text: /*
   * Author: Thomas Ingleby <thomas.c.ingleby@intel.com>
   * Copyright (c) 2014 Intel Corporation.
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #pragma once
  
  /**
   * @file
   * @brief Serial Peripheral Interface
   *
   * This file defines the spi interface for libmraa. A Spi object in libmraa
   * represents a spidev device. Linux spidev devices are created per spi bus and
   * every chip select available on that bus has another spidev 'file'. A lot
   * more information on spidev devices is available
   * [here](https://www.kernel.org/doc/Documentation/spi/spidev).
   *
   * @snippet spi_mcp4261.c Interesting
   */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #include <stdio.h>
  #include <fcntl.h>
  #include <stdint.h>
  
  #include "common.h"
  
  /**
   * MRAA SPI Modes
   */
  typedef enum {
      MRAA_SPI_MODE0 = 0, /**< CPOL = 0, CPHA = 0, Clock idle low, data is clocked in on rising edge, output data (change) on falling edge */
      MRAA_SPI_MODE1 = 1, /**< CPOL = 0, CPHA = 1, Clock idle low, data is clocked in on falling edge, output data (change) on rising edge */
      MRAA_SPI_MODE2 = 2, /**< CPOL = 1, CPHA = 0, Clock idle low, data is clocked in on falling edge, output data (change) on rising edge */
      MRAA_SPI_MODE3 = 3, /**< CPOL = 1, CPHA = 1, Clock idle low, data is clocked in on rising, edge output data (change) on falling edge */
  } mraa_spi_mode_t;
  
  /**
   * Opaque pointer definition to the internal struct _spi
   */
  typedef struct _spi* mraa_spi_context;
  
  /**
   * Initialise SPI_context, uses board mapping. Sets the muxes
   *
   * @param bus Bus to use, as listed in platform definition, normally 0
   * @return Spi context or NULL
   */
  mraa_spi_context mraa_spi_init(int bus);
  
  /**
   * Initialise SPI_context without any board configuration, selects a bus and a mux.
   *
   * @param bus Bus to use as listed by spidev
   * @param cs Chip select to use as listed in spidev
   * @return Spi context or NULL
   */
  mraa_spi_context mraa_spi_init_raw(unsigned int bus, unsigned int cs);
  
  /**
   * Set the SPI device mode. see spidev 0-3.
   *
   * @param dev The Spi context
   * @param mode The SPI mode, See Linux spidev
   * @return Spi context or NULL
   */
  mraa_result_t mraa_spi_mode(mraa_spi_context dev, mraa_spi_mode_t mode);
  
  /** Set the SPI device operating clock frequency.
   *
   * @param dev the Spi context
   * @param hz the frequency in hz
   * @return mraa_spi_context The returned initialised SPI context
   */
  mraa_result_t mraa_spi_frequency(mraa_spi_context dev, int hz);
  
  /** Write Single Byte to the SPI device.
   *
   * @param dev The Spi context
   * @param data Data to send
   * @return Data received on the miso line
   */
  uint8_t mraa_spi_write(mraa_spi_context dev, uint8_t data);
  
  /** Write Two Bytes to the SPI device.
  *
  * @param dev The Spi context
  * @param data Data to send
  * @return Data received on the miso line
  */
  uint16_t mraa_spi_write_word(mraa_spi_context dev, uint16_t data);
  
  /** Write Buffer of bytes to the SPI device. The pointer return has to be
   * free'd by the caller. It will return a NULL pointer in cases of error.
   *
   * @param dev The Spi context
   * @param data to send
   * @param length elements within buffer, Max 4096
   * @return Data received on the miso line, same length as passed in
   */
  uint8_t* mraa_spi_write_buf(mraa_spi_context dev, uint8_t* data, int length);
  
  /** Write Buffer of uint16 to the SPI device. The pointer return has to be
  * free'd by the caller. It will return a NULL pointer in cases of error.
  *
  * @param dev The Spi context
  * @param data to send
  * @param length elements (in bytes) within buffer, Max 4096
  * @return Data received on the miso line, same length as passed in
  */
  uint16_t* mraa_spi_write_buf_word(mraa_spi_context dev, uint16_t* data, int length);
  
  /** Transfer Buffer of bytes to the SPI device. Both send and recv buffers
   * are passed in
   *
   * @param dev The Spi context
   * @param data to send
   * @param rxbuf buffer to recv data back, may be NULL
   * @param length elements within buffer, Max 4096
   * @return Result of operation
   */
  mraa_result_t mraa_spi_transfer_buf(mraa_spi_context dev, uint8_t* data, uint8_t* rxbuf, int length);
  
  /** Transfer Buffer of uint16 to the SPI device. Both send and recv buffers
  * are passed in
  *
  * @param dev The Spi context
  * @param data to send
  * @param rxbuf buffer to recv data back, may be NULL
  * @param length elements (in bytes) within buffer, Max 4096
  * @return Result of operation
  */
  mraa_result_t mraa_spi_transfer_buf_word(mraa_spi_context dev, uint16_t* data, uint16_t* rxbuf, int length);
  
  /**
   * Change the SPI lsb mode
   *
   * @param dev The Spi context
   * @param lsb Use least significant bit transmission. 0 for msbi
   * @return Result of operation
   */
  mraa_result_t mraa_spi_lsbmode(mraa_spi_context dev, mraa_boolean_t lsb);
  
  /**
   * Set bits per mode on transaction, defaults at 8
   *
   * @param dev The Spi context
   * @param bits bits per word
   * @return Result of operation
   */
  mraa_result_t mraa_spi_bit_per_word(mraa_spi_context dev, unsigned int bits);
  
  /**
   * De-inits an mraa_spi_context device
   *
   * @param dev The Spi context
   * @return Result of operation
   */
  mraa_result_t mraa_spi_stop(mraa_spi_context dev);
  
  #ifdef __cplusplus
  }
  #endif
  