/****************************************************************************
 * arch/avr/src/atmega/atmega_lowconsole.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include "atmega_config.h"

#include <assert.h>
#include <debug.h>

#include <arch/irq.h>
#include <arch/board/board.h>
#include <avr/io.h>

#include "up_internal.h"
#include "atmega.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* USART0 Baud rate settings for normal and double speed modes  */

#define AVR_NORMAL_UBRR0 \
  ((((BOARD_CPU_CLOCK / 16) + (CONFIG_USART0_BAUD / 2)) / (CONFIG_USART0_BAUD)) - 1)

#define AVR_DBLSPEED_UBRR0 \
  ((((BOARD_CPU_CLOCK / 8) + (CONFIG_USART0_BAUD / 2)) / (CONFIG_USART0_BAUD)) - 1)

/* Select normal or double speed baud settings.  This is a trade-off between
 * the sampling rate and the accuracy of the divisor for high baud rates.
 *
 * As examples, consider:
 *
 *   BOARD_CPU_CLOCK=8MHz and BAUD=115200:
 *     AVR_NORMAL_UBRR1 = 4 (rounded), actual baud = 125,000
 *     AVR_DBLSPEED_UBRR1 = 9 (rounded), actual baud = 111,111
 *
 *   BOARD_CPU_CLOCK=8MHz and BAUD=9600:
 *     AVR_NORMAL_UBRR1 = 52 (rounded), actual baud = 9615
 *     AVR_DBLSPEED_UBRR1 = 104 (rounded), actual baud = 9615
 */

#undef USART0_DOUBLE_SPEED
#ifdef CONFIG_AVR_USART0
#  if BOARD_CPU_CLOCK <= 4000000
#    if CONFIG_USART0_BAUD <= 9600
#      define AVR_UBRR0 AVR_NORMAL_UBRR0
#    else
#      define AVR_UBRR0 AVR_DBLSPEED_UBRR0
#      define USART0_DOUBLE_SPEED 1
#    endif
#  elif BOARD_CPU_CLOCK <= 8000000
#    if CONFIG_USART0_BAUD <= 19200
#      define AVR_UBRR0 AVR_NORMAL_UBRR0
#    else
#      define AVR_UBRR0 AVR_DBLSPEED_UBRR0
#      define USART0_DOUBLE_SPEED 1
#    endif
#  elif BOARD_CPU_CLOCK <= 12000000
#    if CONFIG_USART0_BAUD <= 28800
#      define AVR_UBRR0 AVR_NORMAL_UBRR0
#    else
#      define AVR_UBRR0 AVR_DBLSPEED_UBRR0
#      define USART0_DOUBLE_SPEED 1
#    endif
#  elif BOARD_CPU_CLOCK <= 16000000
#    if CONFIG_USART0_BAUD <= 38400
#      define AVR_UBRR0 AVR_NORMAL_UBRR0
#    else
#      define AVR_UBRR0 AVR_DBLSPEED_UBRR0
#      define USART0_DOUBLE_SPEED 1
#    endif
#  else
#    if CONFIG_USART0_BAUD <= 57600
#      define AVR_UBRR0 AVR_NORMAL_UBRR0
#    else
#      define AVR_UBRR0 AVR_DBLSPEED_UBRR0
#      define USART0_DOUBLE_SPEED 1
#    endif
#  endif
#endif

/* USART1 Baud rate settings for normal and double speed modes  */

#define AVR_NORMAL_UBRR1 \
  ((((BOARD_CPU_CLOCK / 16) + (CONFIG_USART1_BAUD / 2)) / (CONFIG_USART1_BAUD)) - 1)

#define AVR_DBLSPEED_UBRR1 \
  ((((BOARD_CPU_CLOCK / 8) + (CONFIG_USART1_BAUD / 2)) / (CONFIG_USART1_BAUD)) - 1)

/* Select normal or double speed baud settings.  This is a trade-off between
 * the sampling rate and the accuracy of the divisor for high baud rates.
 *
 * As examples, consider:
 *
 *   BOARD_CPU_CLOCK=8MHz and BAUD=115200:
 *     AVR_NORMAL_UBRR1 = 4 (rounded), actual baud = 125,000
 *     AVR_DBLSPEED_UBRR1 = 9 (rounded), actual baud = 111,111
 *
 *   BOARD_CPU_CLOCK=8MHz and BAUD=9600:
 *     AVR_NORMAL_UBRR1 = 52 (rounded), actual baud = 9615
 *     AVR_DBLSPEED_UBRR1 = 104 (rounded), actual baud = 9615
 */

#undef USART1_DOUBLE_SPEED
#ifdef CONFIG_AVR_USART1
#  if BOARD_CPU_CLOCK <= 4000000
#    if CONFIG_USART1_BAUD <= 9600
#      define AVR_UBRR1 AVR_NORMAL_UBRR1
#    else
#      define AVR_UBRR1 AVR_DBLSPEED_UBRR1
#      define USART1_DOUBLE_SPEED 1
#    endif
#  elif BOARD_CPU_CLOCK <= 8000000
#    if CONFIG_USART1_BAUD <= 19200
#      define AVR_UBRR1 AVR_NORMAL_UBRR1
#    else
#      define AVR_UBRR1 AVR_DBLSPEED_UBRR1
#      define USART1_DOUBLE_SPEED 1
#    endif
#  elif BOARD_CPU_CLOCK <= 12000000
#    if CONFIG_USART1_BAUD <= 28800
#      define AVR_UBRR1 AVR_NORMAL_UBRR1
#    else
#      define AVR_UBRR1 AVR_DBLSPEED_UBRR1
#      define USART1_DOUBLE_SPEED 1
#    endif
#  elif BOARD_CPU_CLOCK <= 16000000
#    if CONFIG_USART1_BAUD <= 38400
#      define AVR_UBRR1 AVR_NORMAL_UBRR1
#    else
#      define AVR_UBRR1 AVR_DBLSPEED_UBRR1
#      define USART1_DOUBLE_SPEED 1
#    endif
#  else
#    if CONFIG_USART1_BAUD <= 57600
#      define AVR_UBRR1 AVR_NORMAL_UBRR1
#    else
#      define AVR_UBRR1 AVR_DBLSPEED_UBRR1
#      define USART1_DOUBLE_SPEED 1
#    endif
#  endif
#endif

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: usart0_reset and usart1_reset
 *
 * Description:
 *   Reset USART0 or USART1.
 *
 ****************************************************************************/

#ifdef CONFIG_AVR_USART0
void usart0_reset(void)
{
  /* Clear USART configuration */

  UCSR0A = 0;
  UCSR0B = 0;
  UCSR0C = 0;

  /* Unconfigure pins (no action needed */

#ifdef CONFIG_ARCH_CHIP_ATMEGA1284P
  DDRD  &= ~(1 << 1);
  PORTD &= ~(1 << 0);
#else
  DDRE  &= ~(1 << 1);
  PORTE &= ~(1 << 0);
#endif

  /* Unconfigure BAUD divisor */

  UBRR0H = 0;
  UBRR0L = 0;
}
#endif

#ifdef CONFIG_AVR_USART1
void usart1_reset(void)
{
  /* Clear USART configuration */

  UCSR1A = 0;
  UCSR1B = 0;
  UCSR1C = 0;

  /* Unconfigure pins */

  DDRD  &= ~(1 << 3);
  PORTD &= ~(1 << 2);

  /* Unconfigure BAUD divisor */

  UBRR1H = 0;
  UBRR1L = 0;
}
#endif

/****************************************************************************
 * Name: usart0_configure and usart1_configure
 *
 * Description:
 *   Configure USART0 or USART1.
 *
 ****************************************************************************/

#ifdef CONFIG_AVR_USART0
void usart0_configure(void)
{
  uint8_t ucsr0b;
  uint8_t ucsr0c;

  /* Select normal or double speed. */

#ifdef USART0_DOUBLE_SPEED
  UCSR0A = (1 << U2X0);
#else
  UCSR0A = 0;
#endif

  /* Select baud, parity, number of bits, stop bits, etc. */

  ucsr0b = ((1 << TXEN0)  | (1 << RXEN0));
  ucsr0c = 0;

  /* Select parity */

#if CONFIG_USART0_PARITY == 1
  ucsr0c |= ((1 << UPM01) | (1 << UPM00)); /* Odd parity */
#elif CONFIG_USART0_PARITY == 2
  ucsr0c |= (1 << UPM00);                  /* Even parity */
#endif

  /* 1 or 2 stop bits */

#if defined(CONFIG_USART0_2STOP) && CONFIG_USART0_2STOP > 0
  ucsr0c |= (1 << USBS0);                  /* Two stop bits */
#endif

  /* Word size */

#if CONFIG_USART0_BITS == 5
#elif CONFIG_USART0_BITS == 6
  ucsr0c |= (1 << UCSZ00);
#elif CONFIG_USART0_BITS == 7
  ucsr0c |= (1 << UCSZ01);
#elif CONFIG_USART0_BITS == 8
  ucsr0c |= ((1 << UCSZ00) | (1 << UCSZ01));
#elif CONFIG_USART0_BITS == 9
  ucsr0c |= ((1 << UCSZ0) | (1 << UCSZ01));
  ucsr0b |= (1 << UCSZ02);
#else
#  error "Unsupported word size"
#endif

  UCSR0B = ucsr0b;
  UCSR0C = ucsr0c;

#ifdef CONFIG_ARCH_CHIP_ATMEGA1284P
  /* Pin Configuration: None necessary, Port D bits 0&1 are automatically
   * configured:
   *
   * Port D, Bit 0: RXD0, USART0 Receive Pin. Receive Data (Data input pin
   *   for the USART0). When the USART0 receiver is enabled this pin is
   *   configured as an input regardless of the value of DDRD0. When the
   *   USART0 forces this pin to be an input, a logical one in PORTD0 will
   *   turn on the internal pull-up.
   *
   * Port D, Bit 1: TXD0, USART0 Transmit pin.
   */

  DDRD  |= (1 << 1);   /* Force Port D pin 1 to be an output -- should not be necessary */
  PORTD |= (1 << 0);   /* Set pull-up on Port D pin 0 */

#else
  /* Pin Configuration: None necessary, Port E bits 0&1 are automatically
   * configured:
   *
   * Port E, Bit 0: RXD0, USART0 Receive Pin. Receive Data (Data input pin
   *   for the USART0). When the USART0 receiver is enabled this pin is
   *   configured as an input regardless of the value of DDRE0. When the
   *   USART0 forces this pin to be an input, a logical one in PORTE0 will
   *   turn on the internal pull-up.
   *
   * Port E, Bit 1: TXD0, USART0 Transmit pin.
   *
   * REVISIT: According to table 41, TXD0 is also automatically configured.
   * However, this is not explicitly stated in the text.
   */

  DDRE  |= (1 << 1);   /* Force Port E pin 1 to be an output -- might not be necessary */
  PORTE |= (1 << 0);   /* Set pull-up on Port E pin 0 */
#endif

  /* Set the baud rate divisor */

  UBRR0H = AVR_UBRR0 >> 8;
  UBRR0L = AVR_UBRR0 & 0xff;
}
#endif

#ifdef CONFIG_AVR_USART1
void usart1_configure(void)
{
  uint8_t ucsr1b;
  uint8_t ucsr1c;

  /* Select normal or double speed. */

#ifdef USART1_DOUBLE_SPEED
  UCSR1A = (1 << U2X1);
#else
  UCSR1A = 0;
#endif

  /* Select baud, parity, number of bits, stop bits, etc. */

  ucsr1b = ((1 << TXEN1)  | (1 << RXEN1));
  ucsr1c = 0;

  /* Select parity */

#if CONFIG_USART1_PARITY == 1
  ucsr1c |= ((1 << UPM11) | (1 << UPM10)); /* Odd parity */
#elif CONFIG_USART1_PARITY == 2
  ucsr1c |= (1 << UPM11);                  /* Even parity */
#endif

  /* 1 or 2 stop bits */

#if defined(CONFIG_USART1_2STOP) && CONFIG_USART1_2STOP > 0
  ucsr1c |= (1 << USBS1);                  /* Two stop bits */
#endif

  /* Word size */

#if CONFIG_USART1_BITS == 5
#elif CONFIG_USART1_BITS == 6
  ucsr1c |= (1 << UCSZ10);
#elif CONFIG_USART1_BITS == 7
  ucsr1c |= (1 << UCSZ11);
#elif CONFIG_USART1_BITS == 8
  ucsr1c |= ((1 << UCSZ10) | (1 << UCSZ11));
#elif CONFIG_USART1_BITS == 9
  ucsr1c |= ((1 << CSZ10) | (1 << UCSZ11));
  ucsr1b |= (1 << UCSZ12);
#else
#  error "Unsupported word size"
#endif

  UCSR1B = ucsr1b;
  UCSR1C = ucsr1c;

  /* Pin Configuration: None necessary, Port D bits 2&3 are automatically
   * configured:
   *
   *   Port D, Bit 2: RXD1, Receive Data (Data input pin for the USART1).
   *     When the USART1 receiver is enabled this pin is configured as an
   *     input regardless of the value of DDD2. When the USART forces this
   *     pin to be an input, the pull-up can still be controlled by the
   *     PORTD2 bit.
   *   Port D, Bit 3: TXD1, Transmit Data (Data output pin for the USART1).
   *     When the USART1 Transmitter is enabled, this pin is configured as
   *     an output regardless of the value of DDD3.
   */

  DDRD  |= (1 << 3);   /* Force Port D pin 3 to be an output -- should not be necessary */
  PORTD |= (1 << 2);   /* Set pull-up on port D pin 2 */

  /* Set the baud rate divisor */

  UBRR1H = AVR_UBRR1 >> 8;
  UBRR1L = AVR_UBRR1 & 0xff;
}
#endif

/****************************************************************************
 * Name: up_consoleinit
 *
 * Description:
 *   Initialize a console for debug output.  This function is called very
 *   early in the initialization sequence to configure the serial console
 *   uart (only).
 *
 ****************************************************************************/

void up_consoleinit(void)
{
#ifdef HAVE_SERIAL_CONSOLE
#  if defined(CONFIG_USART0_SERIAL_CONSOLE)
  usart0_configure();
#  elif defined(CONFIG_USART1_SERIAL_CONSOLE)
  usart1_configure();
#  endif
#endif
}

/****************************************************************************
 * Name: up_lowputc
 *
 * Description:
 *   Output one byte on the serial console
 *
 ****************************************************************************/

void up_lowputc(char ch)
{
#ifdef HAVE_SERIAL_CONSOLE
#  if defined(CONFIG_USART0_SERIAL_CONSOLE)
  while ((UCSR0A & (1 << UDRE0)) == 0);
  UDR0 = ch;
#  elif defined(CONFIG_USART1_SERIAL_CONSOLE)
  while ((UCSR1A & (1 << UDRE1)) == 0);
  UDR1 = ch;
#  endif
#endif
}