Re: [PATCH 2/3] ptp: Add clock name to uevent

[Sven Schnelle <svens@linux.ibm.com>]

Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:

> On Tue, Oct 15, 2024 at 12:54:13PM +0200, Sven Schnelle wrote:
>> To allow users to have stable device names with the help of udev,
>> add the name to the udev event that is sent when a new PtP clock
>> is available. The key is called 'PTP_CLOCK_NAME'.
>
> Where are you documenting this new user/kernel api you are adding?
>
>> 
>> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
>> ---
>>  drivers/ptp/ptp_clock.c | 11 ++++++++++-
>>  1 file changed, 10 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
>> index c56cd0f63909..15937acb79c6 100644
>> --- a/drivers/ptp/ptp_clock.c
>> +++ b/drivers/ptp/ptp_clock.c
>> @@ -25,9 +25,11 @@
>>  #define PTP_PPS_EVENT PPS_CAPTUREASSERT
>>  #define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
>>  
>> +static int ptp_udev_uevent(const struct device *dev, struct kobj_uevent_env *env);
>>  const struct class ptp_class = {
>>  	.name = "ptp",
>> -	.dev_groups = ptp_groups
>> +	.dev_groups = ptp_groups,
>> +	.dev_uevent = ptp_udev_uevent
>>  };
>>  
>>  /* private globals */
>> @@ -514,6 +516,13 @@ EXPORT_SYMBOL(ptp_cancel_worker_sync);
>>  
>>  /* module operations */
>>  
>> +static int ptp_udev_uevent(const struct device *dev, struct kobj_uevent_env *env)
>> +{
>> +	struct ptp_clock *ptp = container_of(dev, struct ptp_clock, dev);
>> +
>> +	return add_uevent_var(env, "PTP_CLOCK_NAME=%s", ptp->info->name);
>
> Why is this needed?  Can't you get the name from the sysfs paths, the
> symlink should be there already.

You mean the 'clock_name' attribute in sysfs? That would require to
write some script to iterate over all ptp devices and check the name,
or is there a way to match that in udev?