1 files changed, 312 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-isch.c b/drivers/i2c/busses/i2c-isch.c
new file mode 100644
index 000000000..2dc7ada06
--- /dev/null
+++ b/drivers/i2c/busses/i2c-isch.c
@@ -0,0 +1,312 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+    i2c-isch.c - Linux kernel driver for Intel SCH chipset SMBus
+    - Based on i2c-piix4.c
+    Copyright (c) 1998 - 2002 Frodo Looijaard <frodol@dds.nl> and
+    Philip Edelbrock <phil@netroedge.com>
+    - Intel SCH support
+    Copyright (c) 2007 - 2008 Jacob Jun Pan <jacob.jun.pan@intel.com>
+
+*/
+
+/*
+   Supports:
+	Intel SCH chipsets (AF82US15W, AF82US15L, AF82UL11L)
+   Note: we assume there can only be one device, with one SMBus interface.
+*/
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/stddef.h>
+#include <linux/ioport.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+
+/* SCH SMBus address offsets */
+#define SMBHSTCNT	(0 + sch_smba)
+#define SMBHSTSTS	(1 + sch_smba)
+#define SMBHSTCLK	(2 + sch_smba)
+#define SMBHSTADD	(4 + sch_smba) /* TSA */
+#define SMBHSTCMD	(5 + sch_smba)
+#define SMBHSTDAT0	(6 + sch_smba)
+#define SMBHSTDAT1	(7 + sch_smba)
+#define SMBBLKDAT	(0x20 + sch_smba)
+
+/* Other settings */
+#define MAX_RETRIES	5000
+
+/* I2C constants */
+#define SCH_QUICK		0x00
+#define SCH_BYTE		0x01
+#define SCH_BYTE_DATA		0x02
+#define SCH_WORD_DATA		0x03
+#define SCH_BLOCK_DATA		0x05
+
+static unsigned short sch_smba;
+static struct i2c_adapter sch_adapter;
+static int backbone_speed = 33000; /* backbone speed in kHz */
+module_param(backbone_speed, int, S_IRUSR | S_IWUSR);
+MODULE_PARM_DESC(backbone_speed, "Backbone speed in kHz, (default = 33000)");
+
+/*
+ * Start the i2c transaction -- the i2c_access will prepare the transaction
+ * and this function will execute it.
+ * return 0 for success and others for failure.
+ */
+static int sch_transaction(void)
+{
+	int temp;
+	int result = 0;
+	int retries = 0;
+
+	dev_dbg(&sch_adapter.dev, "Transaction (pre): CNT=%02x, CMD=%02x, "
+		"ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb(SMBHSTCNT),
+		inb(SMBHSTCMD), inb(SMBHSTADD), inb(SMBHSTDAT0),
+		inb(SMBHSTDAT1));
+
+	/* Make sure the SMBus host is ready to start transmitting */
+	temp = inb(SMBHSTSTS) & 0x0f;
+	if (temp) {
+		/* Can not be busy since we checked it in sch_access */
+		if (temp & 0x01) {
+			dev_dbg(&sch_adapter.dev, "Completion (%02x). "
+				"Clear...\n", temp);
+		}
+		if (temp & 0x06) {
+			dev_dbg(&sch_adapter.dev, "SMBus error (%02x). "
+				"Resetting...\n", temp);
+		}
+		outb(temp, SMBHSTSTS);
+		temp = inb(SMBHSTSTS) & 0x0f;
+		if (temp) {
+			dev_err(&sch_adapter.dev,
+				"SMBus is not ready: (%02x)\n", temp);
+			return -EAGAIN;
+		}
+	}
+
+	/* start the transaction by setting bit 4 */
+	outb(inb(SMBHSTCNT) | 0x10, SMBHSTCNT);
+
+	do {
+		usleep_range(100, 200);
+		temp = inb(SMBHSTSTS) & 0x0f;
+	} while ((temp & 0x08) && (retries++ < MAX_RETRIES));
+
+	/* If the SMBus is still busy, we give up */
+	if (retries > MAX_RETRIES) {
+		dev_err(&sch_adapter.dev, "SMBus Timeout!\n");
+		result = -ETIMEDOUT;
+	}
+	if (temp & 0x04) {
+		result = -EIO;
+		dev_dbg(&sch_adapter.dev, "Bus collision! SMBus may be "
+			"locked until next hard reset. (sorry!)\n");
+		/* Clock stops and slave is stuck in mid-transmission */
+	} else if (temp & 0x02) {
+		result = -EIO;
+		dev_err(&sch_adapter.dev, "Error: no response!\n");
+	} else if (temp & 0x01) {
+		dev_dbg(&sch_adapter.dev, "Post complete!\n");
+		outb(temp, SMBHSTSTS);
+		temp = inb(SMBHSTSTS) & 0x07;
+		if (temp & 0x06) {
+			/* Completion clear failed */
+			dev_dbg(&sch_adapter.dev, "Failed reset at end of "
+				"transaction (%02x), Bus error!\n", temp);
+		}
+	} else {
+		result = -ENXIO;
+		dev_dbg(&sch_adapter.dev, "No such address.\n");
+	}
+	dev_dbg(&sch_adapter.dev, "Transaction (post): CNT=%02x, CMD=%02x, "
+		"ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb(SMBHSTCNT),
+		inb(SMBHSTCMD), inb(SMBHSTADD), inb(SMBHSTDAT0),
+		inb(SMBHSTDAT1));
+	return result;
+}
+
+/*
+ * This is the main access entry for i2c-sch access
+ * adap is i2c_adapter pointer, addr is the i2c device bus address, read_write
+ * (0 for read and 1 for write), size is i2c transaction type and data is the
+ * union of transaction for data to be transferred or data read from bus.
+ * return 0 for success and others for failure.
+ */
+static s32 sch_access(struct i2c_adapter *adap, u16 addr,
+		 unsigned short flags, char read_write,
+		 u8 command, int size, union i2c_smbus_data *data)
+{
+	int i, len, temp, rc;
+
+	/* Make sure the SMBus host is not busy */
+	temp = inb(SMBHSTSTS) & 0x0f;
+	if (temp & 0x08) {
+		dev_dbg(&sch_adapter.dev, "SMBus busy (%02x)\n", temp);
+		return -EAGAIN;
+	}
+	temp = inw(SMBHSTCLK);
+	if (!temp) {
+		/*
+		 * We can't determine if we have 33 or 25 MHz clock for
+		 * SMBus, so expect 33 MHz and calculate a bus clock of
+		 * 100 kHz. If we actually run at 25 MHz the bus will be
+		 * run ~75 kHz instead which should do no harm.
+		 */
+		dev_notice(&sch_adapter.dev,
+			"Clock divider uninitialized. Setting defaults\n");
+		outw(backbone_speed / (4 * 100), SMBHSTCLK);
+	}
+
+	dev_dbg(&sch_adapter.dev, "access size: %d %s\n", size,
+		(read_write)?"READ":"WRITE");
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+		outb((addr << 1) | read_write, SMBHSTADD);
+		size = SCH_QUICK;
+		break;
+	case I2C_SMBUS_BYTE:
+		outb((addr << 1) | read_write, SMBHSTADD);
+		if (read_write == I2C_SMBUS_WRITE)
+			outb(command, SMBHSTCMD);
+		size = SCH_BYTE;
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		outb((addr << 1) | read_write, SMBHSTADD);
+		outb(command, SMBHSTCMD);
+		if (read_write == I2C_SMBUS_WRITE)
+			outb(data->byte, SMBHSTDAT0);
+		size = SCH_BYTE_DATA;
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		outb((addr << 1) | read_write, SMBHSTADD);
+		outb(command, SMBHSTCMD);
+		if (read_write == I2C_SMBUS_WRITE) {
+			outb(data->word & 0xff, SMBHSTDAT0);
+			outb((data->word & 0xff00) >> 8, SMBHSTDAT1);
+		}
+		size = SCH_WORD_DATA;
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+		outb((addr << 1) | read_write, SMBHSTADD);
+		outb(command, SMBHSTCMD);
+		if (read_write == I2C_SMBUS_WRITE) {
+			len = data->block[0];
+			if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
+				return -EINVAL;
+			outb(len, SMBHSTDAT0);
+			for (i = 1; i <= len; i++)
+				outb(data->block[i], SMBBLKDAT+i-1);
+		}
+		size = SCH_BLOCK_DATA;
+		break;
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+	dev_dbg(&sch_adapter.dev, "write size %d to 0x%04x\n", size, SMBHSTCNT);
+	outb((inb(SMBHSTCNT) & 0xb0) | (size & 0x7), SMBHSTCNT);
+
+	rc = sch_transaction();
+	if (rc)	/* Error in transaction */
+		return rc;
+
+	if ((read_write == I2C_SMBUS_WRITE) || (size == SCH_QUICK))
+		return 0;
+
+	switch (size) {
+	case SCH_BYTE:
+	case SCH_BYTE_DATA:
+		data->byte = inb(SMBHSTDAT0);
+		break;
+	case SCH_WORD_DATA:
+		data->word = inb(SMBHSTDAT0) + (inb(SMBHSTDAT1) << 8);
+		break;
+	case SCH_BLOCK_DATA:
+		data->block[0] = inb(SMBHSTDAT0);
+		if (data->block[0] == 0 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
+			return -EPROTO;
+		for (i = 1; i <= data->block[0]; i++)
+			data->block[i] = inb(SMBBLKDAT+i-1);
+		break;
+	}
+	return 0;
+}
+
+static u32 sch_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
+	    I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
+	    I2C_FUNC_SMBUS_BLOCK_DATA;
+}
+
+static const struct i2c_algorithm smbus_algorithm = {
+	.smbus_xfer	= sch_access,
+	.functionality	= sch_func,
+};
+
+static struct i2c_adapter sch_adapter = {
+	.owner		= THIS_MODULE,
+	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
+	.algo		= &smbus_algorithm,
+};
+
+static int smbus_sch_probe(struct platform_device *dev)
+{
+	struct resource *res;
+	int retval;
+
+	res = platform_get_resource(dev, IORESOURCE_IO, 0);
+	if (!res)
+		return -EBUSY;
+
+	if (!devm_request_region(&dev->dev, res->start, resource_size(res),
+				 dev->name)) {
+		dev_err(&dev->dev, "SMBus region 0x%x already in use!\n",
+			sch_smba);
+		return -EBUSY;
+	}
+
+	sch_smba = res->start;
+
+	dev_dbg(&dev->dev, "SMBA = 0x%X\n", sch_smba);
+
+	/* set up the sysfs linkage to our parent device */
+	sch_adapter.dev.parent = &dev->dev;
+
+	snprintf(sch_adapter.name, sizeof(sch_adapter.name),
+		"SMBus SCH adapter at %04x", sch_smba);
+
+	retval = i2c_add_adapter(&sch_adapter);
+	if (retval)
+		sch_smba = 0;
+
+	return retval;
+}
+
+static int smbus_sch_remove(struct platform_device *pdev)
+{
+	if (sch_smba) {
+		i2c_del_adapter(&sch_adapter);
+		sch_smba = 0;
+	}
+
+	return 0;
+}
+
+static struct platform_driver smbus_sch_driver = {
+	.driver = {
+		.name = "isch_smbus",
+	},
+	.probe		= smbus_sch_probe,
+	.remove		= smbus_sch_remove,
+};
+
+module_platform_driver(smbus_sch_driver);
+
+MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@intel.com>");
+MODULE_DESCRIPTION("Intel SCH SMBus driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:isch_smbus");