{
int ret = 0;
struct mem_dev *dev;
unsigned long p;
unsigned long count;
printk("mem_write.\n");
dev = filp->private_data;
count = size;
p = *ppos;
if(p>MEMDEV_SIZE)
{
return 0;
}
if(count >(MEMDEV_SIZE- p))
count = MEMDEV_SIZE - p;
if(down_interruptible(&dev->sem))
return -ERESTARTSYS;
if(copy_from_user(dev->data+p,buf,count))
{
ret = -EFAULT;
printk("copyfrom user failed\n");
}
else
{
*ppos+=count;
ret = count;
printk("writed %d bytes to dev\n",count);
}
up(&dev->sem);
return ret;
}
/*修改文件当前的读写位置*/
static loff_t
mem_llseek(struct file *filp,loff_t offset,int whence)
{
int newpos;
printk("mem_llsek.\n");
switch(whence)
{
case 0 :
newpos =offset;
break;
case 1:
newpos = filp->f_pos +offset;
break;
case 2:
newpos = MEMDEV_SIZE - 1 +offset;
break;
default :
return -EINVAL;
}
if((newpos<0)||(newpos>(MEMDEV_SIZE - 1)))
return -EINVAL;
filp->f_pos = newpos;
return newpos;
}
/*文件操作结构体*/
static const struct file_operations mem_fops ={
.owner = THIS_MODULE,
.open =mem_open,
.write =mem_write,
.read = mem_read,
.release = mem_release,
.llseek=mem_llseek,
};
/*设备驱动模型加载函数*/
static int
__init memdev_init(void)
{
int result;
int err;
int i;
/*申请设备号*/
dev_t devno = MKDEV(mem_major,0);
if(mem_major)
/*注意静态申请的dev_t参数和动态dev_t参数的区别*/
result = register_chrdev_region(devno,MEMDEV_NUM,"memdev");
else
{
result = alloc_chrdev_region(&devno,0,MEMDEV_NUM,"memdev");
mem_major = MAJOR(devno);
}
if(result<0)
{
printk("can not get major devno:%d\n",mem_major);
return result;
}
/*注册设备驱动*/
cdev_init(&mem_cdev,&mem_fops);/*初始化cdev结构*/
mem_cdev.owner = THIS_MODULE;
/*注册字符驱动设备*/
err = cdev_add(&mem_cdev,MKDEV(mem_major,0),MEMDEV_NUM);
if(err)
printk("addcdev faild,err is %d\n",err);
/*分配设备内存*/
mem_devp = kmalloc(MEMDEV_NUM*(sizeof(struct mem_dev)),GFP_KERNEL);
if(!mem_devp)
{
result = -ENOMEM;
goto fail_malloc;
}
memset(mem_devp,0,MEMDEV_NUM*(sizeof(struct mem_dev)));
for(i=0;i
mem_devp[i].size = MEMDEV_SIZE;
mem_devp[i].data = kmalloc(MEMDEV_SIZE,GFP_KERNEL);
memset(mem_devp[i].data,0,MEMDEV_SIZE);
// init_MUTEX(&mem_devp[i].sem); /*初始化互斥锁*/
sema_init(&mem_devp[i].sem,1);
}
return result;
fail_malloc:
unregister_chrdev_region(MKDEV(mem_major,0),MEMDEV_NUM);
return result;
}
/*设备驱动模型卸载函数*/
static void
memdev_exit(void)
{
cdev_del(&mem_cdev);
/*注意释放的设备号个数一定要和申请的设备号个数一致，否则会导致设备号资源流失*/
unregister_chrdev_region(MKDEV(mem_major,0),MEMDEV_NUM);
printk("memdev_exit\n");
}
module_init(memdev_init);
module_exit(memdev_exit);
MODULE_AUTHOR("BQL");
MODULE_LICENSE("GPL");