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linux_old1/Documentation/ABI/testing/sysfs-class-pwm

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pwm: Add sysfs interface 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>
2013-06-12 01:38:59 +08:00
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