linux-kernel - Re: [PATCH RFC/RFT 00/15] gpio: sysfs: add a per-chip export/unexport attribute pair

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMRc=MdRA40RHus9xPpXyq_baVaPObozqX9w8-syXaHjr_9K6w@mail.gmail.com>
Date: Wed, 18 Jun 2025 16:54:49 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Ahmad Fatoum <a.fatoum@...gutronix.de>, Kent Gibson <warthog618@...il.com>, 
	Jan Lübbe <jlu@...gutronix.de>, Marek Vasut <marex@...x.de>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Linus Walleij <linus.walleij@...aro.org>, 
	Bartosz Golaszewski <brgl@...ev.pl>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH RFC/RFT 00/15] gpio: sysfs: add a per-chip export/unexport
 attribute pair

On Tue, Jun 10, 2025 at 4:38 PM Bartosz Golaszewski <brgl@...ev.pl> wrote:
>
> Following our discussion[1], here's a proposal for extending the sysfs
> interface with attributes not referring to GPIO lines by their global
> numbers in a backward compatible way.
>
> Long story short: there is now a new class device for each GPIO chip.
> It's called chipX where X is the ID of the device as per the driver
> model and it lives next to the old gpiochipABC where ABC is the GPIO
> base. Each new chip class device has a pair of export/unexport
> attributes which work similarly to the global ones under /sys/class/gpio
> but take hardware offsets within the chip as input, instead of the
> global numbers. Finally, each exported line appears at the same time as
> the global /sys/class/gpio/gpioABC as well as per-chip
> /sys/class/gpio/chipX/gpioY sysfs group.
>
> First, there are some documentation updates, followed by a set of
> updates to the sysfs code that's useful even without the new
> functionality. Then the actual implementation of a parallel GPIO chip
> entry not containing the base GPIO number in the name and the
> corresponding sysfs attribute group for each exported line that lives
> under the new chip class device. Finally: also allow to compile out the
> legacy parts leaving only the new elements of the sysfs ABI.
>
> This series passes the compatibility tests I wrote while working on the
> user-space compatibility layer for sysfs[2].
>
> [1] https://lore.kernel.org/all/CAMRc=McUCeZcU6co1aN54rTudo+JfPjjForu4iKQ5npwXk6GXA@mail.gmail.com/
> [2] https://github.com/brgl/gpio-sysfs-compat-tests
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
> Bartosz Golaszewski (15):
>       Documentation: gpio: undocument removed behavior
>       Documentation: gpio: document the active_low field in the sysfs ABI
>       gpio: sysfs: call mutex_destroy() in gpiod_unexport()
>       gpio: sysfs: refactor the coding style
>       gpio: sysfs: remove unneeded headers
>       gpio: sysfs: remove the mockdev pointer from struct gpio_device


If there are no objections, I'd like to queue patches 1-6 for v6.17
already in the coming days. They are largely preparatory, have been
reviewed by Linus and don't introduce any changes to the sysfs
interface.

Bart

>       gpio: sysfs: add a parallel class device for each GPIO chip using device IDs
>       gpio: sysfs: only get the dirent reference for the value attr once
>       gpio: sysfs: pass gpiod_data directly to internal GPIO sysfs functions
>       gpio: sysfs: don't use driver data in sysfs callbacks for line attributes
>       gpio: sysfs: rename the data variable in gpiod_(un)export()
>       gpio: sysfs: don't look up exported lines as class devices
>       gpio: sysfs: export the GPIO directory locally in the gpiochip<id> directory
>       gpio: sysfs: allow disabling the legacy parts of the GPIO sysfs interface
>       gpio: TODO: remove the task for the sysfs rework
>
>  Documentation/ABI/obsolete/sysfs-gpio |  12 +-
>  drivers/gpio/Kconfig                  |   8 +
>  drivers/gpio/TODO                     |  13 -
>  drivers/gpio/gpiolib-sysfs.c          | 650 ++++++++++++++++++++++++----------
>  drivers/gpio/gpiolib.h                |   3 -
>  5 files changed, 474 insertions(+), 212 deletions(-)
> ---
> base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
> change-id: 20250402-gpio-sysfs-chip-export-84ac424b61c5
>
> Best regards,
> --
> Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
>