text: /**
   * \file
   *
   * \brief USART driver for AVR XMEGA.
   *
   * Copyright (c) 2009-2012 Atmel Corporation. All rights reserved.
   *
   * \asf_license_start
   *
   * \page License
   *
   * 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. The name of Atmel may not be used to endorse or promote products derived
   *    from this software without specific prior written permission.
   *
   * 4. This software may only be redistributed and used in connection with an
   *    Atmel microcontroller product.
   *
   * THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
   * EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL 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.
   *
   * \asf_license_stop
   *
   */
  #include <stdint.h>
  #include "compiler.h"
  #include "usart.h"
  #include "sysclk.h"
  #include "ioport.h"
  #include "status_codes.h"
  
  /*
   * Fix XMEGA header files
   * USART.CTRLC  bit masks and bit positions
   */
  #ifndef USART_UCPHA_bm
      #define USART_UCPHA_bm 0x02
  #endif
  #ifndef USART_DORD_bm
      #define USART_DORD_bm 0x04
  #endif
  
  /**
   * \brief Initialize USART in RS232 mode.
   *
   * This function initializes the USART module in RS232 mode using the
   * usart_rs232_options_t configuration structure and CPU frequency.
   *
   * \param usart The USART module.
   * \param opt The RS232 configuration option.
   *
   * \retval true if the initialization was successfull
   * \retval false if the initialization failed (error in baud rate calculation)
   */
  bool usart_init_rs232(USART_t *usart, const usart_rs232_options_t *opt)
  {
      bool result;
      sysclk_enable_peripheral_clock(usart);
      usart_set_mode(usart, USART_CMODE_ASYNCHRONOUS_gc);
      usart_format_set(usart, opt->charlength, opt->paritytype,
                       opt->stopbits);
      result = usart_set_baudrate(usart, opt->baudrate, sysclk_get_per_hz());
      usart_tx_enable(usart);
      usart_rx_enable(usart);
  
      return result;
  }
  
  /**
   * \brief Initialize USART in SPI master mode.
   *
   * This function initializes the USART module in SPI master mode using the
   * usart_spi_options_t configuration structure and CPU frequency.
   *
   * \param usart The USART module.
   * \param opt The RS232 configuration option.
   */
  void usart_init_spi(USART_t *usart, const usart_spi_options_t *opt)
  {
      ioport_pin_t sck_pin = 0;
      bool invert_sck;
  
      sysclk_enable_peripheral_clock(usart);
  
      usart_rx_disable(usart);
  
      /* configure Clock polarity using INVEN bit of the correct SCK I/O port **/
      invert_sck = (opt->spimode == 2) || (opt->spimode == 3);
      UNUSED(invert_sck);
  
  #ifdef USARTC0
      if ((uint16_t)usart == (uint16_t)&USARTC0) {
  #  ifdef PORT_USART0_bm
          if (PORTC.REMAP & PORT_USART0_bm) {
              sck_pin = IOPORT_CREATE_PIN(PORTC, 5);
          } else {
              sck_pin = IOPORT_CREATE_PIN(PORTC, 1);
          }
  #  else
          sck_pin = IOPORT_CREATE_PIN(PORTC, 1);
  #  endif
      }
  #endif
  #ifdef USARTC1
      if ((uint16_t)usart == (uint16_t)&USARTC1) {
          sck_pin = IOPORT_CREATE_PIN(PORTC, 5);
      }
  #endif
  #ifdef USARTD0
      if ((uint16_t)usart == (uint16_t)&USARTD0) {
  #  ifdef PORT_USART0_bm
          if (PORTD.REMAP & PORT_USART0_bm) {
              sck_pin = IOPORT_CREATE_PIN(PORTD, 5);
          } else {
              sck_pin = IOPORT_CREATE_PIN(PORTD, 1);
          }
  #  else
          sck_pin = IOPORT_CREATE_PIN(PORTD, 1);
  #  endif
      }
  #endif
  #ifdef USARTD1
      if ((uint16_t)usart == (uint16_t)&USARTD1) {
          sck_pin = IOPORT_CREATE_PIN(PORTD, 5);
      }
  #endif
  #ifdef USARTE0
      if ((uint16_t)usart == (uint16_t)&USARTE0) {
  #  ifdef PORT_USART0_bm
          if(PORTE.REMAP & PORT_USART0_bm) {
              sck_pin = IOPORT_CREATE_PIN(PORTE, 5);
          } else {
              sck_pin = IOPORT_CREATE_PIN(PORTE, 1);
          }
  #  else
          sck_pin = IOPORT_CREATE_PIN(PORTE, 1);
  #  endif
      }
  #endif
  #ifdef USARTE1
      if ((uint16_t)usart == (uint16_t)&USARTE1) {
          sck_pin = IOPORT_CREATE_PIN(PORTE, 5);
      }
  #endif
  #ifdef USARTF0
      if ((uint16_t)usart == (uint16_t)&USARTF0) {
  #  ifdef PORT_USART0_bm
          if(PORTF.REMAP & PORT_USART0_bm) {
              sck_pin = IOPORT_CREATE_PIN(PORTF, 5);
          } else {
              sck_pin = IOPORT_CREATE_PIN(PORTF, 1);
          }
  #  else
          sck_pin = IOPORT_CREATE_PIN(PORTF, 1);
  # endif
      }
  #endif
  #ifdef USARTF1
      if ((uint16_t)usart == (uint16_t)&USARTF1) {
          sck_pin = IOPORT_CREATE_PIN(PORTF, 5);
      }
  #endif
  
      /* Configure the USART output pin */
      ioport_set_pin_dir(sck_pin, IOPORT_DIR_OUTPUT);
      ioport_set_pin_mode(sck_pin,
                          IOPORT_MODE_TOTEM | (invert_sck? IOPORT_MODE_INVERT_PIN : 0));
      ioport_set_pin_level(sck_pin, IOPORT_PIN_LEVEL_HIGH);
  
      usart_set_mode(usart, USART_CMODE_MSPI_gc);
  
      if (opt->spimode == 1 || opt->spimode == 3) {
          usart->CTRLC |= USART_UCPHA_bm;
      } else {
          usart->CTRLC &= ~USART_UCPHA_bm;
      }
      if (opt->data_order) {
          (usart)->CTRLC |= USART_DORD_bm;
      } else {
          (usart)->CTRLC &= ~USART_DORD_bm;
      }
  
      usart_spi_set_baudrate(usart, opt->baudrate, sysclk_get_per_hz());
      usart_tx_enable(usart);
      usart_rx_enable(usart);
  }
  
  /**
   * \brief Send a data with the USART module
   *
   * This function outputs a data using the USART module.
   *
   * \param usart The USART module.
   * \param c The data to send.
   *
   * \return STATUS_OK
   */
  enum status_code usart_putchar(USART_t *usart, uint8_t c)
  {
      while (usart_data_register_is_empty(usart) == false) {
      }
  
      (usart)->DATA = c;
      return STATUS_OK;
  }
  
  /**
   * \brief Receive a data with the USART module
   *
   * This function returns the received data from the USART module.
   *
   * \param usart The USART module.
   *
   * \return The received data.
   */
  uint8_t usart_getchar(USART_t *usart)
  {
      while (usart_rx_is_complete(usart) == false) {
      }
  
      return ((uint8_t)(usart)->DATA);
  }
  
  /**
   * \brief Get the offset for lookup in the baudrate table
   *
   * \param baud The requested baudrate
   *
   * \return The baudrate offset in PROGMEM table
   * \retval USART_BAUD_UNDEFINED for baudrates not in lookup table
   */
  static uint8_t usart_get_baud_offset(uint32_t baud)
  {
      switch (baud) {
      case 1200:
          return (uint8_t)USART_BAUD_1200;
  
      case 2400:
          return (uint8_t)USART_BAUD_2400;
  
      case 4800:
          return (uint8_t)USART_BAUD_4800;
  
      case 9600:
          return (uint8_t)USART_BAUD_9600;
  
      case 19200:
          return (uint8_t)USART_BAUD_19200;
  
      case 38400:
          return (uint8_t)USART_BAUD_38400;
  
      case 57600:
          return (uint8_t)USART_BAUD_57600;
  
      default:
          return (uint8_t)USART_BAUD_UNDEFINED;
      }
  }
  
  /**
   * \brief Set the baudrate by setting the BSEL and BSCALE values in the USART
   *
   * This function sets the selected BSEL and BSCALE value in the BAUDCTRL
   * registers with BSCALE 0. For calculation options, see table 21-1 in XMEGA A
   * manual.
   *
   * \param usart  The USART module.
   * \param bsel   Calculated BSEL value.
   * \param bscale Calculated BSEL value.
   *
   */
  void usart_set_bsel_bscale_value(USART_t *usart, uint16_t bsel, uint8_t bscale)
  {
      (usart)->BAUDCTRLA = (uint8_t)(bsel);
      (usart)->BAUDCTRLB = (uint8_t)(((bsel >> 8) & 0X0F) | (bscale << 4));
  }
  
  /**
   * \brief Set the baudrate using precalculated BAUDCTRL values from PROGMEM
   *
   * \note This function only works for cpu_hz 2Mhz or 32Mhz and baudrate values
   * 1200, 2400, 4800, 9600, 19200, 38400 and 57600.
   *
   * \param usart  The USART module.
   * \param baud   The baudrate.
   * \param cpu_hz The CPU frequency.
   *
   */
  void usart_set_baudrate_precalculated(USART_t *usart, uint32_t baud,
                                        uint32_t cpu_hz)
  {
      uint8_t baud_offset;
      uint16_t baudctrl = 0;
  
      baud_offset = usart_get_baud_offset(baud);
  
      if (cpu_hz == 2000000UL) {
          baudctrl = PROGMEM_READ_WORD(baudctrl_2mhz + baud_offset);
      } else if (cpu_hz == 32000000UL) {
          baudctrl = PROGMEM_READ_WORD(baudctrl_32mhz + baud_offset);
      } else {
          /* Error, system clock speed or USART baud rate is not supported
           * by the look-up table */
          Assert(false);
      }
  
      if (baud_offset != USART_BAUD_UNDEFINED) {
          (usart)->BAUDCTRLB = (uint8_t)((uint16_t)baudctrl);
          (usart)->BAUDCTRLA = (uint8_t)((uint16_t)baudctrl >> 8);
      }
  }
  
  /**
   * \brief Set the baudrate value in the USART module
   *
   * This function sets the baudrate register with scaling regarding the CPU
   * frequency and makes sure the baud rate is supported by the hardware.
   * The function can be used if you don't want to calculate the settings
   * yourself or changes to baudrate at runtime is required.
   *
   * \param usart The USART module.
   * \param baud The baudrate.
   * \param cpu_hz The CPU frequency.
   *
   * \retval true if the hardware supports the baud rate
   * \retval false if the hardware does not support the baud rate (i.e. it's
   *               either too high or too low.)
   */
  bool usart_set_baudrate(USART_t *usart, uint32_t baud, uint32_t cpu_hz)
  {
      int8_t exp;
      uint32_t div;
      uint32_t limit;
      uint32_t ratio;
      uint32_t min_rate;
      uint32_t max_rate;
  
      /*
       * Check if the hardware supports the given baud rate
       */
      /* 8 = (2^0) * 8 * (2^0) = (2^BSCALE_MIN) * 8 * (BSEL_MIN) */
      max_rate = cpu_hz / 8;
      /* 4194304 = (2^7) * 8 * (2^12) = (2^BSCALE_MAX) * 8 * (BSEL_MAX+1) */
      min_rate = cpu_hz / 4194304;
  
      if (!((usart)->CTRLB & USART_CLK2X_bm)) {
          max_rate /= 2;
          min_rate /= 2;
      }
  
      if ((baud > max_rate) || (baud < min_rate)) {
          return false;
      }
  
      /* Check if double speed is enabled. */
      if (!((usart)->CTRLB & USART_CLK2X_bm)) {
          baud *= 2;
      }
  
      /* Find the lowest possible exponent. */
      limit = 0xfffU >> 4;
      ratio = cpu_hz / baud;
  
      for (exp = -7; exp < 7; exp++) {
          if (ratio < limit) {
              break;
          }
  
          limit <<= 1;
  
          if (exp < -3) {
              limit |= 1;
          }
      }
  
      /*
       * Depending on the value of exp, scale either the input frequency or
       * the target baud rate. By always scaling upwards, we never introduce
       * any additional inaccuracy.
       *
       * We are including the final divide-by-8 (aka. right-shift-by-3) in
       * this operation as it ensures that we never exceeed 2**32 at any
       * point.
       *
       * The formula for calculating BSEL is slightly different when exp is
       * negative than it is when exp is positive.
       */
      if (exp < 0) {
          /* We are supposed to subtract 1, then apply BSCALE. We want to
           * apply BSCALE first, so we need to turn everything inside the
           * parenthesis into a single fractional expression.
           */
          cpu_hz -= 8 * baud;
  
          /* If we end up with a left-shift after taking the final
           * divide-by-8 into account, do the shift before the divide.
           * Otherwise, left-shift the denominator instead (effectively
           * resulting in an overall right shift.)
           */
          if (exp <= -3) {
              div = ((cpu_hz << (-exp - 3)) + baud / 2) / baud;
          } else {
              baud <<= exp + 3;
              div = (cpu_hz + baud / 2) / baud;
          }
      } else {
          /* We will always do a right shift in this case, but we need to
           * shift three extra positions because of the divide-by-8.
           */
          baud <<= exp + 3;
          div = (cpu_hz + baud / 2) / baud - 1;
      }
  
      (usart)->BAUDCTRLB = (uint8_t)(((div >> 8) & 0X0F) | (exp << 4));
      (usart)->BAUDCTRLA = (uint8_t)div;
  
      return true;
  }
  
  /**
   * \brief Set the baudrate value in the USART_SPI module
   *
   * This function sets the baudrate register regarding the CPU frequency.
   *
   * \param usart The USART(SPI) module.
   * \param baud The baudrate.
   * \param cpu_hz The CPU frequency.
   */
  void usart_spi_set_baudrate(USART_t *usart, uint32_t baud, uint32_t cpu_hz)
  {
      uint16_t bsel_value;
  
      /* Check if baudrate is less than the maximim limit specified in
       * datasheet */
      if (baud < (cpu_hz / 2)) {
          bsel_value = (cpu_hz / (baud * 2)) - 1;
      } else {
          /* If baudrate is not within the specfication in datasheet,
           * assign maximum baudrate possible for the current CPU frequency */
          bsel_value = 0;
      }
  
      (usart)->BAUDCTRLB = (uint8_t)((~USART_BSCALE_gm) & (bsel_value >> 8));
      (usart)->BAUDCTRLA = (uint8_t)(bsel_value);
  }
  