Hello,
On Tue, Jun 04, 2024 at 11:00:39PM +0200, Linus Walleij wrote:
> Add a software PWM which toggles a GPIO from a high-resolution timer.
>
> Recent discussions in the Raspberry Pi community revealt that a lot
> of users still use MMIO userspace tools for GPIO access. One argument
> for this approach is the lack of a GPIO PWM kernel driver. So this
> series tries to fill this gap.
>
> This continues the work of Vincent Whitchurch [1], which is easier
> to read and more consequent by rejecting sleeping GPIOs than Nicola's
> approach [2]. It further takes over where Stefan Wahren left off.
>
> I have not looked into the interrupt storm problem mentioned in [3]
> but instead focused on some real-life tests:
>
> The IXP4xx NSLU2 has a speaker connected directly to a GPIO, and I
> wanted to use this patch to provide a proper beeper for the machine
> and not have to rely on custom hacks.
>
> I added a DTS patch like this:
>
> gpio_pwm: pwm {
> #pwm-cells = <3>;
> compatible = "pwm-gpio";
> gpios = <&gpio0 4 GPIO_ACTIVE_HIGH>;
> };
>
> beeper {
> compatible = "pwm-beeper";
> pwms = <&gpio_pwm 0 1 0>;
> beeper-hz = <1000>;
> };
Applied both patches to
https://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux.git pwm/for-next
Thanks
Uwe
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