驱动学习１

KERNELRELEASE = $(shell cat include/config/kernel.release 2>

int num = MINOR(inode->

if(num >

filp->

实现*/

int mem_release(struct inode *inode, struct file *flip)

{

return 0;

}

/*read函数的实现*/

static ssize_t mem_read(struct file *filp,char __user *buf, size_t size,loff_t *ppos)

{

unsigned long p = *ppos;

unsigned int count = size;

int ret = 0;

/*获得file结构体上的指针*/

struct mem_dev *dev = filp->private_data;

/*参数的检查*/

if(p >= MEMDEV_SIZE)

return 0;

if(count > MEMDEV_SIZE - p)

count = MEMDEV_SIZE - p;

/*从内核读数据到用户空间*/

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

{

/*出错误*/

ret = -EFAULT;

}

else

{

/*移动当前文件光标的位置*/

*ppos += count;

ret = count;

printk(KERN_INFO "read %d bytes(s) from %d",count,p);

}

return ret;

}

/*write函数的实现*/

static ssize_t mem_write(struct file *filp,const char __user *buf,size_t size,loff_t *ppos)

{

unsigned long p = *ppos;

unsigned int count = size;

int ret = 0;

/*获得设备结构体的指针*/

struct mem_dev *dev = filp->private_data;

/*检查参数的长度*/

if(p >= MEMDEV_SIZE)

return 0;

if(count > MEMDEV_SIZE - p)

count = MEMDEV_SIZE - p;

if(copy_from_user(dev->data + p,buf,count))

ret = -EFAULT;

else

{

/*改变文件位置*/

*ppos += count;

ret = count;

printk(KERN_INFO "writted %d bytes(s) from %d",count,p);

}

return ret;

}

/*lseek的实现*/

static loff_t mem_llseek(struct file *filp,loff_t offset, int whence)

{

loff_t newpos;

switch(whence)

{

case 0:/*SEEK_SET*/

newpos = offset;

break;

case 1:/*SEEK_CUR*/

newpos = filp->f_pos + offset;

break;

case 2:/*SEEK_END*/

newpos = MEMDEV_SIZE - 1 + offset;

break;

default:

return -EINVAL;

}

filp->f_pos = newpos;

return newpos;

}

/*作者以及权限的声明*/

MODULE_AUTHOR("GongPing");

MODULE_LICENSE("GPL");

/*通过宏module_init和module_exit实现模块添加*/

module_init(memdev_init);

module_exit(memdev_exit);

第三个是Makefile：

ifneq ($(KERNELRELEASE),)

obj-m := memdev.o

else

#KDIR :=/usr/src/kernels/2.6.35.14-96.fc14.i686

#KDIR :=/lib/modules/2.6.35.14-96.fc14.i686/build

#KDIR ?=/opt/LinuxKernel/linux-2.6.38.1

KDIR :=/opt/LinuxKernel/linux-2.6.38.1

PWD :=$(shell pwd)

default:

make -C $(KDIR) M=$(PWD) modules

clean:

rm -f *.ko *.o *.mod.o *.mod.c *.symvers

endif

第4个是应用程序：

#include

#include

#include

int main()

{

FILE *fp0 = NULL;

char Buf[4096];

/*复制数据到buf中*/

strcpy(Buf,"Mem is char devices!");

printf("Buf: %s",Buf);

/*打开设备文件*/

fp0 = fopen("/dev/memdev0","rw");

/*错误处理*/

if(fp0 == NULL)

{

printf("Open Memdev0 Error!");

return -1;

}

/*写数据到设备中*/

//fread(Buf,sizeof(Buf),1,fp0);

fwrite(Buf,sizeof(Buf),1,fp0);

/*定位*/

fseek(fp0,0,SEEK_SET);

/*复制数据到Buf*/

strcpy(Buf,"Buf is NULL!");

/*打印*/

printf("Buf: %s",Buf);

/*读数据*/

fread(Buf,sizeof(Buf),1,fp0);

printf("BUF: %s",Buf);

fclose(fp0);

return 0;

}

源码是别人的，我只是做了一下注释，然后做了适当的修改，驱动程序与应用程序以及硬件代码存在较大的差别，以后要多写，多理解，多总结。