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   1 From 20a5b38305df30e25b4429e0e34e35235dd57228 Mon Sep 17 00:00:00 2001
   2 From: Fabrice Gasnier <fabrice.gasnier@st.com>
   3 Date: Mon, 1 Oct 2018 15:23:57 +0200
   4 Subject: [PATCH] pwm: Send a uevent on the pwmchip device upon channel
   5  sysfs (un)export
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 commit 552c02e3e7cfe2744b59de285aaea70021ae95c9 upstream.
  11
  12 This patch sends a uevent (KOBJ_CHANGE) on the pwmchipN device,
  13 everytime a pwmX channel has been exported/unexported via sysfs. This
  14 allows udev to implement rules on such events, like:
  15
  16 SUBSYSTEM=="pwm*", PROGRAM="/bin/sh -c '\
  17         chown -R root:gpio /sys/class/pwm && chmod -R 770 /sys/class/pwm;\
  18         chown -R root:gpio
  19 /sys/devices/platform/soc/*.pwm/pwm/pwmchip* && chmod -R 770
  20 /sys/devices/platform/soc/*.pwm/pwm/pwmchip*\
  21 '"
  22
  23 This is a replacement patch for commit 7e5d1fd75c3d ("pwm: Set class for
  24 exported channels in sysfs"), see [1].
  25
  26 basic testing:
  27 $ udevadm monitor --environment &
  28 $ echo 0 > /sys/class/pwm/pwmchip0/export
  29 KERNEL[197.321736] change   /devices/.../pwm/pwmchip0 (pwm)
  30 ACTION=change
  31 DEVPATH=/devices/.../pwm/pwmchip0
  32 EXPORT=pwm0
  33 SEQNUM=2045
  34 SUBSYSTEM=pwm
  35
  36 [1] https://lkml.org/lkml/2018/9/25/713
  37
  38 Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
  39 Tested-by: Gottfried Haider <gottfried.haider@gmail.com>
  40 Tested-by: Michal Vokáč <michal.vokac@ysoft.com>
  41 Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
  42 ---
  43  drivers/pwm/sysfs.c | 11 +++++++++++
  44  1 file changed, 11 insertions(+)
  45
  46 --- a/drivers/pwm/sysfs.c
  47 +++ b/drivers/pwm/sysfs.c
  48 @@ -249,6 +249,7 @@ static void pwm_export_release(struct de
  49  static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
  50  {
  51         struct pwm_export *export;
  52 +       char *pwm_prop[2];
  53         int ret;
  54
  55         if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
  56 @@ -276,6 +277,10 @@ static int pwm_export_child(struct devic
  57                 export = NULL;
  58                 return ret;
  59         }
  60 +       pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm);
  61 +       pwm_prop[1] = NULL;
  62 +       kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
  63 +       kfree(pwm_prop[0]);
  64
  65         return 0;
  66  }
  67 @@ -288,6 +293,7 @@ static int pwm_unexport_match(struct dev
  68  static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
  69  {
  70         struct device *child;
  71 +       char *pwm_prop[2];
  72
  73         if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
  74                 return -ENODEV;
  75 @@ -296,6 +302,11 @@ static int pwm_unexport_child(struct dev
  76         if (!child)
  77                 return -ENODEV;
  78
  79 +       pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm);
  80 +       pwm_prop[1] = NULL;
  81 +       kobject_uevent_env(&parent->kobj, KOBJ_CHANGE, pwm_prop);
  82 +       kfree(pwm_prop[0]);
  83 +
  84         /* for device_find_child() */
  85         put_device(child);
  86         device_unregister(child);