driver");
+MODULE_LICENSE("GPL");