i2c: Add driver for SMBus Control Method Interface

This driver supports the SMBus Control Method Interface. It needs BIOS declare
ACPI control methods which described in SMBus Control Method Interface Spec.
http://smbus.org/specs/smbus_cmi10.pdf

Signed-off-by: Crane Cai <crane.cai@amd.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/busses/Kconfig

@@ -762,4 +762,15 @@ config SCx200_ACB
 	  This support is also available as a module.  If so, the module
 	  will be called scx200_acb.
 
+config I2C_SCMI
+	tristate "SMBus Control Method Interface"
+	depends on ACPI
+	help
+	  This driver supports the SMBus Control Method Interface. It needs the
+	  BIOS to declare ACPI control methods as described in the SMBus Control
+	  Method Interface specification.
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called i2c-scmi.
+
 endmenu

drivers/i2c/busses/Makefile

@@ -2,6 +2,9 @@
 # Makefile for the i2c bus drivers.
 #
 
+# SMBus CMI driver
+obj-$(CONFIG_I2C_SCMI)		+= i2c-scmi.o
+
 # PC SMBus host controller drivers
 obj-$(CONFIG_I2C_ALI1535)	+= i2c-ali1535.o
 obj-$(CONFIG_I2C_ALI1563)	+= i2c-ali1563.o

drivers/i2c/busses/i2c-scmi.c

@@ -0,0 +1,430 @@
+/*
+ * SMBus driver for ACPI SMBus CMI
+ *
+ * Copyright (C) 2009 Crane Cai <crane.cai@amd.com>
+ *
+ * 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 version 2.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/stddef.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/acpi.h>
+
+#define ACPI_SMBUS_HC_CLASS		"smbus"
+#define ACPI_SMBUS_HC_DEVICE_NAME	"cmi"
+
+ACPI_MODULE_NAME("smbus_cmi");
+
+struct smbus_methods_t {
+	char *mt_info;
+	char *mt_sbr;
+	char *mt_sbw;
+};
+
+struct acpi_smbus_cmi {
+	acpi_handle handle;
+	struct i2c_adapter adapter;
+	u8 cap_info:1;
+	u8 cap_read:1;
+	u8 cap_write:1;
+};
+
+static const struct smbus_methods_t smbus_methods = {
+	.mt_info = "_SBI",
+	.mt_sbr  = "_SBR",
+	.mt_sbw  = "_SBW",
+};
+
+static const struct acpi_device_id acpi_smbus_cmi_ids[] = {
+	{"SMBUS01", 0},
+	{"", 0}
+};
+
+#define ACPI_SMBUS_STATUS_OK			0x00
+#define ACPI_SMBUS_STATUS_FAIL			0x07
+#define ACPI_SMBUS_STATUS_DNAK			0x10
+#define ACPI_SMBUS_STATUS_DERR			0x11
+#define ACPI_SMBUS_STATUS_CMD_DENY		0x12
+#define ACPI_SMBUS_STATUS_UNKNOWN		0x13
+#define ACPI_SMBUS_STATUS_ACC_DENY		0x17
+#define ACPI_SMBUS_STATUS_TIMEOUT		0x18
+#define ACPI_SMBUS_STATUS_NOTSUP		0x19
+#define ACPI_SMBUS_STATUS_BUSY			0x1a
+#define ACPI_SMBUS_STATUS_PEC			0x1f
+
+#define ACPI_SMBUS_PRTCL_WRITE			0x00
+#define ACPI_SMBUS_PRTCL_READ			0x01
+#define ACPI_SMBUS_PRTCL_QUICK			0x02
+#define ACPI_SMBUS_PRTCL_BYTE			0x04
+#define ACPI_SMBUS_PRTCL_BYTE_DATA		0x06
+#define ACPI_SMBUS_PRTCL_WORD_DATA		0x08
+#define ACPI_SMBUS_PRTCL_BLOCK_DATA		0x0a
+
+
+static int
+acpi_smbus_cmi_access(struct i2c_adapter *adap, u16 addr, unsigned short flags,
+		   char read_write, u8 command, int size,
+		   union i2c_smbus_data *data)
+{
+	int result = 0;
+	struct acpi_smbus_cmi *smbus_cmi = adap->algo_data;
+	unsigned char protocol;
+	acpi_status status = 0;
+	struct acpi_object_list input;
+	union acpi_object mt_params[5];
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	union acpi_object *pkg;
+	char *method;
+	int len = 0;
+
+	dev_dbg(&adap->dev, "access size: %d %s\n", size,
+		(read_write) ? "READ" : "WRITE");
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+		protocol = ACPI_SMBUS_PRTCL_QUICK;
+		command = 0;
+		if (read_write == I2C_SMBUS_WRITE) {
+			mt_params[3].type = ACPI_TYPE_INTEGER;
+			mt_params[3].integer.value = 0;
+			mt_params[4].type = ACPI_TYPE_INTEGER;
+			mt_params[4].integer.value = 0;
+		}
+		break;
+
+	case I2C_SMBUS_BYTE:
+		protocol = ACPI_SMBUS_PRTCL_BYTE;
+		if (read_write == I2C_SMBUS_WRITE) {
+			mt_params[3].type = ACPI_TYPE_INTEGER;
+			mt_params[3].integer.value = 0;
+			mt_params[4].type = ACPI_TYPE_INTEGER;
+			mt_params[4].integer.value = 0;
+		} else {
+			command = 0;
+		}
+		break;
+
+	case I2C_SMBUS_BYTE_DATA:
+		protocol = ACPI_SMBUS_PRTCL_BYTE_DATA;
+		if (read_write == I2C_SMBUS_WRITE) {
+			mt_params[3].type = ACPI_TYPE_INTEGER;
+			mt_params[3].integer.value = 1;
+			mt_params[4].type = ACPI_TYPE_INTEGER;
+			mt_params[4].integer.value = data->byte;
+		}
+		break;
+
+	case I2C_SMBUS_WORD_DATA:
+		protocol = ACPI_SMBUS_PRTCL_WORD_DATA;
+		if (read_write == I2C_SMBUS_WRITE) {
+			mt_params[3].type = ACPI_TYPE_INTEGER;
+			mt_params[3].integer.value = 2;
+			mt_params[4].type = ACPI_TYPE_INTEGER;
+			mt_params[4].integer.value = data->word;
+		}
+		break;
+
+	case I2C_SMBUS_BLOCK_DATA:
+		protocol = ACPI_SMBUS_PRTCL_BLOCK_DATA;
+		if (read_write == I2C_SMBUS_WRITE) {
+			len = data->block[0];
+			if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
+				return -EINVAL;
+			mt_params[3].type = ACPI_TYPE_INTEGER;
+			mt_params[3].integer.value = len;
+			mt_params[4].type = ACPI_TYPE_BUFFER;
+			mt_params[4].buffer.pointer = data->block + 1;
+		}
+		break;
+
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	if (read_write == I2C_SMBUS_READ) {
+		protocol |= ACPI_SMBUS_PRTCL_READ;
+		method = smbus_methods.mt_sbr;
+		input.count = 3;
+	} else {
+		protocol |= ACPI_SMBUS_PRTCL_WRITE;
+		method = smbus_methods.mt_sbw;
+		input.count = 5;
+	}
+
+	input.pointer = mt_params;
+	mt_params[0].type = ACPI_TYPE_INTEGER;
+	mt_params[0].integer.value = protocol;
+	mt_params[1].type = ACPI_TYPE_INTEGER;
+	mt_params[1].integer.value = addr;
+	mt_params[2].type = ACPI_TYPE_INTEGER;
+	mt_params[2].integer.value = command;
+
+	status = acpi_evaluate_object(smbus_cmi->handle, method, &input,
+				      &buffer);
+	if (ACPI_FAILURE(status)) {
+		ACPI_ERROR((AE_INFO, "Evaluating %s: %i", method, status));
+		return -EIO;
+	}
+
+	pkg = buffer.pointer;
+	if (pkg && pkg->type == ACPI_TYPE_PACKAGE)
+		obj = pkg->package.elements;
+	else {
+		ACPI_ERROR((AE_INFO, "Invalid argument type"));
+		result = -EIO;
+		goto out;
+	}
+	if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
+		ACPI_ERROR((AE_INFO, "Invalid argument type"));
+		result = -EIO;
+		goto out;
+	}
+
+	result = obj->integer.value;
+	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "%s return status: %i\n",
+			  method, result));
+
+	switch (result) {
+	case ACPI_SMBUS_STATUS_OK:
+		result = 0;
+		break;
+	case ACPI_SMBUS_STATUS_BUSY:
+		result = -EBUSY;
+		goto out;
+	case ACPI_SMBUS_STATUS_TIMEOUT:
+		result = -ETIMEDOUT;
+		goto out;
+	case ACPI_SMBUS_STATUS_DNAK:
+		result = -ENXIO;
+		goto out;
+	default:
+		result = -EIO;
+		goto out;
+	}
+
+	if (read_write == I2C_SMBUS_WRITE || size == I2C_SMBUS_QUICK)
+		goto out;
+
+	obj = pkg->package.elements + 1;
+	if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
+		ACPI_ERROR((AE_INFO, "Invalid argument type"));
+		result = -EIO;
+		goto out;
+	}
+
+	len = obj->integer.value;
+	obj = pkg->package.elements + 2;
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+	case I2C_SMBUS_WORD_DATA:
+		if (obj == NULL || obj->type != ACPI_TYPE_INTEGER) {
+			ACPI_ERROR((AE_INFO, "Invalid argument type"));
+			result = -EIO;
+			goto out;
+		}
+		if (len == 2)
+			data->word = obj->integer.value;
+		else
+			data->byte = obj->integer.value;
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+		if (obj == NULL || obj->type != ACPI_TYPE_BUFFER) {
+			ACPI_ERROR((AE_INFO, "Invalid argument type"));
+			result = -EIO;
+			goto out;
+		}
+		if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
+			return -EPROTO;
+		data->block[0] = len;
+		memcpy(data->block + 1, obj->buffer.pointer, len);
+		break;
+	}
+
+out:
+	kfree(buffer.pointer);
+	dev_dbg(&adap->dev, "Transaction status: %i\n", result);
+	return result;
+}
+
+static u32 acpi_smbus_cmi_func(struct i2c_adapter *adapter)
+{
+	struct acpi_smbus_cmi *smbus_cmi = adapter->algo_data;
+	u32 ret;
+
+	ret = smbus_cmi->cap_read | smbus_cmi->cap_write ?
+		I2C_FUNC_SMBUS_QUICK : 0;
+
+	ret |= smbus_cmi->cap_read ?
+		(I2C_FUNC_SMBUS_READ_BYTE |
+		I2C_FUNC_SMBUS_READ_BYTE_DATA |
+		I2C_FUNC_SMBUS_READ_WORD_DATA |
+		I2C_FUNC_SMBUS_READ_BLOCK_DATA) : 0;
+
+	ret |= smbus_cmi->cap_write ?
+		(I2C_FUNC_SMBUS_WRITE_BYTE |
+		I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
+		I2C_FUNC_SMBUS_WRITE_WORD_DATA |
+		I2C_FUNC_SMBUS_WRITE_BLOCK_DATA) : 0;
+
+	return ret;
+}
+
+static const struct i2c_algorithm acpi_smbus_cmi_algorithm = {
+	.smbus_xfer = acpi_smbus_cmi_access,
+	.functionality = acpi_smbus_cmi_func,
+};
+
+
+static int acpi_smbus_cmi_add_cap(struct acpi_smbus_cmi *smbus_cmi,
+				  const char *name)
+{
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+
+	if (!strcmp(name, smbus_methods.mt_info)) {
+		status = acpi_evaluate_object(smbus_cmi->handle,
+					smbus_methods.mt_info,
+					NULL, &buffer);
+		if (ACPI_FAILURE(status)) {
+			ACPI_ERROR((AE_INFO, "Evaluating %s: %i",
+				   smbus_methods.mt_info, status));
+			return -EIO;
+		}
+
+		obj = buffer.pointer;
+		if (obj && obj->type == ACPI_TYPE_PACKAGE)
+			obj = obj->package.elements;
+		else {
+			ACPI_ERROR((AE_INFO, "Invalid argument type"));
+			kfree(buffer.pointer);
+			return -EIO;
+		}
+
+		if (obj->type != ACPI_TYPE_INTEGER) {
+			ACPI_ERROR((AE_INFO, "Invalid argument type"));
+			kfree(buffer.pointer);
+			return -EIO;
+		} else
+			ACPI_DEBUG_PRINT((ACPI_DB_INFO, "SMBus CMI Version %x"
+					  "\n", (int)obj->integer.value));
+
+		kfree(buffer.pointer);
+		smbus_cmi->cap_info = 1;
+	} else if (!strcmp(name, smbus_methods.mt_sbr))
+		smbus_cmi->cap_read = 1;
+	else if (!strcmp(name, smbus_methods.mt_sbw))
+		smbus_cmi->cap_write = 1;
+	else
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Unsupported CMI method: %s\n",
+				 name));
+
+	return 0;
+}
+
+static acpi_status acpi_smbus_cmi_query_methods(acpi_handle handle, u32 level,
+			void *context, void **return_value)
+{
+	char node_name[5];
+	struct acpi_buffer buffer = { sizeof(node_name), node_name };
+	struct acpi_smbus_cmi *smbus_cmi = context;
+	acpi_status status;
+
+	status = acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
+
+	if (ACPI_SUCCESS(status))
+		acpi_smbus_cmi_add_cap(smbus_cmi, node_name);
+
+	return AE_OK;
+}
+
+static int acpi_smbus_cmi_add(struct acpi_device *device)
+{
+	struct acpi_smbus_cmi *smbus_cmi;
+
+	smbus_cmi = kzalloc(sizeof(struct acpi_smbus_cmi), GFP_KERNEL);
+	if (!smbus_cmi)
+		return -ENOMEM;
+
+	smbus_cmi->handle = device->handle;
+	strcpy(acpi_device_name(device), ACPI_SMBUS_HC_DEVICE_NAME);
+	strcpy(acpi_device_class(device), ACPI_SMBUS_HC_CLASS);
+	device->driver_data = smbus_cmi;
+	smbus_cmi->cap_info = 0;
+	smbus_cmi->cap_read = 0;
+	smbus_cmi->cap_write = 0;
+
+	acpi_walk_namespace(ACPI_TYPE_METHOD, smbus_cmi->handle, 1,
+			    acpi_smbus_cmi_query_methods, smbus_cmi, NULL);
+
+	if (smbus_cmi->cap_info == 0)
+		goto err;
+
+	snprintf(smbus_cmi->adapter.name, sizeof(smbus_cmi->adapter.name),
+		"SMBus CMI adapter %s (%s)",
+		acpi_device_name(device),
+		acpi_device_uid(device));
+	smbus_cmi->adapter.owner = THIS_MODULE;
+	smbus_cmi->adapter.algo = &acpi_smbus_cmi_algorithm;
+	smbus_cmi->adapter.algo_data = smbus_cmi;
+	smbus_cmi->adapter.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+	smbus_cmi->adapter.dev.parent = &device->dev;
+
+	if (i2c_add_adapter(&smbus_cmi->adapter)) {
+		dev_err(&device->dev, "Couldn't register adapter!\n");
+		goto err;
+	}
+
+	return 0;
+
+err:
+	kfree(smbus_cmi);
+	device->driver_data = NULL;
+	return -EIO;
+}
+
+static int acpi_smbus_cmi_remove(struct acpi_device *device, int type)
+{
+	struct acpi_smbus_cmi *smbus_cmi = acpi_driver_data(device);
+
+	i2c_del_adapter(&smbus_cmi->adapter);
+	kfree(smbus_cmi);
+	device->driver_data = NULL;
+
+	return 0;
+}
+
+static struct acpi_driver acpi_smbus_cmi_driver = {
+	.name = ACPI_SMBUS_HC_DEVICE_NAME,
+	.class = ACPI_SMBUS_HC_CLASS,
+	.ids = acpi_smbus_cmi_ids,
+	.ops = {
+		.add = acpi_smbus_cmi_add,
+		.remove = acpi_smbus_cmi_remove,
+	},
+};
+
+static int __init acpi_smbus_cmi_init(void)
+{
+	return acpi_bus_register_driver(&acpi_smbus_cmi_driver);
+}
+
+static void __exit acpi_smbus_cmi_exit(void)
+{
+	acpi_bus_unregister_driver(&acpi_smbus_cmi_driver);
+}
+
+module_init(acpi_smbus_cmi_init);
+module_exit(acpi_smbus_cmi_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Crane Cai <crane.cai@amd.com>");
+MODULE_DESCRIPTION("ACPI SMBus CMI driver");