驱动学习6--新接口alloc_chrdev_region&cdev_alloc的使用

驱动

#include <linux/module.h>       // module_init  module_exit#include <linux/init.h>         // __init   __exit#include <linux/fs.h>           //register_chrdev   file_operations#include <asm/uaccess.h>        //copy_from_user    copy_to_user#include <mach/regs-gpio.h>     //gpio virtual address#include <mach/gpio-bank.h>     //gpio virtual address#include <linux/cdev.h>         #define DEMO_MAJOR  200#define DEMO_CNT    1#define DEMO_NAME   "demo_char"#define GPJ0CON *((volatile unsigned int *)S5PV210_GPJ0CON)#define GPJ0DAT *((volatile unsigned int *)S5PV210_GPJ0DAT)static dev_t mydev;static struct cdev *pcdev;static int demo_chrdev_open(struct inode *inode, struct file *file){    GPJ0CON &= 0xff000fff;    GPJ0CON |= (1<<12)|(1<<16)|(1<<20);    GPJ0DAT |= ((1<<3)|(1<<4)|(1<<5));    printk(KERN_INFO "demo_chrdev_open\n");/*open的调试代码*/    return 0;}static int demo_chrdev_release(struct inode *inode, struct file *file){    GPJ0DAT |= ((1<<3)|(1<<4)|(1<<5));    printk(KERN_INFO "demo_chrdev_release\n");/*close的调试代码*/    return 0;}static ssize_t demo_chrdev_write(struct file *file, const char __user *ubuf, size_t count, loff_t *ppos){    int ret = -1;    char kbuf[100] = {0};    ret = copy_from_user(kbuf,ubuf,count);/*返回值为0成功*/    if(ret)    {        printk(KERN_ERR "copy_from_user fail\n");        return -EINVAL;    }    if(!strcmp(kbuf,"0"))   /*亮*/        GPJ0DAT &= ~((1<<3)|(1<<4)|(1<<5));    else if(!strcmp(kbuf,"1"))  /*灭*/        GPJ0DAT |= ((1<<3)|(1<<4)|(1<<5));    else         printk(KERN_INFO "input err\r\n");    printk(KERN_INFO "copy_from_user %s\r\n",kbuf);    return 0;}static const struct file_operations demo_fops = {    .owner      = THIS_MODULE,/*惯例，直接写即可*/      .open       = demo_chrdev_open,/*把open的api与此函数联系起来*/    .release    = demo_chrdev_release,/*把close的api于此函数联系起来*/    .write      = demo_chrdev_write,/*把write的api于此函数联系起来*/};static int __init chrdev_init(void) /*模块安装*/{       int ret = -1;    ret = alloc_chrdev_region(&mydev,12,DEMO_CNT,DEMO_NAME);/* 自动分配主设备号*/    if(ret<0)    {        printk(KERN_ERR "register_chrdev_region error\r\n");        goto alloc_err;    }    pcdev =  cdev_alloc();  /*给pcdev分配内存，会在cdev_del中自动释放*/    pcdev->owner = THIS_MODULE;    pcdev->ops = &demo_fops;    ret = cdev_add(pcdev, mydev, DEMO_CNT);/*注册设备驱动*/    if(ret)    {        printk(KERN_ERR "cdev_add error\r\n");        goto add_err;    }    printk(KERN_INFO "chrdev_init %d    %d\n",MAJOR(mydev),MINOR(mydev));    return 0;add_err:    cdev_del(pcdev);alloc_err:  return -EINVAL;}static void __exit chrdev_exit(void)/*模块卸载*/{    cdev_del(pcdev);/*注销设备驱动*/    unregister_chrdev_region(mydev,DEMO_CNT);/*注销申请的设备号*/}module_init(chrdev_init);module_exit(chrdev_exit);MODULE_LICENSE("GPL");/*描述模块的许可证*/MODULE_AUTHOR("Xin-Ya Zhu<[e-mail]>");/*描述模块的作者*/MODULE_DESCRIPTION("demo test");/*描述模块的介绍信息*/   MODULE_ALIAS("alias xxx");/*描述模块的别名信息*/

应用

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <sys/types.h>  //open close#include <sys/stat.h>#include <fcntl.h>#define FILE    "/dev/demo_text"#define LED_ON  "0"#define LED_OFF "1"int main(void){    int fd = -1;    char buf[100] = {0};    fd = open(FILE,O_RDWR);    if(fd<0)    {        printf("open error.\n");        return -1;    }    write(fd,LED_ON,strlen(LED_ON));    sleep(1);    write(fd,LED_OFF,strlen(LED_OFF));    sleep(1);    write(fd,LED_ON,strlen(LED_ON));    sleep(1);    write(fd,LED_OFF,strlen(LED_OFF));    sleep(1);    close(fd);    return 0;}/***************************[root@zhuxinya text]# insmod demo.ko [   16.507874] chrdev_init 250  12[root@zhuxinya text]# mknod /dev/demo_text c 250 012[root@zhuxinya text]# ./app [   30.405199] demo_chrdev_open[   30.407220] copy_from_user 0[   31.489561] copy_from_user 1[   32.491128] copy_from_user 0[   33.492682] copy_from_user 1[   34.494248] demo_chrdev_release[root@zhuxinya text]# rm /dev/demo_text [root@zhuxinya text]# rmmod demo.ko *****************************/