提交 cf3e43db 编写于 作者: J Jonathan Corbet 提交者: Linus Torvalds

[PATCH] cdev documentation

Add some documentation comments for the cdev interface.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Acked-by: N"Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
上级 5785c95b
...@@ -454,6 +454,11 @@ X!Edrivers/pnp/system.c ...@@ -454,6 +454,11 @@ X!Edrivers/pnp/system.c
!Eblock/ll_rw_blk.c !Eblock/ll_rw_blk.c
</chapter> </chapter>
<chapter id="chrdev">
<title>Char devices</title>
!Efs/char_dev.c
</chapter>
<chapter id="miscdev"> <chapter id="miscdev">
<title>Miscellaneous Devices</title> <title>Miscellaneous Devices</title>
!Edrivers/char/misc.c !Edrivers/char/misc.c
......
...@@ -183,6 +183,15 @@ __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct) ...@@ -183,6 +183,15 @@ __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
return cd; 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) int register_chrdev_region(dev_t from, unsigned count, const char *name)
{ {
struct char_device_struct *cd; struct char_device_struct *cd;
...@@ -208,6 +217,17 @@ int register_chrdev_region(dev_t from, unsigned count, const char *name) ...@@ -208,6 +217,17 @@ int register_chrdev_region(dev_t from, unsigned count, const char *name)
return PTR_ERR(cd); 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, int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
const char *name) const char *name)
{ {
...@@ -277,6 +297,15 @@ int register_chrdev(unsigned int major, const char *name, ...@@ -277,6 +297,15 @@ int register_chrdev(unsigned int major, const char *name,
return err; 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) void unregister_chrdev_region(dev_t from, unsigned count)
{ {
dev_t to = from + count; dev_t to = from + count;
...@@ -414,6 +443,16 @@ static int exact_lock(dev_t dev, void *data) ...@@ -414,6 +443,16 @@ static int exact_lock(dev_t dev, void *data)
return cdev_get(p) ? 0 : -1; 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) int cdev_add(struct cdev *p, dev_t dev, unsigned count)
{ {
p->dev = dev; p->dev = dev;
...@@ -426,6 +465,13 @@ static void cdev_unmap(dev_t dev, unsigned count) ...@@ -426,6 +465,13 @@ static void cdev_unmap(dev_t dev, unsigned count)
kobj_unmap(cdev_map, dev, 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) void cdev_del(struct cdev *p)
{ {
cdev_unmap(p->dev, p->count); cdev_unmap(p->dev, p->count);
...@@ -454,6 +500,11 @@ static struct kobj_type ktype_cdev_dynamic = { ...@@ -454,6 +500,11 @@ static struct kobj_type ktype_cdev_dynamic = {
.release = cdev_dynamic_release, .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 *cdev_alloc(void)
{ {
struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
...@@ -465,6 +516,14 @@ struct cdev *cdev_alloc(void) ...@@ -465,6 +516,14 @@ struct cdev *cdev_alloc(void)
return p; 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) void cdev_init(struct cdev *cdev, const struct file_operations *fops)
{ {
memset(cdev, 0, sizeof *cdev); memset(cdev, 0, sizeof *cdev);
......
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