This patch sends a uevent (KOBJ_CHANGE) on the pwmchipN device, everytime
a pwmX channel has been exported/unexported via sysfs.
This allows udev to implement rules on such events, like:
SUBSYSTEM=="pwm*", PROGRAM="/bin/sh -c '\
chown -R root:gpio /sys/class/pwm && chmod -R 770 /sys/class/pwm;\
chown -R root:gpio
/sys/devices/platform/soc/*.pwm/pwm/pwmchip* && chmod -R 770
/sys/devices/platform/soc/*.pwm/pwm/pwmchip*\
'"
This is a replacement patch for commit 7e5d1fd75c3d ("pwm: Set class for
exported channels in sysfs"), see [1].
basic testing:
$ udevadm monitor --environment &
$ echo 0 > /sys/class/pwm/pwmchip0/export
KERNEL[197.321736] change /devices/.../pwm/pwmchip0 (pwm)
ACTION=change
DEVPATH=/devices/.../pwm/pwmchip0
EXPORT=pwm0
SEQNUM=2045
SUBSYSTEM=pwm
[1] https://lkml.org/lkml/2018/9/25/713
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
Tested-by: Gottfried Haider <gottfried.haider@xxxxxxxxx>