linux设备驱动初学(二)

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>#include <linux/types.h>#include <linux/fs.h>#include <linux/mm.h>#include <linux/errno.h>#include <asm/segment.h>#include <linux/module.h>#include <linux/sched.h>#include <linux/cdev.h>MODULE_LICENSE("Dual BSD/GPL");unsigned int test_major=0;static char *book_name = "dissecting Linux Device Drviver";static int num = 4000;static int global_major = 0;struct cc_dev_t{  struct cdev cdev;} cc_dev;static int cc_read(struct inode *inode,struct file *file,char *buf,int count){    printk(KERN_INFO "*******cc_read********\n");    return 0;}static int cc_write(struct inode *inode,struct file *file,const char *buf,int count){  printk(KERN_INFO "*******cc_write*******\n");  return 0;}static int cc_open(struct inode *inode,struct file *file){  printk(KERN_INFO "********cc_open*******\n");  return 0;}static void cc_release(struct inode *inode,struct file *file){  printk(KERN_INFO "*******cc_release*****\n");}struct file_operations cc_fops={ .owner = THIS_MODULE, .read = cc_read, .write = cc_write, .open = cc_open, .release = cc_release,};static int __init cc_init(void){  int result,err;  dev_t devno = MKDEV(0,0);  result = alloc_chrdev_region(&devno,0,1,"cc");  global_major = MAJOR(devno);  if(result < 0)  {    return result;  }  cdev_init(&cc_dev.cdev,&cc_fops);  err = cdev_add(&cc_dev.cdev,devno,1);  if(err)    printk(KERN_NOTICE "Error");  return 0;}void cc_exit(void){  cdev_del(&cc_dev.cdev);  unregister_chrdev_region(MKDEV(global_major,0),1);}module_init(cc_init);module_exit(cc_exit);module_param(num,int,S_IRUGO);module_param(book_name,charp,S_IRUGO);MODULE_AUTHOR("xyl");MODULE_DESCRIPTION("A simple Hello world Moudle");MODULE_ALIAS("a simplest moudle");写完驱动部分 make一下 在/proc/devices下面就会有对应的主设备号了makefile文件    PWD = $(shell pwd)    CC=gcc    KERNEL_SRC = /usr/src/linux-source-2.6.38/    obj-m := cc.o    module-objs := cc.oall:       $(MAKE) -C $(KERNEL_SRC)  M=$(PWD) modulesclean:    rm *.ko    rm *.o之后在/dev下面创建设备节点  cat /proc/devices获得主设备号  mknod /dev/cc c major minor在/dev下面就会有对应的设备节点了  如果想要删除的话直接rm掉下面是test.c#include<stdio.h>#include<fcntl.h>int main(){  int myfile;  char buffer[100];  int retval;  myfile = open("/dev/cc",O_RDWR);  if(myfile < 0)    printf("Open filed /n");  write(myfile,"hello_world",sizeof("hello_world"));  retval = read(myfile,buffer,100);  buffer[retval] = 1;  printf("redponse:%s/n",buffer);  close(myfile);}其中close对应驱动中的release.上面的 write read 内容就随便写啦，因为我驱动中并没有实现。编译一下执行，看内核输出信息dmesg 如下[ 5096.422497] ********cc_open*******[ 5096.422512] *******cc_write*******[ 5096.422519] *******cc_read********[ 5096.422572] *******cc_release*****这样就说明调用成功了