关于SPI中QSPI接口的问题

发布于 2020-02-17 16:08:26 浏览：2022 订阅该版

各位好！
使用RTThread SPI时遇到如下问题：
1.在qspi_core.c中，
rt_qspi_send调用了rt_qspi_transfer_message,
而且rt_qspi_send中，对QSPI的参数做了赋值，见红色字体
```rt_err_t rt_qspi_send(struct rt_qspi_device *device, const void *send_buf, rt_size_t length)
{
    RT_ASSERT(send_buf);
    RT_ASSERT(length != 0);

struct rt_qspi_message message;
    char *ptr = (char *)send_buf;
    rt_size_t  count = 0;
    rt_err_t result = 0;

message.instruction.content = ptr[0];
 message.instruction.qspi_lines = 1;
 count++;

/* get address */
 if (length > 1)
 {
 if (device->config.medium_size > 0x1000000 && length >= 5)
 {
 /* medium size greater than 16Mb, address size is 4 Byte */
 message.address.content = (ptr[1] << 24) | (ptr[2] << 16) | (ptr[3] << 8) | (ptr[4]);
 message.address.size = 32;
 message.address.qspi_lines = 1;
 count += 4;
 }
 else if (length >= 4)
 {
 /* address size is 3 Byte */
 message.address.content = (ptr[1] << 16) | (ptr[2] << 8) | (ptr[3]);
 message.address.size = 24;
 message.address.qspi_lines = 1;
 count += 3;
 }
 else
 {
 return -RT_ERROR;
 }

}
    else
    {
        /* no address stage */
        message.address.content = 0 ;
        message.address.qspi_lines = 0;
        message.address.size = 0;
    }

message.alternate_bytes.content = 0;
    message.alternate_bytes.size = 0;
    message.alternate_bytes.qspi_lines = 0;

message.dummy_cycles = 0;

/* determine if there is data to send */
    if (length - count > 0)
    {
        message.qspi_data_lines = 1;
    }
    else
    {
        message.qspi_data_lines = 0;

}
 
 /* set send buf and send size */
 message.parent.send_buf = ptr + count;
 message.parent.recv_buf = RT_NULL;
 message.parent.length = length - count;
 message.parent.cs_take = 1;
 message.parent.cs_release = 1;

result = rt_qspi_transfer_message(device, &message);
    if (result == 0)
    {
        result = -RT_EIO;
    }
    else
    {
        result = length;
    }

return result;
}
```
但rt_qspi_transfer_message 是直接调用了蓝色字体部分的接口。
该参数是rt_spi_message结构的。
那么，QSPI的参数是在哪里处理和发送给spi总线的呢？
```rt_size_t rt_qspi_transfer_message(struct rt_qspi_device  *device, struct rt_qspi_message *message)
{
    rt_err_t result;

RT_ASSERT(device != RT_NULL);
    RT_ASSERT(message != RT_NULL);

result = rt_mutex_take(&(device->parent.bus->lock), RT_WAITING_FOREVER);
    if (result != RT_EOK)
    {
        rt_set_errno(-RT_EBUSY);

return 0;
    }

/* reset errno */
    rt_set_errno(RT_EOK);

/* configure SPI bus */
    if (device->parent.bus->owner != &device->parent)
    {
        /* not the same owner as current, re-configure SPI bus */
        result = device->parent.bus->ops->configure(&device->parent, &device->parent.config);
        if (result == RT_EOK)
        {
            /* set SPI bus owner */
            device->parent.bus->owner = &device->parent;
        }
        else
        {
            /* configure SPI bus failed */
            rt_set_errno(-RT_EIO);
            goto __exit;
        }
    }

/* transmit each SPI message */

result = device->parent.bus->ops->xfer(&device->parent, &message->parent);
 if (result == 0)
 {
 rt_set_errno(-RT_EIO);
 }

__exit:
    /* release bus lock */
    rt_mutex_release(&(device->parent.bus->lock));

return result;
}
```