On Mon, Jun 07, 2021 at 02:26:39PM +0200, Jiri Prchal wrote:
> 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 <jiri.prchal@xxxxxxxxxxx>
> ---
> 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
> ---
> 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 3b7ffef1f0d7..a28dfd7e1798 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, 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;
> +
> + at25 = dev_get_drvdata(dev);
> + return sysfs_emit(buf, "%016llx\n", *(unsigned long long *)at25->sernum);
That's a horrid hack, why not use the %*phN modifier?
Look in the printk-formats.rst file for help.
thanks,
greg k-h
