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RIOT/drivers/periph_common/spi.c 2.03 KB
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  /*
   * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
   *
   * This file is subject to the terms and conditions of the GNU Lesser General
   * Public License v2.1. See the file LICENSE in the top level directory for more
   * details.
   */
  
  /**
   * @ingroup drivers
   * @{
   *
   * @file
   * @brief       common SPI function fallback implementations
   *
   * @author      Kaspar Schleiser <kaspar@schleiser.de>
   *
   * @}
   */
  #include <stddef.h>
  
  #include "board.h"
  #include "cpu.h"
  #include "periph/spi.h"
  #include "periph_cpu.h"
  
  #if SPI_NUMOF
  
  #ifdef PERIPH_SPI_NEEDS_TRANSFER_BYTES
  int spi_transfer_bytes(spi_t dev, char *out, char *in, unsigned int length)
  {
      int trans_ret;
      unsigned trans_bytes = 0;
      char in_temp;
  
      for (trans_bytes = 0; trans_bytes < length; trans_bytes++) {
          if (out != NULL) {
              trans_ret = spi_transfer_byte(dev, out[trans_bytes], &in_temp);
          }
          else {
              trans_ret = spi_transfer_byte(dev, 0, &in_temp);
          }
          if (trans_ret < 0) {
              return -1;
          }
          if (in != NULL) {
              in[trans_bytes] = in_temp;
          }
      }
  
      return trans_bytes;
  }
  #endif
  
  #ifdef PERIPH_SPI_NEEDS_TRANSFER_BYTE
  int spi_transfer_byte(spi_t dev, char out, char *in)
  {
      return spi_transfer_bytes(dev, &out, in, 1);
  }
  #endif
  
  #ifdef PERIPH_SPI_NEEDS_TRANSFER_REG
  int spi_transfer_reg(spi_t dev, uint8_t reg, char out, char *in)
  {
      int trans_ret;
  
      trans_ret = spi_transfer_byte(dev, reg, in);
      if (trans_ret < 0) {
          return -1;
      }
      trans_ret = spi_transfer_byte(dev, out, in);
      if (trans_ret < 0) {
          return -1;
      }
  
      return 1;
  }
  #endif
  
  #ifdef PERIPH_SPI_NEEDS_TRANSFER_REGS
  int spi_transfer_regs(spi_t dev, uint8_t reg, char *out, char *in, unsigned int length)
  {
      int trans_ret;
  
      trans_ret = spi_transfer_byte(dev, reg, in);
      if (trans_ret < 0) {
          return -1;
      }
      trans_ret = spi_transfer_bytes(dev, out, in, length);
      if (trans_ret < 0) {
          return -1;
      }
  
      return trans_ret;
  }
  #endif
  
  #endif /* SPI_NUMOF */