linux驱动 ioctl（）

first let's look at the struct  file_operation
{
.ioctl = fun_name,(if in linux-digilent ti is   .unlocked_ioctl = fun_name)
}

 function declare：
static int my_ioctl(unsigned int reg_num,unsigned int cmd,struct data *arg);
now we know, there is a struct named data

struct data{
int reg_num;
int reg_val;
};

there also has a function to init the struct data

struct data makedata(int x,int y)
{
　　struct data temp;
　　temp.reg_num = x;
　　temp.reg_val = y;
　　return temp;
}

static int my_ioctl(unsigned int reg_num,unsigned int cmd,struct data *arg){
struct data * p = arg ;
int tmp;

switch(cmd){
　　　　　case 0: 
　　　　　　　　　　prink("read_reg%d\n",p->reg_num);
　　　　　　　　　　tmp = ioread32(( (p->reg_num)*4   )+ aes_slave_reg0_addr);  break;

　　　　　case 1: 

　　　　　　　　　　prink("write_reg%d\n",p->reg_num);

　　　　　　　　　tmp =iowrite32(( (p->reg_num)*4   )+ aes_slave_reg0_addr,p->val);break;
　　　　default:　return 0xff;

　　　　　　}

          return tmp;

}