[PATCH v4 4/4] nvmem: eeprom: at25: export FRAM serial num

Jiri Prchal
2021-05-20T05:47:33Z

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
a4 36 44 f2 ae 6c 00 00

Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
---
v2: no change here
v3: resend and added more recipients
v4: resend
---
drivers/misc/eeprom/at25.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index 4f6e983c278b..b2cffeb3af2c 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c
@@ -38,6 +38,7 @@ struct at25_data {
struct nvmem_config nvmem_config;
struct nvmem_device *nvmem;
int has_sernum;
+ char *sernum;
};

#define AT25_WREN 0x06 /* latch the write enable */
@@ -172,6 +173,19 @@ static int fm25_aux_read(struct at25_data *at25, char *buf, uint8_t command,
return status;
}

+static ssize_t sernum_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct at25_data *at25;
+ int i;
+
+ at25 = dev_get_drvdata(dev);
+ for (i = 0; i < FM25_SN_LEN; i++)
+ buf += sprintf(buf, "%02x ", at25->sernum[i]);
+ sprintf(--buf, "\n");
+ return (3 * i);
+}
+static DEVICE_ATTR_RO(sernum);
+
static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
{
struct at25_data *at25 = priv;
@@ -427,8 +441,13 @@ static int at25_probe(struct spi_device *spi)
else
at25->chip.flags |= EE_ADDR2;

- if (id[8])
+ if (id[8]) {
at25->has_sernum = 1;
+ at25->sernum = kzalloc(FM25_SN_LEN, GFP_KERNEL);
+ if (!at25->sernum)
+ return -ENOMEM;
+ fm25_aux_read(at25, at25->sernum, FM25_RDSN, FM25_SN_LEN);
+ }
else
at25->has_sernum = 0;

@@ -467,6 +486,13 @@ static int at25_probe(struct spi_device *spi)
if (IS_ERR(at25->nvmem))
return PTR_ERR(at25->nvmem);

+ /* Export the FM25 serial number */
+ if (at25->has_sernum) {
+ err = device_create_file(&spi->dev, &dev_attr_sernum);
+ if (err)
+ return err;
+ }
+
dev_info(&spi->dev, "%d %s %s %s%s, pagesize %u\n",
(chip.byte_len < 1024) ? chip.byte_len : (chip.byte_len / 1024),
(chip.byte_len < 1024) ? "Byte" : "KByte",
--
2.25.1