Linux下的简单字符驱动--改自宋宝华《Linux驱动开发详解第2版》在kernel2.6.38通过

Linux下的简单字符驱动--改自宋宝华《Linux驱动开发详解第2版》在kernel2.6.38通过,实验过程：在fedora9虚拟机上完成交叉编译，生成mini6410_globalmem.ko,复制到tiny6410开发板上。可以用insmod及rmmod添加删除/*globalmemdriverasanexampleofchardevicedrivers

mini6410_globalmem.c

TheinitialdeveloperoftheoriginalcodeisBaohuaSong

<author@linuxdriver.cn>.AllRightsReserved.

======================================================================*/

#include<linux/module.h>

#include<linux/types.h>

#include<linux/fs.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/device.h>

#include<linux/slab.h>

#defineGLOBALMEM_SIZE0x1000/*全局内存最大4K字节*/

#defineMEM_CLEAR0x1/*清0全局内存*/

#defineGLOBALMEM_MAJOR233/*预设的globalmem的主设备号*/

structclass*my_class;

staticglobalmem_major=GLOBALMEM_MAJOR;

/*globalmem设备结构体*/

structglobalmem_dev

{

structcdevcdev;/*cdev结构体*/

unsignedcharmem[GLOBALMEM_SIZE];/*全局内存*/

structsemaphoresem;

};

structglobalmem_dev*globalmem_devp;/*设备结构体指针*/

/*文件打开函数*/

intglobalmem_open(structinode*inode,structfile*filp)

{

/*将设备结构体指针赋值给文件私有数据指针*/

filp->private_data=globalmem_devp;

return0;

}

/*文件释放函数*/

intglobalmem_release(structinode*inode,structfile*filp)

{

return0;

}

/*ioctl设备控制函数afterkernel2.6.36removeioctl,addunlocked_ioctl*/

staticintglobalmem_unlocked_ioctl(structinode*inodep,structfile*filp,unsigned

intcmd,unsignedlongarg)

{

structglobalmem_dev*dev=filp->private_data;//获得设备结构体指针

switch(cmd)

{

caseMEM_CLEAR:

if(down_interruptible(&dev->sem))

return-ERESTARTSYS;

memset(dev->mem,0,GLOBALMEM_SIZE);

up(&dev->sem);

printk(KERN_INFO"globalmemissettozero\n");

break;

default:

return-EINVAL;

}

return0;

}

/*读函数*/

staticssize_tglobalmem_read(structfile*filp,char__user*buf,size_tsize,

loff_t*ppos)

{

unsignedlongp=*ppos;

unsignedintcount=size;

intret=0;

structglobalmem_dev*dev=filp->private_data;/*获得设备结构体指针*/

/*分析和获取有效的写长度*/

if(p>=GLOBALMEM_SIZE)

returncount?-ENXIO:0;

if(count>GLOBALMEM_SIZE-p)

count=GLOBALMEM_SIZE-p;

if(down_interruptible(&dev->sem))

return-ERESTARTSYS;

/*内核空间->用户空间*/

if(copy_to_user(buf,(void*)(dev->mem+p),count))

{

ret=-EFAULT;

}

else

{

*ppos+=count;

ret=count;

printk(KERN_INFO"read%dbytes(s)from%d\n",count,p);

}

up(&dev->sem);

returnret;

}

/*写函数*/

staticssize_tglobalmem_write(structfile*filp,constchar__user*buf,

size_tsize,loff_t*ppos)

{

unsignedlongp=*ppos;

unsignedintcount=size;

intret=0;

structglobalmem_dev*dev=filp->private_data;/*获得设备结构体指针*/

/*分析和获取有效的写长度*/

if(p>=GLOBALMEM_SIZE)

returncount?-ENXIO:0;

if(count>GLOBALMEM_SIZE-p)

count=GLOBALMEM_SIZE-p;

if(down_interruptible(&dev->sem))

return-ERESTARTSYS;

/*用户空间->内核空间*/

if(copy_from_user(dev->mem+p,buf,count))//p是偏移，也就是写入的起始地址

ret=-EFAULT;

else

{

*ppos+=count;

ret=count;

printk(KERN_INFO"written%dbytes(s)from%d\n",count,p);

}

up(&dev->sem);

returnret;

}

/*seek文件定位函数*/

staticloff_tglobalmem_llseek(structfile*filp,loff_toffset,intorig)

{

loff_tret=0;

switch(orig)

{

case0:/*相对文件开始位置偏移*/

if(offset<0)

{

ret=-EINVAL;

break;

}

if((unsignedint)offset>GLOBALMEM_SIZE)

{

ret=-EINVAL;

break;

}

filp->f_pos=(unsignedint)offset;

ret=filp->f_pos;

break;

case1:/*相对文件当前位置偏移*/

if((filp->f_pos+offset)>GLOBALMEM_SIZE)

{

ret=-EINVAL;

break;

}

if((filp->f_pos+offset)<0)

{

ret=-EINVAL;

break;

}

filp->f_pos+=offset;

ret=filp->f_pos;

break;

default:

ret=-EINVAL;

break;

}

returnret;

}

/*文件操作结构体*/

staticconststructfile_operationsglobalmem_fops=

{

.owner=THIS_MODULE,

.llseek=globalmem_llseek,

.read=globalmem_read,

.write=globalmem_write,

.unlocked_ioctl=globalmem_unlocked_ioctl,

.open=globalmem_open,

.release=globalmem_release,

};

/*初始化并注册cdev*/

staticvoidglobalmem_setup_cdev(structglobalmem_dev*dev,intindex)

{

interr,devno=MKDEV(globalmem_major,index);

cdev_init(&dev->cdev,&globalmem_fops);

dev->cdev.owner=THIS_MODULE;

dev->cdev.ops=&globalmem_fops;

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

if(err)

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

}

/*设备驱动模块加载函数*/

intglobalmem_init(void)

{

intresult;

dev_tdevno=MKDEV(globalmem_major,0);

/*申请设备号*/

if(globalmem_major)

result=register_chrdev_region(devno,1,"globalmem");

else/*动态申请设备号*/

{

result=alloc_chrdev_region(&devno,0,1,"globalmem");

globalmem_major=MAJOR(devno);

}

if(result<0)

returnresult;

/*kmalloc*/

globalmem_devp=kmalloc(sizeof(structglobalmem_dev),GFP_KERNEL);

if(!globalmem_devp)/*申请失败*/

{

result=-ENOMEM;

gotofail_malloc;

}

memset(globalmem_devp,0,sizeof(structglobalmem_dev));

globalmem_setup_cdev(globalmem_devp,0);

sema_init(&globalmem_devp->sem,1);//init_MUTEX(&globalmem_devp->sem);

/*createyourownclassunder/sysfs*/

/*class_create-->class_register()*/

my_class=class_create(THIS_MODULE,"globalmem");

if(IS_ERR(my_class)){

printk("Err:failedincreatingclass.\n");

gotofail_malloc;

}

/*registeryourowndeviceinsysfs,andthiswillcauseudevtocreatecorrespondingdevicenode*/

device_create(my_class,NULL,MKDEV(globalmem_major,0),NULL,"globalmem");

printk(KERN_INFO"Registeredcharacterdriver\n");

return0;

fail_malloc:unregister_chrdev_region(devno,1);

returnresult;

}

/*模块卸载函数*/

voidglobalmem_exit(void)

{

cdev_del(&globalmem_devp->cdev);/*注销cdev*/

kfree(globalmem_devp);/*释放设备结构体内存*/

unregister_chrdev_region(MKDEV(globalmem_major,0),1);/*释放设备号*/

}

MODULE_AUTHOR("SongBaohua");

MODULE_LICENSE("DualBSD/GPL");

module_param(globalmem_major,int,S_IRUGO);

module_init(globalmem_init);

module_exit(globalmem_exit);