i2c: slave-eeprom: add support for 24c512 EEPROMs

I don't plan to support every EEPROM type, but the 24c512 ones need a
tiny code update, so let's have that upstream.
Reported-by: Patrick Williams <patrick@stwcx.xyz>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Patrick Williams <patrick@stwcx.xyz>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/i2c-slave-eeprom.c

@@ -41,7 +41,7 @@ struct eeprom_data {
 #define I2C_SLAVE_BYTELEN GENMASK(15, 0)
 #define I2C_SLAVE_FLAG_ADDR16 BIT(16)
 #define I2C_SLAVE_FLAG_RO BIT(17)
-#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | (_len))
+#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | ((_len) - 1))
 
 static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
 				     enum i2c_slave_event event, u8 *val)
@@ -145,7 +145,7 @@ static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_de
 {
 	struct eeprom_data *eeprom;
 	int ret;
-	unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data);
+	unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data) + 1;
 	unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);
 
 	eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
@@ -200,6 +200,8 @@ static const struct i2c_device_id i2c_slave_eeprom_id[] = {
 	{ "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
 	{ "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
 	{ "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
+	{ "slave-24c512", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16) },
+	{ "slave-24c512ro", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);