Merge branch 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging

* 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
  i2c: Clearly mark ACPI drivers as such
  i2c: Add driver for SMBus Control Method Interface
  i2c-pnx: Correct use of request_region/request_mem_region
  MAINTAINERS: Add maintainer for AT24 and PCA9564/PCA9665
  i2c-piix4: Add AMD SB900 SMBus device ID
  i2c/chips: Remove deprecated pcf8574 driver
  i2c/chips: Remove deprecated pca9539 driver
  i2c/chips: Remove deprecated pcf8575 driver
  gpio/pcf857x: Copy i2c_device_id from old pcf8574 driver
  i2c/scx200_acb: Provide more information on bus errors
  i2c: Provide compatibility links for i2c adapters
  i2c: Convert i2c adapters to bus devices
  i2c: Convert i2c clients to a device type
  i2c/tsl2550: Use combined SMBus transactions
  i2c-taos-evm: Switch echo off to improve performance
  i2c: Drop unused i2c_driver.id field

7 files changed, 489 insertions, 30 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 8206442fbab..6bedd2fcfc1 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -113,7 +113,7 @@ config I2C_ISCH
 	  will be called i2c-isch.
 
 config I2C_PIIX4
-	tristate "Intel PIIX4 and compatible (ATI/Serverworks/Broadcom/SMSC)"
+	tristate "Intel PIIX4 and compatible (ATI/AMD/Serverworks/Broadcom/SMSC)"
 	depends on PCI
 	help
 	  If you say yes to this option, support will be included for the Intel
@@ -128,6 +128,7 @@ config I2C_PIIX4
 	    ATI SB600
 	    ATI SB700
 	    ATI SB800
+	    AMD SB900
 	    Serverworks OSB4
 	    Serverworks CSB5
 	    Serverworks CSB6
@@ -231,6 +232,22 @@ config I2C_VIAPRO
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-viapro.
 
+if ACPI
+
+comment "ACPI drivers"
+
+config I2C_SCMI
+	tristate "SMBus Control Method Interface"
+	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.
+
+endif # ACPI
+
 comment "Mac SMBus host controller drivers"
 	depends on PPC_CHRP || PPC_PMAC
 
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index e654263bfc0..ff937ac69f5 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -2,6 +2,9 @@
 # Makefile for the i2c bus drivers.
 #
 
+# ACPI drivers
+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
diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 0249a7d762b..a782c7a08f9 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -22,6 +22,7 @@
 	Intel PIIX4, 440MX
 	Serverworks OSB4, CSB5, CSB6, HT-1000, HT-1100
 	ATI IXP200, IXP300, IXP400, SB600, SB700, SB800
+	AMD SB900
 	SMSC Victory66
 
    Note: we assume there can only be one device, with one SMBus interface.
@@ -479,6 +480,7 @@ static struct pci_device_id piix4_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP300_SMBUS) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP400_SMBUS) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_SB900_SMBUS) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
 		     PCI_DEVICE_ID_SERVERWORKS_OSB4) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
@@ -499,9 +501,10 @@ static int __devinit piix4_probe(struct pci_dev *dev,
 {
 	int retval;
 
-	if ((dev->vendor == PCI_VENDOR_ID_ATI) &&
-	    (dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS) &&
-	    (dev->revision >= 0x40))
+	if ((dev->vendor == PCI_VENDOR_ID_ATI &&
+	     dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
+	     dev->revision >= 0x40) ||
+	    dev->vendor == PCI_VENDOR_ID_AMD)
 		/* base address location etc changed in SB800 */
 		retval = piix4_setup_sb800(dev, id);
 	else
diff --git a/drivers/i2c/busses/i2c-pnx.c b/drivers/i2c/busses/i2c-pnx.c
index ec15cff556b..6ff6c20f1e7 100644
--- a/drivers/i2c/busses/i2c-pnx.c
+++ b/drivers/i2c/busses/i2c-pnx.c
@@ -586,7 +586,8 @@ static int __devinit i2c_pnx_probe(struct platform_device *pdev)
 	alg_data->mif.timer.data = (unsigned long)i2c_pnx->adapter;
 
 	/* Register I/O resource */
-	if (!request_region(alg_data->base, I2C_PNX_REGION_SIZE, pdev->name)) {
+	if (!request_mem_region(alg_data->base, I2C_PNX_REGION_SIZE,
+				pdev->name)) {
 		dev_err(&pdev->dev,
 		       "I/O region 0x%08x for I2C already in use.\n",
 		       alg_data->base);
@@ -650,7 +651,7 @@ out_clock:
 out_unmap:
 	iounmap((void *)alg_data->ioaddr);
 out_release:
-	release_region(alg_data->base, I2C_PNX_REGION_SIZE);
+	release_mem_region(alg_data->base, I2C_PNX_REGION_SIZE);
 out_drvdata:
 	platform_set_drvdata(pdev, NULL);
 out:
@@ -667,7 +668,7 @@ static int __devexit i2c_pnx_remove(struct platform_device *pdev)
 	i2c_del_adapter(adap);
 	i2c_pnx->set_clock_stop(pdev);
 	iounmap((void *)alg_data->ioaddr);
-	release_region(alg_data->base, I2C_PNX_REGION_SIZE);
+	release_mem_region(alg_data->base, I2C_PNX_REGION_SIZE);
 	platform_set_drvdata(pdev, NULL);
 
 	return 0;
diff --git a/drivers/i2c/busses/i2c-scmi.c b/drivers/i2c/busses/i2c-scmi.c
new file mode 100644
index 00000000000..276a046ac93
--- /dev/null
+++ b/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");
diff --git a/drivers/i2c/busses/i2c-taos-evm.c b/drivers/i2c/busses/i2c-taos-evm.c
index 224aa12ee7c..dd39c1eb03e 100644
--- a/drivers/i2c/busses/i2c-taos-evm.c
+++ b/drivers/i2c/busses/i2c-taos-evm.c
@@ -32,10 +32,12 @@
 
 #define TAOS_STATE_INIT		0
 #define TAOS_STATE_IDLE		1
-#define TAOS_STATE_SEND		2
+#define TAOS_STATE_EOFF		2
 #define TAOS_STATE_RECV		3
 
 #define TAOS_CMD_RESET		0x12
+#define TAOS_CMD_ECHO_ON	'+'
+#define TAOS_CMD_ECHO_OFF	'-'
 
 static DECLARE_WAIT_QUEUE_HEAD(wq);
 
@@ -102,17 +104,9 @@ static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 
 	/* Send the transaction to the TAOS EVM */
 	dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
-	taos->pos = 0;
-	taos->state = TAOS_STATE_SEND;
-	serio_write(serio, taos->buffer[0]);
-	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
-					 msecs_to_jiffies(250));
-	if (taos->state != TAOS_STATE_IDLE) {
-		dev_err(&adapter->dev, "Transaction failed "
-			"(state=%d, pos=%d)\n", taos->state, taos->pos);
-		taos->addr = 0;
-		return -EIO;
-	}
+	for (p = taos->buffer; *p; p++)
+		serio_write(serio, *p);
+
 	taos->addr = addr;
 
 	/* Start the transaction and read the answer */
@@ -122,7 +116,7 @@ static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
 					 msecs_to_jiffies(150));
 	if (taos->state != TAOS_STATE_IDLE
-	 || taos->pos != 6) {
+	 || taos->pos != 5) {
 		dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
 			taos->pos);
 		return -EIO;
@@ -130,7 +124,7 @@ static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 	dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
 
 	/* Interpret the returned string */
-	p = taos->buffer + 2;
+	p = taos->buffer + 1;
 	p[3] = '\0';
 	if (!strcmp(p, "NAK"))
 		return -ENODEV;
@@ -173,13 +167,9 @@ static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
 			wake_up_interruptible(&wq);
 		}
 		break;
-	case TAOS_STATE_SEND:
-		if (taos->buffer[++taos->pos])
-			serio_write(serio, taos->buffer[taos->pos]);
-		else {
-			taos->state = TAOS_STATE_IDLE;
-			wake_up_interruptible(&wq);
-		}
+	case TAOS_STATE_EOFF:
+		taos->state = TAOS_STATE_IDLE;
+		wake_up_interruptible(&wq);
 		break;
 	case TAOS_STATE_RECV:
 		taos->buffer[taos->pos++] = data;
@@ -257,6 +247,19 @@ static int taos_connect(struct serio *serio, struct serio_driver *drv)
 	}
 	strlcpy(adapter->name, name, sizeof(adapter->name));
 
+	/* Turn echo off for better performance */
+	taos->state = TAOS_STATE_EOFF;
+	serio_write(serio, TAOS_CMD_ECHO_OFF);
+
+	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
+					 msecs_to_jiffies(250));
+	if (taos->state != TAOS_STATE_IDLE) {
+		err = -ENODEV;
+		dev_err(&adapter->dev, "Echo off failed "
+			"(state=%d)\n", taos->state);
+		goto exit_close;
+	}
+
 	err = i2c_add_adapter(adapter);
 	if (err)
 		goto exit_close;
diff --git a/drivers/i2c/busses/scx200_acb.c b/drivers/i2c/busses/scx200_acb.c
index 648ecc6f60e..cf994bd01d9 100644
--- a/drivers/i2c/busses/scx200_acb.c
+++ b/drivers/i2c/busses/scx200_acb.c
@@ -217,8 +217,10 @@ static void scx200_acb_machine(struct scx200_acb_iface *iface, u8 status)
 	return;
 
  error:
-	dev_err(&iface->adapter.dev, "%s in state %s\n", errmsg,
-		scx200_acb_state_name[iface->state]);
+	dev_err(&iface->adapter.dev,
+		"%s in state %s (addr=0x%02x, len=%d, status=0x%02x)\n", errmsg,
+		scx200_acb_state_name[iface->state], iface->address_byte,
+		iface->len, status);
 
 	iface->state = state_idle;
 	iface->result = -EIO;