[PATCH] misc/at24: distinguish between eeprom and fram chips

[Lars Poeschel]

Add a AT24_FLAGS_FRAM state to the flags to make userspace able to
distinguish if it is using eeprom or fram. The sysfs entry gets the
name "fram" instead of "eeprom".
For frams the bytes/write can be at least 128 bytes, since these
chips have no need to internally buffer writes.

Signed-off-by: Lars Poeschel <poeschel@xxxxxxxxxxx>

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index c9e695e..55948a5 100644
--- a/drivers/misc/eeprom/Kconfig
+++ b/drivers/misc/eeprom/Kconfig
@@ -12,6 +12,12 @@ config EEPROM_AT24
 	     24c00, 24c01, 24c02, spd (readonly 24c02), 24c04, 24c08,
 	     24c16, 24c32, 24c64, 24c128, 24c256, 24c512, 24c1024
 
+	  This driver also supports I2C FRAM chips that are feature
+	  compatible to the 24cxx ones. In your at24_platform_data set
+	  .flags = AT24_FLAG_FRAM. These generic names are supported:
+
+	     fm24c04
+
 	  Unless you like data loss puzzles, always be sure that any chip
 	  you configure as a 24c32 (32 kbit) or larger is NOT really a
 	  24c16 (16 kbit) or smaller, and vice versa. Marking the chip
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index ab1ad41..02a03a1 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -125,6 +125,7 @@ static const struct i2c_device_id at24_ids[] = {
 	{ "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) },
+	{ "fm24c04", AT24_DEVICE_MAGIC(4096 / 8, AT24_FLAG_FRAM) },
 	{ "at24", 0 },
 	{ /* END OF LIST */ }
 };
@@ -504,8 +505,13 @@ static int at24_probe(struct i2c_client *client, const 
struct i2c_device_id *id)
 		 * This is slow, but we can't know all eeproms, so we better
 		 * play safe. Specifying custom eeprom-types via platform_data
 		 * is recommended anyhow.
+		 * For fram chips, we can allow minmum 128 bytes, as there is
+		 * no page size and 128 is the smallest so far seen chip.
 		 */
-		chip.page_size = 1;
+		if (chip.flags & AT24_FLAG_FRAM)
+			chip.page_size = 128;
+		else
+			chip.page_size = 1;
 
 		/* update chipdata if OF is present */
 		at24_get_ofdata(client, &chip);
@@ -570,7 +576,10 @@ static int at24_probe(struct i2c_client *client, const 
struct i2c_device_id *id)
 	 * By default, only root should see the data (maybe passwords etc)
 	 */
 	sysfs_bin_attr_init(&at24->bin);
-	at24->bin.attr.name = "eeprom";
+	if (chip.flags & AT24_FLAG_FRAM)
+		at24->bin.attr.name = "fram";
+	else
+		at24->bin.attr.name = "eeprom";
 	at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
 	at24->bin.read = at24_bin_read;
 	at24->bin.size = chip.byte_len;
diff --git a/include/linux/i2c/at24.h b/include/linux/i2c/at24.h
index 285025a..d786b71 100644
--- a/include/linux/i2c/at24.h
+++ b/include/linux/i2c/at24.h
@@ -47,6 +47,7 @@ struct at24_platform_data {
 #define AT24_FLAG_READONLY	0x40	/* sysfs-entry will be read-only */
 #define AT24_FLAG_IRUGO		0x20	/* sysfs-entry will be world-readable */
 #define AT24_FLAG_TAKE8ADDR	0x10	/* take always 8 addresses (24c00) */
+#define AT24_FLAG_FRAM          0x08    /* chip is fram not eeprom */
 
 	void		(*setup)(struct memory_accessor *, void *context);
 	void		*context;
-- 
1.7.10.4

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