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| author | Vincent Whitchurch <vincent.whitchurch@axis.com> | 2024-06-04 23:00:41 +0200 |
|---|---|---|
| committer | Uwe Kleine-König <ukleinek@kernel.org> | 2024-07-10 17:52:47 +0200 |
| commit | 7f61257cd6e1ad4769b4b819668cab00f68f2556 (patch) | |
| tree | ca7a481f89118ad80ab7a38d86f4c851c60a6779 /Documentation/driver-api | |
| parent | 1577ddaa515e3af2614e1f52711c287bebc338cf (diff) | |
| download | linux-7f61257cd6e1ad4769b4b819668cab00f68f2556.tar.gz linux-7f61257cd6e1ad4769b4b819668cab00f68f2556.tar.bz2 linux-7f61257cd6e1ad4769b4b819668cab00f68f2556.zip | |
pwm: Add GPIO PWM driver
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>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/gpio/drivers-on-gpio.rst | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/driver-api/gpio/drivers-on-gpio.rst b/Documentation/driver-api/gpio/drivers-on-gpio.rst index af632d764ac6..95572d2a94ce 100644 --- a/Documentation/driver-api/gpio/drivers-on-gpio.rst +++ b/Documentation/driver-api/gpio/drivers-on-gpio.rst @@ -27,7 +27,12 @@ hardware descriptions such as device tree or ACPI: to the lines for a more permanent solution of this type. - gpio-beeper: drivers/input/misc/gpio-beeper.c is used to provide a beep from - an external speaker connected to a GPIO line. + an external speaker connected to a GPIO line. (If the beep is controlled by + off/on, for an actual PWM waveform, see pwm-gpio below.) + +- pwm-gpio: drivers/pwm/pwm-gpio.c is used to toggle a GPIO with a high + resolution timer producing a PWM waveform on the GPIO line, as well as + Linux high resolution timers can do. - extcon-gpio: drivers/extcon/extcon-gpio.c is used when you need to read an external connector status, such as a headset line for an audio driver or an |