Adding upstream version 4.19.249.upstream/4.19.249upstream

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

1 files changed, 907 insertions, 0 deletions

diff --git a/drivers/mtd/spi-nor/aspeed-smc.c b/drivers/mtd/spi-nor/aspeed-smc.c
new file mode 100644
index 000000000..95e54468c
--- /dev/null
+++ b/drivers/mtd/spi-nor/aspeed-smc.c
@@ -0,0 +1,907 @@
+/*
+ * ASPEED Static Memory Controller driver
+ *
+ * Copyright (c) 2015-2016, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/bug.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/spi-nor.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/sizes.h>
+#include <linux/sysfs.h>
+
+#define DEVICE_NAME	"aspeed-smc"
+
+/*
+ * The driver only support SPI flash
+ */
+enum aspeed_smc_flash_type {
+	smc_type_nor  = 0,
+	smc_type_nand = 1,
+	smc_type_spi  = 2,
+};
+
+struct aspeed_smc_chip;
+
+struct aspeed_smc_info {
+	u32 maxsize;		/* maximum size of chip window */
+	u8 nce;			/* number of chip enables */
+	bool hastype;		/* flash type field exists in config reg */
+	u8 we0;			/* shift for write enable bit for CE0 */
+	u8 ctl0;		/* offset in regs of ctl for CE0 */
+
+	void (*set_4b)(struct aspeed_smc_chip *chip);
+};
+
+static void aspeed_smc_chip_set_4b_spi_2400(struct aspeed_smc_chip *chip);
+static void aspeed_smc_chip_set_4b(struct aspeed_smc_chip *chip);
+
+static const struct aspeed_smc_info fmc_2400_info = {
+	.maxsize = 64 * 1024 * 1024,
+	.nce = 5,
+	.hastype = true,
+	.we0 = 16,
+	.ctl0 = 0x10,
+	.set_4b = aspeed_smc_chip_set_4b,
+};
+
+static const struct aspeed_smc_info spi_2400_info = {
+	.maxsize = 64 * 1024 * 1024,
+	.nce = 1,
+	.hastype = false,
+	.we0 = 0,
+	.ctl0 = 0x04,
+	.set_4b = aspeed_smc_chip_set_4b_spi_2400,
+};
+
+static const struct aspeed_smc_info fmc_2500_info = {
+	.maxsize = 256 * 1024 * 1024,
+	.nce = 3,
+	.hastype = true,
+	.we0 = 16,
+	.ctl0 = 0x10,
+	.set_4b = aspeed_smc_chip_set_4b,
+};
+
+static const struct aspeed_smc_info spi_2500_info = {
+	.maxsize = 128 * 1024 * 1024,
+	.nce = 2,
+	.hastype = false,
+	.we0 = 16,
+	.ctl0 = 0x10,
+	.set_4b = aspeed_smc_chip_set_4b,
+};
+
+enum aspeed_smc_ctl_reg_value {
+	smc_base,		/* base value without mode for other commands */
+	smc_read,		/* command reg for (maybe fast) reads */
+	smc_write,		/* command reg for writes */
+	smc_max,
+};
+
+struct aspeed_smc_controller;
+
+struct aspeed_smc_chip {
+	int cs;
+	struct aspeed_smc_controller *controller;
+	void __iomem *ctl;			/* control register */
+	void __iomem *ahb_base;			/* base of chip window */
+	u32 ahb_window_size;			/* chip mapping window size */
+	u32 ctl_val[smc_max];			/* control settings */
+	enum aspeed_smc_flash_type type;	/* what type of flash */
+	struct spi_nor nor;
+};
+
+struct aspeed_smc_controller {
+	struct device *dev;
+
+	struct mutex mutex;			/* controller access mutex */
+	const struct aspeed_smc_info *info;	/* type info of controller */
+	void __iomem *regs;			/* controller registers */
+	void __iomem *ahb_base;			/* per-chip windows resource */
+	u32 ahb_window_size;			/* full mapping window size */
+
+	struct aspeed_smc_chip *chips[0];	/* pointers to attached chips */
+};
+
+/*
+ * SPI Flash Configuration Register (AST2500 SPI)
+ *     or
+ * Type setting Register (AST2500 FMC).
+ * CE0 and CE1 can only be of type SPI. CE2 can be of type NOR but the
+ * driver does not support it.
+ */
+#define CONFIG_REG			0x0
+#define CONFIG_DISABLE_LEGACY		BIT(31) /* 1 */
+
+#define CONFIG_CE2_WRITE		BIT(18)
+#define CONFIG_CE1_WRITE		BIT(17)
+#define CONFIG_CE0_WRITE		BIT(16)
+
+#define CONFIG_CE2_TYPE			BIT(4) /* AST2500 FMC only */
+#define CONFIG_CE1_TYPE			BIT(2) /* AST2500 FMC only */
+#define CONFIG_CE0_TYPE			BIT(0) /* AST2500 FMC only */
+
+/*
+ * CE Control Register
+ */
+#define CE_CONTROL_REG			0x4
+
+/*
+ * CEx Control Register
+ */
+#define CONTROL_AAF_MODE		BIT(31)
+#define CONTROL_IO_MODE_MASK		GENMASK(30, 28)
+#define CONTROL_IO_DUAL_DATA		BIT(29)
+#define CONTROL_IO_DUAL_ADDR_DATA	(BIT(29) | BIT(28))
+#define CONTROL_IO_QUAD_DATA		BIT(30)
+#define CONTROL_IO_QUAD_ADDR_DATA	(BIT(30) | BIT(28))
+#define CONTROL_CE_INACTIVE_SHIFT	24
+#define CONTROL_CE_INACTIVE_MASK	GENMASK(27, \
+					CONTROL_CE_INACTIVE_SHIFT)
+/* 0 = 16T ... 15 = 1T   T=HCLK */
+#define CONTROL_COMMAND_SHIFT		16
+#define CONTROL_DUMMY_COMMAND_OUT	BIT(15)
+#define CONTROL_IO_DUMMY_HI		BIT(14)
+#define CONTROL_IO_DUMMY_HI_SHIFT	14
+#define CONTROL_CLK_DIV4		BIT(13) /* others */
+#define CONTROL_IO_ADDRESS_4B		BIT(13) /* AST2400 SPI */
+#define CONTROL_RW_MERGE		BIT(12)
+#define CONTROL_IO_DUMMY_LO_SHIFT	6
+#define CONTROL_IO_DUMMY_LO		GENMASK(7, \
+						CONTROL_IO_DUMMY_LO_SHIFT)
+#define CONTROL_IO_DUMMY_MASK		(CONTROL_IO_DUMMY_HI | \
+					 CONTROL_IO_DUMMY_LO)
+#define CONTROL_IO_DUMMY_SET(dummy)				 \
+	(((((dummy) >> 2) & 0x1) << CONTROL_IO_DUMMY_HI_SHIFT) | \
+	 (((dummy) & 0x3) << CONTROL_IO_DUMMY_LO_SHIFT))
+
+#define CONTROL_CLOCK_FREQ_SEL_SHIFT	8
+#define CONTROL_CLOCK_FREQ_SEL_MASK	GENMASK(11, \
+						CONTROL_CLOCK_FREQ_SEL_SHIFT)
+#define CONTROL_LSB_FIRST		BIT(5)
+#define CONTROL_CLOCK_MODE_3		BIT(4)
+#define CONTROL_IN_DUAL_DATA		BIT(3)
+#define CONTROL_CE_STOP_ACTIVE_CONTROL	BIT(2)
+#define CONTROL_COMMAND_MODE_MASK	GENMASK(1, 0)
+#define CONTROL_COMMAND_MODE_NORMAL	0
+#define CONTROL_COMMAND_MODE_FREAD	1
+#define CONTROL_COMMAND_MODE_WRITE	2
+#define CONTROL_COMMAND_MODE_USER	3
+
+#define CONTROL_KEEP_MASK						\
+	(CONTROL_AAF_MODE | CONTROL_CE_INACTIVE_MASK | CONTROL_CLK_DIV4 | \
+	 CONTROL_CLOCK_FREQ_SEL_MASK | CONTROL_LSB_FIRST | CONTROL_CLOCK_MODE_3)
+
+/*
+ * The Segment Register uses a 8MB unit to encode the start address
+ * and the end address of the mapping window of a flash SPI slave :
+ *
+ *        | byte 1 | byte 2 | byte 3 | byte 4 |
+ *        +--------+--------+--------+--------+
+ *        |  end   |  start |   0    |   0    |
+ */
+#define SEGMENT_ADDR_REG0		0x30
+#define SEGMENT_ADDR_START(_r)		((((_r) >> 16) & 0xFF) << 23)
+#define SEGMENT_ADDR_END(_r)		((((_r) >> 24) & 0xFF) << 23)
+#define SEGMENT_ADDR_VALUE(start, end)					\
+	(((((start) >> 23) & 0xFF) << 16) | ((((end) >> 23) & 0xFF) << 24))
+#define SEGMENT_ADDR_REG(controller, cs)	\
+	((controller)->regs + SEGMENT_ADDR_REG0 + (cs) * 4)
+
+/*
+ * In user mode all data bytes read or written to the chip decode address
+ * range are transferred to or from the SPI bus. The range is treated as a
+ * fifo of arbitratry 1, 2, or 4 byte width but each write has to be aligned
+ * to its size. The address within the multiple 8kB range is ignored when
+ * sending bytes to the SPI bus.
+ *
+ * On the arm architecture, as of Linux version 4.3, memcpy_fromio and
+ * memcpy_toio on little endian targets use the optimized memcpy routines
+ * that were designed for well behavied memory storage. These routines
+ * have a stutter if the source and destination are not both word aligned,
+ * once with a duplicate access to the source after aligning to the
+ * destination to a word boundary, and again with a duplicate access to
+ * the source when the final byte count is not word aligned.
+ *
+ * When writing or reading the fifo this stutter discards data or sends
+ * too much data to the fifo and can not be used by this driver.
+ *
+ * While the low level io string routines that implement the insl family do
+ * the desired accesses and memory increments, the cross architecture io
+ * macros make them essentially impossible to use on a memory mapped address
+ * instead of a a token from the call to iomap of an io port.
+ *
+ * These fifo routines use readl and friends to a constant io port and update
+ * the memory buffer pointer and count via explicit code. The final updates
+ * to len are optimistically suppressed.
+ */
+static int aspeed_smc_read_from_ahb(void *buf, void __iomem *src, size_t len)
+{
+	size_t offset = 0;
+
+	if (IS_ALIGNED((uintptr_t)src, sizeof(uintptr_t)) &&
+	    IS_ALIGNED((uintptr_t)buf, sizeof(uintptr_t))) {
+		ioread32_rep(src, buf, len >> 2);
+		offset = len & ~0x3;
+		len -= offset;
+	}
+	ioread8_rep(src, (u8 *)buf + offset, len);
+	return 0;
+}
+
+static int aspeed_smc_write_to_ahb(void __iomem *dst, const void *buf,
+				   size_t len)
+{
+	size_t offset = 0;
+
+	if (IS_ALIGNED((uintptr_t)dst, sizeof(uintptr_t)) &&
+	    IS_ALIGNED((uintptr_t)buf, sizeof(uintptr_t))) {
+		iowrite32_rep(dst, buf, len >> 2);
+		offset = len & ~0x3;
+		len -= offset;
+	}
+	iowrite8_rep(dst, (const u8 *)buf + offset, len);
+	return 0;
+}
+
+static inline u32 aspeed_smc_chip_write_bit(struct aspeed_smc_chip *chip)
+{
+	return BIT(chip->controller->info->we0 + chip->cs);
+}
+
+static void aspeed_smc_chip_check_config(struct aspeed_smc_chip *chip)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	u32 reg;
+
+	reg = readl(controller->regs + CONFIG_REG);
+
+	if (reg & aspeed_smc_chip_write_bit(chip))
+		return;
+
+	dev_dbg(controller->dev, "config write is not set ! @%p: 0x%08x\n",
+		controller->regs + CONFIG_REG, reg);
+	reg |= aspeed_smc_chip_write_bit(chip);
+	writel(reg, controller->regs + CONFIG_REG);
+}
+
+static void aspeed_smc_start_user(struct spi_nor *nor)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+	u32 ctl = chip->ctl_val[smc_base];
+
+	/*
+	 * When the chip is controlled in user mode, we need write
+	 * access to send the opcodes to it. So check the config.
+	 */
+	aspeed_smc_chip_check_config(chip);
+
+	ctl |= CONTROL_COMMAND_MODE_USER |
+		CONTROL_CE_STOP_ACTIVE_CONTROL;
+	writel(ctl, chip->ctl);
+
+	ctl &= ~CONTROL_CE_STOP_ACTIVE_CONTROL;
+	writel(ctl, chip->ctl);
+}
+
+static void aspeed_smc_stop_user(struct spi_nor *nor)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+
+	u32 ctl = chip->ctl_val[smc_read];
+	u32 ctl2 = ctl | CONTROL_COMMAND_MODE_USER |
+		CONTROL_CE_STOP_ACTIVE_CONTROL;
+
+	writel(ctl2, chip->ctl);	/* stop user CE control */
+	writel(ctl, chip->ctl);		/* default to fread or read mode */
+}
+
+static int aspeed_smc_prep(struct spi_nor *nor, enum spi_nor_ops ops)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+
+	mutex_lock(&chip->controller->mutex);
+	return 0;
+}
+
+static void aspeed_smc_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+
+	mutex_unlock(&chip->controller->mutex);
+}
+
+static int aspeed_smc_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+
+	aspeed_smc_start_user(nor);
+	aspeed_smc_write_to_ahb(chip->ahb_base, &opcode, 1);
+	aspeed_smc_read_from_ahb(buf, chip->ahb_base, len);
+	aspeed_smc_stop_user(nor);
+	return 0;
+}
+
+static int aspeed_smc_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
+				int len)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+
+	aspeed_smc_start_user(nor);
+	aspeed_smc_write_to_ahb(chip->ahb_base, &opcode, 1);
+	aspeed_smc_write_to_ahb(chip->ahb_base, buf, len);
+	aspeed_smc_stop_user(nor);
+	return 0;
+}
+
+static void aspeed_smc_send_cmd_addr(struct spi_nor *nor, u8 cmd, u32 addr)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+	__be32 temp;
+	u32 cmdaddr;
+
+	switch (nor->addr_width) {
+	default:
+		WARN_ONCE(1, "Unexpected address width %u, defaulting to 3\n",
+			  nor->addr_width);
+		/* FALLTHROUGH */
+	case 3:
+		cmdaddr = addr & 0xFFFFFF;
+		cmdaddr |= cmd << 24;
+
+		temp = cpu_to_be32(cmdaddr);
+		aspeed_smc_write_to_ahb(chip->ahb_base, &temp, 4);
+		break;
+	case 4:
+		temp = cpu_to_be32(addr);
+		aspeed_smc_write_to_ahb(chip->ahb_base, &cmd, 1);
+		aspeed_smc_write_to_ahb(chip->ahb_base, &temp, 4);
+		break;
+	}
+}
+
+static ssize_t aspeed_smc_read_user(struct spi_nor *nor, loff_t from,
+				    size_t len, u_char *read_buf)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+	int i;
+	u8 dummy = 0xFF;
+
+	aspeed_smc_start_user(nor);
+	aspeed_smc_send_cmd_addr(nor, nor->read_opcode, from);
+	for (i = 0; i < chip->nor.read_dummy / 8; i++)
+		aspeed_smc_write_to_ahb(chip->ahb_base, &dummy, sizeof(dummy));
+
+	aspeed_smc_read_from_ahb(read_buf, chip->ahb_base, len);
+	aspeed_smc_stop_user(nor);
+	return len;
+}
+
+static ssize_t aspeed_smc_write_user(struct spi_nor *nor, loff_t to,
+				     size_t len, const u_char *write_buf)
+{
+	struct aspeed_smc_chip *chip = nor->priv;
+
+	aspeed_smc_start_user(nor);
+	aspeed_smc_send_cmd_addr(nor, nor->program_opcode, to);
+	aspeed_smc_write_to_ahb(chip->ahb_base, write_buf, len);
+	aspeed_smc_stop_user(nor);
+	return len;
+}
+
+static int aspeed_smc_unregister(struct aspeed_smc_controller *controller)
+{
+	struct aspeed_smc_chip *chip;
+	int n;
+
+	for (n = 0; n < controller->info->nce; n++) {
+		chip = controller->chips[n];
+		if (chip)
+			mtd_device_unregister(&chip->nor.mtd);
+	}
+
+	return 0;
+}
+
+static int aspeed_smc_remove(struct platform_device *dev)
+{
+	return aspeed_smc_unregister(platform_get_drvdata(dev));
+}
+
+static const struct of_device_id aspeed_smc_matches[] = {
+	{ .compatible = "aspeed,ast2400-fmc", .data = &fmc_2400_info },
+	{ .compatible = "aspeed,ast2400-spi", .data = &spi_2400_info },
+	{ .compatible = "aspeed,ast2500-fmc", .data = &fmc_2500_info },
+	{ .compatible = "aspeed,ast2500-spi", .data = &spi_2500_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, aspeed_smc_matches);
+
+/*
+ * Each chip has a mapping window defined by a segment address
+ * register defining a start and an end address on the AHB bus. These
+ * addresses can be configured to fit the chip size and offer a
+ * contiguous memory region across chips. For the moment, we only
+ * check that each chip segment is valid.
+ */
+static void __iomem *aspeed_smc_chip_base(struct aspeed_smc_chip *chip,
+					  struct resource *res)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	u32 offset = 0;
+	u32 reg;
+
+	if (controller->info->nce > 1) {
+		reg = readl(SEGMENT_ADDR_REG(controller, chip->cs));
+
+		if (SEGMENT_ADDR_START(reg) >= SEGMENT_ADDR_END(reg))
+			return NULL;
+
+		offset = SEGMENT_ADDR_START(reg) - res->start;
+	}
+
+	return controller->ahb_base + offset;
+}
+
+static u32 aspeed_smc_ahb_base_phy(struct aspeed_smc_controller *controller)
+{
+	u32 seg0_val = readl(SEGMENT_ADDR_REG(controller, 0));
+
+	return SEGMENT_ADDR_START(seg0_val);
+}
+
+static u32 chip_set_segment(struct aspeed_smc_chip *chip, u32 cs, u32 start,
+			    u32 size)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	void __iomem *seg_reg;
+	u32 seg_oldval, seg_newval, ahb_base_phy, end;
+
+	ahb_base_phy = aspeed_smc_ahb_base_phy(controller);
+
+	seg_reg = SEGMENT_ADDR_REG(controller, cs);
+	seg_oldval = readl(seg_reg);
+
+	/*
+	 * If the chip size is not specified, use the default segment
+	 * size, but take into account the possible overlap with the
+	 * previous segment
+	 */
+	if (!size)
+		size = SEGMENT_ADDR_END(seg_oldval) - start;
+
+	/*
+	 * The segment cannot exceed the maximum window size of the
+	 * controller.
+	 */
+	if (start + size > ahb_base_phy + controller->ahb_window_size) {
+		size = ahb_base_phy + controller->ahb_window_size - start;
+		dev_warn(chip->nor.dev, "CE%d window resized to %dMB",
+			 cs, size >> 20);
+	}
+
+	end = start + size;
+	seg_newval = SEGMENT_ADDR_VALUE(start, end);
+	writel(seg_newval, seg_reg);
+
+	/*
+	 * Restore default value if something goes wrong. The chip
+	 * might have set some bogus value and we would loose access
+	 * to the chip.
+	 */
+	if (seg_newval != readl(seg_reg)) {
+		dev_err(chip->nor.dev, "CE%d window invalid", cs);
+		writel(seg_oldval, seg_reg);
+		start = SEGMENT_ADDR_START(seg_oldval);
+		end = SEGMENT_ADDR_END(seg_oldval);
+		size = end - start;
+	}
+
+	dev_info(chip->nor.dev, "CE%d window [ 0x%.8x - 0x%.8x ] %dMB",
+		 cs, start, end, size >> 20);
+
+	return size;
+}
+
+/*
+ * The segment register defines the mapping window on the AHB bus and
+ * it needs to be configured depending on the chip size. The segment
+ * register of the following CE also needs to be tuned in order to
+ * provide a contiguous window across multiple chips.
+ *
+ * This is expected to be called in increasing CE order
+ */
+static u32 aspeed_smc_chip_set_segment(struct aspeed_smc_chip *chip)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	u32 ahb_base_phy, start;
+	u32 size = chip->nor.mtd.size;
+
+	/*
+	 * Each controller has a chip size limit for direct memory
+	 * access
+	 */
+	if (size > controller->info->maxsize)
+		size = controller->info->maxsize;
+
+	/*
+	 * The AST2400 SPI controller only handles one chip and does
+	 * not have segment registers. Let's use the chip size for the
+	 * AHB window.
+	 */
+	if (controller->info == &spi_2400_info)
+		goto out;
+
+	/*
+	 * The AST2500 SPI controller has a HW bug when the CE0 chip
+	 * size reaches 128MB. Enforce a size limit of 120MB to
+	 * prevent the controller from using bogus settings in the
+	 * segment register.
+	 */
+	if (chip->cs == 0 && controller->info == &spi_2500_info &&
+	    size == SZ_128M) {
+		size = 120 << 20;
+		dev_info(chip->nor.dev,
+			 "CE%d window resized to %dMB (AST2500 HW quirk)",
+			 chip->cs, size >> 20);
+	}
+
+	ahb_base_phy = aspeed_smc_ahb_base_phy(controller);
+
+	/*
+	 * As a start address for the current segment, use the default
+	 * start address if we are handling CE0 or use the previous
+	 * segment ending address
+	 */
+	if (chip->cs) {
+		u32 prev = readl(SEGMENT_ADDR_REG(controller, chip->cs - 1));
+
+		start = SEGMENT_ADDR_END(prev);
+	} else {
+		start = ahb_base_phy;
+	}
+
+	size = chip_set_segment(chip, chip->cs, start, size);
+
+	/* Update chip base address on the AHB bus */
+	chip->ahb_base = controller->ahb_base + (start - ahb_base_phy);
+
+	/*
+	 * Now, make sure the next segment does not overlap with the
+	 * current one we just configured, even if there is no
+	 * available chip. That could break access in Command Mode.
+	 */
+	if (chip->cs < controller->info->nce - 1)
+		chip_set_segment(chip, chip->cs + 1, start + size, 0);
+
+out:
+	if (size < chip->nor.mtd.size)
+		dev_warn(chip->nor.dev,
+			 "CE%d window too small for chip %dMB",
+			 chip->cs, (u32)chip->nor.mtd.size >> 20);
+
+	return size;
+}
+
+static void aspeed_smc_chip_enable_write(struct aspeed_smc_chip *chip)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	u32 reg;
+
+	reg = readl(controller->regs + CONFIG_REG);
+
+	reg |= aspeed_smc_chip_write_bit(chip);
+	writel(reg, controller->regs + CONFIG_REG);
+}
+
+static void aspeed_smc_chip_set_type(struct aspeed_smc_chip *chip, int type)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	u32 reg;
+
+	chip->type = type;
+
+	reg = readl(controller->regs + CONFIG_REG);
+	reg &= ~(3 << (chip->cs * 2));
+	reg |= chip->type << (chip->cs * 2);
+	writel(reg, controller->regs + CONFIG_REG);
+}
+
+/*
+ * The first chip of the AST2500 FMC flash controller is strapped by
+ * hardware, or autodetected, but other chips need to be set. Enforce
+ * the 4B setting for all chips.
+ */
+static void aspeed_smc_chip_set_4b(struct aspeed_smc_chip *chip)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	u32 reg;
+
+	reg = readl(controller->regs + CE_CONTROL_REG);
+	reg |= 1 << chip->cs;
+	writel(reg, controller->regs + CE_CONTROL_REG);
+}
+
+/*
+ * The AST2400 SPI flash controller does not have a CE Control
+ * register. It uses the CE0 control register to set 4Byte mode at the
+ * controller level.
+ */
+static void aspeed_smc_chip_set_4b_spi_2400(struct aspeed_smc_chip *chip)
+{
+	chip->ctl_val[smc_base] |= CONTROL_IO_ADDRESS_4B;
+	chip->ctl_val[smc_read] |= CONTROL_IO_ADDRESS_4B;
+}
+
+static int aspeed_smc_chip_setup_init(struct aspeed_smc_chip *chip,
+				      struct resource *res)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	const struct aspeed_smc_info *info = controller->info;
+	u32 reg, base_reg;
+
+	/*
+	 * Always turn on the write enable bit to allow opcodes to be
+	 * sent in user mode.
+	 */
+	aspeed_smc_chip_enable_write(chip);
+
+	/* The driver only supports SPI type flash */
+	if (info->hastype)
+		aspeed_smc_chip_set_type(chip, smc_type_spi);
+
+	/*
+	 * Configure chip base address in memory
+	 */
+	chip->ahb_base = aspeed_smc_chip_base(chip, res);
+	if (!chip->ahb_base) {
+		dev_warn(chip->nor.dev, "CE%d window closed", chip->cs);
+		return -EINVAL;
+	}
+
+	/*
+	 * Get value of the inherited control register. U-Boot usually
+	 * does some timing calibration on the FMC chip, so it's good
+	 * to keep them. In the future, we should handle calibration
+	 * from Linux.
+	 */
+	reg = readl(chip->ctl);
+	dev_dbg(controller->dev, "control register: %08x\n", reg);
+
+	base_reg = reg & CONTROL_KEEP_MASK;
+	if (base_reg != reg) {
+		dev_dbg(controller->dev,
+			"control register changed to: %08x\n",
+			base_reg);
+	}
+	chip->ctl_val[smc_base] = base_reg;
+
+	/*
+	 * Retain the prior value of the control register as the
+	 * default if it was normal access mode. Otherwise start with
+	 * the sanitized base value set to read mode.
+	 */
+	if ((reg & CONTROL_COMMAND_MODE_MASK) ==
+	    CONTROL_COMMAND_MODE_NORMAL)
+		chip->ctl_val[smc_read] = reg;
+	else
+		chip->ctl_val[smc_read] = chip->ctl_val[smc_base] |
+			CONTROL_COMMAND_MODE_NORMAL;
+
+	dev_dbg(controller->dev, "default control register: %08x\n",
+		chip->ctl_val[smc_read]);
+	return 0;
+}
+
+static int aspeed_smc_chip_setup_finish(struct aspeed_smc_chip *chip)
+{
+	struct aspeed_smc_controller *controller = chip->controller;
+	const struct aspeed_smc_info *info = controller->info;
+	u32 cmd;
+
+	if (chip->nor.addr_width == 4 && info->set_4b)
+		info->set_4b(chip);
+
+	/* This is for direct AHB access when using Command Mode. */
+	chip->ahb_window_size = aspeed_smc_chip_set_segment(chip);
+
+	/*
+	 * base mode has not been optimized yet. use it for writes.
+	 */
+	chip->ctl_val[smc_write] = chip->ctl_val[smc_base] |
+		chip->nor.program_opcode << CONTROL_COMMAND_SHIFT |
+		CONTROL_COMMAND_MODE_WRITE;
+
+	dev_dbg(controller->dev, "write control register: %08x\n",
+		chip->ctl_val[smc_write]);
+
+	/*
+	 * TODO: Adjust clocks if fast read is supported and interpret
+	 * SPI-NOR flags to adjust controller settings.
+	 */
+	if (chip->nor.read_proto == SNOR_PROTO_1_1_1) {
+		if (chip->nor.read_dummy == 0)
+			cmd = CONTROL_COMMAND_MODE_NORMAL;
+		else
+			cmd = CONTROL_COMMAND_MODE_FREAD;
+	} else {
+		dev_err(chip->nor.dev, "unsupported SPI read mode\n");
+		return -EINVAL;
+	}
+
+	chip->ctl_val[smc_read] |= cmd |
+		CONTROL_IO_DUMMY_SET(chip->nor.read_dummy / 8);
+
+	dev_dbg(controller->dev, "base control register: %08x\n",
+		chip->ctl_val[smc_read]);
+	return 0;
+}
+
+static int aspeed_smc_setup_flash(struct aspeed_smc_controller *controller,
+				  struct device_node *np, struct resource *r)
+{
+	const struct spi_nor_hwcaps hwcaps = {
+		.mask = SNOR_HWCAPS_READ |
+			SNOR_HWCAPS_READ_FAST |
+			SNOR_HWCAPS_PP,
+	};
+	const struct aspeed_smc_info *info = controller->info;
+	struct device *dev = controller->dev;
+	struct device_node *child;
+	unsigned int cs;
+	int ret = -ENODEV;
+
+	for_each_available_child_of_node(np, child) {
+		struct aspeed_smc_chip *chip;
+		struct spi_nor *nor;
+		struct mtd_info *mtd;
+
+		/* This driver does not support NAND or NOR flash devices. */
+		if (!of_device_is_compatible(child, "jedec,spi-nor"))
+			continue;
+
+		ret = of_property_read_u32(child, "reg", &cs);
+		if (ret) {
+			dev_err(dev, "Couldn't not read chip select.\n");
+			break;
+		}
+
+		if (cs >= info->nce) {
+			dev_err(dev, "Chip select %d out of range.\n",
+				cs);
+			ret = -ERANGE;
+			break;
+		}
+
+		if (controller->chips[cs]) {
+			dev_err(dev, "Chip select %d already in use by %s\n",
+				cs, dev_name(controller->chips[cs]->nor.dev));
+			ret = -EBUSY;
+			break;
+		}
+
+		chip = devm_kzalloc(controller->dev, sizeof(*chip), GFP_KERNEL);
+		if (!chip) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		chip->controller = controller;
+		chip->ctl = controller->regs + info->ctl0 + cs * 4;
+		chip->cs = cs;
+
+		nor = &chip->nor;
+		mtd = &nor->mtd;
+
+		nor->dev = dev;
+		nor->priv = chip;
+		spi_nor_set_flash_node(nor, child);
+		nor->read = aspeed_smc_read_user;
+		nor->write = aspeed_smc_write_user;
+		nor->read_reg = aspeed_smc_read_reg;
+		nor->write_reg = aspeed_smc_write_reg;
+		nor->prepare = aspeed_smc_prep;
+		nor->unprepare = aspeed_smc_unprep;
+
+		ret = aspeed_smc_chip_setup_init(chip, r);
+		if (ret)
+			break;
+
+		/*
+		 * TODO: Add support for Dual and Quad SPI protocols
+		 * attach when board support is present as determined
+		 * by of property.
+		 */
+		ret = spi_nor_scan(nor, NULL, &hwcaps);
+		if (ret)
+			break;
+
+		ret = aspeed_smc_chip_setup_finish(chip);
+		if (ret)
+			break;
+
+		ret = mtd_device_register(mtd, NULL, 0);
+		if (ret)
+			break;
+
+		controller->chips[cs] = chip;
+	}
+
+	if (ret)
+		aspeed_smc_unregister(controller);
+
+	return ret;
+}
+
+static int aspeed_smc_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	struct aspeed_smc_controller *controller;
+	const struct of_device_id *match;
+	const struct aspeed_smc_info *info;
+	struct resource *res;
+	int ret;
+
+	match = of_match_device(aspeed_smc_matches, &pdev->dev);
+	if (!match || !match->data)
+		return -ENODEV;
+	info = match->data;
+
+	controller = devm_kzalloc(&pdev->dev,
+				  struct_size(controller, chips, info->nce),
+				  GFP_KERNEL);
+	if (!controller)
+		return -ENOMEM;
+	controller->info = info;
+	controller->dev = dev;
+
+	mutex_init(&controller->mutex);
+	platform_set_drvdata(pdev, controller);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	controller->regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(controller->regs))
+		return PTR_ERR(controller->regs);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	controller->ahb_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(controller->ahb_base))
+		return PTR_ERR(controller->ahb_base);
+
+	controller->ahb_window_size = resource_size(res);
+
+	ret = aspeed_smc_setup_flash(controller, np, res);
+	if (ret)
+		dev_err(dev, "Aspeed SMC probe failed %d\n", ret);
+
+	return ret;
+}
+
+static struct platform_driver aspeed_smc_driver = {
+	.probe = aspeed_smc_probe,
+	.remove = aspeed_smc_remove,
+	.driver = {
+		.name = DEVICE_NAME,
+		.of_match_table = aspeed_smc_matches,
+	}
+};
+
+module_platform_driver(aspeed_smc_driver);
+
+MODULE_DESCRIPTION("ASPEED Static Memory Controller Driver");
+MODULE_AUTHOR("Cedric Le Goater <clg@kaod.org>");
+MODULE_LICENSE("GPL v2");