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-nforce2: Remove redundant error messages on ACPI conflict
  i2c: Use <linux/io.h> instead of <asm/io.h>
  i2c-algo-pca: Fix coding style issues
  i2c-dev: Fix all coding style issues
  i2c-core: Fix some coding style issues
  i2c-gpio: Move initialization code to subsys_initcall()
  i2c-parport: Make template structure const
  i2c-dev: Remove unnecessary casts
  at24: Fall back to byte or word reads if needed
  i2c-stub: Expose the default functionality flags
  i2c/scx200_acb: Make PCI device ids constant
  i2c-i801: Fix all checkpatch warnings
  i2c-i801: All newer devices have all the optional features
  i2c-i801: Let the user disable selected driver features

1 files changed, 48 insertions, 11 deletions

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index a79a62f..f7ca3a4 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -54,7 +54,7 @@
 struct at24_data {
 	struct at24_platform_data chip;
 	struct memory_accessor macc;
-	bool use_smbus;
+	int use_smbus;
 
 	/*
 	 * Lock protects against activities from other Linux tasks,
@@ -184,11 +184,19 @@ static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
 	if (count > io_limit)
 		count = io_limit;
 
-	if (at24->use_smbus) {
+	switch (at24->use_smbus) {
+	case I2C_SMBUS_I2C_BLOCK_DATA:
 		/* Smaller eeproms can work given some SMBus extension calls */
 		if (count > I2C_SMBUS_BLOCK_MAX)
 			count = I2C_SMBUS_BLOCK_MAX;
-	} else {
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		count = 2;
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		count = 1;
+		break;
+	default:
 		/*
 		 * When we have a better choice than SMBus calls, use a
 		 * combined I2C message. Write address; then read up to
@@ -219,10 +227,27 @@ static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
 	timeout = jiffies + msecs_to_jiffies(write_timeout);
 	do {
 		read_time = jiffies;
-		if (at24->use_smbus) {
+		switch (at24->use_smbus) {
+		case I2C_SMBUS_I2C_BLOCK_DATA:
 			status = i2c_smbus_read_i2c_block_data(client, offset,
 					count, buf);
-		} else {
+			break;
+		case I2C_SMBUS_WORD_DATA:
+			status = i2c_smbus_read_word_data(client, offset);
+			if (status >= 0) {
+				buf[0] = status & 0xff;
+				buf[1] = status >> 8;
+				status = count;
+			}
+			break;
+		case I2C_SMBUS_BYTE_DATA:
+			status = i2c_smbus_read_byte_data(client, offset);
+			if (status >= 0) {
+				buf[0] = status;
+				status = count;
+			}
+			break;
+		default:
 			status = i2c_transfer(client->adapter, msg, 2);
 			if (status == 2)
 				status = count;
@@ -436,7 +461,7 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
 	struct at24_platform_data chip;
 	bool writable;
-	bool use_smbus = false;
+	int use_smbus = 0;
 	struct at24_data *at24;
 	int err;
 	unsigned i, num_addresses;
@@ -477,12 +502,19 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 			err = -EPFNOSUPPORT;
 			goto err_out;
 		}
-		if (!i2c_check_functionality(client->adapter,
+		if (i2c_check_functionality(client->adapter,
 				I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+			use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
+		} else if (i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_READ_WORD_DATA)) {
+			use_smbus = I2C_SMBUS_WORD_DATA;
+		} else if (i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+			use_smbus = I2C_SMBUS_BYTE_DATA;
+		} else {
 			err = -EPFNOSUPPORT;
 			goto err_out;
 		}
-		use_smbus = true;
 	}
 
 	if (chip.flags & AT24_FLAG_TAKE8ADDR)
@@ -568,11 +600,16 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	dev_info(&client->dev, "%zu byte %s EEPROM %s\n",
 		at24->bin.size, client->name,
 		writable ? "(writable)" : "(read-only)");
+	if (use_smbus == I2C_SMBUS_WORD_DATA ||
+	    use_smbus == I2C_SMBUS_BYTE_DATA) {
+		dev_notice(&client->dev, "Falling back to %s reads, "
+			   "performance will suffer\n", use_smbus ==
+			   I2C_SMBUS_WORD_DATA ? "word" : "byte");
+	}
 	dev_dbg(&client->dev,
-		"page_size %d, num_addresses %d, write_max %d%s\n",
+		"page_size %d, num_addresses %d, write_max %d, use_smbus %d\n",
 		chip.page_size, num_addresses,
-		at24->write_max,
-		use_smbus ? ", use_smbus" : "");
+		at24->write_max, use_smbus);
 
 	/* export data to kernel code */
 	if (chip.setup)