stm32 spi driver

#include "spidrv.h"
#include "uart.h"
#include <stdio.h>

#define MOD_NAME "spiddrv.c"
#define DEBUG 1

#define GYRO_CS GPIO_Pin_10
#define AXEL_CS GPIO_Pin_11
#define GYRO_RD 0x8000
//#define AXEL_RD 0x0000

void spi2_init()
{
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
  GPIO_InitTypeDef GPIO_InitStructure;
  SPI_InitTypeDef SPI_InitStructure;

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_InitStructure.GPIO_Pin = GYRO_CS | AXEL_CS;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

  GPIO_SetBits(GPIOB, GYRO_CS);
  GPIO_SetBits(GPIOB, AXEL_CS);


  RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);

  SPI_I2S_DeInit(SPI2);

  SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
  SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
  SPI_InitStructure.SPI_DataSize = SPI_DataSize_16b;

  SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
  SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
  SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;

  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_128;

  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(SPI2, &SPI_InitStructure);

  //SPI_CalculateCRC(SPI2, DISABLE);

  SPI_Cmd(SPI2, ENABLE);

#ifdef DEBUG
  //printf("%s %s - spi2_init() - OK\n\r", DBG,MOD_NAME);
  uart_print("spidrv.c - spi2_init() - OK\n\r");
#endif
}

void spi2_write(spiDev dev, uint8_t reg, uint8_t val)
{
  uint16_t data;
  switch (dev)
  {
  case SPI_GYRO:
    {
      GPIO_ResetBits(GPIOB, GYRO_CS);
      GPIO_SetBits(GPIOB, AXEL_CS);

      data = (reg << 8) | val;

      //while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);
      SPI_I2S_SendData(SPI2, data);
      while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);

      GPIO_SetBits(GPIOB, GYRO_CS | AXEL_CS);
    }
  break;

  case SPI_AXEL:
    {
      GPIO_ResetBits(GPIOB, AXEL_CS);
      GPIO_SetBits(GPIOB, GYRO_CS);

      GPIO_SetBits(GPIOB, GYRO_CS | AXEL_CS);
    }
  break;
  }
}


uint16_t spi2_read(spiDev dev, uint8_t reg)
{
  uint16_t ret;
  uint16_t data;
  switch (dev)
  {
  case SPI_GYRO:
    {
      GPIO_ResetBits(GPIOB, GYRO_CS);
      GPIO_SetBits(GPIOB, AXEL_CS);
      data = GYRO_RD | (reg << 8);

      while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);
      SPI_I2S_SendData(SPI2, data);

      while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);
      ret = SPI_I2S_ReceiveData(SPI2);

      GPIO_SetBits(GPIOB, GYRO_CS | AXEL_CS);
    }
  break;

  case SPI_AXEL:
    {
      GPIO_ResetBits(GPIOB, AXEL_CS);
      GPIO_SetBits(GPIOB, GYRO_CS);

      GPIO_SetBits(GPIOB, GYRO_CS | AXEL_CS);
    }
  break;
  }

  return ret;
}