/************************************************************************************//**
* \file         Source\ARM7_LPC2000\uart.c
* \brief        Bootloader UART communication interface source file.
* \ingroup      Target_ARM7_LPC2000
* \internal
*----------------------------------------------------------------------------------------
*                          C O P Y R I G H T
*----------------------------------------------------------------------------------------
*   Copyright (c) 2011  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          */


#if (BOOT_COM_UART_ENABLE > 0)
/****************************************************************************************
* Macro definitions
****************************************************************************************/
/** \brief Timeout time for the reception of a CTO packet. The timer is started upon
 *         reception of the first packet byte.
 */
#define UART_CTO_RX_PACKET_TIMEOUT_MS (100u)
/** \brief Timeout for transmitting a byte in milliseconds. */
#define UART_BYTE_TX_TIMEOUT_MS       (10u)

/** \brief Divisor latch access bit. */
#define UART_DLAB      (0x80)
/** \brief 8 data and 1 stop bit, no parity. */
#define UART_MODE_8N1  (0x03)
/** \brief FIFO reset and RX FIFO 1 deep. */
#define UART_FIFO_RX1  (0x07)
/** \brief Receiver data ready. */
#define UART_RDR       (0x01)
/** \brief Transmitter holding register empty. */
#define UART_THRE      (0x20)


/****************************************************************************************
* Register definitions
****************************************************************************************/
/** \brief U0RBR UART register. */
#define U0RBR          (*((volatile blt_int8u *) 0xE000C000))
/** \brief U0THR UART register. */
#define U0THR          (*((volatile blt_int8u *) 0xE000C000))
/** \brief U0IER UART register. */
#define U0IER          (*((volatile blt_int8u *) 0xE000C004))
/** \brief U0IIR UART register. */
#define U0IIR          (*((volatile blt_int8u *) 0xE000C008))
/** \brief U0FCR UART register. */
#define U0FCR          (*((volatile blt_int8u *) 0xE000C008))
/** \brief U0LCR UART register. */
#define U0LCR          (*((volatile blt_int8u *) 0xE000C00C))
/** \brief U0LSR UART register. */
#define U0LSR          (*((volatile blt_int8u *) 0xE000C014))
/** \brief U0SCR UART register. */
#define U0SCR          (*((volatile blt_int8u *) 0xE000C01C))
/** \brief U0DLL UART register. */
#define U0DLL          (*((volatile blt_int8u *) 0xE000C000))
/** \brief U0DLM UART register. */
#define U0DLM          (*((volatile blt_int8u *) 0xE000C004))


/****************************************************************************************
* Function prototypes
****************************************************************************************/
static blt_bool UartReceiveByte(blt_int8u *data);
static blt_bool UartTransmitByte(blt_int8u data);


/************************************************************************************//**
** \brief     Initializes the UART communication interface.
** \return    none.
**
****************************************************************************************/
void UartInit(void)
{
  blt_int32u baud_reg_value;                           /* baudrate register value      */

  /* the current implementation supports UART0. throw an assertion error in case
   * a different UART channel is configured.
   */
  ASSERT_CT(BOOT_COM_UART_CHANNEL_INDEX == 0);
  /* disable UART related interrupt generation. this driver works in polling mode */
  U0IER = 0;
  /* clear interrupt id register */
  U0IIR = 0;
  /* clear line status register */
  U0LSR = 0;
  /* set divisor latch DLAB = 1 so buadrate can be configured */
  U0LCR = UART_DLAB;
  /* Baudrate calculation:
   *   y = BOOT_CPU_SYSTEM_SPEED_KHZ * 1000 / 16 / BOOT_COM_UART_BAUDRATE and add
   *   smartness to automatically round the value up/down using the following trick:
   *     y = x/n can round with y = (x + (n + 1)/2 ) / n
   */
  /* check that baudrate register value is not 0 */
  ASSERT_CT((((BOOT_CPU_SYSTEM_SPEED_KHZ*1000/16)+((BOOT_COM_UART_BAUDRATE+1)/2))/  \
             BOOT_COM_UART_BAUDRATE) > 0);
  /* check that baudrate register value is not greater than max 16-bit unsigned value */
  ASSERT_CT((((BOOT_CPU_SYSTEM_SPEED_KHZ*1000/16)+((BOOT_COM_UART_BAUDRATE+1)/2))/  \
             BOOT_COM_UART_BAUDRATE) <= 65535);
  baud_reg_value = (((BOOT_CPU_SYSTEM_SPEED_KHZ*1000/16)+ \
                     ((BOOT_COM_UART_BAUDRATE+1)/2))/BOOT_COM_UART_BAUDRATE);
  /* write the calculated baudrate selector value to the registers */
  U0DLL = (blt_int8u)baud_reg_value;
  U0DLM = (blt_int8u)(baud_reg_value >> 8);
  /* configure 8 data bits, no parity and 1 stop bit and set DLAB = 0 */
  U0LCR = UART_MODE_8N1;
  /* enable and reset transmit and receive FIFO. necessary for UART operation */
  U0FCR = UART_FIFO_RX1;
} /*** end of UartInit ***/


/************************************************************************************//**
** \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 UartTransmitPacket(blt_int8u *data, blt_int8u len)
{
  blt_int16u data_index;
  blt_bool result;

  /* verify validity of the len-paramenter */
  ASSERT_RT(len <= BOOT_COM_UART_TX_MAX_DATA);

  /* first transmit the length of the packet */
  result = UartTransmitByte(len);
  ASSERT_RT(result == BLT_TRUE);

  /* transmit all the packet bytes one-by-one */
  for (data_index = 0; data_index < len; data_index++)
  {
    /* keep the watchdog happy */
    CopService();
    /* write byte */
    result = UartTransmitByte(data[data_index]);
    ASSERT_RT(result == BLT_TRUE);
  }
} /*** end of UartTransmitPacket ***/


/************************************************************************************//**
** \brief     Receives a communication interface packet if one is present.
** \param     data Pointer to byte array where the data is to be stored.
** \param     len Pointer where the length of the packet is to be stored.
** \return    BLT_TRUE if a packet was received, BLT_FALSE otherwise.
**
****************************************************************************************/
blt_bool UartReceivePacket(blt_int8u *data, blt_int8u *len)
{
  static blt_int8u xcpCtoReqPacket[BOOT_COM_UART_RX_MAX_DATA+1];  /* one extra for length */
  static blt_int8u xcpCtoRxLength;
  static blt_bool  xcpCtoRxInProgress = BLT_FALSE;
  static blt_int32u xcpCtoRxStartTime = 0;

  /* start of cto packet received? */
  if (xcpCtoRxInProgress == BLT_FALSE)
  {
    /* store the message length when received */
    if (UartReceiveByte(&xcpCtoReqPacket[0]) == BLT_TRUE)
    {
      if ( (xcpCtoReqPacket[0] > 0) && 
           (xcpCtoReqPacket[0] <= BOOT_COM_UART_RX_MAX_DATA) )
      {
        /* store the start time */
        xcpCtoRxStartTime = TimerGet();
        /* reset packet data count */
        xcpCtoRxLength = 0;
        /* indicate that a cto packet is being received */
        xcpCtoRxInProgress = BLT_TRUE;
      }
    }
  }
  else
  {
    /* store the next packet byte */
    if (UartReceiveByte(&xcpCtoReqPacket[xcpCtoRxLength+1]) == BLT_TRUE)
    {
      /* increment the packet data count */
      xcpCtoRxLength++;

      /* check to see if the entire packet was received */
      if (xcpCtoRxLength == xcpCtoReqPacket[0])
      {
        /* copy the packet data */
        CpuMemCopy((blt_int32u)data, (blt_int32u)&xcpCtoReqPacket[1], xcpCtoRxLength);
        /* done with cto packet reception */
        xcpCtoRxInProgress = BLT_FALSE;
        /* set the packet length */
        *len = xcpCtoRxLength;
        /* packet reception complete */
        return BLT_TRUE;
      }
    }
    else
    {
      /* check packet reception timeout */
      if (TimerGet() > (xcpCtoRxStartTime + UART_CTO_RX_PACKET_TIMEOUT_MS))
      {
        /* cancel cto packet reception due to timeout. note that that automaticaly
         * discards the already received packet bytes, allowing the host to retry.
         */
        xcpCtoRxInProgress = BLT_FALSE;
      }
    }
  }
  /* packet reception not yet complete */
  return BLT_FALSE;
} /*** end of UartReceivePacket ***/


/************************************************************************************//**
** \brief     Receives a communication interface byte if one is present.
** \param     data Pointer to byte where the data is to be stored.
** \return    BLT_TRUE if a byte was received, BLT_FALSE otherwise.
**
****************************************************************************************/
static blt_bool UartReceiveByte(blt_int8u *data)
{
  /* check if a new byte was received by means of the RDR-bit */
  if ((U0LSR & UART_RDR) != 0)
  {
    /* store the received byte */
    data[0] = U0RBR;
    /* inform caller of the newly received byte */
    return BLT_TRUE;
  }
  /* inform caller that no new data was received */
  return BLT_FALSE;
} /*** end of UartReceiveByte ***/


/************************************************************************************//**
** \brief     Transmits a communication interface byte.
** \param     data Value of byte that is to be transmitted.
** \return    BLT_TRUE if the byte was transmitted, BLT_FALSE otherwise.
**
****************************************************************************************/
static blt_bool UartTransmitByte(blt_int8u data)
{
  blt_int32u timeout;
  blt_bool result = BLT_TRUE;

  /* check if tx holding register can accept new data */
  if ((U0LSR & UART_THRE) == 0)
  {
    /* UART not ready. should not happen */
    return BLT_FALSE;
  }
  /* write byte to transmit holding register */
  U0THR = data;
  /* set timeout time to wait for transmit completion. */
  timeout = TimerGet() + UART_BYTE_TX_TIMEOUT_MS;
  /* wait for tx holding register to be empty */
  while ((U0LSR & UART_THRE) == 0)
  {
    /* keep the watchdog happy */
    CopService();
    /* break loop upon timeout. this would indicate a hardware failure. */
    if (TimerGet() > timeout)
    {
      result = BLT_FALSE;
      break;
    }
  }
  /* give the result back to the caller */
  return result;
} /*** end of UartTransmitByte ***/
#endif /* BOOT_COM_UART_ENABLE > 0 */


/*********************************** end of uart.c *************************************/