Re: [PATCH v8 4/5] nvmem: eeprom: at25: export FRAM serial num

This exports serial number of FRAM in sysfs file named "sernum".
Formatted in hex, each byte separated by space.
Example:
$ cat /sys/class/spi_master/spi0/spi0.0/sernum
0000a43644f2ae6c

Signed-off-by: Jiri Prchal <redacted>
---
v2: no change here
v3: resend and added more recipients
v4: resend
v5: reworked up on Greg comments: no spaces in string, sysfs done correctly
v6: no change here
v7: moved FM25_SN_LEN, static array, used sysfs_emit, DEVICE_ATTR_RO
v8: clarify sysfs_emit format
---
 drivers/misc/eeprom/at25.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index e25cec7c474b..4a47a7e2d90d 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c

@@ -31,6 +31,7 @@
  *   AT25M02, AT25128B
  */
 
+#define	FM25_SN_LEN	8		/* serial number length */
 struct at25_data {
 	struct spi_device	*spi;
 	struct mutex		lock;

@@ -39,6 +40,7 @@ struct at25_data {
 	struct nvmem_config	nvmem_config;
 	struct nvmem_device	*nvmem;
 	int has_sernum;
+	u8 sernum[FM25_SN_LEN];
 };
 
 #define	AT25_WREN	0x06		/* latch the write enable */

@@ -172,6 +174,21 @@ static int fm25_aux_read(struct at25_data *at25, u8 *buf, uint8_t command,
 	return status;
 }
 
+static ssize_t sernum_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct at25_data *at25;
+
+	at25 = dev_get_drvdata(dev);
+	return sysfs_emit(buf, "%*phN\n", sizeof at25->sernum, at25->sernum);