char_dev.c File Reference

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/kdev_t.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/kobject.h>
#include <linux/kobj_map.h>
#include <linux/cdev.h>
#include <linux/mutex.h>
#include <linux/backing-dev.h>
#include <linux/tty.h>
#include "internal.h"

Go to the source code of this file.

Data Structures
struct	char_device_struct

Functions
: the name of the device or driver.
register_chrdev_region() - register a range of device numbers : the first in the desired range of device numbers; must include the major number. : the number of consecutive device numbers required Return value is zero on success, a negative error code on failure.
int	register_chrdev_region (dev_t from, unsigned count, const char *name)
: the name of the associated device or driver
alloc_chrdev_region() - register a range of char device numbers : output parameter for first assigned number : first of the requested range of minor numbers : the number of minor numbers required Allocates a range of char device numbers. The major number will be chosen dynamically, and returned (along with the first minor number) in . Returns zero or a negative error code.
int	alloc_chrdev_region (dev_t *dev, unsigned baseminor, unsigned count, const char *name)

Variables
struct backing_dev_info	directly_mappable_cdev_bdi

: name of this range of devices
__unregister_chrdev - unregister and destroy a cdev : major device number : first of the range of minor numbers : the number of minor numbers this cdev is occupying Unregister and destroy the cdev occupying the region described by , and . This function undoes what __register_chrdev() did.
struct file_operations	def_chr_fops
int	__register_chrdev (unsigned int major, unsigned int baseminor, unsigned int count, const char *name, const struct file_operations *fops)
void	unregister_chrdev_region (dev_t from, unsigned count)
void	__unregister_chrdev (unsigned int major, unsigned int baseminor, unsigned int count, const char *name)
void	cdev_put (struct cdev *p)
void	cd_forget (struct inode *inode)
int	cdev_add (struct cdev *p, dev_t dev, unsigned count)
void	cdev_del (struct cdev *p)
struct cdev *	cdev_alloc (void)
void	cdev_init (struct cdev *cdev, const struct file_operations *fops)
void __init	chrdev_init (void)
	EXPORT_SYMBOL (register_chrdev_region)
	EXPORT_SYMBOL (unregister_chrdev_region)
	EXPORT_SYMBOL (alloc_chrdev_region)
	EXPORT_SYMBOL (cdev_init)
	EXPORT_SYMBOL (cdev_alloc)
	EXPORT_SYMBOL (cdev_del)
	EXPORT_SYMBOL (cdev_add)
	EXPORT_SYMBOL (__register_chrdev)
	EXPORT_SYMBOL (__unregister_chrdev)
	EXPORT_SYMBOL (directly_mappable_cdev_bdi)

Function Documentation

int __register_chrdev	(	unsigned int	major,
		unsigned int	baseminor,
		unsigned int	count,
		const char *	name,
		const struct file_operations *	fops
	)

Definition at line 264 of file char_dev.c.

void __unregister_chrdev	(	unsigned int	major,
		unsigned int	baseminor,
		unsigned int	count,
		const char *	name
	)

Definition at line 331 of file char_dev.c.

int alloc_chrdev_region	(	dev_t *	dev,
		unsigned	baseminor,
		unsigned	count,
		const char *	name
	)

Definition at line 232 of file char_dev.c.

void cd_forget

(

struct inode *

inode

)

Definition at line 420 of file char_dev.c.

int cdev_add	(	struct cdev *	p,
		dev_t	dev,
		unsigned	count
	)

cdev_add() - add a char device to the system : the cdev structure for the device : the first device number for which this device is responsible : the number of consecutive minor numbers corresponding to this device

cdev_add() adds the device represented by to the system, making it live immediately. A negative error code is returned on failure.

Definition at line 472 of file char_dev.c.

struct cdev* cdev_alloc ( void  )

read

cdev_alloc() - allocate a cdev structure

Allocates and returns a cdev structure, or NULL on failure.

Definition at line 540 of file char_dev.c.

void cdev_del

(

struct cdev *

p

)

cdev_del() - remove a cdev from the system : the cdev structure to be removed

cdev_del() removes from the system, possibly freeing the structure itself.

Definition at line 501 of file char_dev.c.

void cdev_init	(	struct cdev *	cdev,
		const struct file_operations *	fops
	)

cdev_init() - initialize a cdev structure : the structure to initialize : the file_operations for this device

Initializes , remembering , making it ready to add to the system with cdev_add().

Definition at line 558 of file char_dev.c.

void cdev_put

(

struct cdev *

p

)

Definition at line 357 of file char_dev.c.

void __init chrdev_init

(

void

)

Definition at line 574 of file char_dev.c.

EXPORT_SYMBOL

(

register_chrdev_region

)

EXPORT_SYMBOL

(

unregister_chrdev_region

)

EXPORT_SYMBOL

(

alloc_chrdev_region

)

EXPORT_SYMBOL

(

cdev_init

)

EXPORT_SYMBOL

(

cdev_alloc

)

EXPORT_SYMBOL

(

cdev_del

)

EXPORT_SYMBOL

(

cdev_add

)

EXPORT_SYMBOL

(

__register_chrdev

)

EXPORT_SYMBOL

(

__unregister_chrdev

)

EXPORT_SYMBOL

(

directly_mappable_cdev_bdi

)

int register_chrdev_region	(	dev_t	from,
		unsigned	count,
		const char *	name
	)

Definition at line 196 of file char_dev.c.

void unregister_chrdev_region	(	dev_t	from,
		unsigned	count
	)

unregister_chrdev_region() - return a range of device numbers : the first in the range of numbers to unregister : the number of device numbers to unregister

This function will unregister a range of device numbers, starting with . The caller should normally be the one who allocated those numbers in the first place...

Definition at line 307 of file char_dev.c.

Variable Documentation

struct file_operations def_chr_fops

Initial value:

= {
    .open = chrdev_open,
    .llseek = noop_llseek,
}

Definition at line 445 of file char_dev.c.

struct backing_dev_info directly_mappable_cdev_bdi

Initial value:

= {
    .name = "char",
    .capabilities   = (




        
        BDI_CAP_MAP_DIRECT |
        BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP |
        
        BDI_CAP_NO_ACCT_AND_WRITEBACK),
}

Definition at line 34 of file char_dev.c.