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76abbdde2d
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>
80 lines
2.2 KiB
Plaintext
80 lines
2.2 KiB
Plaintext
What: /sys/class/pwm/
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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The pwm/ class sub-directory belongs to the Generic PWM
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Framework and provides a sysfs interface for using PWM
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channels.
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What: /sys/class/pwm/pwmchipN/
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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A /sys/class/pwm/pwmchipN directory is created for each
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probed PWM controller/chip where N is the base of the
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PWM chip.
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What: /sys/class/pwm/pwmchipN/npwm
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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The number of PWM channels supported by the PWM chip.
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What: /sys/class/pwm/pwmchipN/export
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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Exports a PWM channel from the PWM chip for sysfs control.
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Value is between 0 and /sys/class/pwm/pwmchipN/npwm - 1.
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What: /sys/class/pwm/pwmchipN/unexport
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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Unexports a PWM channel.
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What: /sys/class/pwm/pwmchipN/pwmX
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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A /sys/class/pwm/pwmchipN/pwmX directory is created for
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each exported PWM channel where X is the exported PWM
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channel number.
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What: /sys/class/pwm/pwmchipN/pwmX/period
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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Sets the PWM signal period in nanoseconds.
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What: /sys/class/pwm/pwmchipN/pwmX/duty_cycle
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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Sets the PWM signal duty cycle in nanoseconds.
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What: /sys/class/pwm/pwmchipN/pwmX/polarity
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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Sets the output polarity of the PWM signal to "normal" or
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"inversed".
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What: /sys/class/pwm/pwmchipN/pwmX/enable
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Date: May 2013
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KernelVersion: 3.11
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Contact: H Hartley Sweeten <hsweeten@visionengravers.com>
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Description:
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Enable/disable the PWM signal.
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0 is disabled
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1 is enabled
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