C语言软件spi虚拟总线中间层设计详解

struct mr_soft_spi_bus
{
  void (*set_clk)(mr_uint8_t level);		// 操作 CLK 的函数指针
  void (*set_mosi)(mr_uint8_t level);		// 操作 MOSI 的函数指针
  mr_uint8_t (*get_miso)(void);				// 读取 MISO 的函数指针
  struct mr_soft_spi *owner;				// 当前该总线的所有者
  mr_uint8_t lock;							// 互斥锁
};

struct mr_soft_spi
{
  mr_uint8_t mode         :2;				// SPI 工作模式
  mr_uint8_t cs_active    :1;				// CS/NSS 的有效电平（一般为低）
  struct mr_soft_spi_bus *bus;				// 该设备归属的总线
  void (*set_cs)(mr_uint8_t level);			// 操作 CS/NSS 的函数指针
};

void mr_soft_spi_attach(struct mr_soft_spi *spi, struct mr_soft_spi_bus *spi_bus)
{
  spi->bus = spi_bus;
}

mr_err_t mr_soft_spi_bus_take(struct mr_soft_spi *spi)
{
  mr_uint8_t spi_bus_lock;
  /* check spi-bus owner */
  if(spi->bus->owner != spi)
  {
    /* check mutex lock */
    do{
      spi_bus_lock = spi->bus->lock;
    } while(spi_bus_lock != MR_UNLOCK);
    /* lock mutex lock */
    spi->bus->lock = MR_LOCK;
    /* stop spi cs */
    if(spi->bus->owner != MR_NULL)
      spi->bus->owner->set_cs(!spi->bus->owner->cs_active);
    /* exchange spi-bus owner */
    spi->bus->owner = spi;
    /* start spi cs */
    spi->set_cs(spi->cs_active);
  }
  else
  {
    /* lock mutex lock */
    spi->bus->lock = MR_LOCK;
    /* start spi cs */
    spi->set_cs(spi->cs_active);
  }
  return MR_EOK;
}

mr_err_t mr_soft_spi_bus_release(struct mr_soft_spi *spi)
{
  /* check spi-bus owner */
  if(spi->bus->owner == spi)
  {
    /* stop spi cs */
    spi->set_cs(!spi->cs_active);
    /* unlock mutex lock */
    spi->bus->lock = MR_UNLOCK;
    return MR_EOK;
  }
  return -MR_ERROR;
}

struct mr_soft_spi_msg
{
  mr_uint8_t read_write;                        // 读写模式：SPI_WR/ SPI_RD/ SPI_RDWR/ SPI_WR_THEN_RD
  mr_uint8_t *send_buffer;						// 发送数据地址
  mr_size_t send_size;							// 发送数据个数
  mr_uint8_t *recv_buffer;						// 接收数据地址
  mr_size_t recv_size;							//接收数据个数
};

mr_err_t mr_soft_spi_transfer(struct mr_soft_spi *spi, struct mr_soft_spi_msg msg)
{
  mr_err_t ret;
  /* check function args */
  MR_DEBUG_ARGS_NULL(spi,-MR_EINVAL);
  MR_DEBUG_ARGS_IF(msg.read_write > SPI_WR_THEN_RD,-MR_EINVAL);
  /* take spi-bus */
  ret = mr_soft_spi_bus_take(spi);
  if(ret != MR_EOK)
    return ret;
  if(msg.read_write == SPI_WR || msg.recv_buffer == MR_NULL)
    msg.recv_size = 0;
  if(msg.read_write == SPI_RD || msg.send_buffer == MR_NULL)
    msg.send_size = 0;
  switch (msg.read_write) {
    case SPI_RD:
      /* receive */
      while (msg.recv_size) {
        *msg.recv_buffer = mr_soft_spi_bus_transmit(spi,0u);
        ++msg.recv_buffer;
        --msg.recv_size;
      }
      break;
    case SPI_WR:
      /* send */
      while (msg.send_size) {
        mr_soft_spi_bus_transmit(spi,*msg.send_buffer);
        ++msg.send_buffer;
        --msg.send_size;
      }
      break;
    case SPI_WR_THEN_RD:
      /* send */
      while (msg.send_size) {
        mr_soft_spi_bus_transmit(spi,*msg.send_buffer);
        ++msg.send_buffer;
        --msg.send_size;
      }
      /* receive */
      while (msg.recv_size) {
        *msg.recv_buffer = mr_soft_spi_bus_transmit(spi,0u);
        ++msg.recv_buffer;
        --msg.recv_size;
      }
      break;
    case SPI_RDWR:
      /* transmit */
      while (msg.send_size) {
        *msg.recv_buffer = mr_soft_spi_bus_transmit(spi,*msg.send_buffer);
        ++msg.send_buffer;
        ++msg.recv_buffer;
        --msg.send_size;
      }
      break;
  }
  /* release spi-bus */
  mr_soft_spi_bus_release(spi);
  return MR_EOK;
}

/* -------------------- 配置 -------------------- */
/* 创建一条 spi 总线 */
struct mr_soft_spi_bus spi_bus;
/* 适配 spi 总线接口 */
void set_clk(mr_uint8_t level)
{
  GPIO_WriteBit(GPIOA,GPIO_Pin_0,level);
}
void set_mosi(mr_uint8_t level)
{
  GPIO_WriteBit(GPIOA,GPIO_Pin_1,level);
}
mr_uint8_t get_miso(void)
{
  return GPIO_ReadInputDataBit(GPIOA,GPIO_Pin_2);
}
/* 配置 spi 总线 */
spi_bus.set_clk = set_clk;
spi_bus.set_mosi = set_mosi;
spi_bus.get_miso = get_miso;
spi_bus.lock = MR_UNLOCK;
spi_bus.owner = MR_NULL;
/* 创建一个 spi 设备 */
struct mr_soft_spi spi_device;
/* 适配 spi 设备接口 */
void set_cs(mr_uint8_t level)
{
  GPIO_WriteBit(GPIOA,GPIO_Pin_3,level);
}
/* 配置 spi 设备 */
spi_device.mode = SPI_MODE_0;       //SPI MODE 0
spi_device.cs_active = LEVEL_LOW;   //CS 引脚低电平有效
spi_device.set_cs = set_cs;
/* -------------------- 使用 -------------------- */
int main(void)
{
    /* 需要发送的数据 */
    mr_uint8_t buffer[10]={0,1,2,3,4,5,6,7,8,9};
    /* 初始化 gpio */
    GPIO_InitTypeDef GPIO_InitStructure = {0};
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
    /* 挂载 spi 设备到 spi 总线 */
    mr_soft_spi_attach(&spi_device,&spi_bus);
    /* 创建 spi 消息 */
    struct mr_soft_spi_msg spi_msg;
    spi_msg.send_buffer = buffer;   //发送数据地址
    spi_msg.send_size = 10;         //发送数据数量
    spi_msg.recv_buffer = MR_NULL;  //读取数据地址
    spi_msg.recv_size = 0;          //读取数据数量
    spi_msg.read_write = SPI_WR;    //只读模式
    /* 发送消息 */
    mr_soft_spi_transfer(&spi_device,spi_msg);
}