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pwm: Send a uevent on the pwmchip device upon channel sysfs (un)export

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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 7e5d1fd75c ("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@st.com>
Tested-by: Gottfried Haider <gottfried.haider@gmail.com>
Tested-by: Michal Vokáč <michal.vokac@ysoft.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Fabrice Gasnier 2018-10-01 15:23:57 +02:00 • committed by Thierry Reding
parent c289d66252
commit 552c02e3e7
1 changed files with 11 additions and 0 deletions
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11
drivers/pwm/sysfs.c
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@ -249,6 +249,7 @@ static void pwm_export_release(struct device *child)
static int pwm_export_child(struct device *parent, struct pwm_device *pwm) static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
{ {
struct pwm_export *export; struct pwm_export *export;
char *pwm_prop[2];
int ret; int ret;
if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags)) if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
@ -276,6 +277,10 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
export = NULL; export = NULL;
return ret; return ret;
} }
pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm);
pwm_prop[1] = NULL;
kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
kfree(pwm_prop[0]);
return 0; return 0;
} }
@ -288,6 +293,7 @@ static int pwm_unexport_match(struct device *child, void *data)
static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
{ {
struct device *child; struct device *child;
char *pwm_prop[2];
if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags)) if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
return -ENODEV; return -ENODEV;
@ -296,6 +302,11 @@ static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
if (!child) if (!child)
return -ENODEV; return -ENODEV;
pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm);
pwm_prop[1] = NULL;
kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
kfree(pwm_prop[0]);
/* for device_find_child() */ /* for device_find_child() */
put_device(child); put_device(child);
device_unregister(child); device_unregister(child);