versions/v1_4_0/mynewt-core/hw/mcu/stm/stm32_common/src/stm32_driver_mod_i2c_v2.c

/**
  * <h2><center>&copy; COPYRIGHT(c) 2016 STMicroelectronics</center></h2>
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  */

#include <os/os_time.h>
#include <mcu/stm32_hal.h>
#include <syscfg/syscfg.h>

#if !MYNEWT_VAL(STM32_HAL_I2C_HAS_CLOCKSPEED)

#define I2C_TIMEOUT_BUSY    (25U)          /*!< 25 ms */

#define MAX_NBYTE_SIZE      255U

static const uint8_t HAL_I2C_MODE_MASTER_SEL = 0x11;
static const uint8_t HAL_NACK = HAL_TIMEOUT + 1;

/**
  * @brief  This function handles I2C Communication Timeout.
  * @param  hi2c Pointer to a I2C_HandleTypeDef structure that contains
  *         the configuration information for I2C module
  * @param  Flag specifies the I2C flag to check.
  * @param  Status The new Flag status (SET or RESET).
  * @param  Timeout Timeout duration
  * @param  Tickstart Tick start value
  * @retval HAL status
  */
/*
 * FIXME: this function is similar enough that it could be shared between
 * both i2c drivers.
 */
static HAL_StatusTypeDef I2C_WaitOnFlagUntilTimeout(I2C_HandleTypeDef *hi2c,
        uint32_t Flag, FlagStatus Status, uint32_t Timeout, uint32_t Tickstart)
{
  while (__HAL_I2C_GET_FLAG(hi2c, Flag) == Status)
  {
    /* Check for the Timeout */
    if (Timeout != HAL_MAX_DELAY)
    {
      if ((Timeout == 0U) || ((HAL_GetTick() - Tickstart) > Timeout))
      {
        hi2c->State = HAL_I2C_STATE_READY;
        hi2c->Mode = HAL_I2C_MODE_NONE;

        /* Process Unlocked */
        __HAL_UNLOCK(hi2c);
        return HAL_TIMEOUT;
      }
    }
  }
  return HAL_OK;
}

/**
  * @brief  Handles I2Cx communication when starting transfer or during transfer (TC or TCR flag are set).
  * @param  hi2c I2C handle.
  * @param  DevAddress Specifies the slave address to be programmed.
  * @param  Size Specifies the number of bytes to be programmed.
  *   This parameter must be a value between 0 and 255.
  * @param  Mode New state of the I2C START condition generation.
  *   This parameter can be one of the following values:
  *     @arg @ref I2C_RELOAD_MODE Enable Reload mode .
  *     @arg @ref I2C_AUTOEND_MODE Enable Automatic end mode.
  *     @arg @ref I2C_SOFTEND_MODE Enable Software end mode.
  * @param  Request New state of the I2C START condition generation.
  *   This parameter can be one of the following values:
  *     @arg @ref I2C_NO_STARTSTOP Don't Generate stop and start condition.
  *     @arg @ref I2C_GENERATE_STOP Generate stop condition (Size should be set to 0).
  *     @arg @ref I2C_GENERATE_START_READ Generate Restart for read request.
  *     @arg @ref I2C_GENERATE_START_WRITE Generate Restart for write request.
  * @retval None
  */
static void I2C_TransferConfig(I2C_HandleTypeDef *hi2c,  uint16_t DevAddress, uint8_t Size, uint32_t Mode, uint32_t Request)
{
  uint32_t tmpreg = 0U;

  /* Check the parameters */
  assert_param(IS_I2C_ALL_INSTANCE(hi2c->Instance));
  assert_param(IS_TRANSFER_MODE(Mode));
  assert_param(IS_TRANSFER_REQUEST(Request));

  /* Get the CR2 register value */
  tmpreg = hi2c->Instance->CR2;

  /* clear tmpreg specific bits */
  tmpreg &= (uint32_t)~((uint32_t)(I2C_CR2_SADD | I2C_CR2_NBYTES | I2C_CR2_RELOAD | I2C_CR2_AUTOEND | I2C_CR2_RD_WRN | I2C_CR2_START | I2C_CR2_STOP));

  /* update tmpreg */
  tmpreg |= (uint32_t)(((uint32_t)DevAddress & I2C_CR2_SADD) | (((uint32_t)Size << 16) & I2C_CR2_NBYTES) | \
                       (uint32_t)Mode | (uint32_t)Request);

  /* update CR2 register */
  hi2c->Instance->CR2 = tmpreg;
}

/**
  * @brief  I2C Tx data register flush process.
  * @param  hi2c I2C handle.
  * @retval None
  */
static void I2C_Flush_TXDR(I2C_HandleTypeDef *hi2c)
{
  /* If a pending TXIS flag is set */
  /* Write a dummy data in TXDR to clear it */
  if (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_TXIS) != RESET)
  {
    hi2c->Instance->TXDR = 0x00U;
  }

  /* Flush TX register if not empty */
  if (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_TXE) == RESET)
  {
    __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_TXE);
  }
}

/**
  * @brief  This function handles Acknowledge failed detection during an I2C Communication.
  * @param  hi2c Pointer to a I2C_HandleTypeDef structure that contains
  *                the configuration information for the specified I2C.
  * @param  Timeout Timeout duration
  * @param  Tickstart Tick start value
  * @retval HAL status
  */
static HAL_StatusTypeDef I2C_IsAcknowledgeFailed(I2C_HandleTypeDef *hi2c, uint32_t Timeout, uint32_t Tickstart)
{
  if (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_AF) == SET)
  {
    /* Wait until STOP Flag is reset */
    /* AutoEnd should be initiate after AF */
    while (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_STOPF) == RESET)
    {
      /* Check for the Timeout */
      if (Timeout != HAL_MAX_DELAY)
      {
        if ((Timeout == 0U) || ((HAL_GetTick() - Tickstart) > Timeout))
        {
          hi2c->State = HAL_I2C_STATE_READY;
          hi2c->Mode = HAL_I2C_MODE_NONE;

          /* Process Unlocked */
          __HAL_UNLOCK(hi2c);
          return HAL_TIMEOUT;
        }
      }
    }

    /* Clear NACKF Flag */
    __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_AF);

    /* Clear STOP Flag */
    __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_STOPF);

    /* Flush TX register */
    I2C_Flush_TXDR(hi2c);

    /* Clear Configuration Register 2 */
    I2C_RESET_CR2(hi2c);

    hi2c->ErrorCode = HAL_I2C_ERROR_AF;
    hi2c->State = HAL_I2C_STATE_READY;
    hi2c->Mode = HAL_I2C_MODE_NONE;

    /* Process Unlocked */
    __HAL_UNLOCK(hi2c);

    return HAL_ERROR;
  }
  return HAL_OK;
}

/**
  * @brief  This function handles I2C Communication Timeout for specific usage of TXIS flag.
  * @param  hi2c Pointer to a I2C_HandleTypeDef structure that contains
  *                the configuration information for the specified I2C.
  * @param  Timeout Timeout duration
  * @param  Tickstart Tick start value
  * @retval HAL status
  */
static HAL_StatusTypeDef I2C_WaitOnTXISFlagUntilTimeout(I2C_HandleTypeDef *hi2c, uint32_t Timeout, uint32_t Tickstart)
{
  while (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_TXIS) == RESET)
  {
    /* Check if a NACK is detected */
    if (I2C_IsAcknowledgeFailed(hi2c, Timeout, Tickstart) != HAL_OK)
    {
      return HAL_ERROR;
    }

    /* Check for the Timeout */
    if (Timeout != HAL_MAX_DELAY)
    {
      if ((Timeout == 0U) || ((HAL_GetTick() - Tickstart) > Timeout))
      {
        hi2c->ErrorCode |= HAL_I2C_ERROR_TIMEOUT;
        hi2c->State = HAL_I2C_STATE_READY;
        hi2c->Mode = HAL_I2C_MODE_NONE;

        /* Process Unlocked */
        __HAL_UNLOCK(hi2c);

        return HAL_TIMEOUT;
      }
    }
  }
  return HAL_OK;
}

/**
  * @brief  This function handles I2C Communication Timeout for specific usage of STOP flag.
  * @param  hi2c Pointer to a I2C_HandleTypeDef structure that contains
  *                the configuration information for the specified I2C.
  * @param  Timeout Timeout duration
  * @param  Tickstart Tick start value
  * @retval HAL status
  */
static HAL_StatusTypeDef I2C_WaitOnSTOPFlagUntilTimeout(I2C_HandleTypeDef *hi2c, uint32_t Timeout, uint32_t Tickstart)
{
  while (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_STOPF) == RESET)
  {
    /* Check if a NACK is detected */
    if (I2C_IsAcknowledgeFailed(hi2c, Timeout, Tickstart) != HAL_OK)
    {
      return HAL_ERROR;
    }

    /* Check for the Timeout */
    if ((Timeout == 0U) || ((HAL_GetTick() - Tickstart) > Timeout))
    {
      hi2c->ErrorCode |= HAL_I2C_ERROR_TIMEOUT;
      hi2c->State = HAL_I2C_STATE_READY;
      hi2c->Mode = HAL_I2C_MODE_NONE;

      /* Process Unlocked */
      __HAL_UNLOCK(hi2c);

      return HAL_TIMEOUT;
    }
  }
  return HAL_OK;
}

/**
  * @brief  Transmits in master mode an amount of data in blocking mode.
  * @param  hi2c Pointer to a I2C_HandleTypeDef structure that contains
  *                the configuration information for the specified I2C.
  * @param  DevAddress Target device address The device 7 bits address value
  *         in datasheet must be shifted to the left before calling the interface
  * @param  pData Pointer to data buffer
  * @param  Size Amount of data to be sent
  * @param  Timeout Timeout duration
  * @param  LastOp If set sends STOP, otherwise no STOP
  * @retval HAL status
  */
HAL_StatusTypeDef HAL_I2C_Master_Transmit_Custom(I2C_HandleTypeDef *hi2c,
        uint16_t DevAddress, uint8_t *pData, uint16_t Size, uint32_t Timeout,
        uint8_t LastOp)
{
  uint32_t tickstart = 0U;
  uint8_t prev_mode = 0;

  if (hi2c->State == HAL_I2C_STATE_READY)
  {
    /* Process Locked */
    __HAL_LOCK(hi2c);

    /* Init tickstart for timeout management*/
    tickstart = HAL_GetTick();

    prev_mode = hi2c->Mode;
    if (prev_mode != HAL_I2C_MODE_MASTER_SEL)
    {
      if (I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_BUSY, SET, I2C_TIMEOUT_BUSY, tickstart) != HAL_OK)
      {
        return HAL_TIMEOUT;
      }
    }

    hi2c->State     = HAL_I2C_STATE_BUSY_TX;
    hi2c->Mode      = HAL_I2C_MODE_MASTER;
    hi2c->ErrorCode = HAL_I2C_ERROR_NONE;

    /* Prepare transfer parameters */
    hi2c->pBuffPtr  = pData;
    hi2c->XferCount = Size;
    hi2c->XferISR   = NULL;

    /* Send Slave Address */
    /* Set NBYTES to write and reload if hi2c->XferCount > MAX_NBYTE_SIZE and generate RESTART */
    if (hi2c->XferCount > MAX_NBYTE_SIZE)
    {
      hi2c->XferSize = MAX_NBYTE_SIZE;
      I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_RELOAD_MODE, I2C_GENERATE_START_WRITE);
    }
    else if (!LastOp)
    {
      hi2c->XferSize = hi2c->XferCount;
      I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_SOFTEND_MODE, I2C_GENERATE_START_WRITE);
    }
    else
    {
      hi2c->XferSize = hi2c->XferCount;
      I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_AUTOEND_MODE, I2C_GENERATE_START_WRITE);
    }

    /*
     * Wait RESTART to be accepted
     */
    if (prev_mode == HAL_I2C_MODE_MASTER_SEL)
    {
      if (I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_TC, RESET, Timeout, tickstart) != HAL_OK)
      {
        return HAL_TIMEOUT;
      }
    }

    while (hi2c->XferCount > 0U)
    {
      /* Wait until TXIS flag is set */
      if (I2C_WaitOnTXISFlagUntilTimeout(hi2c, Timeout, tickstart) != HAL_OK)
      {
        if (hi2c->ErrorCode == HAL_I2C_ERROR_AF)
        {
          return HAL_ERROR;
        }
        else
        {
          return HAL_TIMEOUT;
        }
      }
      /* Write data to TXDR */
      hi2c->Instance->TXDR = (*hi2c->pBuffPtr++);
      hi2c->XferCount--;
      hi2c->XferSize--;

      if ((hi2c->XferSize == 0U) && (hi2c->XferCount != 0U))
      {
        /* Wait until TCR flag is set */
        if (I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_TCR, RESET, Timeout, tickstart) != HAL_OK)
        {
          return HAL_TIMEOUT;
        }

        if (hi2c->XferCount > MAX_NBYTE_SIZE)
        {
          hi2c->XferSize = MAX_NBYTE_SIZE;
          I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_RELOAD_MODE, I2C_NO_STARTSTOP);
        }
        else if (!LastOp)
        {
          hi2c->XferSize = hi2c->XferCount;
          I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_SOFTEND_MODE, I2C_NO_STARTSTOP);
        }
        else
        {
          hi2c->XferSize = hi2c->XferCount;
          I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_AUTOEND_MODE, I2C_NO_STARTSTOP);
        }
      }
    }

    if (LastOp)
    {
      /* No need to Check TC flag, with AUTOEND mode the stop is automatically generated */
      /* Wait until STOPF flag is set */
      if (I2C_WaitOnSTOPFlagUntilTimeout(hi2c, Timeout, tickstart) != HAL_OK)
      {
        if (hi2c->ErrorCode == HAL_I2C_ERROR_AF)
        {
          return HAL_ERROR;
        }
        else
        {
          return HAL_TIMEOUT;
        }
      }

      /* Clear STOP Flag */
      __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_STOPF);
    }
    else
    {
      /* No autoend/reload was requested, make sure transmission of last byte
       * has finished... */
      if (I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_TC, SET, Timeout, tickstart) != HAL_OK)
      {
        return HAL_TIMEOUT;
      }
    }

    /* Clear Configuration Register 2 */
    I2C_RESET_CR2(hi2c);

    hi2c->State = HAL_I2C_STATE_READY;
    if (LastOp)
    {
      hi2c->Mode = HAL_I2C_MODE_NONE;
    }
    else
    {
      hi2c->Mode = HAL_I2C_MODE_MASTER_SEL;
    }

    /* Process Unlocked */
    __HAL_UNLOCK(hi2c);

    return HAL_OK;
  }
  else
  {
    return HAL_BUSY;
  }
}

/**
  * @brief  This function handles I2C Communication Timeout for specific usage of RXNE flag.
  * @param  hi2c Pointer to a I2C_HandleTypeDef structure that contains
  *                the configuration information for the specified I2C.
  * @param  Timeout Timeout duration
  * @param  Tickstart Tick start value
  * @retval HAL status
  */
static HAL_StatusTypeDef I2C_WaitOnRXNEFlagUntilTimeout(I2C_HandleTypeDef *hi2c, uint32_t Timeout, uint32_t Tickstart, uint8_t prev_mode)
{
  while (__HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_RXNE) == RESET)
  {
    /* Check if a NACK is detected */
    if (I2C_IsAcknowledgeFailed(hi2c, Timeout, Tickstart) != HAL_OK)
    {
      return HAL_NACK;
    }

    /*
     * FIXME: need to re-check if what is supposed to be a RESTART is not also
     * triggering a STOP along...
     */
    /* Check if a STOPF is detected */
    if (prev_mode != HAL_I2C_MODE_MASTER_SEL && __HAL_I2C_GET_FLAG(hi2c, I2C_FLAG_STOPF) == SET)
    {
      /* Clear STOP Flag */
      __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_STOPF);

      /* Clear Configuration Register 2 */
      I2C_RESET_CR2(hi2c);

      hi2c->ErrorCode = HAL_I2C_ERROR_NONE;
      hi2c->State = HAL_I2C_STATE_READY;
      hi2c->Mode = HAL_I2C_MODE_NONE;

      /* Process Unlocked */
      __HAL_UNLOCK(hi2c);

      return HAL_ERROR;
    }

    /* Check for the Timeout */
    if ((Timeout == 0U) || ((HAL_GetTick() - Tickstart) > Timeout))
    {
      hi2c->ErrorCode |= HAL_I2C_ERROR_TIMEOUT;
      hi2c->State = HAL_I2C_STATE_READY;

      /* Process Unlocked */
      __HAL_UNLOCK(hi2c);

      return HAL_TIMEOUT;
    }
  }
  return HAL_OK;
}

/**
  * @brief  Receives in master mode an amount of data in blocking mode. 
  * @param  hi2c Pointer to a I2C_HandleTypeDef structure that contains
  *                the configuration information for the specified I2C.
  * @param  DevAddress Target device address The device 7 bits address value
  *         in datasheet must be shifted to the left before calling the interface
  * @param  pData Pointer to data buffer
  * @param  Size Amount of data to be sent
  * @param  Timeout Timeout duration
  * @param  LastOp If set sends STOP, otherwise no STOP
  * @retval HAL status
  */
HAL_StatusTypeDef HAL_I2C_Master_Receive_Custom(I2C_HandleTypeDef *hi2c,
        uint16_t DevAddress, uint8_t *pData, uint16_t Size, uint32_t Timeout,
        uint8_t LastOp)
{
  uint32_t tickstart = 0U;
  uint8_t prev_mode = 0;
  HAL_StatusTypeDef rc;

  if (hi2c->State == HAL_I2C_STATE_READY)
  {
    /* Process Locked */
    __HAL_LOCK(hi2c);

    /* Init tickstart for timeout management */
    tickstart = HAL_GetTick();

    prev_mode = hi2c->Mode;
    if (prev_mode != HAL_I2C_MODE_MASTER_SEL)
    {
      if (I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_BUSY, SET, I2C_TIMEOUT_BUSY, tickstart) != HAL_OK)
      {
        return HAL_TIMEOUT;
      }
    }

    hi2c->State     = HAL_I2C_STATE_BUSY_RX;
    hi2c->Mode      = HAL_I2C_MODE_MASTER;
    hi2c->ErrorCode = HAL_I2C_ERROR_NONE;

    /* Prepare transfer parameters */
    hi2c->pBuffPtr  = pData;
    hi2c->XferCount = Size;
    hi2c->XferISR   = NULL;

    /* Send Slave Address */
    /* Set NBYTES to write and reload if hi2c->XferCount > MAX_NBYTE_SIZE and generate RESTART */
    if (hi2c->XferCount > MAX_NBYTE_SIZE)
    {
      hi2c->XferSize = MAX_NBYTE_SIZE;
      I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_RELOAD_MODE, I2C_GENERATE_START_READ);
    }
    else if (!LastOp)
    {
      hi2c->XferSize = hi2c->XferCount;
      I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_SOFTEND_MODE, I2C_GENERATE_START_READ);
    }
    else
    {
      hi2c->XferSize = hi2c->XferCount;
      I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_AUTOEND_MODE, I2C_GENERATE_START_READ);
    }

    while (hi2c->XferCount > 0U)
    {
      /* Wait until RXNE flag is set */
      rc = I2C_WaitOnRXNEFlagUntilTimeout(hi2c, Timeout, tickstart, prev_mode);
      if (rc != HAL_OK && rc != HAL_NACK)
      {
        if (hi2c->ErrorCode == HAL_I2C_ERROR_AF)
        {
          return HAL_ERROR;
        }
        else
        {
          return HAL_TIMEOUT;
        }
      }

      /* Read data from RXDR */
      (*hi2c->pBuffPtr++) = hi2c->Instance->RXDR;
      hi2c->XferSize--;
      hi2c->XferCount--;

      if (rc == HAL_NACK)
      {
        break;
      }

      if ((hi2c->XferSize == 0U) && (hi2c->XferCount != 0U))
      {
        /* Wait until TCR flag is set */
        if (I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_TCR, RESET, Timeout, tickstart) != HAL_OK)
        {
          return HAL_TIMEOUT;
        }

        if (hi2c->XferCount > MAX_NBYTE_SIZE)
        {
          hi2c->XferSize = MAX_NBYTE_SIZE;
          I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_RELOAD_MODE, I2C_NO_STARTSTOP);
        }
        else if (!LastOp)
        {
          hi2c->XferSize = hi2c->XferCount;
          I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_SOFTEND_MODE, I2C_NO_STARTSTOP);
        }
        else
        {
          hi2c->XferSize = hi2c->XferCount;
          I2C_TransferConfig(hi2c, DevAddress, hi2c->XferSize, I2C_AUTOEND_MODE, I2C_NO_STARTSTOP);
        }
      }
    }

    if (LastOp)
    {
      /* No need to Check TC flag, with AUTOEND mode the stop is automatically generated */
      /* Wait until STOPF flag is set */
      if (I2C_WaitOnSTOPFlagUntilTimeout(hi2c, Timeout, tickstart) != HAL_OK)
      {
        if (hi2c->ErrorCode == HAL_I2C_ERROR_AF)
        {
          return HAL_ERROR;
        }
        else
        {
          return HAL_TIMEOUT;
        }
      }

      /* Clear STOP Flag */
      __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_STOPF);
    }
    else
    {
      /* No autoend/reload was requested, make sure transmission of last byte
       * has finished... */
      if (I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_TC, SET, Timeout, tickstart) != HAL_OK)
      {
        return HAL_TIMEOUT;
      }
    }

    /* Clear Configuration Register 2 */
    I2C_RESET_CR2(hi2c);

    hi2c->State = HAL_I2C_STATE_READY;
    if (LastOp)
    {
      hi2c->Mode  = HAL_I2C_MODE_NONE;
    }
    else
    {
      hi2c->Mode  = HAL_I2C_MODE_MASTER_SEL;
    }

    /* Process Unlocked */
    __HAL_UNLOCK(hi2c);

    return HAL_OK;
  }
  else
  {
    return HAL_BUSY;
  }
}

#endif /* !MYNEWT_VAL(STM32_HAL_I2C_HAS_CLOCKSPEED) */