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2024-02-14Documentation: gpio: clarify sysfs line values are logicalKent Gibson1-2/+2
Clarify that line values are logical, not physical, by replacing high/low terminology with active/inactive. Signed-off-by: Kent Gibson <warthog618@gmail.com> Reviewed-by: Andy Shevchenko <amdy.shevchenko@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-25Documentation: gpio: describe uAPI behaviour for unsupported configKent Gibson6-7/+106
The existing uAPI documentation does not adequately describe how the kernel handles the case where the underlying hardware or driver does not support the requested configuration. Add a Configuration Support section describing that behaviour to both the v1 and v2 documentation, and better document the errors returned where the requested configuration cannot be supported. Signed-off-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-22Documentation: gpio: add chardev v1 userspace API documentationKent Gibson12-1/+762
Add documentation for v1 of the GPIO character device userspace API to the obsolete section of both the admin-guide and userspace-api books. Signed-off-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-22Documentation: gpio: update sysfs documentation to reference new chardev docKent Gibson1-12/+15
Update GPIO sysfs interface documentation to reference the new chardev document rather than gpio.h. Signed-off-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-22Documentation: gpio: move sysfs into an obsolete sectionKent Gibson3-0/+178
The GPIO sysfs API is long obsolete, so highlight this even further by moving it into an obsolete APIs section in both the admin-guide and userspace-api books. Signed-off-by: Kent Gibson <warthog618@gmail.com> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-22Documentation: gpio: add chardev userspace API documentationKent Gibson13-0/+838
Add documentation for the GPIO character device userspace API. Added to the userspace-api book, but also provide a link from the admin-guide book, as historically the GPIO documentation has been there. Signed-off-by: Kent Gibson <warthog618@gmail.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>