Merge branch 'i2c/for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c updates from Wolfram Sang:
 "I2C has the following changes for you:

   - new flag to mark DMA safe buffers in i2c_msg. Also, some
     infrastructure around it. And docs.

   - huge refactoring of the at24 driver led by the new maintainer
     Bartosz

   - update I2C bus recovery to send STOP after recovery

   - conversion from gpio to gpiod for I2C bus recovery

   - adding a fault-injector to the i2c-gpio driver

   - lots of small driver improvements, and bigger ones to
     i2c-sh_mobile"

* 'i2c/for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (99 commits)
  i2c: mv64xxx: Add myself as maintainer for this driver
  i2c: mv64xxx: Fix clock resource by adding an optional bus clock
  i2c: mv64xxx: Remove useless test before clk_disable_unprepare
  i2c: mxs: use true and false for boolean values
  i2c: meson: update doc description to fix build warnings
  i2c: meson: add configurable divider factors
  dt-bindings: i2c: update documentation for the Meson-AXG
  i2c: imx-lpi2c: add runtime pm support
  i2c: rcar: fix some trivial typos in comments
  i2c: davinci: fix the cpufreq transition
  i2c: rk3x: add proper kerneldoc header
  i2c: rk3x: account for const type of of_device_id.data
  i2c: acorn: remove outdated path from file header
  i2c: acorn: add MODULE_LICENSE tag
  i2c: rcar: implement bus recovery
  i2c: send STOP after successful bus recovery
  i2c: ensure SDA is released in recovery if SDA is controllable
  i2c: add 'set_sda' to bus_recovery_info
  i2c: add identifier in declarations for i2c_bus_recovery
  i2c: make kerneldoc about bus recovery more precise
  ...

2 files changed, 255 insertions, 477 deletions

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index de58762097c4..68a1ac929917 100644
--- a/drivers/misc/eeprom/Kconfig
+++ b/drivers/misc/eeprom/Kconfig
@@ -4,6 +4,7 @@ config EEPROM_AT24
 	tristate "I2C EEPROMs / RAMs / ROMs from most vendors"
 	depends on I2C && SYSFS
 	select NVMEM
+	select REGMAP_I2C
 	help
 	  Enable this driver to get read/write support to most I2C EEPROMs
 	  and compatible devices like FRAMs, SRAMs, ROMs etc. After you
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 4d63ac8a82e0..01f9c4921c50 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -24,8 +24,10 @@
 #include <linux/acpi.h>
 #include <linux/i2c.h>
 #include <linux/nvmem-provider.h>
+#include <linux/regmap.h>
 #include <linux/platform_data/at24.h>
 #include <linux/pm_runtime.h>
+#include <linux/gpio/consumer.h>
 
 /*
  * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
@@ -55,14 +57,13 @@
  * which won't work on pure SMBus systems.
  */
 
+struct at24_client {
+	struct i2c_client *client;
+	struct regmap *regmap;
+};
+
 struct at24_data {
 	struct at24_platform_data chip;
-	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,
@@ -70,18 +71,20 @@ struct at24_data {
 	 */
 	struct mutex lock;
 
-	u8 *writebuf;
-	unsigned write_max;
-	unsigned num_addresses;
+	unsigned int write_max;
+	unsigned int num_addresses;
+	unsigned int offset_adj;
 
 	struct nvmem_config nvmem_config;
 	struct nvmem_device *nvmem;
 
+	struct gpio_desc *wp_gpio;
+
 	/*
 	 * Some chips tie up multiple I2C addresses; dummy devices reserve
 	 * them for us, and we'll use them with SMBus calls.
 	 */
-	struct i2c_client *client[];
+	struct at24_client client[];
 };
 
 /*
@@ -93,27 +96,17 @@ struct at24_data {
  *
  * This value is forced to be a power of two so that writes align on pages.
  */
-static unsigned io_limit = 128;
-module_param(io_limit, uint, 0);
-MODULE_PARM_DESC(io_limit, "Maximum bytes per I/O (default 128)");
+static unsigned int at24_io_limit = 128;
+module_param_named(io_limit, at24_io_limit, uint, 0);
+MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
 
 /*
  * Specs often allow 5 msec for a page write, sometimes 20 msec;
  * it's important to recover from write timeouts.
  */
-static unsigned write_timeout = 25;
-module_param(write_timeout, uint, 0);
-MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
-
-#define AT24_SIZE_BYTELEN 5
-#define AT24_SIZE_FLAGS 8
-
-#define AT24_BITMASK(x) (BIT(x) - 1)
-
-/* create non-zero magic value for given eeprom parameters */
-#define AT24_DEVICE_MAGIC(_len, _flags) 		\
-	((1 << AT24_SIZE_FLAGS | (_flags)) 		\
-	    << AT24_SIZE_BYTELEN | ilog2(_len))
+static unsigned int at24_write_timeout = 25;
+module_param_named(write_timeout, at24_write_timeout, uint, 0);
+MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
 
 /*
  * Both reads and writes fail if the previous write didn't complete yet. This
@@ -126,118 +119,123 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
  * 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; \
+#define at24_loop_until_timeout(tout, op_time)				\
+	for (tout = jiffies + msecs_to_jiffies(at24_write_timeout),	\
+	     op_time = 0;						\
 	     op_time ? time_before(op_time, tout) : true;		\
 	     usleep_range(1000, 1500), op_time = jiffies)
 
+struct at24_chip_data {
+	/*
+	 * these fields mirror their equivalents in
+	 * struct at24_platform_data
+	 */
+	u32 byte_len;
+	u8 flags;
+};
+
+#define AT24_CHIP_DATA(_name, _len, _flags)				\
+	static const struct at24_chip_data _name = {			\
+		.byte_len = _len, .flags = _flags,			\
+	}
+
+/* needs 8 addresses as A0-A2 are ignored */
+AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
+/* old variants can't be handled with this generic entry! */
+AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs01, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs02, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
+	AT24_FLAG_MAC | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
+	AT24_FLAG_MAC | AT24_FLAG_READONLY);
+/* spd is a 24c02 in memory DIMMs */
+AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
+	AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
+AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs04, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+/* 24rf08 quirk is handled at i2c-core */
+AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs08, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
+AT24_CHIP_DATA(at24_data_24cs16, 16,
+	AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24cs32, 16,
+	AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24cs64, 16,
+	AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
+AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
+AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
+/* identical to 24c08 ? */
+AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
+
 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) },
-	/* old variants can't be handled with this generic entry! */
-	{ "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) },
-	{ "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) },
-	{ "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 },
+	{ "24c00",	(kernel_ulong_t)&at24_data_24c00 },
+	{ "24c01",	(kernel_ulong_t)&at24_data_24c01 },
+	{ "24cs01",	(kernel_ulong_t)&at24_data_24cs01 },
+	{ "24c02",	(kernel_ulong_t)&at24_data_24c02 },
+	{ "24cs02",	(kernel_ulong_t)&at24_data_24cs02 },
+	{ "24mac402",	(kernel_ulong_t)&at24_data_24mac402 },
+	{ "24mac602",	(kernel_ulong_t)&at24_data_24mac602 },
+	{ "spd",	(kernel_ulong_t)&at24_data_spd },
+	{ "24c04",	(kernel_ulong_t)&at24_data_24c04 },
+	{ "24cs04",	(kernel_ulong_t)&at24_data_24cs04 },
+	{ "24c08",	(kernel_ulong_t)&at24_data_24c08 },
+	{ "24cs08",	(kernel_ulong_t)&at24_data_24cs08 },
+	{ "24c16",	(kernel_ulong_t)&at24_data_24c16 },
+	{ "24cs16",	(kernel_ulong_t)&at24_data_24cs16 },
+	{ "24c32",	(kernel_ulong_t)&at24_data_24c32 },
+	{ "24cs32",	(kernel_ulong_t)&at24_data_24cs32 },
+	{ "24c64",	(kernel_ulong_t)&at24_data_24c64 },
+	{ "24cs64",	(kernel_ulong_t)&at24_data_24cs64 },
+	{ "24c128",	(kernel_ulong_t)&at24_data_24c128 },
+	{ "24c256",	(kernel_ulong_t)&at24_data_24c256 },
+	{ "24c512",	(kernel_ulong_t)&at24_data_24c512 },
+	{ "24c1024",	(kernel_ulong_t)&at24_data_24c1024 },
+	{ "at24",	0 },
 	{ /* END OF LIST */ }
 };
 MODULE_DEVICE_TABLE(i2c, at24_ids);
 
 static const struct of_device_id at24_of_match[] = {
-	{
-		.compatible = "atmel,24c00",
-		.data = (void *)AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR)
-	},
-	{
-		.compatible = "atmel,24c01",
-		.data = (void *)AT24_DEVICE_MAGIC(1024 / 8, 0)
-	},
-	{
-		.compatible = "atmel,24c02",
-		.data = (void *)AT24_DEVICE_MAGIC(2048 / 8, 0)
-	},
-	{
-		.compatible = "atmel,spd",
-		.data = (void *)AT24_DEVICE_MAGIC(2048 / 8,
-				AT24_FLAG_READONLY | AT24_FLAG_IRUGO)
-	},
-	{
-		.compatible = "atmel,24c04",
-		.data = (void *)AT24_DEVICE_MAGIC(4096 / 8, 0)
-	},
-	{
-		.compatible = "atmel,24c08",
-		.data = (void *)AT24_DEVICE_MAGIC(8192 / 8, 0)
-	},
-	{
-		.compatible = "atmel,24c16",
-		.data = (void *)AT24_DEVICE_MAGIC(16384 / 8, 0)
-	},
-	{
-		.compatible = "atmel,24c32",
-		.data = (void *)AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16)
-	},
-	{
-		.compatible = "atmel,24c64",
-		.data = (void *)AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16)
-	},
-	{
-		.compatible = "atmel,24c128",
-		.data = (void *)AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16)
-	},
-	{
-		.compatible = "atmel,24c256",
-		.data = (void *)AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16)
-	},
-	{
-		.compatible = "atmel,24c512",
-		.data = (void *)AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16)
-	},
-	{
-		.compatible = "atmel,24c1024",
-		.data = (void *)AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16)
-	},
-	{ },
+	{ .compatible = "atmel,24c00",		.data = &at24_data_24c00 },
+	{ .compatible = "atmel,24c01",		.data = &at24_data_24c01 },
+	{ .compatible = "atmel,24cs01",		.data = &at24_data_24cs01 },
+	{ .compatible = "atmel,24c02",		.data = &at24_data_24c02 },
+	{ .compatible = "atmel,24cs02",		.data = &at24_data_24cs02 },
+	{ .compatible = "atmel,24mac402",	.data = &at24_data_24mac402 },
+	{ .compatible = "atmel,24mac602",	.data = &at24_data_24mac602 },
+	{ .compatible = "atmel,spd",		.data = &at24_data_spd },
+	{ .compatible = "atmel,24c04",		.data = &at24_data_24c04 },
+	{ .compatible = "atmel,24cs04",		.data = &at24_data_24cs04 },
+	{ .compatible = "atmel,24c08",		.data = &at24_data_24c08 },
+	{ .compatible = "atmel,24cs08",		.data = &at24_data_24cs08 },
+	{ .compatible = "atmel,24c16",		.data = &at24_data_24c16 },
+	{ .compatible = "atmel,24cs16",		.data = &at24_data_24cs16 },
+	{ .compatible = "atmel,24c32",		.data = &at24_data_24c32 },
+	{ .compatible = "atmel,24cs32",		.data = &at24_data_24cs32 },
+	{ .compatible = "atmel,24c64",		.data = &at24_data_24c64 },
+	{ .compatible = "atmel,24cs64",		.data = &at24_data_24cs64 },
+	{ .compatible = "atmel,24c128",		.data = &at24_data_24c128 },
+	{ .compatible = "atmel,24c256",		.data = &at24_data_24c256 },
+	{ .compatible = "atmel,24c512",		.data = &at24_data_24c512 },
+	{ .compatible = "atmel,24c1024",	.data = &at24_data_24c1024 },
+	{ /* END OF LIST */ },
 };
 MODULE_DEVICE_TABLE(of, at24_of_match);
 
 static const struct acpi_device_id at24_acpi_ids[] = {
-	{ "INT3499", AT24_DEVICE_MAGIC(8192 / 8, 0) },
-	{ }
+	{ "INT3499",	(kernel_ulong_t)&at24_data_INT3499 },
+	{ /* END OF LIST */ }
 };
 MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
 
@@ -251,20 +249,11 @@ MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
  * 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 int *offset)
+static struct at24_client *at24_translate_offset(struct at24_data *at24,
+						 unsigned int *offset)
 {
-	unsigned i;
+	unsigned int i;
 
 	if (at24->chip.flags & AT24_FLAG_ADDR16) {
 		i = *offset >> 16;
@@ -274,168 +263,55 @@ static struct i2c_client *at24_translate_offset(struct at24_data *at24,
 		*offset &= 0xff;
 	}
 
-	return at24->client[i];
+	return &at24->client[i];
 }
 
-static ssize_t at24_eeprom_read_smbus(struct at24_data *at24, char *buf,
+static size_t at24_adjust_read_count(struct at24_data *at24,
 				      unsigned int offset, size_t count)
 {
-	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));
-	client = at24_translate_offset(at24, &offset);
-
-	if (count > io_limit)
-		count = io_limit;
+	unsigned int bits;
+	size_t remainder;
 
 	/*
-	 * 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.
+	 * In case of multi-address chips that don't rollover reads to
+	 * the next slave address: truncate the count to the slave boundary,
+	 * so that the read never straddles slaves.
 	 */
-	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;
+	if (at24->chip.flags & AT24_FLAG_NO_RDROL) {
+		bits = (at24->chip.flags & AT24_FLAG_ADDR16) ? 16 : 8;
+		remainder = BIT(bits) - offset;
+		if (count > remainder)
+			count = remainder;
 	}
 
-	return -ETIMEDOUT;
+	if (count > at24_io_limit)
+		count = at24_io_limit;
+
+	return count;
 }
 
-static ssize_t at24_eeprom_read_serial(struct at24_data *at24, char *buf,
-				       unsigned int offset, size_t count)
+static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
+				unsigned int offset, size_t count)
 {
 	unsigned long timeout, read_time;
+	struct at24_client *at24_client;
 	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;
-
-	/*
-	 * 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.
-	 */
-	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;
-	}
-
-	msg[1].addr = client->addr;
-	msg[1].flags = I2C_M_RD;
-	msg[1].buf = buf;
-	msg[1].len = count;
+	struct regmap *regmap;
+	int ret;
 
-	loop_until_timeout(timeout, read_time) {
-		status = i2c_transfer(client->adapter, msg, 2);
-		if (status == 2)
-			return count;
-	}
+	at24_client = at24_translate_offset(at24, &offset);
+	regmap = at24_client->regmap;
+	client = at24_client->client;
+	count = at24_adjust_read_count(at24, offset, count);
 
-	return -ETIMEDOUT;
-}
+	/* adjust offset for mac and serial read ops */
+	offset += at24->offset_adj;
 
-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;
-	/* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
-	addrbuf[0] = 0xa0 - at24->chip.byte_len + 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)
+	at24_loop_until_timeout(timeout, read_time) {
+		ret = regmap_bulk_read(regmap, offset, buf, count);
+		dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
+			count, offset, ret, jiffies);
+		if (!ret)
 			return count;
 	}
 
@@ -454,7 +330,7 @@ static ssize_t at24_eeprom_read_mac(struct at24_data *at24, char *buf,
 static size_t at24_adjust_write_count(struct at24_data *at24,
 				      unsigned int offset, size_t count)
 {
-	unsigned next_page;
+	unsigned int next_page;
 
 	/* write_max is at most a page */
 	if (count > at24->write_max)
@@ -468,91 +344,25 @@ static size_t at24_adjust_write_count(struct at24_data *at24,
 	return count;
 }
 
-static ssize_t at24_eeprom_write_smbus_block(struct at24_data *at24,
-					     const char *buf,
-					     unsigned int offset, size_t count)
+static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
+				 unsigned int offset, size_t count)
 {
 	unsigned long timeout, write_time;
+	struct at24_client *at24_client;
 	struct i2c_client *client;
-	ssize_t status = 0;
-
-	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);
-
-		if (status == count)
-			return 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;
+	struct regmap *regmap;
+	int ret;
 
-	client = at24_translate_offset(at24, &offset);
+	at24_client = at24_translate_offset(at24, &offset);
+	regmap = at24_client->regmap;
+	client = at24_client->client;
 	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;
-
-	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)
+	at24_loop_until_timeout(timeout, write_time) {
+		ret = regmap_bulk_write(regmap, offset, buf, count);
+		dev_dbg(&client->dev, "write %zu@%d --> %d (%ld)\n",
+			count, offset, ret, jiffies);
+		if (!ret)
 			return count;
 	}
 
@@ -562,7 +372,7 @@ static ssize_t at24_eeprom_write_i2c(struct at24_data *at24, const char *buf,
 static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at24_data *at24 = priv;
-	struct device *dev = &at24->client[0]->dev;
+	struct device *dev = &at24->client[0].client->dev;
 	char *buf = val;
 	int ret;
 
@@ -587,7 +397,7 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 	while (count) {
 		int	status;
 
-		status = at24->read_func(at24, buf, off, count);
+		status = at24_regmap_read(at24, buf, off, count);
 		if (status < 0) {
 			mutex_unlock(&at24->lock);
 			pm_runtime_put(dev);
@@ -608,7 +418,7 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at24_data *at24 = priv;
-	struct device *dev = &at24->client[0]->dev;
+	struct device *dev = &at24->client[0].client->dev;
 	char *buf = val;
 	int ret;
 
@@ -629,12 +439,14 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 	 * from this host, but not from other I2C masters.
 	 */
 	mutex_lock(&at24->lock);
+	gpiod_set_value_cansleep(at24->wp_gpio, 0);
 
 	while (count) {
 		int status;
 
-		status = at24->write_func(at24, buf, off, count);
+		status = at24_regmap_write(at24, buf, off, count);
 		if (status < 0) {
+			gpiod_set_value_cansleep(at24->wp_gpio, 1);
 			mutex_unlock(&at24->lock);
 			pm_runtime_put(dev);
 			return status;
@@ -644,6 +456,7 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 		count -= status;
 	}
 
+	gpiod_set_value_cansleep(at24->wp_gpio, 1);
 	mutex_unlock(&at24->lock);
 
 	pm_runtime_put(dev);
@@ -658,6 +471,8 @@ static void at24_get_pdata(struct device *dev, struct at24_platform_data *chip)
 
 	if (device_property_present(dev, "read-only"))
 		chip->flags |= AT24_FLAG_READONLY;
+	if (device_property_present(dev, "no-read-rollover"))
+		chip->flags |= AT24_FLAG_NO_RDROL;
 
 	err = device_property_read_u32(dev, "size", &val);
 	if (!err)
@@ -676,16 +491,38 @@ static void at24_get_pdata(struct device *dev, struct at24_platform_data *chip)
 	}
 }
 
+static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
+{
+	if (flags & AT24_FLAG_MAC) {
+		/* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
+		return 0xa0 - byte_len;
+	} else if (flags & AT24_FLAG_SERIAL && 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.
+		 */
+		return 0x0800;
+	} else if (flags & AT24_FLAG_SERIAL) {
+		/*
+		 * Otherwise the word address must begin with a '10' sequence,
+		 * regardless of the intended address.
+		 */
+		return 0x0080;
+	} else {
+		return 0;
+	}
+}
+
 static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
-	struct at24_platform_data chip;
-	kernel_ulong_t magic = 0;
+	struct at24_platform_data chip = { 0 };
+	const struct at24_chip_data *cd = NULL;
 	bool writable;
-	int use_smbus = 0;
-	int use_smbus_write = 0;
 	struct at24_data *at24;
 	int err;
-	unsigned i, num_addresses;
+	unsigned int i, num_addresses;
+	struct regmap_config regmap_config = { };
 	u8 test_byte;
 
 	if (client->dev.platform_data) {
@@ -698,28 +535,22 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		 */
 		if (client->dev.of_node &&
 		    of_match_device(at24_of_match, &client->dev)) {
-			magic = (kernel_ulong_t)
-				of_device_get_match_data(&client->dev);
+			cd = of_device_get_match_data(&client->dev);
 		} else if (id) {
-			magic = id->driver_data;
+			cd = (void *)id->driver_data;
 		} else {
 			const struct acpi_device_id *aid;
 
 			aid = acpi_match_device(at24_acpi_ids, &client->dev);
 			if (aid)
-				magic = aid->driver_data;
+				cd = (void *)aid->driver_data;
 		}
-		if (!magic)
+		if (!cd)
 			return -ENODEV;
 
-		chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
-		magic >>= AT24_SIZE_BYTELEN;
-		chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
-
+		chip.byte_len = cd->byte_len;
+		chip.flags = cd->flags;
 		at24_get_pdata(&client->dev, &chip);
-
-		chip.setup = NULL;
-		chip.context = NULL;
 	}
 
 	if (!is_power_of_2(chip.byte_len))
@@ -733,43 +564,10 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		dev_warn(&client->dev,
 			"page_size looks suspicious (no power of 2)!\n");
 
-	/*
-	 * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while
-	 * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4.
-	 *
-	 * Eventually we'll get rid of the magic values altoghether in favor of
-	 * real structs, but for now just manually set the right size.
-	 */
-	if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4)
-		chip.byte_len = 6;
-
-	/* Use I2C operations unless we're stuck with SMBus extensions. */
-	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
-		if (chip.flags & AT24_FLAG_ADDR16)
-			return -EPFNOSUPPORT;
-
-		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 {
-			return -EPFNOSUPPORT;
-		}
-
-		if (i2c_check_functionality(client->adapter,
-				I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
-			use_smbus_write = I2C_SMBUS_I2C_BLOCK_DATA;
-		} else if (i2c_check_functionality(client->adapter,
-				I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
-			use_smbus_write = I2C_SMBUS_BYTE_DATA;
-			chip.page_size = 1;
-		}
-	}
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
+	    !i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WRITE_I2C_BLOCK))
+		chip.page_size = 1;
 
 	if (chip.flags & AT24_FLAG_TAKE8ADDR)
 		num_addresses = 8;
@@ -777,16 +575,28 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		num_addresses =	DIV_ROUND_UP(chip.byte_len,
 			(chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
 
+	regmap_config.val_bits = 8;
+	regmap_config.reg_bits = (chip.flags & AT24_FLAG_ADDR16) ? 16 : 8;
+
 	at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
-		num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
+		num_addresses * sizeof(struct at24_client), GFP_KERNEL);
 	if (!at24)
 		return -ENOMEM;
 
 	mutex_init(&at24->lock);
-	at24->use_smbus = use_smbus;
-	at24->use_smbus_write = use_smbus_write;
 	at24->chip = chip;
 	at24->num_addresses = num_addresses;
+	at24->offset_adj = at24_get_offset_adj(chip.flags, chip.byte_len);
+
+	at24->wp_gpio = devm_gpiod_get_optional(&client->dev,
+						"wp", GPIOD_OUT_HIGH);
+	if (IS_ERR(at24->wp_gpio))
+		return PTR_ERR(at24->wp_gpio);
+
+	at24->client[0].client = client;
+	at24->client[0].regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(at24->client[0].regmap))
+		return PTR_ERR(at24->client[0].regmap);
 
 	if ((chip.flags & AT24_FLAG_SERIAL) && (chip.flags & AT24_FLAG_MAC)) {
 		dev_err(&client->dev,
@@ -794,59 +604,32 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		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) {
-
-			unsigned write_max = chip.page_size;
-
-			if (write_max > io_limit)
-				write_max = io_limit;
-			if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
-				write_max = I2C_SMBUS_BLOCK_MAX;
-			at24->write_max = write_max;
-
-			/* buffer (data + address at the beginning) */
-			at24->writebuf = devm_kzalloc(&client->dev,
-				write_max + 2, GFP_KERNEL);
-			if (!at24->writebuf)
-				return -ENOMEM;
-		} else {
-			dev_warn(&client->dev,
-				"cannot write due to controller restrictions.");
-		}
+		at24->write_max = min_t(unsigned int,
+					chip.page_size, at24_io_limit);
+		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
+		    at24->write_max > I2C_SMBUS_BLOCK_MAX)
+			at24->write_max = I2C_SMBUS_BLOCK_MAX;
 	}
 
-	at24->client[0] = client;
-
 	/* use dummy devices for multiple-address chips */
 	for (i = 1; i < num_addresses; i++) {
-		at24->client[i] = i2c_new_dummy(client->adapter,
-					client->addr + i);
-		if (!at24->client[i]) {
+		at24->client[i].client = i2c_new_dummy(client->adapter,
+						       client->addr + i);
+		if (!at24->client[i].client) {
 			dev_err(&client->dev, "address 0x%02x unavailable\n",
 					client->addr + i);
 			err = -EADDRINUSE;
 			goto err_clients;
 		}
+		at24->client[i].regmap = devm_regmap_init_i2c(
+						at24->client[i].client,
+						&regmap_config);
+		if (IS_ERR(at24->client[i].regmap)) {
+			err = PTR_ERR(at24->client[i].regmap);
+			goto err_clients;
+		}
 	}
 
 	i2c_set_clientdata(client, at24);
@@ -890,12 +673,6 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	dev_info(&client->dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
 		chip.byte_len, client->name,
 		writable ? "writable" : "read-only", at24->write_max);
-	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");
-	}
 
 	/* export data to kernel code */
 	if (chip.setup)
@@ -905,8 +682,8 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 err_clients:
 	for (i = 1; i < num_addresses; i++)
-		if (at24->client[i])
-			i2c_unregister_device(at24->client[i]);
+		if (at24->client[i].client)
+			i2c_unregister_device(at24->client[i].client);
 
 	pm_runtime_disable(&client->dev);
 
@@ -923,7 +700,7 @@ static int at24_remove(struct i2c_client *client)
 	nvmem_unregister(at24->nvmem);
 
 	for (i = 1; i < at24->num_addresses; i++)
-		i2c_unregister_device(at24->client[i]);
+		i2c_unregister_device(at24->client[i].client);
 
 	pm_runtime_disable(&client->dev);
 	pm_runtime_set_suspended(&client->dev);
@@ -946,12 +723,12 @@ static struct i2c_driver at24_driver = {
 
 static int __init at24_init(void)
 {
-	if (!io_limit) {
-		pr_err("at24: io_limit must not be 0!\n");
+	if (!at24_io_limit) {
+		pr_err("at24: at24_io_limit must not be 0!\n");
 		return -EINVAL;
 	}
 
-	io_limit = rounddown_pow_of_two(io_limit);
+	at24_io_limit = rounddown_pow_of_two(at24_io_limit);
 	return i2c_add_driver(&at24_driver);
 }
 module_init(at24_init);