From cf3e43dbe0cc4a7ee7f6ab1bb5231dcfda164e02 Mon Sep 17 00:00:00 2001 From: Jonathan Corbet Date: Fri, 29 Sep 2006 02:00:44 -0700 Subject: [PATCH] cdev documentation Add some documentation comments for the cdev interface. Signed-off-by: Jonathan Corbet Cc: Rolf Eike Beer Acked-by: "Randy.Dunlap" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/char_dev.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) (limited to 'fs/char_dev.c') diff --git a/fs/char_dev.c b/fs/char_dev.c index 33b95af89da..1f3285affa3 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -183,6 +183,15 @@ __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) 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 @@ fail: 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 @@ out2: 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 @@ static int exact_lock(dev_t dev, void *data) 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 @@ static void cdev_unmap(dev_t dev, unsigned count) 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 @@ static struct kobj_type ktype_cdev_dynamic = { .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 @@ struct cdev *cdev_alloc(void) 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); -- cgit v1.2.3