linux驱动中ioctl使用

在驱动头文件中定义幻数

/* 定义幻数 */
#define OLED_IOC_MAGIC  'k'
/* 定义命令 */
#define OLED_IOC_OPEN   _IO(OLED_IOC_MAGIC, 1)
#define OLED_IOC_CLOSE _IO(OLED_IOC_MAGIC, 2)
#define OLED_IOC_SET_POINT _IOR(OLED_IOC_MAGIC, 3, int)
#define OLED_IOC_SET_STRING _IOW(OLED_IOC_MAGIC, 4, int)
#define OLED_IOC_REFRESH _IO(OLED_IOC_MAGIC, 5)
#define OLED_IOC_CLEAR _IO(OLED_IOC_MAGIC, 6)
#define OLED_IOC_MAXNR 6

在驱动源文件中实现ioctl函数

static int oled12864_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
    int err = 0;
    int ret = 0;
    /* 检测命令的有效性 */
    if (_IOC_TYPE(cmd) != OLED_IOC_MAGIC) 
        return -EINVAL;
    if (_IOC_NR(cmd) > OLED_IOC_MAXNR) 
        return -EINVAL;
    /* 根据命令类型，检测参数空间是否可以访问 */
    if (_IOC_DIR(cmd) & _IOC_READ)
        err = !access_ok(VERIFY_WRITE, (void *)arg, _IOC_SIZE(cmd));
    else if (_IOC_DIR(cmd) & _IOC_WRITE)
        err = !access_ok(VERIFY_READ, (void *)arg, _IOC_SIZE(cmd));
    if (err) 
        return -EFAULT;
    /* 根据命令，执行相应的操作 */
    switch(cmd) {
        /* 打印当前设备信息 */
        case OLED_IOC_OPEN:
            OLED_DisPlay_On();
            printk("<--- CMD OLED_IOC_OPEN Done--->\n\n");
            break;
            /* 打印当前设备信息 */
        case OLED_IOC_CLOSE:
            OLED_DisPlay_Off();
            printk("<--- CMD OLED_IOC_CLOSE Done--->\n\n");
            break;
        case OLED_IOC_REFRESH:
            OLED_Refresh();
            break;
        case OLED_IOC_CLEAR:
            OLED_Clear();
            break;
        /* 获取参数 */
        case OLED_IOC_SET_POINT: 
            {
                pointData tmp;
                //定义结构体，从用户空间传入结构体数据，再进行解析
                copy_from_user((unsigned char *)&tmp,(unsigned char *)arg,sizeof(stringData));
                // OLED_Clear();
                if(tmp.on = 0){
                    OLED_ClearPoint(tmp.p.x, tmp.p.y);
                }else{
                    OLED_DrawPoint(tmp.p.x, tmp.p.y);
                }
                printk("<--- In Kernel = %d %d %d %d--->\n\n", tmp.p.x, tmp.p.y, tmp.on, 16);
            }
            break;
        
        /* 设置参数 */
        case OLED_IOC_SET_STRING:
            {
                stringData tmp;
                copy_from_user((unsigned char *)&tmp,(unsigned char *)arg,sizeof(stringData));
                // OLED_Clear();
                OLED_ShowString(tmp.p.x, tmp.p.y, tmp.data, tmp.len);
                OLED_Refresh();
                printk("<--- In Kernel = %d %d %s %d--->\n\n", tmp.p.x, tmp.p.y, tmp.data, 16);
            }
            break;
        default:  
            return -EINVAL;
    }
    return ret;
}

ops操作集合

static const struct file_operations oled12864_ops = {
    .owner = THIS_MODULE,
    .open = oled12864_open,
    .read = oled12864_read,
    .write = oled12864_write,
    .unlocked_ioctl = oled12864_ioctl,
    .release = oled12864_release,
};