android 字符设备驱动模块及在 /dev 下自动创建设备节点问题

转载时请注明出处和作者文章出处：http://blog.csdn.net/lbmygf/archive/2011/06/16/6547946.aspx

作者：曼云-->孤峰

#include <linux/input.h>

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/mm.h>

#include <linux/sched.h>

#include <linux/init.h>

#include <linux/cdev.h>

#include <asm/io.h>

#include <asm/system.h>

#include <asm/uaccess.h>

#include <linux/security.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/fs.h>

#include <linux/device.h>

#define MRY_MAJOR 99

#define uint unsigned int

#define ulong unsigned long

static int mry_major=MRY_MAJOR;

typedef struct

{

struct cdev dev;

//add private data

}mry_dev;

mry_dev *_pdev;

static int mry_open(struct inode *pinode,struct file *pfile)

{

printk("in open now--------------------------------------------------------/n");

return 0;

}

static int mry_ioctl(struct inode *pinode,struct file *pfile,uint cmd,ulong arg)

{

printk("cmd == %d arg == %ld --------------------------------------------------------/n", cmd, arg);

switch(cmd)

{

case 1:

break;

default:

return -1;

}

return 0;

}

static const struct file_operations _fops=

{

.owner=THIS_MODULE,

.ioctl=mry_ioctl,

.open=mry_open,

};

static void mry_setup_cdev(mry_dev *pdev,int index)

{

int err,devno=MKDEV(mry_major,index);

cdev_init(&pdev->dev,&_fops);

pdev->dev.owner=THIS_MODULE;

pdev->dev.ops=&_fops;

err=cdev_add(&pdev->dev,devno,1);

if(err)

printk(KERN_NOTICE "Error %d adding LED %d",err,index);

}

struct class *my_class;

int mry_init(void)

{

int rs;

dev_t devno=MKDEV(mry_major,0); //获取设备节点号

if(mry_major)

rs=register_chrdev_region(devno,1,"gps_sleep"); // 注册gps_sleep 设备

else

{

rs=alloc_chrdev_region(&devno,0,1,"gps_sleep"); //动态注册gps_sleep设备，也就是自动获取设备号

mry_major=MAJOR(devno); //获取主设备号

}

if(rs<0){

return rs;

}

_pdev=kmalloc(sizeof(mry_dev),GFP_KERNEL); //为 _pdev分配空间

if(!_pdev)

{

rs=-ENOMEM;

goto fail_malloc;

}

memset(_pdev,0,sizeof(mry_dev)); //初始化_pdev

mry_setup_cdev(_pdev,0);

my_class = class_create(THIS_MODULE, "gps_sleep");

//class_create和device_create 自动在/dev目录下创建设备节点gps_sleep

if(IS_ERR(my_class))

{

printk("Err: failed in creating class.--------------------------------------------/n");

return -1;

}

device_create(my_class, NULL, MKDEV(mry_major, 0), NULL, "gps_sleep");

//在这里需要注意了，由于内核版本不同，导致device_create的参数可能有变化，

//我就遇到了，在网上找了一个，一用就出问题了，系统会跑死，现在这个的内核是2.6.35的

printk(KERN_INFO "mry driver ok----------------------------------------------------------------");

return 0;

fail_malloc:

printk(KERN_INFO "failed");

unregister_chrdev_region(devno,1);

return rs;

}

void mry_exit(void)

{

dev_t devno = MKDEV (mry_major, 0);

cdev_del(&_pdev->dev);

device_destroy(my_class, MKDEV(mry_major, 0)); //delete device node under /dev

class_destroy(my_class); //delete class created by us

kfree(_pdev);

unregister_chrdev_region(MKDEV(mry_major,0),1);

}

module_init(mry_init);

module_exit(mry_exit);

MODULE_AUTHOR("liu");

MODULE_DESCRIPTION("gps sleep wake driver");

MODULE_LICENSE("GPL");