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Each GPIO in the Aspeed GPIO controller can choose one of four input debounce states: to disable debouncing for an input, or select from one of three programmable debounce timer values. Each GPIO in a four-bank-set is assigned one bit in each of two debounce configuration registers dedicated to the set, and selects a debounce state by configuring the two bits to select one of the four options. The limitation on debounce timer values is managed by mapping offsets onto a configured timer value and keeping count of the number of users a timer has. Timer values are configured on a first-come-first-served basis. A small twist in the hardware design is that the debounce configuration register numbering is reversed with respect to the binary representation of the debounce timer of interest (i.e. debounce register 1 represents bit 1, and debounce register 2 represents bit 0 of the timer numbering). Tested on an AST2500EVB with additional inspection under QEMU's romulus-bmc machine. 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.