[PATCH] cdev documentation
Add some documentation comments for the cdev interface.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Acked-by: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 33b95af..1f3285a 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -183,6 +183,15 @@
return cd;
}
+/**
+ * register_chrdev_region() - register a range of device numbers
+ * @from: the first in the desired range of device numbers; must include
+ * the major number.
+ * @count: the number of consecutive device numbers required
+ * @name: the name of the device or driver.
+ *
+ * Return value is zero on success, a negative error code on failure.
+ */
int register_chrdev_region(dev_t from, unsigned count, const char *name)
{
struct char_device_struct *cd;
@@ -208,6 +217,17 @@
return PTR_ERR(cd);
}
+/**
+ * alloc_chrdev_region() - register a range of char device numbers
+ * @dev: output parameter for first assigned number
+ * @baseminor: first of the requested range of minor numbers
+ * @count: the number of minor numbers required
+ * @name: the name of the associated device or driver
+ *
+ * Allocates a range of char device numbers. The major number will be
+ * chosen dynamically, and returned (along with the first minor number)
+ * in @dev. Returns zero or a negative error code.
+ */
int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
const char *name)
{
@@ -277,6 +297,15 @@
return err;
}
+/**
+ * unregister_chrdev_region() - return a range of device numbers
+ * @from: the first in the range of numbers to unregister
+ * @count: the number of device numbers to unregister
+ *
+ * This function will unregister a range of @count device numbers,
+ * starting with @from. The caller should normally be the one who
+ * allocated those numbers in the first place...
+ */
void unregister_chrdev_region(dev_t from, unsigned count)
{
dev_t to = from + count;
@@ -414,6 +443,16 @@
return cdev_get(p) ? 0 : -1;
}
+/**
+ * cdev_add() - add a char device to the system
+ * @p: the cdev structure for the device
+ * @dev: the first device number for which this device is responsible
+ * @count: the number of consecutive minor numbers corresponding to this
+ * device
+ *
+ * cdev_add() adds the device represented by @p to the system, making it
+ * live immediately. A negative error code is returned on failure.
+ */
int cdev_add(struct cdev *p, dev_t dev, unsigned count)
{
p->dev = dev;
@@ -426,6 +465,13 @@
kobj_unmap(cdev_map, dev, count);
}
+/**
+ * cdev_del() - remove a cdev from the system
+ * @p: the cdev structure to be removed
+ *
+ * cdev_del() removes @p from the system, possibly freeing the structure
+ * itself.
+ */
void cdev_del(struct cdev *p)
{
cdev_unmap(p->dev, p->count);
@@ -454,6 +500,11 @@
.release = cdev_dynamic_release,
};
+/**
+ * cdev_alloc() - allocate a cdev structure
+ *
+ * Allocates and returns a cdev structure, or NULL on failure.
+ */
struct cdev *cdev_alloc(void)
{
struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
@@ -465,6 +516,14 @@
return p;
}
+/**
+ * cdev_init() - initialize a cdev structure
+ * @cdev: the structure to initialize
+ * @fops: the file_operations for this device
+ *
+ * Initializes @cdev, remembering @fops, making it ready to add to the
+ * system with cdev_add().
+ */
void cdev_init(struct cdev *cdev, const struct file_operations *fops)
{
memset(cdev, 0, sizeof *cdev);