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Add a software PWM which toggles a GPIO from a high-resolution timer. This will naturally not be as accurate or as efficient as a hardware PWM, but it is useful in some cases. I have for example used it for evaluating LED brightness handling (via leds-pwm) on a board where the LED was just hooked up to a GPIO, and for a simple verification of the timer frequency on another platform. Since high-resolution timers are used, sleeping GPIO chips are not supported and are rejected in the probe function. Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Co-developed-by: Stefan Wahren <wahrenst@gmx.net> Signed-off-by: Stefan Wahren <wahrenst@gmx.net> Co-developed-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Andy Shevchenko <andy@kernel.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Dhruva Gole <d-gole@ti.com> Link: https://lore.kernel.org/r/20240604-pwm-gpio-v7-2-6b67cf60db92@linaro.org Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.