驅(qū)動學(xué)習(xí)１

作者：時間：2016-12-01 來源：網(wǎng)絡(luò)

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/*清除空間*/

memset(mem_devp,0,sizeof(struct mem_dev));

for(i = 0; i < MEMDEV_NR_DEVS; ++i)

{

mem_devp[i].size = MEMDEV_SIZE;

mem_devp[i].data = kmalloc(MEMDEV_SIZE,GFP_KERNEL);

/*問題，沒有進(jìn)行錯誤的控制*/

memset(mem_devp[i].data,0,MEMDEV_SIZE);

}

return 0;

fail_malloc:

unregister_chrdev_region(devno,1);

return result;

}

/*模塊清除函數(shù)*/

static void memdev_exit(void)

{

cdev_del(&cdev);/*注銷字符設(shè)備*/

/*釋放兩個物理內(nèi)存*/

kfree(mem_devp[0].data);

kfree(mem_devp[1].data);

kfree(mem_devp);/*釋放設(shè)備結(jié)構(gòu)體內(nèi)存*/

unregister_chrdev_region(MKDEV(mem_major,0),2);

}

/*定義相關(guān)的操作函數(shù)*/

/*mem_open*/

int mem_open(struct inode *inode,struct file *filp)

{

struct mem_dev *dev;

/*判斷設(shè)備文件的次設(shè)備號*/

int num = MINOR(inode->i_rdev);

if(num >= MEMDEV_NR_DEVS)

return -ENODEV;

dev = &mem_devp[num];

/*將數(shù)據(jù)指向兩個內(nèi)存空間*/

filp->private_data = dev;

return 0;

}

/*release函數(shù)的實現(xiàn)*/

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

{

return 0;

}

/*read函數(shù)的實現(xiàn)*/

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;

/*獲得file結(jié)構(gòu)體上的指針*/

struct mem_dev *dev = filp->private_data;

/*參數(shù)的檢查*/

if(p >= MEMDEV_SIZE)

return 0;

if(count > MEMDEV_SIZE - p)

count = MEMDEV_SIZE - p;

/*從內(nèi)核讀數(shù)據(jù)到用戶空間*/

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

{

/*出錯誤*/

ret = -EFAULT;

}

else

{

/*移動當(dāng)前文件光標(biāo)的位置*/

*ppos += count;

ret = count;

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

}

return ret;

}

/*write函數(shù)的實現(xiàn)*/

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;

/*獲得設(shè)備結(jié)構(gòu)體的指針*/

struct mem_dev *dev = filp->private_data;

/*檢查參數(shù)的長度*/

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

{

/*改變文件位置*/

*ppos += count;

ret = count;

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

}

return ret;

}

/*lseek的實現(xiàn)*/

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;

}

/*作者以及權(quán)限的聲明*/

MODULE_AUTHOR("GongPing");

MODULE_LICENSE("GPL");

/*通過宏module_init和module_exit實現(xiàn)模塊添加*/

module_init(memdev_init);

module_exit(memdev_exit);

第三個是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個是應(yīng)用程序：

#include

int main()

{

FILE *fp0 = NULL;

char Buf[4096];

/*復(fù)制數(shù)據(jù)到buf中*/

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

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

/*打開設(shè)備文件*/

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

/*錯誤處理*/

if(fp0 == NULL)

{

printf("Open Memdev0 Error!");

return -1;

}

/*寫數(shù)據(jù)到設(shè)備中*/

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

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

/*定位*/

fseek(fp0,0,SEEK_SET);

/*復(fù)制數(shù)據(jù)到Buf*/

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

/*打印*/

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

/*讀數(shù)據(jù)*/

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

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

fclose(fp0);

return 0;

}

源碼是別人的，我只是做了一下注釋，然后做了適當(dāng)?shù)男薷?，?qū)動程序與應(yīng)用程序以及硬件代碼存在較大的差別，以后要多寫，多理解，多總結(jié)。

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