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NPal.2
NPal.2
Associate III
September 13, 2021
Solved

PWM Kernel Driver API

  • September 13, 2021
  • 6 replies
  • 1742 views

Hi all,

I wish to perform PWM for certain leds connected to STM32MP1 pins.

I wish to do it from the user space application.

I got it working via sysfs interface , but I am more interested in controlling it via a user space application based on some logic. How can I do this ?

Is there API documentation for it?

TIA

This topic has been closed for replies.
Best answer by PatrickF

Hi,

I'm not SW expert, but for me the pwm_device content is retrieved (mostly from DT I guess) by some available pwm kernel functions.

See https://www.kernel.org/doc/html/latest/driver-api/miscellaneous.html#c.pwm_get

This is not related to ST drivers, but supported by kernel, I think the example for Rockchip you pointed is probably working on STM32MP1 without much issues.

Regards.

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6 replies

PatrickF
PatrickF
ST Employee
September 13, 2021

Hi,

Did you already found this wiki https://wiki.st.com/stm32mpu/wiki/PWM_overview#Example_of_PWM_usage_with_kernel_PWM_API ?

Regards.

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NPal.2
NPal.2Author
Associate III
September 14, 2021

Hi @PatrickF​ ,

Thanks for the response.

I did went through it but it just mentions data for device tree configuration. There is no help around how can I use the driver in custom application.

Can you please help me get more details around this ? I really appreciate the help.

PatrickF
PatrickF
ST Employee
September 15, 2021

Hi,

Have you seen this 'C' example links on that wiki page ?

Several in-kernel drivers use kernel PWM API. Below a few examples:

API is documented here : https://www.kernel.org/doc/html/latest/driver-api/pwm.html

Regards.

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