linux-kernel - Re: [RFC PATCH v1 10/20] tools: gpio: Add GPIO output generation user application

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Date:   Thu, 16 Sep 2021 23:52:18 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     "D, Lakshmi Sowjanya" <lakshmi.sowjanya.d@...el.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Lee Jones <lee.jones@...aro.org>
Cc:     "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Saha, Tamal" <tamal.saha@...el.com>, bala.senthil@...el.com,
        Dipen Patel <dipenp@...dia.com>
Subject: Re: [RFC PATCH v1 10/20] tools: gpio: Add GPIO output generation user application

On Tue, Aug 24, 2021 at 6:48 PM <lakshmi.sowjanya.d@...el.com> wrote:

> From: Christopher Hall <christopher.s.hall@...el.com>
>
> Add GPIO user application - gpio_event_gen - to generate output using
> output methods added to GPIO lib. The output produced is 1 Hz clock
> aligned to the system clock using singly scheduled edges.
>
> gpio_event_gen accepts similar arguments to gpio-event-mon.
>
> Example output:
>         $ gpio-event-gen -n gpiochip0 -o 0 -c 3
>         Generating events on line 0 on gpiochip1
>         clock realtime : 1612453529996832765
>         GPIO EVENT TRIGGER: 1612453531000000000
>         clock realtime 2 2 : 1612453531500000000
>         GPIO EVENT TRIGGER: 1612453531500000000
>         clock realtime 2 2 : 1612453532000000000
>         GPIO EVENT TRIGGER: 1612453532000000000
>         clock realtime 2 2 : 1612453532500000000
>
> Produces 3 events of 1 Hz output on line 0 of chip/device 0.
>
> Signed-off-by: Christopher Hall <christopher.s.hall@...el.com>
> Signed-off-by: Tamal Saha <tamal.saha@...el.com>
> Co-developed-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@...el.com>
> Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@...el.com>
> Reviewed-by: Mark Gross <mgross@...ux.intel.com>

To me this looks as very similar to what the PWM subsystem
is doing, just with a restricted number of periods.
Especially with that command line example.

Yours,
Linus Walleij