summaryrefslogtreecommitdiffstats
path: root/Documentation/ABI/testing/sysfs-gpio
diff options
context:
space:
mode:
authorDavid S. Miller <davem@davemloft.net>2008-10-01 06:12:56 -0700
committerDavid S. Miller <davem@davemloft.net>2008-10-01 06:12:56 -0700
commitb262e60309e1b0eb25d300c7e739427d5316abb1 (patch)
treebf319d78c79bb5cb617ff0c8340c73aa349bba15 /Documentation/ABI/testing/sysfs-gpio
parent93c8b90f01f0dc73891da4e84b26524b61d29d66 (diff)
parent0523820482dcb42784572ffd2296c2f08c275a2b (diff)
Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts: drivers/net/wireless/ath9k/core.c drivers/net/wireless/ath9k/main.c net/core/dev.c
Diffstat (limited to 'Documentation/ABI/testing/sysfs-gpio')
-rw-r--r--Documentation/ABI/testing/sysfs-gpio26
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-gpio b/Documentation/ABI/testing/sysfs-gpio
new file mode 100644
index 00000000000..8aab8092ad3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-gpio
@@ -0,0 +1,26 @@
+What: /sys/class/gpio/
+Date: July 2008
+KernelVersion: 2.6.27
+Contact: David Brownell <dbrownell@users.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)
+