已经挂载文件系统，如何调用EMMC设备驱动直接访问地址，不经过文件操作

发布于 2021-07-01 10:57:36 浏览：1467 订阅该版

根据论坛上的问答，修改了EMMC驱动初始化的偏移和大小
```c
    blk_dev->part.offset = 512*1024*2;
    blk_dev->part.size   = 0;
    blk_dev->part.lock = rt_sem_create("sem_sd0", 1, RT_IPC_FLAG_FIFO);
    
    /* register mmcsd device */
    blk_dev->dev.type  = RT_Device_Class_Block;
#ifdef RT_USING_DEVICE_OPS
    blk_dev->dev.ops  = &mmcsd_blk_ops;
#else
    blk_dev->dev.init = rt_mmcsd_init;
    blk_dev->dev.open = rt_mmcsd_open;
    blk_dev->dev.close = rt_mmcsd_close;
    blk_dev->dev.read = rt_mmcsd_read;
    blk_dev->dev.write = rt_mmcsd_write;
    blk_dev->dev.control = rt_mmcsd_control;
#endif
    blk_dev->dev.user_data = blk_dev;
    blk_dev->card = card;

blk_dev->geometry.bytes_per_sector = 1<<9;
    blk_dev->geometry.block_size = card->card_blksize;
    blk_dev->geometry.sector_count = card->card_capacity * (1024 / 512) - (512*1024*2);
    
    rt_device_register(&blk_dev->dev, "sd0", RT_DEVICE_FLAG_RDWR | RT_DEVICE_FLAG_REMOVABLE | RT_DEVICE_FLAG_STANDALONE);
    rt_list_insert_after(&blk_devices, &blk_dev->list);
```

但是如果直接调用设备驱动进行读写，会出现断言错误
```c
rt_device_t p_device = rt_device_find("sd0");

if(p_device != NULL)
{
	rt_device_write(p_device, addr, date, lenth);
}
```

![image.png](https://oss-club.rt-thread.org/uploads/20210701/c362c6df7c4bd9e59efb56fa525bdbd3.png)

尝试注册SD1设备，对SD1进行访问也会出现上述错误，请问有什么办法可以做到标题的描述，多谢解惑