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The get_direction callback function allows gpiolib to know the current direction (input vs output) for a given GPIO. This is particularly useful on ACPI systems, where the GPIOs are configured only by firmware (typically UEFI), so the only way to know the initial values to query the hardware directly. Without this function, gpiolib thinks that all GPIOs are configured for input. Signed-off-by: Timur Tabi <timur@codeaurora.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.