diff options
| author | Jani Nikula <ext-jani.1.nikula@nokia.com> | 2009-09-23 01:46:33 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-23 16:39:46 +0200 |
| commit | a4177ee7f1a83eecb1d75e85d32664b023ef65e9 (patch) | |
| tree | 614b12b1f28a1a9090d96bea33639265e3e79839 /Documentation/gpio.txt | |
| parent | rtc: add boot_timesource sysfs attribute (diff) | |
| download | linux-a4177ee7f1a83eecb1d75e85d32664b023ef65e9.tar.xz linux-a4177ee7f1a83eecb1d75e85d32664b023ef65e9.zip | |
gpiolib: allow exported GPIO nodes to be named using sysfs links
Commit 926b663ce8215ba448960e1ff6e58b67a2c3b99b (gpiolib: allow GPIOs to
be named) already provides naming on the chip level. This patch provides
more flexibility by allowing multiple names where ever in sysfs on a per
GPIO basis.
Adapted from David Brownell's comments on a similar concept:
http://lkml.org/lkml/2009/4/20/203.
[randy.dunlap@oracle.com: fix build for CONFIG_GENERIC_GPIO=n]
Signed-off-by: Jani Nikula <ext-jani.1.nikula@nokia.com>
Acked-by: David Brownell <david-b@pacbell.net>
Cc: Daniel Silverstone <dsilvers@simtec.co.uk>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/gpio.txt')
| -rw-r--r-- | Documentation/gpio.txt | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index e4b6985044a2..566edaa56a53 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -555,6 +555,11 @@ requested using gpio_request(): /* reverse gpio_export() */ void gpio_unexport(); + /* create a sysfs link to an exported GPIO node */ + int gpio_export_link(struct device *dev, const char *name, + unsigned gpio) + + After a kernel driver requests a GPIO, it may only be made available in the sysfs interface by gpio_export(). The driver can control whether the signal direction may change. This helps drivers prevent userspace code @@ -563,3 +568,8 @@ from accidentally clobbering important system state. This explicit exporting can help with debugging (by making some kinds of experiments easier), or can provide an always-there interface that's suitable for documenting as part of a board support package. + +After the GPIO has been exported, gpio_export_link() allows creating +symlinks from elsewhere in sysfs to the GPIO sysfs node. Drivers can +use this to provide the interface under their own device in sysfs with +a descriptive name. |