text: /****************************************************************************
   * arch/z80/src/ez80/ez80_loweruart.c
   *
   *   Copyright (C) 2008-2009, 2012 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * 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 NuttX 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 OWNER 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.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <stdint.h>
  #include <string.h>
  
  #include <arch/io.h>
  #include <nuttx/arch.h>
  #include <nuttx/sched.h>
  
  #include "chip/chip.h"
  #include "common/up_internal.h"
  
  #ifdef USE_LOWSERIALINIT
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /* Is there any serial support?  This might be the case if the board does
   * not have serial ports but supports stdout through, say, an LCD.
   */
  
  #if defined(CONFIG_EZ80_UART0) || defined(CONFIG_EZ80_UART1)
  #  define HAVE_SERIAL
  #else
  #  undef HAVE_SERIAL
  #endif
  
  /* Is one of the serial ports a console? */
  
  #if defined(CONFIG_UART0_SERIAL_CONSOLE) && defined(CONFIG_EZ80_UART0)
  #  define HAVE_SERIALCONSOLE 1
  #  undef CONFIG_UART1_SERIAL_CONSOLE
  #elif defined(CONFIG_UART1_SERIAL_CONSOLE) && defined(CONFIG_EZ80_UART1)
  #  define HAVE_SERIALCONSOLE 1
  #  undef CONFIG_UART0_SERIAL_CONSOLE
  #else
  #  warning "No console is defined"
  #  if defined(CONFIG_UART0_SERIAL_CONSOLE) || defined(CONFIG_UART1_SERIAL_CONSOLE)
  #    error "A serial console selected, but corresponding UART not enabled"
  #  endif
  #  undef CONFIG_UART0_SERIAL_CONSOLE
  #  undef CONFIG_UART1_SERIAL_CONSOLE
  #  undef HAVE_SERIALCONSOLE
  #endif
  
  /* Select UART parameters for the selected console */
  
  #if defined(CONFIG_UART0_SERIAL_CONSOLE)
  #  define ez80_inp(offs)       inp((EZ80_UART0_BASE+(offs)))
  #  define ez80_outp(offs,val)  outp((EZ80_UART0_BASE+(offs)), (val))
  #  define CONFIG_UART_BAUD     CONFIG_UART0_BAUD
  #  if CONFIG_UART0_BITS == 7
  #    define CONFIG_UART_BITS   EZ80_UARTCHAR_7BITS
  #  else
  #    define CONFIG_UART_BITS   EZ80_UARTCHAR_8BITS
  #  endif
  #  if CONFIG_UART0_2STOP != 0
  #    define CONFIG_UART_2STOP  EZ80_UARTLCTl_2STOP
  #  else
  #    define CONFIG_UART_2STOP 0
  #  endif
  #  if CONFIG_UART0_PARITY == 1 /* Odd parity */
  #    define CONFIG_UART_PARITY EZ80_UARTLCTL_PEN
  #  elif CONFIG_UART0_PARITY == 2  /* Even parity */
  #    define CONFIG_UART_PARITY (EZ80_UARTLCTL_PEN|EZ80_UARTLCTL_EPS)
  #  else
  #    define CONFIG_UART_PARITY 0
  #  endif
  #elif defined(CONFIG_UART1_SERIAL_CONSOLE)
  #  define ez80_inp(offs)       inp((EZ80_UART1_BASE+(offs)))
  #  define ez80_outp(offs.val)  outp((EZ80_UART1_BASE+(offs)), (val))
  #  define CONFIG_UART_BAUD     CONFIG_UART1_BAUD
  #  if CONFIG_UART1_BITS == 7
  #    define CONFIG_UART_BITS   EZ80_UARTCHAR_7BITS
  #  else
  #    define CONFIG_UART_BITS   EZ80_UARTCHAR_8BITS
  #  endif
  #  if CONFIG_UART1_2STOP != 0
  #    define CONFIG_UART_2STOP  EZ80_UARTLCTl_2STOP
  #  else
  #    define CONFIG_UART_2STOP  0
  #  endif
  #  if CONFIG_UART1_PARITY == 1 /* Odd parity */
  #    define CONFIG_UART_PARITY EZ80_UARTLCTL_PEN
  #  elif CONFIG_UART1_PARITY == 2  /* Even parity */
  #    define CONFIG_UART_PARITY (EZ80_UARTLCTL_PEN|EZ80_UARTLCTL_EPS)
  #  else
  #    define CONFIG_UART_PARITY 0
  #  endif
  #endif
  
  /****************************************************************************
   * Private Data
   ****************************************************************************/
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  #if defined(HAVE_SERIALCONSOLE) && !defined(CONFIG_SUPPRESS_UART_CONFIG)
  static void ez80_setbaud(void)
  {
    uint32_t brg_divisor;
    uint8_t lctl;
  
    /* The resulting BAUD and depends on the system clock frequency and the
     * BRG divisor as follows:
     *
     *   BAUD = SYSTEM_CLOCK_FREQUENCY / (16 * BRG_Divisor)
     *
     * Or
     *
     *   BRG_Divisor = SYSTEM_CLOCK_FREQUENCY / 16 / BAUD
     *
     * NOTE: The system clock frequency value is defined in the board.h file
     */
  
     brg_divisor = (ez80_systemclock + (CONFIG_UART_BAUD << 3)) / (CONFIG_UART_BAUD << 4);
  
     /* Set the DLAB bit to enable access to the BRG registers */
  
     lctl = ez80_inp(EZ80_UART_LCTL);
     lctl |= EZ80_UARTLCTL_DLAB;
     ez80_outp(EZ80_UART_LCTL, lctl);
  
     ez80_outp(EZ80_UART_BRGL, (uint8_t)(brg_divisor & 0xff));
     ez80_outp(EZ80_UART_BRGH, (uint8_t)(brg_divisor >> 8));
  
     lctl &= ~EZ80_UARTLCTL_DLAB;
     ez80_outp(EZ80_UART_LCTL, lctl);
  }
  #endif /* HAVE_SERIALCONSOLE && !CONFIG_SUPPRESS_UART_CONFIG */
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_lowserialinit
   ****************************************************************************/
  
  void up_lowserialinit(void)
  {
  #ifdef HAVE_SERIAL
    uint8_t regval;
  
    /* Configure pins for usage of UARTs (whether or not we have a console) */
  
  #ifdef CONFIG_EZ80_UART0
    /* Set Port D, pins 0 and 1 for their alternate function (Mode 7) to enable UART0 */
  
    regval  = inp(EZ80_PD_DDR);
    regval |= 3;
    outp(EZ80_PD_DDR, regval);
  
    regval  = inp(EZ80_PD_ALT1);
    regval &= ~3;
    outp(EZ80_PD_ALT1, regval);
  
    regval  = inp(EZ80_PD_ALT2);
    regval |= 3;
    outp(EZ80_PD_ALT2, regval);
  #endif
  
  #ifdef CONFIG_EZ80_UART1
    /* Set Port C, pins 0 and 1 for their alternate function (Mode 7) to enable UART1 */
  
    regval  = inp(EZ80_PC_DDR);
    regval |= 3;
    outp(EZ80_PC_DDR, regval);
  
    regval  = inp(EZ80_PC_ALT1);
    regval &= ~3;
    outp(EZ80_PC_ALT1, regval);
  
    regval  = inp(EZ80_PC_ALT2);
    regval |= 3;
    outp(EZ80_PC_ALT2, regval);
  #endif
  
  #if defined(HAVE_SERIALCONSOLE) && !defined(CONFIG_SUPPRESS_UART_CONFIG)
    /* Disable interrupts from the UART */
  
    regval = ez80_inp(EZ80_UART_IER);
    regval &= ~EZ80_UARTEIR_INTMASK;
    ez80_outp(EZ80_UART_IER, regval);
  
    /* Set the baud rate */
  
    ez80_setbaud();
    ez80_outp(EZ80_UART_MCTL, 0);
  
    /* Set the character properties */
  
    regval = ez80_inp(EZ80_UART_LCTL);
    regval &= ~EZ80_UARTLCTL_MASK;
    regval |= (CONFIG_UART_BITS | CONFIG_UART_2STOP | CONFIG_UART_PARITY);
    ez80_outp(EZ80_UART_LCTL, regval);
  
    /* Enable and flush the receive FIFO */
  
    regval = EZ80_UARTFCTL_FIFOEN;
    ez80_outp(EZ80_UART_FCTL, regval);
    regval |= (EZ80_UARTFCTL_CLRTxF|EZ80_UARTFCTL_CLRRxF);
    ez80_outp(EZ80_UART_FCTL, regval);
  
    /* Set the receive trigger level to 1 */
  
    regval |= EZ80_UARTTRIG_1;
    ez80_outp(EZ80_UART_FCTL, regval);
  
  #endif /* HAVE_SERIALCONSOLE && !CONFIG_SUPPRESS_UART_CONFIG */
  #endif /* HAVE_SERIAL */
  }
  
  #endif /* USE_LOWSERIALINIT */
  