Re: [PATCH v3 5/8] pwm: Add support for pwmchip devices for faster and easier userspace access

[Kent Gibson <warthog618@gmail.com>]

On Mon, Jul 29, 2024 at 04:34:21PM +0200, Uwe Kleine-König wrote:
> With this change each pwmchip defining the new-style waveform callbacks
> can be accessed from userspace via a character device. Compared to the
> sysfs-API this is faster (on a stm32mp157 applying a new configuration
> takes approx 25% only) and allows to pass the whole configuration in a
> single ioctl allowing atomic application.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>

> diff --git a/include/uapi/linux/pwm.h b/include/uapi/linux/pwm.h
> new file mode 100644
> index 000000000000..c89ba3e3def8
> --- /dev/null
> +++ b/include/uapi/linux/pwm.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
> +
> +#ifndef _UAPI_PWM_H_
> +#define _UAPI_PWM_H_
> +
> +#include <linux/ioctl.h>
> +#include <linux/types.h>
> +
> +struct pwmchip_waveform {
> +	unsigned int hwpwm;
> +	unsigned int __pad; /* padding, must be zero */
> +	__u64 period_length_ns;
> +	__u64 duty_length_ns;
> +	__u64 duty_offset_ns;
> +};
> +

I would go with __u32, rather than unsigned int, to be absolutely clear
on sizing.

Cheers,
Kent.