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 reverts commit 7e5d1fd75c ("pwm: Set
class for exported channels in sysfs") as it causes regression with
multiple pwm chip[1], when exporting a pwm channel (echo X > export):
- ABI (Documentation/ABI/testing/sysfs-class-pwm) states pwmX should be
created in /sys/class/pwm/pwmchipN/pwmX
- Reverted patch causes new entry to be also created directly in
/sys/class/pwm/pwmX
- 1st time, exporting pwmX will create an entry in /sys/class/pwm/pwmX
- class attributes are added under pwmX folder, such as export, unexport
npwm, symlinks. This is wrong as it belongs to pwmchipN. It may cause
bad behavior and report wrong values.
- when another export happens on another pwmchip, it can't be created
(e.g. -EEXIST). This is causing the issue with multiple pwmchip.
Example on stm32 (stm32429i-eval) platform:
$ ls /sys/class/pwm
pwmchip0 pwmchip4
$ cd /sys/class/pwm/pwmchip0/
$ echo 0 > export
$ ls /sys/class/pwm
pwm0 pwmchip0 pwmchip4
$ cd /sys/class/pwm/pwmchip4/
$ echo 0 > export
sysfs: cannot create duplicate filename '/class/pwm/pwm0'
...Exception stack follows...
This is also seen on other platform [2]
[1] https://lkml.org/lkml/2018/9/25/713
[2] https://lkml.org/lkml/2018/9/25/447
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>
Never directly free @dev after calling device_register(), even if it
returned an error! Always use put_device() to give up the reference
initialized.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Notifications for devices without bus or class set get dropped by
dev_uevent_filter(). Adding the class to the exported child matches
what the GPIO subsystem is doing.
With this change exporting a channel triggers a udev event, which
gives userspace a chance to fixup permissions and makes it possible
for non-root users to make use of the PWM subsystem.
Signed-off-by: Gottfried Haider <gottfried.haider@gmail.com>
CC: Thierry Reding <thierry.reding@gmail.com>
CC: H Hartley Sweeten <hsweeten@visionengravers.com>
CC: linux-pwm@vger.kernel.org
CC: linux-arm-kernel@lists.infradead.org
CC: linux-rpi-kernel@lists.infradead.org
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Make sure to drop the reference to the parent device taken by
class_find_device() after "unexporting" any children when deregistering
a PWM chip.
Fixes: 0733424c9b ("pwm: Unexport children before chip removal")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Exported pwm channels aren't removed before the pwmchip and are
leaked. This results in invalid sysfs files. This fix removes
all exported pwm channels before chip removal.
Signed-off-by: David Hsu <davidhsu@google.com>
Fixes: 76abbdde2d ("pwm: Add sysfs interface")
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Allow a user to read PWM capture results from sysfs. To start a capture
and read the result, simply read the file:
$ cat $PWMCHIP/capture
The output format is "<period> <duty cycle>".
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This patch adds to check the return value from pwm_apply_state()
used in enable_store(). The error of enable_store() doesn't work
if the return value doesn't received.
Signed-off-by: Ryo Kodama <ryo.kodama.vz@renesas.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Fixes: 39100ceea7 ("pwm: Switch to the atomic API")
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
PWM devices are not protected against concurrent accesses. The lock in
struct pwm_device might let PWM users think it is, but it's actually
only protecting the enabled state.
Removing this lock should be fine as long as all PWM users are aware
that accesses to the PWM device have to be serialized, which seems to be
the case for all of them except the sysfs interface. Patch the sysfs
code by adding a lock to the pwm_export struct and making sure it's
taken for all relevant accesses to the exported PWM device.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
For the npwm property the PWM sysfs interface already made use of the
DEVICE_ATTR_RO macro. This patch expands this to the other sysfs
properties so that the code base is concise and makes use of this
helpful macro.
This has the advantage of slightly reducing the code size, improving
readability and no longer using magic values for permissions.
Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Use the result of pwm_is_enabled() directly instead of storing it in a
temporary variable.
Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Padding initializers so that assignment operators align is bound to lead
to inconsistencies or churn. Single spaces around the assignment is just
fine.
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The current code will check for polarity in a boolean way. While it is
correct that polarity is either normal or inversed, make it more obvious
that it's an enumeration by using a switch statement and explicit
matches on the enumeration values.
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Use the pwm_get_xxx() helpers instead of directly accessing the fields
in struct pwm_device. This will allow us to smoothly move to the atomic
update approach.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Some PWM drivers are testing the PWMF_ENABLED flag. Create a helper
function to hide the logic behind enabled test. This will allow us to
smoothly move from the current approach to an atomic PWM update
approach.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Use new ATTRIBUTE_GROUPS macro to reduce the number of lines of code.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
The dev_attrs field of struct class is going away soon, dev_groups
should be used instead. This converts the PWM class code to use the
correct field.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Add a simple sysfs interface to the generic PWM framework.
/sys/class/pwm/
`-- pwmchipN/ for each PWM chip
|-- export (w/o) ask the kernel to export a PWM channel
|-- npwm (r/o) number of PWM channels in this PWM chip
|-- pwmX/ for each exported PWM channel
| |-- duty_cycle (r/w) duty cycle (in nanoseconds)
| |-- enable (r/w) enable/disable PWM
| |-- period (r/w) period (in nanoseconds)
| `-- polarity (r/w) polarity of PWM (normal/inversed)
`-- unexport (w/o) return a PWM channel to the kernel
Based on work by Lars Poeschel.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Lars Poeschel <poeschel@lemonage.de>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
