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authorJani Nikula <ext-jani.1.nikula@nokia.com>2009-09-22 16:46:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 07:39:46 -0700
commita4177ee7f1a83eecb1d75e85d32664b023ef65e9 (patch)
tree614b12b1f28a1a9090d96bea33639265e3e79839 /drivers/gpio
parentd8c1acb1664d17dd995e34507533321e986d9215 (diff)
downloadlinux-a4177ee7f1a83eecb1d75e85d32664b023ef65e9.tar.bz2
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 'drivers/gpio')
-rw-r--r--drivers/gpio/gpiolib.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 51a8d4103be5..aef6b3d8e2cf 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -505,6 +505,51 @@ static int match_export(struct device *dev, void *data)
}
/**
+ * gpio_export_link - create a sysfs link to an exported GPIO node
+ * @dev: device under which to create symlink
+ * @name: name of the symlink
+ * @gpio: gpio to create symlink to, already exported
+ *
+ * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
+ * node. Caller is responsible for unlinking.
+ *
+ * Returns zero on success, else an error.
+ */
+int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
+{
+ struct gpio_desc *desc;
+ int status = -EINVAL;
+
+ if (!gpio_is_valid(gpio))
+ goto done;
+
+ mutex_lock(&sysfs_lock);
+
+ desc = &gpio_desc[gpio];
+
+ if (test_bit(FLAG_EXPORT, &desc->flags)) {
+ struct device *tdev;
+
+ tdev = class_find_device(&gpio_class, NULL, desc, match_export);
+ if (tdev != NULL) {
+ status = sysfs_create_link(&dev->kobj, &tdev->kobj,
+ name);
+ } else {
+ status = -ENODEV;
+ }
+ }
+
+ mutex_unlock(&sysfs_lock);
+
+done:
+ if (status)
+ pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
+
+ return status;
+}
+EXPORT_SYMBOL_GPL(gpio_export_link);
+
+/**
* gpio_unexport - reverse effect of gpio_export()
* @gpio: gpio to make unavailable
*