SPI

请教rt_spi_configure函数理解

发布于 2015-07-28 20:04:39
rt_err_t rt_spi_configure(struct rt_spi_device *device,
struct rt_spi_configuration *cfg)
{
rt_err_t result;

RT_ASSERT(device != RT_NULL);

/* set configuration */
device->config.data_width = cfg->data_width;
device->config.mode = cfg->mode & RT_SPI_MODE_MASK ;
device->config.max_hz = cfg->max_hz ;

if (device->bus != RT_NULL)
{
result = rt_mutex_take(&(device->bus->lock), RT_WAITING_FOREVER);
if (result == RT_EOK)
{
if (device->bus->owner == device)
{
device->bus->ops->configure(device, &device->config);
}

/* release lock */
rt_mutex_release(&(device->bus->lock));
}
}

return RT_EOK;
}

以sst25vfxx为例使用到device->bus->owner主要是以下2个函数,并没有对owner进行赋值 ,导致今天调试时发现底层的configure没有执行,请大家指教是我理解出错,还是其他原因。
rt_err_t sst25vfxx_init(const char * flash_device_name, const char * spi_device_name)
/* config spi */
{
struct rt_spi_configuration cfg;
cfg.data_width = 8;
cfg.mode = RT_SPI_MODE_0 | RT_SPI_MSB; /* SPI Compatible: Mode 0 and Mode 3 */
cfg.max_hz = 50000000; /* 50M */
rt_spi_configure(spi_flash->rt_spi_device, &cfg);
}


rt_err_t rt_spi_bus_register(struct rt_spi_bus *bus,
const char *name,
const struct rt_spi_ops *ops)
{
rt_err_t result;

result = rt_spi_bus_device_init(bus, name);
if (result != RT_EOK)
return result;

/* initialize mutex lock */
rt_mutex_init(&(bus->lock), name, RT_IPC_FLAG_FIFO);
/* set ops */
bus->ops = ops;
/* initialize owner */
bus->owner = RT_NULL;

return RT_EOK;
}

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3 个回答
aozima
aozima 2015-07-28
rt_spi_configure(spi_flash->rt_spi_device, &cfg);

只保证将配置写入内存里面,如果当前就是自己在使用SPI,则写入硬件中。
不然就等下次实际操作硬件时再真正写入硬件中。

否则,如果当前SPI正在被其它人使用,直接写入硬件就会出问题。

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