Linux驱动开发: 杂项字符设备

struct miscdevice  {
    int minor;                       //次设备号，杂项设备的主设备号为10
    const char *name;                //设备的名称
    const struct file_operations *fops;   //文件操作
    /* 下面的成员是供内核使用，驱动编写不需要理会 */
    struct list_head list;      //misc_list的链表头
    struct device *parent;      //父设备
    struct device *this_device; //当前设备，是device_create的返回值
};

/*驱动代码 misc.c */
#include <linux/module.h>       /* Needed by all modules */
#include <linux/init.h>         /* Needed for the module-macros */
#include <linux/fs.h>
#include <linux/miscdevice.h>
<p>static ssize_t misc_read (struct file <em>pfile,
char __user </em>buff,
size_t size, loff_t *off)
{
printk(KERN_EMERG "line:%d,%s is call\n",<strong>LINE</strong>,<strong>FUNCTION</strong>);
return 0;
}</p><p>static ssize_t misc_write(struct file <em>pfile,
const char __user </em>buff,
size_t size, loff_t *off)
{
printk(KERN_EMERG "line:%d,%s is call\n",<strong>LINE</strong>,<strong>FUNCTION</strong>);
return 0;
}</p><p>static int  misc_open(struct inode <em>pinode, struct file </em>pfile)
{
printk(KERN_EMERG "line:%d,%s is call\n",<strong>LINE</strong>,<strong>FUNCTION</strong>);
return 0;
}</p><p>static int misc_release(struct inode <em>pinode, struct file </em>pfile)
{
printk(KERN_EMERG "line:%d,%s is call\n",<strong>LINE</strong>,<strong>FUNCTION</strong>);
return 0;
}</p><p>//文件操作方法：根据具体设备实现需要的功能
static const  struct file_operations misc_fops = {
.read     = misc_read,
.write    = misc_write,
.release  = misc_release,
.open     = misc_open,
};</p><h1>define DEV_NAME  "abc"</h1><h1>if 1  //C99 标准 新增加的结构体初始化方法，这种可以选其中部分进行初始化，初始化顺序不限</h1><p>static struct miscdevice  misc_dev =  {
.fops  =  &misc_fops,       /<em> 设备文件操作方法 </em>/
.minor = 255,                    /<em> 次设备号 </em>/
.name  =  DEV_NAME,           /<em> 设备名/dev/下的设备节点名   </em>/
};</p><h1>else  //c89标准风格的结构体成员初始，只能按顺序初始化成员（做了解）</h1><p>static struct miscdevice  misc_dev =  {
255,              /<em> 次设备号 </em>/
DEV_NAME,         /<em> 设备名/dev/下的设备节点名   </em>/
&misc_fops        /<em> 设备文件操作方法 </em>/
};</p><h1>endif</h1><p>static int __init hello_init(void)  {
misc_register(&misc_dev);
printk(KERN_EMERG "misc init \n");
return 0;
}</p><p>static void  __exit hello_exit(void){
misc_deregister(&misc_dev);
printk(KERN_EMERG "Goodbye,misc\n");
}</p><p>module_init(hello_init);
module_exit(hello_exit);
MODULE_LICENSE("GPL");

#include <stdio.h></p><h1>include <stdlib.h></h1><h1>include <string.h></h1><h1>include <unistd.h></h1><h1>include <sys/types.h></h1><h1>include <sys/stat.h></h1><h1>include <fcntl.h></h1><h1>define DEV_NAME  "/dev/abc"</h1><p>int main(void){
char buf[] = {1, 0, 0, 0};
int i = 0;
int fd;       //打开设备文件 O_RDWR,  O_RDONLY, O_WRONLY,
fd = open(DEV_NAME, O_RDWR);
if(fd < 0){
perror("open");
exit(1);
}</p><pre class="brush:php;toolbar:false;"><code>while(1){
    i++;
    if(i > 10000)
        break;
    write(fd, buf, 4);
    sleep(1);
}
close(fd);
return 0;

obj-m := misc.o
KDIR   := /home/work/linux-3.5</p><p>all:
make -C $(KDIR) M=$(PWD) modules
rm -f <em>.o </em>.mod.o <em>.mod.c </em>.symvers <em>.markers </em>.unsigned <em>.order </em>~
arm-linux-gcc app.c -o app
cp -f *.ko  app /home/work/rootfs/root</p><p>clean:
rm -f <em>.ko </em>.o <em>.mod.o </em>.mod.c <em>.symvers </em>.markers <em>.unsigned </em>.order *~