linux_dsm_epyc7002/Documentation/ABI/testing/sysfs-class-pwm
Lee Jones 1a366fe915 pwm: sysfs: Add PWM capture support
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>
2016-06-10 16:01:40 +02:00

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What: /sys/class/pwm/
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
The pwm/ class sub-directory belongs to the Generic PWM
Framework and provides a sysfs interface for using PWM
channels.
What: /sys/class/pwm/pwmchipN/
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
A /sys/class/pwm/pwmchipN directory is created for each
probed PWM controller/chip where N is the base of the
PWM chip.
What: /sys/class/pwm/pwmchipN/npwm
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
The number of PWM channels supported by the PWM chip.
What: /sys/class/pwm/pwmchipN/export
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
Exports a PWM channel from the PWM chip for sysfs control.
Value is between 0 and /sys/class/pwm/pwmchipN/npwm - 1.
What: /sys/class/pwm/pwmchipN/unexport
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
Unexports a PWM channel.
What: /sys/class/pwm/pwmchipN/pwmX
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
A /sys/class/pwm/pwmchipN/pwmX directory is created for
each exported PWM channel where X is the exported PWM
channel number.
What: /sys/class/pwm/pwmchipN/pwmX/period
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
Sets the PWM signal period in nanoseconds.
What: /sys/class/pwm/pwmchipN/pwmX/duty_cycle
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
Sets the PWM signal duty cycle in nanoseconds.
What: /sys/class/pwm/pwmchipN/pwmX/polarity
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
Sets the output polarity of the PWM signal to "normal" or
"inversed".
What: /sys/class/pwm/pwmchipN/pwmX/enable
Date: May 2013
KernelVersion: 3.11
Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
Description:
Enable/disable the PWM signal.
0 is disabled
1 is enabled
What: /sys/class/pwm/pwmchipN/pwmX/capture
Date: June 2016
KernelVersion: 4.8
Contact: Lee Jones <lee.jones@linaro.org>
Description:
Capture information about a PWM signal. The output format is a
pair unsigned integers (period and duty cycle), separated by a
single space.