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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:
parent
d8c1acb166
commit
a4177ee7f1
4 changed files with 74 additions and 0 deletions
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@ -504,6 +504,51 @@ static int match_export(struct device *dev, void *data)
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return dev_get_drvdata(dev) == data;
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}
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/**
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* gpio_export_link - create a sysfs link to an exported GPIO node
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* @dev: device under which to create symlink
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* @name: name of the symlink
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* @gpio: gpio to create symlink to, already exported
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*
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* Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
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* node. Caller is responsible for unlinking.
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*
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* Returns zero on success, else an error.
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*/
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int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
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{
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struct gpio_desc *desc;
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int status = -EINVAL;
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if (!gpio_is_valid(gpio))
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goto done;
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mutex_lock(&sysfs_lock);
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desc = &gpio_desc[gpio];
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if (test_bit(FLAG_EXPORT, &desc->flags)) {
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struct device *tdev;
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tdev = class_find_device(&gpio_class, NULL, desc, match_export);
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if (tdev != NULL) {
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status = sysfs_create_link(&dev->kobj, &tdev->kobj,
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name);
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} else {
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status = -ENODEV;
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}
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}
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mutex_unlock(&sysfs_lock);
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done:
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if (status)
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pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
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return status;
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}
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EXPORT_SYMBOL_GPL(gpio_export_link);
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/**
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* gpio_unexport - reverse effect of gpio_export()
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* @gpio: gpio to make unavailable
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