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Several pinconf parameters have a fairly straight-forward mapping onto the Aspeed pin controller. These include management of pull-down bias, drive-strength, and some debounce configuration. Pin biasing largely is managed on a per-GPIO-bank basis, aside from the ADC and RMII/RGMII pins. As the bias configuration for each pin in a bank maps onto a single per-bank bit, configuration tables will be introduced to describe the ranges of pins and the supported pinconf parameter. The use of tables also helps with the sparse support of pinconf properties, and the fact that not all GPIO banks support biasing or drive-strength configuration. Further, as the pin controller uses a consistent approach for bias and drive strength configuration at the register level, a second table is defined for looking up the the bit-state required to enable or query the provided configuration. Testing for pinctrl-aspeed-g4 was performed on an OpenPOWER Palmetto system, and pinctrl-aspeed-g5 on an AST2500EVB as well as under QEMU. The test method was to set the appropriate bits via devmem and verify the result through the controller's pinconf-pins debugfs file. This simultaneously validates the get() path and half of the set() path. The remainder of the set() path was validated by configuring a handful of pins via the devicetree with the supported pinconf properties and verifying the appropriate registers were touched. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> 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.