/************************************************************************************//**
* \file         Source\ARMCM3_LM3S\can.c
* \brief        Bootloader CAN communication interface source file.
* \ingroup      Target_ARMCM3_LM3S
* \internal
*----------------------------------------------------------------------------------------
*                          C O P Y R I G H T
*----------------------------------------------------------------------------------------
*   Copyright (c) 2012  by Feaser    http://www.feaser.com    All rights reserved
*
*----------------------------------------------------------------------------------------
*                            L I C E N S E
*----------------------------------------------------------------------------------------
* This file is part of OpenBLT. OpenBLT is free software: you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* OpenBLT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You have received a copy of the GNU General Public License along with OpenBLT. It
* should be located in ".\Doc\license.html". If not, contact Feaser to obtain a copy.
*
* \endinternal
****************************************************************************************/


/****************************************************************************************
* Include files
****************************************************************************************/
#include "boot.h"                                /* bootloader generic header          */
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#if (BOOT_COM_CAN_ENABLE > 0)
#include "driverlib/sysctl.h"
#include "driverlib/canlib.h"
#endif


#if (BOOT_COM_CAN_ENABLE > 0)
/****************************************************************************************
* Macro definitions
****************************************************************************************/
/** \brief Index of the used reception message object. */
#define CAN_RX_MSGOBJECT_IDX   (0)
/** \brief Index of the used transmission message object. */
#define CAN_TX_MSGOBJECT_IDX   (1)


/****************************************************************************************
* Local constant declarations
****************************************************************************************/
/** \brief Lookup table to quickly and efficiently convert a bit number to a bit mask */
static const blt_int16u canBitNum2Mask[] =
{
  0x0001, /* bit  0 */
  0x0002  /* bit  1 */
};


/************************************************************************************//**
** \brief     Attempts to match the bittiming parameters to the requested baudrate
**            for a sample point between 65 and 75%, through a linear search
**            algorithm. It is based on the equation:
**              baudrate = CAN Clock Freq/((1+PropSeg+Phase1Seg+Phase2Seg)*Prescaler)
** \return    BLT_TRUE if a valid bittiming configuration was found and set. BLT_FALSE
**            otherwise.
**
****************************************************************************************/
static blt_int8u CanSetBittiming(void)
{
  tCANBitClkParms bitClkParms;
  blt_int8u       samplepoint;

  /* init SJW to maximum value */
  bitClkParms.uSJW = 4;

  /* use a double loop to iterate through all possible settings of uSyncPropPhase1Seg
   * and uPhase2Seg.
   */
  for (bitClkParms.uSyncPropPhase1Seg = 16; bitClkParms.uSyncPropPhase1Seg >= 1; bitClkParms.uSyncPropPhase1Seg--)
  {
    for (bitClkParms.uPhase2Seg = 8; bitClkParms.uPhase2Seg >= 1; bitClkParms.uPhase2Seg--)
    {
      samplepoint = ((1+bitClkParms.uSyncPropPhase1Seg) * 100) / (1+bitClkParms.uSyncPropPhase1Seg+bitClkParms.uPhase2Seg);
      /* check that sample points is within the preferred range */
      if ((samplepoint >= 65) && (samplepoint <= 75))
      {
        /* does a prescaler exist to get the exact baudrate with these bittiming
         * settings?
         */
        if ((((BOOT_CPU_XTAL_SPEED_KHZ*1000)/BOOT_COM_CAN_BAUDRATE) % (1+bitClkParms.uSyncPropPhase1Seg+bitClkParms.uPhase2Seg)) == 0)
        {
          /* bittiming configuration found. now update SJW to that it is never greater
           * than one of the phase segments. Giving the fact that the sample point is
           * rather high, only phase seg 2 need to be considered for this.
           */
          if (bitClkParms.uPhase2Seg < 4)
          {
            bitClkParms.uSJW = bitClkParms.uPhase2Seg;
          }
          /* calculate the actual prescaler value */
          bitClkParms.uQuantumPrescaler = ((BOOT_CPU_XTAL_SPEED_KHZ*1000)/BOOT_COM_CAN_BAUDRATE)/(1+bitClkParms.uSyncPropPhase1Seg+bitClkParms.uPhase2Seg);
          /* apply this bittiming configuration */
          CANSetBitTiming(CAN0_BASE, &bitClkParms);
          /* break loop and return from function */
          return BLT_TRUE;
        }
      }
    }
  }
  /* no valid bittiming configuration found */
  return BLT_FALSE;
} /*** end of CanSetBittiming ***/


/************************************************************************************//**
** \brief     Initializes the CAN controller and synchronizes it to the CAN bus.
** \return    none.
**
****************************************************************************************/
void CanInit(void)
{
  blt_bool      result;
  tCANMsgObject rxMsgObject;

  /* the current implementation supports CAN0. throw an assertion error in case a
   * different CAN channel is configured.
   */
  ASSERT_CT(BOOT_COM_CAN_CHANNEL_INDEX == 0);
  /* enable the CAN controller */
  SysCtlPeripheralEnable(SYSCTL_PERIPH_CAN0);
  /* reset the state of the CAN controller, including the message objects */
  CANInit(CAN0_BASE);
  /* set the bittiming */
  result = CanSetBittiming();
  ASSERT_RT(result == BLT_TRUE);
  /* take the CAN controller out of the initialization state */
  CANEnable(CAN0_BASE);
  /* setup message object 1 to receive the BOOT_COM_CAN_RX_MSG_ID message*/
  rxMsgObject.ulMsgID = BOOT_COM_CAN_RX_MSG_ID;
  rxMsgObject.ulMsgIDMask = 0x7ff;
  rxMsgObject.ulFlags = MSG_OBJ_USE_ID_FILTER;
  rxMsgObject.ulMsgLen = 8;
  /* is it a 29-bit extended CAN identifier? */
  if ((BOOT_COM_CAN_RX_MSG_ID & 0x80000000) != 0)
  {
    /* configure reception acceptance filter for 29-bit CAN identifier. */
    rxMsgObject.ulMsgID &= ~0x80000000;
    rxMsgObject.ulMsgIDMask = 0x1fffffff;
    rxMsgObject.ulFlags |= MSG_OBJ_EXTENDED_ID;
  }
  CANMessageSet(CAN0_BASE, CAN_RX_MSGOBJECT_IDX+1, &rxMsgObject, MSG_OBJ_TYPE_RX);
} /*** end of CanInit ***/


/************************************************************************************//**
** \brief     Transmits a packet formatted for the communication interface.
** \param     data Pointer to byte array with data that it to be transmitted.
** \param     len  Number of bytes that are to be transmitted.
** \return    none.
**
****************************************************************************************/
void CanTransmitPacket(blt_int8u *data, blt_int8u len)
{
  blt_int32u    status;
  tCANMsgObject msgObject;

  /* get bitmask of message objects that are busy transmitting messages */
  status = CANStatusGet(CAN0_BASE, CAN_STS_TXREQUEST);
  /* make sure that the transmit message object is ready to accept a new message */
  ASSERT_RT((status & canBitNum2Mask[CAN_TX_MSGOBJECT_IDX]) == 0);
  /* prepare the message and submit it for transmission */
  msgObject.ulMsgID = BOOT_COM_CAN_TX_MSG_ID;
  msgObject.ulFlags = 0;
  /* is it a 29-bit extended CAN identifier? */
  if ((BOOT_COM_CAN_TX_MSG_ID & 0x80000000) != 0)
  {
    msgObject.ulMsgID &= ~0x80000000;
    msgObject.ulFlags |= MSG_OBJ_EXTENDED_ID;
  }
  msgObject.ulMsgLen = len;
  msgObject.pucMsgData = data;
  CANMessageSet(CAN0_BASE, CAN_TX_MSGOBJECT_IDX+1, &msgObject, MSG_OBJ_TYPE_TX);
  /* now wait for the transmission to complete */
  do
  {
    status = CANStatusGet(CAN0_BASE, CAN_STS_TXREQUEST);
    /* service the watchdog */
    CopService();
  }
  while ((status & canBitNum2Mask[CAN_TX_MSGOBJECT_IDX]) != 0);
} /*** end of CanTransmitPacket ***/


/************************************************************************************//**
** \brief     Receives a communication interface packet if one is present.
** \param     data Pointer to byte array where the data is to be stored.
** \return    BLT_TRUE is a packet was received, BLT_FALSE otherwise.
**
****************************************************************************************/
blt_bool CanReceivePacket(blt_int8u *data)
{
  blt_int32u    status;
  tCANMsgObject msgObject;

  /* get bitmask of message objects with new data */
  status = CANStatusGet(CAN0_BASE, CAN_STS_NEWDAT);
  /* check if the BOOT_COM_CAN_RX_MSG_ID message was received */
  if ((status & canBitNum2Mask[CAN_RX_MSGOBJECT_IDX]) == 0)
  {
    /* message not received */
    return BLT_FALSE;
  }
  /* read the message data */
  msgObject.pucMsgData = data;
  CANMessageGet(CAN0_BASE, CAN_RX_MSGOBJECT_IDX+1, &msgObject, true);
  /* message was successfully received */
  return BLT_TRUE;
} /*** end of CanReceivePacket ***/
#endif /* BOOT_COM_CAN_ENABLE > 0 */


/*********************************** end of can.c **************************************/