一、

1、头文件

include/linux/fs.h

2、API

静态申请设备号

int register_chrdev_region(dev_t, unsigned, const char *);

动态分配设备号

int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);

3、注销设备号

void unregister_chrdev_region(dev_t, unsigned);

二、静态申请设备号实例

1、驱动源代码

#include #include #include #include static int hello_major = 248; // 主设备号

static int hello_minor = 0; // 次设备号

static int number_of_devices = 1; // 设备的数量

static __init char_driver_init(void)

{

int result;

dev_t dev = 0;

dev = MKDEV (hello_major, hello_minor); // 主设备号、次设备号合并为设备号

result = register_chrdev_region (dev, number_of_devices, "hello"); // 静态注册设备号: name 体现在"/proc/devices"中

if (result<0) {

printk (KERN_ERR "char_driver_init: can't get major number %d\n", hello_major);

return result;

}

printk(KERN_INFO "char_driver_init\n");

return 0;

}

static __exit char_driver_exit(void)

{

dev_t devno = MKDEV (hello_major, hello_minor);// 主设备号、次设备号合并为设备号

unregister_chrdev_region (devno, number_of_devices);// 注销设备号

printk(KERN_INFO "char_driver_exit\n");

}

module_init(char_driver_init);

module_exit(char_driver_exit);

MODULE_LICENSE("GPL");

MODULE_VERSION("v1.0");

MODULE_AUTHOR("xz@vichip.com.cn");

MODULE_DESCRIPTION("Char Driver Module");

MODULE_ALIAS("char driver module");

2、Makefile

ifeq ($(KERNELRELEASE),)

KERNELDIR ?= /lib/modules/$(shell uname -r)/build

PWD := $(shell pwd)

all:

$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

clean:

$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

else

obj-m := char_reg.o

endif

3、验证

1)make

2)sudo insmod char_reg.ko

3)cat /proc/devices

xiezhi@sdtpad-desktop:~/xiezhi/linux_drivers/char_reg$ cat /proc/devices

Character devices:

1 mem

4 /dev/vc/0

4 tty

4 ttyS

5 /dev/tty

5 /dev/console

5 /dev/ptmx

5 ttyprintk

6 lp

7 vcs

10 misc

13 input

14 sound

21 sg

29 fb

99 ppdev

108 ppp

116 alsa

128 ptm

136 pts

180 usb

189 usb_device

216 rfcomm

226 drm

248 hello

250 mei

251 hidraw

252 usbmon

253 bsg

254 rtc4)sudo rmmod char_reg