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From 20a5b38305df30e25b4429e0e34e35235dd57228 Mon Sep 17 00:00:00 2001
From: Fabrice Gasnier <fabrice.gasnier@st.com>
Date: Mon, 1 Oct 2018 15:23:57 +0200
Subject: [PATCH] pwm: Send a uevent on the pwmchip device upon channel
sysfs (un)export
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
commit 552c02e3e7cfe2744b59de285aaea70021ae95c9 upstream.
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@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>
---
drivers/pwm/sysfs.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -249,6 +249,7 @@ static void pwm_export_release(struct de
static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
{
struct pwm_export *export;
+ char *pwm_prop[2];
int ret;
if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
@@ -276,6 +277,10 @@ static int pwm_export_child(struct devic
export = NULL;
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;
}
@@ -288,6 +293,7 @@ static int pwm_unexport_match(struct dev
static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
{
struct device *child;
+ char *pwm_prop[2];
if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
return -ENODEV;
@@ -296,6 +302,11 @@ static int pwm_unexport_child(struct dev
if (!child)
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() */
put_device(child);
device_unregister(child);
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