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Message-Id: <200809120951.22570.david-b@pacbell.net> Date: Fri, 12 Sep 2008 09:51:22 -0700 From: David Brownell <david-b@...bell.net> To: Andrew Morton <akpm@...ux-foundation.org> Cc: gregkh@...e.de, lkml <linux-kernel@...r.kernel.org> Subject: [patch 2.6.27-rc6] Documentation/ABI: /sys/class/gpio From: David Brownell <dbrownell@...rs.sourceforge.net> Provide summary ABI docs about the /sys/class/gpio files. Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net> Cc: Greg Kroah-Hartman <gregkh@...e.de> --- For 2.6.27 ... let's make Greg happy. :) Documentation/ABI/testing/sysfs-gpio | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ b/Documentation/ABI/testing/sysfs-gpio 2008-07-25 12:38:50.000000000 -0700 @@ -0,0 +1,26 @@ +What: /sys/class/gpio/ +Date: July 2008 +KernelVersion: 2.6.27 +Contact: David Brownell <dbrownell@...rs.sourceforge.net> +Description: + + As a Kconfig option, individual GPIO signals may be accessed from + userspace. GPIOs are only made available to userspace by an explicit + "export" operation. If a given GPIO is not claimed for use by + kernel code, it may be exported by userspace (and unexported later). + Kernel code may export it for complete or partial access. + + GPIOs are identified as they are inside the kernel, using integers in + the range 0..INT_MAX. See Documentation/gpio.txt for more information. + + /sys/class/gpio + /export ... asks the kernel to export a GPIO to userspace + /unexport ... to return a GPIO to the kernel + /gpioN ... for each exported GPIO #N + /value ... always readable, writes fail for input GPIOs + /direction ... r/w as: in, out (default low); write: high, low + /gpiochipN ... for each gpiochip; #N is its first GPIO + /base ... (r/o) same as N + /label ... (r/o) descriptive, not necessarily unique + /ngpio ... (r/o) number of GPIOs; numbered N to N + (ngpio - 1) + -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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