gpiolib: allow exported GPIO nodes to be named using sysfs links

Commit 926b663ce8 (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.

[[email protected]: fix build for CONFIG_GENERIC_GPIO=n]
Signed-off-by: Jani Nikula <[email protected]>
Acked-by: David Brownell <[email protected]>
Cc: Daniel Silverstone <[email protected]>
Signed-off-by: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Jani Nikula 2009-09-22 16:46:33 -07:00 • committed by Linus Torvalds
commit a4177ee7f1
4 changed files with 74 additions and 0 deletions

View file

@ -504,6 +504,51 @@ static int match_export(struct device *dev, void *data)
return dev_get_drvdata(dev) == 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