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2028f854b3
In order to enable moving away from the global GPIO numberspace-based exporting of lines over sysfs: add a parallel, per-chip entry under /sys/class/gpio/ for every registered GPIO chip, denoted by device ID in the file name and not its base GPIO number. Compared to the existing chip group: it does not contain the "base" attribute as the goal of this change is to not refer to GPIOs by their global number from user-space anymore. It also contains its own, per-chip export/unexport attribute pair which allow to export lines by their hardware offset within the chip. Caveat #1: the new device cannot be a link to (or be linked to by) the existing "gpiochip<BASE>" entry as we cannot create links in /sys/class/xyz/. Caveat #2: the new entry cannot be named "gpiochipX" as it could conflict with devices whose base is statically defined to a low number. Let's go with "chipX" instead. While at it: the chip label is unique so update the untrue statement when extending the docs. Acked-by: Linus Walleij <linus.walleij@linaro.org> Link: https://lore.kernel.org/r/20250704-gpio-sysfs-chip-export-v4-2-9289d8758243@linaro.org Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.