Merge branch 'i2c/for-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c updates from Wolfram Sang:
 "Here is the I2C pull request for 4.8:

   - the core and i801 driver gained support for SMBus Host Notify

   - core support for more than one address in DT

   - i2c_add_adapter() has now better error messages.  We can remove all
     error messages from drivers calling it as a next step.

   - bigger updates to rk3x driver to support rk3399 SoC

   - the at24 eeprom driver got refactored and can now read special
     variants with unique serials or fixed MAC addresses.

  The rest is regular driver updates and bugfixes"

* 'i2c/for-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (66 commits)
  i2c: i801: use IS_ENABLED() instead of checking for built-in or module
  Documentation: i2c: slave: give proper example for pm usage
  Documentation: i2c: slave: describe buffer problems a bit better
  i2c: bcm2835: Don't complain on -EPROBE_DEFER from getting our clock
  i2c: i2c-smbus: drop useless stubs
  i2c: efm32: fix a failure path in efm32_i2c_probe()
  Revert "i2c: core: Cleanup I2C ACPI namespace"
  Revert "i2c: core: Add function for finding the bus speed from ACPI"
  i2c: Update the description of I2C_SMBUS
  i2c: i2c-smbus: fix i2c_handle_smbus_host_notify documentation
  eeprom: at24: tweak the loop_until_timeout() macro
  eeprom: at24: add support for at24mac series
  eeprom: at24: support reading the serial number for 24csxx
  eeprom: at24: platform_data: use BIT() macro
  eeprom: at24: split at24_eeprom_write() into specialized functions
  eeprom: at24: split at24_eeprom_read() into specialized functions
  eeprom: at24: hide the read/write loop behind a macro
  eeprom: at24: call read/write functions via function pointers
  eeprom: at24: coding style fixes
  eeprom: at24: move at24_read() below at24_eeprom_write()
  ...

1 files changed, 343 insertions, 155 deletions

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 9ceb63b62be5..3cdf8e1ca0ad 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -58,6 +58,10 @@ struct at24_data {
 	int use_smbus;
 	int use_smbus_write;
 
+	ssize_t (*read_func)(struct at24_data *, char *, unsigned int, size_t);
+	ssize_t (*write_func)(struct at24_data *,
+			      const char *, unsigned int, size_t);
+
 	/*
 	 * Lock protects against activities from other Linux tasks,
 	 * but not from changes by other I2C masters.
@@ -109,25 +113,63 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
 	((1 << AT24_SIZE_FLAGS | (_flags)) 		\
 	    << AT24_SIZE_BYTELEN | ilog2(_len))
 
+/*
+ * Both reads and writes fail if the previous write didn't complete yet. This
+ * macro loops a few times waiting at least long enough for one entire page
+ * write to work while making sure that at least one iteration is run before
+ * checking the break condition.
+ *
+ * It takes two parameters: a variable in which the future timeout in jiffies
+ * will be stored and a temporary variable holding the time of the last
+ * iteration of processing the request. Both should be unsigned integers
+ * holding at least 32 bits.
+ */
+#define loop_until_timeout(tout, op_time)				\
+	for (tout = jiffies + msecs_to_jiffies(write_timeout), op_time = 0; \
+	     op_time ? time_before(op_time, tout) : true;		\
+	     usleep_range(1000, 1500), op_time = jiffies)
+
 static const struct i2c_device_id at24_ids[] = {
 	/* needs 8 addresses as A0-A2 are ignored */
-	{ "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
+	{ "24c00",	AT24_DEVICE_MAGIC(128 / 8,	AT24_FLAG_TAKE8ADDR) },
 	/* old variants can't be handled with this generic entry! */
-	{ "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
-	{ "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
+	{ "24c01",	AT24_DEVICE_MAGIC(1024 / 8,	0) },
+	{ "24cs01",	AT24_DEVICE_MAGIC(16,
+				AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
+	{ "24c02",	AT24_DEVICE_MAGIC(2048 / 8,	0) },
+	{ "24cs02",	AT24_DEVICE_MAGIC(16,
+				AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
+	{ "24mac402",	AT24_DEVICE_MAGIC(48 / 8,
+				AT24_FLAG_MAC | AT24_FLAG_READONLY) },
+	{ "24mac602",	AT24_DEVICE_MAGIC(64 / 8,
+				AT24_FLAG_MAC | AT24_FLAG_READONLY) },
 	/* spd is a 24c02 in memory DIMMs */
-	{ "spd", AT24_DEVICE_MAGIC(2048 / 8,
-		AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
-	{ "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
+	{ "spd",	AT24_DEVICE_MAGIC(2048 / 8,
+				AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
+	{ "24c04",	AT24_DEVICE_MAGIC(4096 / 8,	0) },
+	{ "24cs04",	AT24_DEVICE_MAGIC(16,
+				AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
 	/* 24rf08 quirk is handled at i2c-core */
-	{ "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
-	{ "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
-	{ "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
-	{ "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
-	{ "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
-	{ "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
-	{ "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
-	{ "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
+	{ "24c08",	AT24_DEVICE_MAGIC(8192 / 8,	0) },
+	{ "24cs08",	AT24_DEVICE_MAGIC(16,
+				AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
+	{ "24c16",	AT24_DEVICE_MAGIC(16384 / 8,	0) },
+	{ "24cs16",	AT24_DEVICE_MAGIC(16,
+				AT24_FLAG_SERIAL | AT24_FLAG_READONLY) },
+	{ "24c32",	AT24_DEVICE_MAGIC(32768 / 8,	AT24_FLAG_ADDR16) },
+	{ "24cs32",	AT24_DEVICE_MAGIC(16,
+				AT24_FLAG_ADDR16 |
+				AT24_FLAG_SERIAL |
+				AT24_FLAG_READONLY) },
+	{ "24c64",	AT24_DEVICE_MAGIC(65536 / 8,	AT24_FLAG_ADDR16) },
+	{ "24cs64",	AT24_DEVICE_MAGIC(16,
+				AT24_FLAG_ADDR16 |
+				AT24_FLAG_SERIAL |
+				AT24_FLAG_READONLY) },
+	{ "24c128",	AT24_DEVICE_MAGIC(131072 / 8,	AT24_FLAG_ADDR16) },
+	{ "24c256",	AT24_DEVICE_MAGIC(262144 / 8,	AT24_FLAG_ADDR16) },
+	{ "24c512",	AT24_DEVICE_MAGIC(524288 / 8,	AT24_FLAG_ADDR16) },
+	{ "24c1024",	AT24_DEVICE_MAGIC(1048576 / 8,	AT24_FLAG_ADDR16) },
 	{ "at24", 0 },
 	{ /* END OF LIST */ }
 };
@@ -145,9 +187,22 @@ MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
  * This routine supports chips which consume multiple I2C addresses. It
  * computes the addressing information to be used for a given r/w request.
  * Assumes that sanity checks for offset happened at sysfs-layer.
+ *
+ * Slave address and byte offset derive from the offset. Always
+ * set the byte address; on a multi-master board, another master
+ * may have changed the chip's "current" address pointer.
+ *
+ * REVISIT some multi-address chips don't rollover page reads to
+ * the next slave address, so we may need to truncate the count.
+ * Those chips might need another quirk flag.
+ *
+ * If the real hardware used four adjacent 24c02 chips and that
+ * were misconfigured as one 24c08, that would be a similar effect:
+ * one "eeprom" file not four, but larger reads would fail when
+ * they crossed certain pages.
  */
 static struct i2c_client *at24_translate_offset(struct at24_data *at24,
-		unsigned *offset)
+						unsigned int *offset)
 {
 	unsigned i;
 
@@ -162,123 +217,168 @@ static struct i2c_client *at24_translate_offset(struct at24_data *at24,
 	return at24->client[i];
 }
 
-static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
-		unsigned offset, size_t count)
+static ssize_t at24_eeprom_read_smbus(struct at24_data *at24, char *buf,
+				      unsigned int offset, size_t count)
 {
-	struct i2c_msg msg[2];
-	u8 msgbuf[2];
+	unsigned long timeout, read_time;
 	struct i2c_client *client;
+	int status;
+
+	client = at24_translate_offset(at24, &offset);
+
+	if (count > io_limit)
+		count = io_limit;
+
+	/* Smaller eeproms can work given some SMBus extension calls */
+	if (count > I2C_SMBUS_BLOCK_MAX)
+		count = I2C_SMBUS_BLOCK_MAX;
+
+	loop_until_timeout(timeout, read_time) {
+		status = i2c_smbus_read_i2c_block_data_or_emulated(client,
+								   offset,
+								   count, buf);
+
+		dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
+				count, offset, status, jiffies);
+
+		if (status == count)
+			return count;
+	}
+
+	return -ETIMEDOUT;
+}
+
+static ssize_t at24_eeprom_read_i2c(struct at24_data *at24, char *buf,
+				    unsigned int offset, size_t count)
+{
 	unsigned long timeout, read_time;
+	struct i2c_client *client;
+	struct i2c_msg msg[2];
 	int status, i;
+	u8 msgbuf[2];
 
 	memset(msg, 0, sizeof(msg));
-
-	/*
-	 * REVISIT some multi-address chips don't rollover page reads to
-	 * the next slave address, so we may need to truncate the count.
-	 * Those chips might need another quirk flag.
-	 *
-	 * If the real hardware used four adjacent 24c02 chips and that
-	 * were misconfigured as one 24c08, that would be a similar effect:
-	 * one "eeprom" file not four, but larger reads would fail when
-	 * they crossed certain pages.
-	 */
-
-	/*
-	 * Slave address and byte offset derive from the offset. Always
-	 * set the byte address; on a multi-master board, another master
-	 * may have changed the chip's "current" address pointer.
-	 */
 	client = at24_translate_offset(at24, &offset);
 
 	if (count > io_limit)
 		count = io_limit;
 
-	if (at24->use_smbus) {
-		/* Smaller eeproms can work given some SMBus extension calls */
-		if (count > I2C_SMBUS_BLOCK_MAX)
-			count = I2C_SMBUS_BLOCK_MAX;
-	} else {
-		/*
-		 * When we have a better choice than SMBus calls, use a
-		 * combined I2C message. Write address; then read up to
-		 * io_limit data bytes. Note that read page rollover helps us
-		 * here (unlike writes). msgbuf is u8 and will cast to our
-		 * needs.
-		 */
-		i = 0;
-		if (at24->chip.flags & AT24_FLAG_ADDR16)
-			msgbuf[i++] = offset >> 8;
-		msgbuf[i++] = offset;
-
-		msg[0].addr = client->addr;
-		msg[0].buf = msgbuf;
-		msg[0].len = i;
-
-		msg[1].addr = client->addr;
-		msg[1].flags = I2C_M_RD;
-		msg[1].buf = buf;
-		msg[1].len = count;
-	}
-
 	/*
-	 * Reads fail if the previous write didn't complete yet. We may
-	 * loop a few times until this one succeeds, waiting at least
-	 * long enough for one entire page write to work.
+	 * When we have a better choice than SMBus calls, use a combined I2C
+	 * message. Write address; then read up to io_limit data bytes. Note
+	 * that read page rollover helps us here (unlike writes). msgbuf is
+	 * u8 and will cast to our needs.
 	 */
-	timeout = jiffies + msecs_to_jiffies(write_timeout);
-	do {
-		read_time = jiffies;
-		if (at24->use_smbus) {
-			status = i2c_smbus_read_i2c_block_data_or_emulated(client, offset,
-									   count, buf);
-		} else {
-			status = i2c_transfer(client->adapter, msg, 2);
-			if (status == 2)
-				status = count;
-		}
+	i = 0;
+	if (at24->chip.flags & AT24_FLAG_ADDR16)
+		msgbuf[i++] = offset >> 8;
+	msgbuf[i++] = offset;
+
+	msg[0].addr = client->addr;
+	msg[0].buf = msgbuf;
+	msg[0].len = i;
+
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].buf = buf;
+	msg[1].len = count;
+
+	loop_until_timeout(timeout, read_time) {
+		status = i2c_transfer(client->adapter, msg, 2);
+		if (status == 2)
+			status = count;
+
 		dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
 				count, offset, status, jiffies);
 
 		if (status == count)
 			return count;
-
-		usleep_range(1000, 1500);
-	} while (time_before(read_time, timeout));
+	}
 
 	return -ETIMEDOUT;
 }
 
-static int at24_read(void *priv, unsigned int off, void *val, size_t count)
+static ssize_t at24_eeprom_read_serial(struct at24_data *at24, char *buf,
+				       unsigned int offset, size_t count)
 {
-	struct at24_data *at24 = priv;
-	char *buf = val;
+	unsigned long timeout, read_time;
+	struct i2c_client *client;
+	struct i2c_msg msg[2];
+	u8 addrbuf[2];
+	int status;
 
-	if (unlikely(!count))
-		return count;
+	client = at24_translate_offset(at24, &offset);
+
+	memset(msg, 0, sizeof(msg));
+	msg[0].addr = client->addr;
+	msg[0].buf = addrbuf;
 
 	/*
-	 * Read data from chip, protecting against concurrent updates
-	 * from this host, but not from other I2C masters.
+	 * The address pointer of the device is shared between the regular
+	 * EEPROM array and the serial number block. The dummy write (part of
+	 * the sequential read protocol) ensures the address pointer is reset
+	 * to the desired position.
 	 */
-	mutex_lock(&at24->lock);
+	if (at24->chip.flags & AT24_FLAG_ADDR16) {
+		/*
+		 * For 16 bit address pointers, the word address must contain
+		 * a '10' sequence in bits 11 and 10 regardless of the
+		 * intended position of the address pointer.
+		 */
+		addrbuf[0] = 0x08;
+		addrbuf[1] = offset;
+		msg[0].len = 2;
+	} else {
+		/*
+		 * Otherwise the word address must begin with a '10' sequence,
+		 * regardless of the intended address.
+		 */
+		addrbuf[0] = 0x80 + offset;
+		msg[0].len = 1;
+	}
 
-	while (count) {
-		int	status;
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].buf = buf;
+	msg[1].len = count;
 
-		status = at24_eeprom_read(at24, buf, off, count);
-		if (status < 0) {
-			mutex_unlock(&at24->lock);
-			return status;
-		}
-		buf += status;
-		off += status;
-		count -= status;
+	loop_until_timeout(timeout, read_time) {
+		status = i2c_transfer(client->adapter, msg, 2);
+		if (status == 2)
+			return count;
 	}
 
-	mutex_unlock(&at24->lock);
+	return -ETIMEDOUT;
+}
 
-	return 0;
+static ssize_t at24_eeprom_read_mac(struct at24_data *at24, char *buf,
+				    unsigned int offset, size_t count)
+{
+	unsigned long timeout, read_time;
+	struct i2c_client *client;
+	struct i2c_msg msg[2];
+	u8 addrbuf[2];
+	int status;
+
+	client = at24_translate_offset(at24, &offset);
+
+	memset(msg, 0, sizeof(msg));
+	msg[0].addr = client->addr;
+	msg[0].buf = addrbuf;
+	addrbuf[0] = 0x90 + offset;
+	msg[0].len = 1;
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].buf = buf;
+	msg[1].len = count;
+
+	loop_until_timeout(timeout, read_time) {
+		status = i2c_transfer(client->adapter, msg, 2);
+		if (status == 2)
+			return count;
+	}
+
+	return -ETIMEDOUT;
 }
 
 /*
@@ -286,21 +386,15 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
  * chip is normally write protected. But there are plenty of product
  * variants here, including OTP fuses and partial chip protect.
  *
- * We only use page mode writes; the alternative is sloooow. This routine
- * writes at most one page.
+ * We only use page mode writes; the alternative is sloooow. These routines
+ * write at most one page.
  */
-static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
-		unsigned offset, size_t count)
+
+static size_t at24_adjust_write_count(struct at24_data *at24,
+				      unsigned int offset, size_t count)
 {
-	struct i2c_client *client;
-	struct i2c_msg msg;
-	ssize_t status = 0;
-	unsigned long timeout, write_time;
 	unsigned next_page;
 
-	/* Get corresponding I2C address and adjust offset */
-	client = at24_translate_offset(at24, &offset);
-
 	/* write_max is at most a page */
 	if (count > at24->write_max)
 		count = at24->write_max;
@@ -310,62 +404,132 @@ static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
 	if (offset + count > next_page)
 		count = next_page - offset;
 
-	/* If we'll use I2C calls for I/O, set up the message */
-	if (!at24->use_smbus) {
-		int i = 0;
+	return count;
+}
 
-		msg.addr = client->addr;
-		msg.flags = 0;
+static ssize_t at24_eeprom_write_smbus_block(struct at24_data *at24,
+					     const char *buf,
+					     unsigned int offset, size_t count)
+{
+	unsigned long timeout, write_time;
+	struct i2c_client *client;
+	ssize_t status = 0;
 
-		/* msg.buf is u8 and casts will mask the values */
-		msg.buf = at24->writebuf;
-		if (at24->chip.flags & AT24_FLAG_ADDR16)
-			msg.buf[i++] = offset >> 8;
+	client = at24_translate_offset(at24, &offset);
+	count = at24_adjust_write_count(at24, offset, count);
+
+	loop_until_timeout(timeout, write_time) {
+		status = i2c_smbus_write_i2c_block_data(client,
+							offset, count, buf);
+		if (status == 0)
+			status = count;
+
+		dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
+				count, offset, status, jiffies);
 
-		msg.buf[i++] = offset;
-		memcpy(&msg.buf[i], buf, count);
-		msg.len = i + count;
+		if (status == count)
+			return count;
 	}
 
-	/*
-	 * Writes fail if the previous one didn't complete yet. We may
-	 * loop a few times until this one succeeds, waiting at least
-	 * long enough for one entire page write to work.
-	 */
-	timeout = jiffies + msecs_to_jiffies(write_timeout);
-	do {
-		write_time = jiffies;
-		if (at24->use_smbus_write) {
-			switch (at24->use_smbus_write) {
-			case I2C_SMBUS_I2C_BLOCK_DATA:
-				status = i2c_smbus_write_i2c_block_data(client,
-						offset, count, buf);
-				break;
-			case I2C_SMBUS_BYTE_DATA:
-				status = i2c_smbus_write_byte_data(client,
-						offset, buf[0]);
-				break;
-			}
-
-			if (status == 0)
-				status = count;
-		} else {
-			status = i2c_transfer(client->adapter, &msg, 1);
-			if (status == 1)
-				status = count;
-		}
+	return -ETIMEDOUT;
+}
+
+static ssize_t at24_eeprom_write_smbus_byte(struct at24_data *at24,
+					    const char *buf,
+					    unsigned int offset, size_t count)
+{
+	unsigned long timeout, write_time;
+	struct i2c_client *client;
+	ssize_t status = 0;
+
+	client = at24_translate_offset(at24, &offset);
+
+	loop_until_timeout(timeout, write_time) {
+		status = i2c_smbus_write_byte_data(client, offset, buf[0]);
+		if (status == 0)
+			status = count;
+
 		dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
 				count, offset, status, jiffies);
 
 		if (status == count)
 			return count;
+	}
+
+	return -ETIMEDOUT;
+}
+
+static ssize_t at24_eeprom_write_i2c(struct at24_data *at24, const char *buf,
+				     unsigned int offset, size_t count)
+{
+	unsigned long timeout, write_time;
+	struct i2c_client *client;
+	struct i2c_msg msg;
+	ssize_t status = 0;
+	int i = 0;
+
+	client = at24_translate_offset(at24, &offset);
+	count = at24_adjust_write_count(at24, offset, count);
+
+	msg.addr = client->addr;
+	msg.flags = 0;
+
+	/* msg.buf is u8 and casts will mask the values */
+	msg.buf = at24->writebuf;
+	if (at24->chip.flags & AT24_FLAG_ADDR16)
+		msg.buf[i++] = offset >> 8;
 
-		usleep_range(1000, 1500);
-	} while (time_before(write_time, timeout));
+	msg.buf[i++] = offset;
+	memcpy(&msg.buf[i], buf, count);
+	msg.len = i + count;
+
+	loop_until_timeout(timeout, write_time) {
+		status = i2c_transfer(client->adapter, &msg, 1);
+		if (status == 1)
+			status = count;
+
+		dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
+				count, offset, status, jiffies);
+
+		if (status == count)
+			return count;
+	}
 
 	return -ETIMEDOUT;
 }
 
+static int at24_read(void *priv, unsigned int off, void *val, size_t count)
+{
+	struct at24_data *at24 = priv;
+	char *buf = val;
+
+	if (unlikely(!count))
+		return count;
+
+	/*
+	 * Read data from chip, protecting against concurrent updates
+	 * from this host, but not from other I2C masters.
+	 */
+	mutex_lock(&at24->lock);
+
+	while (count) {
+		int	status;
+
+		status = at24->read_func(at24, buf, off, count);
+		if (status < 0) {
+			mutex_unlock(&at24->lock);
+			return status;
+		}
+		buf += status;
+		off += status;
+		count -= status;
+	}
+
+	mutex_unlock(&at24->lock);
+
+	return 0;
+}
+
 static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at24_data *at24 = priv;
@@ -383,7 +547,7 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 	while (count) {
 		int status;
 
-		status = at24_eeprom_write(at24, buf, off, count);
+		status = at24->write_func(at24, buf, off, count);
 		if (status < 0) {
 			mutex_unlock(&at24->lock);
 			return status;
@@ -400,7 +564,7 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 
 #ifdef CONFIG_OF
 static void at24_get_ofdata(struct i2c_client *client,
-		struct at24_platform_data *chip)
+			    struct at24_platform_data *chip)
 {
 	const __be32 *val;
 	struct device_node *node = client->dev.of_node;
@@ -415,7 +579,7 @@ static void at24_get_ofdata(struct i2c_client *client,
 }
 #else
 static void at24_get_ofdata(struct i2c_client *client,
-		struct at24_platform_data *chip)
+			    struct at24_platform_data *chip)
 { }
 #endif /* CONFIG_OF */
 
@@ -518,6 +682,30 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	at24->chip = chip;
 	at24->num_addresses = num_addresses;
 
+	if ((chip.flags & AT24_FLAG_SERIAL) && (chip.flags & AT24_FLAG_MAC)) {
+		dev_err(&client->dev,
+			"invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
+		return -EINVAL;
+	}
+
+	if (chip.flags & AT24_FLAG_SERIAL) {
+		at24->read_func = at24_eeprom_read_serial;
+	} else if (chip.flags & AT24_FLAG_MAC) {
+		at24->read_func = at24_eeprom_read_mac;
+	} else {
+		at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus
+						  : at24_eeprom_read_i2c;
+	}
+
+	if (at24->use_smbus) {
+		if (at24->use_smbus_write == I2C_SMBUS_I2C_BLOCK_DATA)
+			at24->write_func = at24_eeprom_write_smbus_block;
+		else
+			at24->write_func = at24_eeprom_write_smbus_byte;
+	} else {
+		at24->write_func = at24_eeprom_write_i2c;
+	}
+
 	writable = !(chip.flags & AT24_FLAG_READONLY);
 	if (writable) {
 		if (!use_smbus || use_smbus_write) {