From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
Harish Jenny K N <harish_kandiga@mentor.com>,
Eugeniu Rosca <erosca@de.adit-jv.com>,
Alexander Graf <graf@amazon.com>,
Peter Maydell <peter.maydell@linaro.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Phil Reid <preid@electromag.com.au>,
Marc Zyngier <marc.zyngier@arm.com>,
Christoffer Dall <christoffer.dall@arm.com>,
Magnus Damm <magnus.damm@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH v5 3/5] gpio: Add GPIO Aggregator
Date: Tue, 17 Mar 2020 12:32:31 +0100 [thread overview]
Message-ID: <CAMuHMdWXJKdD7j6QiRb4fL+fFsyDKpc7aGK-nER=CZd7bxGyPg@mail.gmail.com> (raw)
In-Reply-To: <20200218151812.7816-4-geert+renesas@glider.be>
On Tue, Feb 18, 2020 at 4:18 PM Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
> GPIO controllers are exported to userspace using /dev/gpiochip*
> character devices. Access control to these devices is provided by
> standard UNIX file system permissions, on an all-or-nothing basis:
> either a GPIO controller is accessible for a user, or it is not.
> Currently no mechanism exists to control access to individual GPIOs.
>
> Hence add a GPIO driver to aggregate existing GPIOs, and expose them as
> a new gpiochip.
>
> This supports the following use cases:
> - Aggregating GPIOs using Sysfs
> This is useful for implementing access control, and assigning a set
> of GPIOs to a specific user or virtual machine.
> - Generic GPIO Driver
> This is useful for industrial control, where it can provide
> userspace access to a simple GPIO-operated device described in DT,
> cfr. e.g. spidev for SPI-operated devices.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> --- /dev/null
> +++ b/drivers/gpio/gpio-aggregator.c
> +static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
> + unsigned long config)
> +{
> + struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
> +
> + chip = fwd->descs[offset]->gdev->chip;
> + if (chip->set_config)
- chip = fwd->descs[offset]->gdev->chip;
- if (chip->set_config)
+ chip = gpiod_to_chip(fwd->descs[offset]);
+ if (chip && chip->set_config)
> + return chip->set_config(chip, offset, config);
This is not correct: offset should be translated, too, i.e.
offset = gpio_chip_hwgpio(fwd->descs[offset]);
Which adds a new dependency on "gpiolib.h"...
Is there a better alternative, than providing a public gpiod_set_config()
helper?
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2020-03-17 11:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 15:18 [PATCH v5 0/5] gpio: Add GPIO Aggregator Geert Uytterhoeven
2020-02-18 15:18 ` [PATCH v5 1/5] gpiolib: Add support for gpiochipN-based table lookup Geert Uytterhoeven
2020-03-12 14:23 ` Linus Walleij
2020-03-17 8:41 ` Geert Uytterhoeven
2020-02-18 15:18 ` [PATCH v5 2/5] gpiolib: Add support for GPIO line " Geert Uytterhoeven
2020-02-19 10:17 ` Geert Uytterhoeven
2020-03-12 14:21 ` Linus Walleij
2020-03-17 8:48 ` Geert Uytterhoeven
2020-02-18 15:18 ` [PATCH v5 3/5] gpio: Add GPIO Aggregator Geert Uytterhoeven
2020-03-12 14:57 ` Linus Walleij
2020-03-17 10:50 ` Geert Uytterhoeven
2020-03-17 11:32 ` Geert Uytterhoeven [this message]
2020-02-18 15:18 ` [PATCH v5 4/5] docs: gpio: Add GPIO Aggregator documentation Geert Uytterhoeven
2020-02-18 18:29 ` Randy Dunlap
2020-02-18 19:09 ` Geert Uytterhoeven
2020-02-21 16:34 ` Geert Uytterhoeven
2020-02-21 16:35 ` Randy Dunlap
2020-02-18 15:18 ` [PATCH v5 5/5] MAINTAINERS: Add GPIO Aggregator section Geert Uytterhoeven
2020-02-18 17:04 ` [PATCH v5 0/5] gpio: Add GPIO Aggregator Eugeniu Rosca
2020-02-21 16:39 ` Geert Uytterhoeven
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