简单的字符设备驱动__struct_count_include_unsigned_return_

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简单的字符设备驱动

来源: 互联网发布时间：2016-07-16

本文导语: 错误百出高手帮忙看看吧 #include #include #include #include #include #include #include #include #include #include #include #include #include MODULE_LICENSE("Dual BSD/GPL"); #define GLOBALMEM_SIZE 0x1000 //内存 4kb #define MEM_CLEAR 0x1 //清零内...

错误百出   高手帮忙看看吧
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
MODULE_LICENSE("Dual BSD/GPL");
#define GLOBALMEM_SIZE 0x1000 //内存  4kb
#define MEM_CLEAR  0x1  //清零内存
#define GLOBALMEM_MAJOR 254 //预设主设备号
static  int globalmem_major=GLOBALMEM_MAJOR;
struct globalmem_dev
{
    struct cdev cdev;
    unsigned char mem[GLOBALMEM_MAJOR];
}
struct globalmem_dev *globalmem_devp;
int globalmem_open(struct inode *inode,struct file* flip)
{
     filp->private_data=globalmem_devp;
     return 0;
}
int global_release(struct inode* inode,struct file *flip)
{
     return 0;
}

static int globalmem_ioctl(struct inode *inodep,struct file *flip,unsigned int
cmd ,unsigned long arg)
{
     struct globalmem_dev *dev=flip->private_data;
     switch(cmd)
                {
         case MEM_CLEAR:
          memset(dev->mem,0,GLOBALMEM_SIZE);
          printk(KERN_INFO "globalmem is set to zero n");
          break;
         default:
          return -EINVAL;
                 }
     return 0;
}

//读写函数
static ssize_t globalmem_read(struct file *flip,char __user *buf,size_t
size,loff_t *ppos)
{
    unsigned long p=*ppos ;
    unsigned int count=size;
    int ret =0;
    struct globalmem_dev *dev =filp->private_data;

    if(p>=GLOBALMEM_SIZE)
               {
       return count? -ENXIO:0;
                }
    if(count>GLOBALMEM_SIZE-p)
                 {
          count=GLOBALMEM_SIZE-p;
                  }
    if(copy_to_user(buf,(void*)(dev->mem+p),count))
               {
           ret=-EFAULT;
               }
    else
               {
        *ppos+=count;
         ret=count;
         printk(KERN_INFO "rea %d bytes(s) from %d n",count,p);
                 }
     return  ret;
}
static ssize_t globalmem_write(struct file *flip,const char __user *buf,size_t
size,loff_t *ppos)
{
    unsigned long p=*ppos;
    unsigned int count=size;
    int ret =0;
    struct globalmem_dev * dev=flip->private_data;
    if(p>=GLOBALMEM_SIZE)return count? -ENXIO:0;
    if(count>GLOBAL_SIZE-p)count=GLOBALMEM_SIZE-p;
    if(copy_from_user(dev->mem+p,buf,count))ret=-EFAULT;
    else
           {
       *ppos+=count;
        ret=count;
        printk(KEN_INFO "write %d bytes(s) from %d n",count,p);
            }
    return ret;
}
//seek 函数。
static loff_t globalmem_llseek(struc file *flip,loff_t offset,int orig)
{
     loff_t ret=0;
     switch(orig)
                  {
        case 0:
          if(offsetGLOBALMEM_SIZE)
                                {
               ret=-EINVAL;
               break;
                                  }
          flip->f_pos =(unsigned int)offset;
          ret=flip->f_pos;
          break;
       case 1:
           if((flip->f_pos+offset)>GLOBALMEM_SIZE)
                                  {
               ret=-EINVAL;
               break;
                                   }
           if((flip->f_pos+offset)f_pos+=offset;
           ret=flip->f_pos;
           break;
        default:
           ret=-EINVAL;
                   }
     return ret;
}
//ioctl()函数用于清零
static int globalmem_ioctl(struct inode* inodep,struct file *flip,unsigned int
cmd ,unsigned long arg)
{
    switch(cmd)
            {
       case MEM_CLEAR:
         memset(dev->mem,0,GLOBALMEM_SIZE);
         printk(KERN_INFO "globalmem is set to zeron");
         break;
       default:
         return -EINVAL;//不支持其他命令
            }
  return 0;
}

static const struct file_operations globalmem_fops=
{
    .owner=THIS_MODULE,
    .llseek=globalmem_llseek,
    .read=globalmem_read,
    .write=globalmem_write,
    .ioctl=globalmem_ioctl,
    .open=globalmem_open,
    .release=globalmem_release,
};
static void globalmem_setup_cdev(struct globalmem_dev *dev,int index)
{
     int err,devno=MKDEV(globalmem_major,0);
     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 %d adding globalmem",err);
}
int globalmem_init(void)
{
    int result;
    dev_t devno=MKDEV(globalmem_major,0);
    if(globalmem_major)result=register_chrdev_region(devno,1,"globalmem");
    else
               {
        result=alloc_chrdev_region(&devno,0,1,"globalmem");
                     globalmem_major=MAJOR(devno);
                }
    if(result