text: /****************************************************************************
   * arch/renesas/src/m16c/m16c_serial.c
   *
   *   Copyright (C) 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 <sys/types.h>
  #include <stdint.h>
  #include <stdbool.h>
  #include <unistd.h>
  #include <semaphore.h>
  #include <string.h>
  #include <errno.h>
  #include <debug.h>
  
  #include <nuttx/irq.h>
  #include <nuttx/arch.h>
  #include <nuttx/serial/serial.h>
  #include <arch/serial.h>
  
  #include "chip.h"
  #include "up_arch.h"
  #include "up_internal.h"
  #include "m16c_uart.h"
  
  /* Is there any serial support?  This might be the case if the board does
   * not have serial ports but supports a console through, say, an LCD.
   */
  
  #if defined(CONFIG_M16C_UART0) || defined(CONFIG_M16C_UART1) || defined(CONFIG_M16C_UART2)
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /* Configuration **********************************************************/
  
  #ifndef M16C_XIN_PRESCALER
  #  define M16C_XIN_PRESCALER 1
  #endif
  
  /* Make sure interrupt priorities are defined.  If not, use a default of 5 */
  
  #ifndef M16C_S2T_PRIO
  #  define  M16C_S2T_PRIO   5            /* UART2 transmit interrupt priority */
  #endif
  #ifndef M16C_S2R_PRIO
  #  define  M16C_S2R_PRIO   5            /* UART2 receive interrupt priority */
  #endif
  #ifndef M16C_S0T_PRIO
  #  define  M16C_S0T_PRIO   5            /* UART0 transmit interrupt priority */
  #endif
  #ifndef M16C_S0R_PRIO
  #  define  M16C_S0R_PRIO   5            /* UART0 receive interrupt priority */
  #endif
  #ifndef M16C_S1T_PRIO
  #  define  M16C_S1T_PRIO   5            /* UART1 transmit interrupt priority */
  #endif
  #ifndef M16C_S1R_PRIO
  #  define  M16C_S1R_PRIO   5            /* UART1 receive interrupt priority */
  #endif
  
  /* Some sanity checks *******************************************************/
  
  /* Are there any UARTs? */
  
  #if !defined(CONFIG_M16C_UART0) && !defined(CONFIG_M16C_UART1) && !defined(CONFIG_M16C_UART2)
  #  ifdef USE_SERIALDRIVER
  #    error "Serial driver selected, but No UARTs is enabled"
  #    undef USE_SERIALDRIVER
  #  endif
  #endif
  
  /* Is there a serial console? */
  
  #if defined(CONFIG_UART0_SERIAL_CONSOLE) && defined(CONFIG_M16C_UART0)
  #  define HAVE_SERIALCONSOLE 1
  #  undef CONFIG_UART1_SERIAL_CONSOLE
  #  undef CONFIG_UART2_SERIAL_CONSOLE
  #elif defined(CONFIG_UART1_SERIAL_CONSOLE) && defined(CONFIG_M16C_UART1)
  #  define HAVE_SERIALCONSOLE 1
  #  undef CONFIG_UART0_SERIAL_CONSOLE
  #  undef CONFIG_UART2_SERIAL_CONSOLE
  #elif defined(CONFIG_UART2_SERIAL_CONSOLE) && defined(CONFIG_M16C_UART2)
  #  define HAVE_SERIALCONSOLE 1
  #  undef CONFIG_UART0_SERIAL_CONSOLE
  #  undef CONFIG_UART1_SERIAL_CONSOLE
  #else
  #  if defined(CONFIG_UART0_SERIAL_CONSOLE) || defined(CONFIG_UART1_SERIAL_CONSOLE)|| defined(CONFIG_UART2_SERIAL_CONSOLE)
  #    error "Serial console selected, but corresponding UART not enabled"
  #  endif
  #  undef HAVE_SERIALCONSOLE
  #  undef CONFIG_UART0_SERIAL_CONSOLE
  #  undef CONFIG_UART1_SERIAL_CONSOLE
  #  undef CONFIG_UART2_SERIAL_CONSOLE
  #endif
  
  #if defined(HAVE_SERIALCONSOLE) && defined(CONFIG_LCD_CONSOLE)
  #  error "Both serial and LCD consoles are defined"
  #elif !defined(HAVE_SERIALCONSOLE) && !defined(CONFIG_LCD_CONSOLE)
  #  warning "No console is defined"
  #endif
  
  #ifdef USE_SERIALDRIVER
  
  /* Which UART with be tty0/console and which tty1 and tty2? */
  
  /* CONFIG_UART0_SERIAL_CONSOLE (implies CONFIG_M16C_UART0 also defined) */
  
  #if defined(CONFIG_UART0_SERIAL_CONSOLE)
  #  define CONSOLE_DEV     g_uart0port     /* UART0 is console */
  #  define TTYS0_DEV       g_uart0port     /* UART0 is tty0 */
  #  ifdef CONFIG_M16C_UART1
  #    define TTYS1_DEV     g_uart1port     /* UART1 is tty1 */
  #    ifdef CONFIG_M16C_UART2
  #      define TTYS2_DEV   g_uart2port     /* UART2 is tty2 */
  #    endif
  #  else
  #    ifdef CONFIG_M16C_UART2
  #      define TTYS2_DEV   g_uart2port     /* UART2 is tty1 */
  #    else
  #      undef TTYS1_DEV                    /* No tty1 */
  #    endif
  #    undef TTYS2_DEV                      /* No tty2 */
  #  endif
  
  /* CONFIG_UART1_SERIAL_CONSOLE (implies CONFIG_M16C_UART1 also defined) */
  
  #elif defined(CONFIG_UART1_SERIAL_CONSOLE)
  #  define CONSOLE_DEV     g_uart1port     /* UART1 is console */
  #  define TTYS0_DEV       g_uart1port     /* UART1 is tty0 */
  #  ifdef CONFIG_M16C_UART0
  #    define TTYS1_DEV     g_uart0port     /* UART0 is tty1 */
  #    ifdef CONFIG_M16C_UART2
  #      define TTYS2_DEV   g_uart2port     /* UART2 is tty2 */
  #    endif
  #  else
  #    ifdef CONFIG_M16C_UART2
  #      define TTYS2_DEV   g_uart2port     /* UART2 is tty1 */
  #    else
  #      undef TTYS1_DEV                    /* No tty1 */
  #    endif
  #    undef TTYS2_DEV                      /* No tty2 */
  #  endif
  
  /* CONFIG_UART2_SERIAL_CONSOLE (implies CONFIG_M16C_UART2 also defined) */
  
  #elif defined(CONFIG_UART2_SERIAL_CONSOLE)
  #  define CONSOLE_DEV     g_uart2port     /* UART2 is console */
  #  define TTYS0_DEV       g_uart2port     /* UART2 is tty0 */
  #  ifdef CONFIG_M16C_UART0
  #    define TTYS1_DEV     g_uart0port     /* UART0 is tty1 */
  #    ifdef CONFIG_M16C_UART1
  #      define TTYS2_DEV   g_uart1port     /* UART1 is tty2 */
  #    endif
  #  else
  #    ifdef CONFIG_M16C_UART1
  #      define TTYS1_DEV   g_uart1port     /* UART1 is tty1 */
  #    else
  #      undef TTYS1_DEV                    /* No tty1 */
  #    endif
  #    undef TTYS2_DEV                      /* No tty2 */
  #  endif
  
  /* No console, at least one of CONFIG_M16C_UART0/1/2 defined */
  
  #elif defined(CONFIG_M16C_UART0)
  #  undef  CONSOLE_DEV                     /* No console */
  #  define TTYS0_DEV       g_uart0port     /* UART0 is tty0 */
  #  ifdef CONFIG_M16C_UART1
  #    define TTYS1_DEV     g_uart1port     /* UART1 is tty1 */
  #    ifdef CONFIG_M16C_UART2
  #      define TTYS2_DEV   g_uart2port     /* UART2 is tty2 */
  #    endif
  #  else
  #    ifdef CONFIG_M16C_UART2
  #      define TTYS1_DEV   g_uart1port     /* UART2 is tty1 */
  #    else
  #      undef TTYS1_DEV                    /* No tty1 */
  #    endif
  #    undef TTYS2_DEV                      /* No tty2 */
  #  endif
  
  elif defined(CONFIG_M16C_UART1)
  #  undef  CONSOLE_DEV                     /* No console */
  #  undef  TTYS2_DEV                       /* No tty2 */
  #  define TTYS0_DEV       g_uart1port     /* UART1 is tty0 */
  #  ifdef CONFIG_M16C_UART2
  #    define TTYS1_DEV     g_uart2port     /* UART2 is tty1 */
  #  else
  #    undef TTYS1_DEV                      /* No tty1 */
  #  endif
  
  /* Otherwise, there is no console and only CONFIG_M16C_UART2 is defined */
  
  #else
  #  undef  CONSOLE_DEV                    /* No console */
  #  define TTYS0_DEV       g_uart2port    /* UART2 is tty0 */
  #  undef TTYS1_DEV                       /* No tty1 */
  #  undef TTYS1_DEV                       /* No tty2 */
  #endif
  
  /* Pre-processor Definitions for the enable field of the device structure */
  
  #define M16C_RXENABLED     0x01
  #define M16C_TXENABLED     0x02
  
  /****************************************************************************
   * Private Types
   ****************************************************************************/
  
  struct up_dev_s
  {
            uint32_t baud;      /* Configured baud */
            uint16_t uartbase;  /* Base address of UART registers */
             uint8_t uartno;    /* UART number */
   volatile  uint8_t ucon;      /* Saved SCR value */
   volatile  uint8_t ssr;       /* Saved SR value (only used during interrupt processing) */
             uint8_t rcvirq;    /* UART receive data available IRQ */
             uint8_t xmtirq;    /* UART transmit complete IRQ */
             uint8_t enables;   /* Bit 0: 1=RX enabled, Bit 1: 1=TX enabled */
             uint8_t parity;    /* 0=none, 1=odd, 2=even */
             uint8_t bits;      /* Number of bits (7 or 8) */
                bool stopbits2; /* true: Configure with 2 stop bits instead of 1 */
  };
  
  /****************************************************************************
   * Private Function Prototypes
   ****************************************************************************/
  
  static int  up_setup(struct uart_dev_s *dev);
  static void up_shutdown(struct uart_dev_s *dev);
  static int  up_attach(struct uart_dev_s *dev);
  static void up_detach(struct uart_dev_s *dev);
  static int  up_rcvinterrupt(int irq, void *context);
  static int  up_receive(struct uart_dev_s *dev, unsigned int *status);
  static void m16c_rxint(struct up_dev_s *dev, bool enable);
  static void up_rxint(struct uart_dev_s *dev, bool enable);
  static bool up_rxavailable(struct uart_dev_s *dev);
  static int  up_xmtinterrupt(int irq, void *context);
  static void up_send(struct uart_dev_s *dev, int ch);
  static void m16c_txint(struct up_dev_s *dev, bool enable);
  static void up_txint(struct uart_dev_s *dev, bool enable);
  static bool up_txready(struct uart_dev_s *dev);
  
  /****************************************************************************
   * Private Data
   ****************************************************************************/
  
  static const struct uart_ops_s g_uart_ops =
  {
    .setup          = up_setup,
    .shutdown       = up_shutdown,
    .attach         = up_attach,
    .detach         = up_detach,
    .receive        = up_receive,
    .rxint          = up_rxint,
    .rxavailable    = up_rxavailable,
  #ifdef CONFIG_SERIAL_IFLOWCONTROL
    .rxflowcontrol  = NULL,
  #endif
    .send           = up_send,
    .txint          = up_txint,
    .txready        = up_txready,
    .txempty        = up_txready,
  };
  
  /* I/O buffers */
  
  #ifdef CONFIG_M16C_UART0
  static char g_uart0rxbuffer[CONFIG_UART0_RXBUFSIZE];
  static char g_uart0txbuffer[CONFIG_UART0_TXBUFSIZE];
  #endif
  #ifdef CONFIG_M16C_UART1
  static char g_uart1rxbuffer[CONFIG_UART1_RXBUFSIZE];
  static char g_uart1txbuffer[CONFIG_UART1_TXBUFSIZE];
  #endif
  #ifdef CONFIG_M16C_UART2
  static char g_uart2rxbuffer[CONFIG_UART2_RXBUFSIZE];
  static char g_uart2txbuffer[CONFIG_UART2_TXBUFSIZE];
  #endif
  
  /* This describes the state of the M16C UART0 port. */
  
  #ifdef CONFIG_M16C_UART0
  static struct up_dev_s g_uart0priv =
  {
    .baud           = CONFIG_UART0_BAUD,
    .uartbase       = M16C_UART0_BASE,
    .uartno         = 0,
    .rcvirq         = M16C_UART0RCV_IRQ,
    .xmtirq         = M16C_UART0XMT_IRQ,
    .parity         = CONFIG_UART0_PARITY,
    .bits           = CONFIG_UART0_BITS,
    .stopbits2      = CONFIG_UART0_2STOP,
  };
  
  static uart_dev_t g_uart0port =
  {
    .recv     =
    {
      .size   = CONFIG_UART0_RXBUFSIZE,
      .buffer = g_uart0rxbuffer,
    },
    .xmit     =
    {
      .size   = CONFIG_UART0_TXBUFSIZE,
      .buffer = g_uart0txbuffer,
    },
    .ops      = &g_uart_ops,
    .priv     = &g_uart0priv,
  };
  #endif
  
  /* This describes the state of the M16C UART1 port. */
  
  #ifdef CONFIG_M16C_UART1
  static struct up_dev_s g_uart1priv =
  {
    .baud           = CONFIG_UART1_BAUD,
    .uartbase       = M16C_UART1_BASE,
    .uartno         = 1,
    .rcvirq         = M16C_UART1RCV_IRQ,
    .xmtirq         = M16C_UART1XMT_IRQ,
    .parity         = CONFIG_UART1_PARITY,
    .bits           = CONFIG_UART1_BITS,
    .stopbits2      = CONFIG_UART1_2STOP,
  };
  
  static uart_dev_t g_uart1port =
  {
    .recv     =
    {
      .size   = CONFIG_UART1_RXBUFSIZE,
      .buffer = g_uart1rxbuffer,
    },
    .xmit     =
    {
      .size   = CONFIG_UART1_TXBUFSIZE,
      .buffer = g_uart1txbuffer,
     },
    .ops      = &g_uart_ops,
    .priv     = &g_uart1priv,
  };
  #endif
  
  /* This describes the state of the M16C UART2 port. */
  
  #ifdef CONFIG_M16C_UART2
  static struct up_dev_s g_uart2priv =
  {
    .baud           = CONFIG_UART2_BAUD,
    .uartbase       = M16C_UART2_BASE,
    .uartno         = 2,
    .rcvirq         = M16C_UART2RCV_IRQ,
    .xmtirq         = M16C_UART2XMT_IRQ,
    .parity         = CONFIG_UART2_PARITY,
    .bits           = CONFIG_UART2_BITS,
    .stopbits2      = CONFIG_UART2_2STOP,
  };
  
  static uart_dev_t g_uart2port =
  {
    .recv     =
    {
      .size   = CONFIG_UART2_RXBUFSIZE,
      .buffer = g_uart2rxbuffer,
    },
    .xmit     =
    {
      .size   = CONFIG_UART2_TXBUFSIZE,
      .buffer = g_uart2txbuffer,
     },
    .ops      = &g_uart_ops,
    .priv     = &g_uart2priv,
  };
  #endif
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_serialin
   ****************************************************************************/
  
  static inline uint8_t up_serialin(struct up_dev_s *priv, int offset)
  {
    return getreg8(priv->uartbase + offset);
  }
  
  /****************************************************************************
   * Name: up_serialin16
   ****************************************************************************/
  
  static inline uint16_t up_serialin16(struct up_dev_s *priv, int offset)
  {
    return getreg16(priv->uartbase + offset);
  }
  
  /****************************************************************************
   * Name: up_serialout
   ****************************************************************************/
  
  static inline void up_serialout(struct up_dev_s *priv, int offset, uint8_t value)
  {
    putreg8(value, priv->uartbase + offset);
  }
  
  /****************************************************************************
   * Name: up_serialout16
   ****************************************************************************/
  
  static inline void up_serialout16(struct up_dev_s *priv, int offset, uint16_t value)
  {
    putreg16(value, priv->uartbase + offset);
  }
  
  /****************************************************************************
   * Name: up_disableuartint
   ****************************************************************************/
  
  static inline void up_disableuartint(struct up_dev_s *priv, uint8_t *penables)
  {
    uint8_t enables = priv->enables;
    m16c_txint(priv, false);
    m16c_rxint(priv, false);
  
    if (enables)
      {
        *penables = enables;
      }
  }
  
  /****************************************************************************
   * Name: up_restoreuartint
   ****************************************************************************/
  
  static inline void up_restoreuartint(struct up_dev_s *priv, uint8_t enables)
  {
    m16c_rxint(priv, (enables & M16C_RXENABLED) != 0);
    m16c_txint(priv, (enables & M16C_TXENABLED) != 0);
  }
  
  /****************************************************************************
   * Name: up_waittxready
   ****************************************************************************/
  
  #ifdef HAVE_SERIALCONSOLE
  static inline void up_waittxready(struct up_dev_s *priv)
  {
    int tmp;
  
    /* Limit how long we will wait for the TDR empty condition */
  
    for (tmp = 1000 ; tmp > 0 ; tmp--)
      {
        /* Check the TI bit in the CI register.  1=Transmit buffer empty */
  
        if ((up_serialin(priv, M16C_UART_C1) & UART_C1_TI) != 0)
         {
            /* The transmit buffer is empty... return */
            break;
          }
      }
  }
  #endif
  
  /****************************************************************************
   * Name: ub_setbrg
   *
   * Description:
   *   Calculate the correct value for the BRG given the configured frequency
   *   and the desired BAUD settings.
   *
   ****************************************************************************/
  
  static inline void ub_setbrg(struct up_dev_s *priv, unsigned int baud)
  {
    uint16_t brg;
  
    /* The Bit Rate Generator (BRG) value can be calculated by:
     *
     * BRG = source-frequency / prescaler / 16 / baud rate - 1
     *
     * Example:
     *  source-frequency = 20,000,000 (20MHz)
     *  prescaler = 1
     *  baud rate = 19200
     *  BRG = 20,000,000/1/16/19200 - 1 = 64
     */
  
    brg = (M16C_XIN_FREQ / (16L * M16C_XIN_PRESCALER * (uint32_t)baud)) - 1;
    up_serialout(priv, M16C_UART_BRG, brg);
  }
  
  /****************************************************************************
   * Name: up_setup
   *
   * Description:
   *   Configure the UART baud, bits, parity, fifos, etc. This
   *   method is called the first time that the serial port is
   *   opened.
   *
   ****************************************************************************/
  
  static int up_setup(struct uart_dev_s *dev)
  {
  #ifndef CONFIG_SUPPRESS_UART_CONFIG
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
    uint8_t regval;
  
    /* Set the baud rate generator */
  
    ub_setbrg(priv, priv->baud);
  
    /* Disable CTS/RTS */
  
    up_serialout(priv, M16C_UART_C0, UART_C0_CRD);
  
    /* Disable RX/TX interrupts */
  
    m16c_rxint(priv, false);
    m16c_txint(priv, false);
  
  /* Set interrupt cause=TX complete and continuous receive mode */
  
  #ifdef CONFIG_M16C_UART0
    if (priv->uartno == 0)
      {
        regval  = getreg8(M16C_UCON);
        regval |= (UART_CON_U0IRS|UART_CON_U0RRM);
        putreg8(regval, M16C_UCON);
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART1
    if (priv->uartno == 1)
      {
        regval  = getreg8(M16C_UCON);
        regval |= (UART_CON_U1IRS|UART_CON_U1RRM);
        putreg8(regval, M16C_UCON);
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART2
    if (priv->uartno == 2)
      {
        regval  = getreg8(M16C_U2C1);
        regval |= ((UART_C1_U2IRS|UART_C1_U2RRM);
        putreg8(regval, M16C_U2C1);
      }
    else
  #endif
      {
        _err("ERROR: Invalid UART #\n");
      }
  
    /* Set UART transmit/receive control register 1 to enable transmit and receive */
  
    up_serialout(priv, M16C_UART_C1, UART_C1_TE|UART_C1_RE);
  
    /* Set UART transmit/receive mode register data bits, stop bits, parity */
  
    regval = 0;
  
    if (priv->bits == 7)
      {
        regval |= UART_MR_SMD7BITS;
      }
    else if (priv->bits == 8)
      {
        regval |= UART_MR_SMD8BITS;
      }
    else if (priv->bits == 9)
      {
        regval |= UART_MR_SMD9BITS;
      }
    else
      {
        _err("ERROR: Invalid bits=%d\n", priv->bits);
      }
  
    if (priv->parity != 0)
      {
        regval |= UART_MR_PRYE;
        if (priv->parity == 2)
          {
            regval |= UART_MR_PRY;
          }
      }
  
    if (priv->stopbits2)
      {
        regval |= UART_MR_STPS;
      }
  
    up_serialout(priv, M16C_UART_MR, regval);
  
    /* Set port direction registers for Rx/TX pins */
  
  #ifdef CONFIG_M16C_UART0
    if (priv->uartno == 0)
      {
        regval  = getreg8(M16C_PD6);
        regval &= ~(1 << 2);                         /* PD6-2:RxD1 */
        regval |=  (1 << 3);                         /* PD6-3:TxD1 */
        putreg8(regval, M16C_PD6);
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART1
    if (priv->uartno == 1)
      {
        regval  = getreg8(M16C_PD6);
        regval &= ~(1 << 6);                         /* PD6-6:RxD1 */
        regval |=  (1 << 7);                         /* PD6-7:TxD1 */
        putreg8(regval, M16C_PD6);
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART2
    if (priv->uartno == 2)
      {
        regval  = getreg8(M16C_PD7);
        regval &= ~(1 << 1);                         /* PD7-1:RxD1 */
        regval &=  (1 << 0);                         /* PD7-0:TxD1 */
        putreg8(regval, M16C_PD7);
      }
    else
  #endif
      {
        _err("ERROR: Invalid UART #\n");
      }
  
    /* Read any data left in the RX fifo */
  
    regval = (uint8_t)up_serialin16(priv, M16C_UART_RB);
  #endif
    return OK;
  }
  
  /****************************************************************************
   * Name: up_shutdown
   *
   * Description:
   *   Disable the UART.  This method is called when the serial port is closed
   *
   ****************************************************************************/
  
  static void up_shutdown(struct uart_dev_s *dev)
  {
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
    up_disableuartint(priv, NULL);
  }
  
  /****************************************************************************
   * Name: up_attach
   *
   * Description:
   *   Configure the UART to operation in interrupt driven mode.  This method is
   *   called when the serial port is opened.  Normally, this is just after the
   *   the setup() method is called, however, the serial console may operate in
   *   a non-interrupt driven mode during the boot phase.
   *
   *   RX and TX interrupts are not enabled when by the attach method (unless the
   *   hardware supports multiple levels of interrupt enabling).  The RX and TX
   *   interrupts are not enabled until the txint() and rxint() methods are called.
   *
   ****************************************************************************/
  
  static int up_attach(struct uart_dev_s *dev)
  {
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
    int ret;
  
    /* Attach the UART receive data available IRQ */
  
    ret = irq_attach(priv->rcvirq, up_rcvinterrupt);
    if (ret == OK)
      {
        /* Attach the UART transmit complete IRQ */
  
        ret = irq_attach(priv->xmtirq, up_xmtinterrupt);
        if (ret != OK)
          {
            /* Detach the ERI interrupt on failure */
  
            (void)irq_detach(priv->rcvirq);
          }
      }
  
    return ret;
  }
  
  /****************************************************************************
   * Name: up_detach
   *
   * Description:
   *   Detach UART interrupts.  This method is called when the serial port is
   *   closed normally just before the shutdown method is called.  The exception is
   *   the serial console which is never shutdown.
   *
   ****************************************************************************/
  
  static void up_detach(struct uart_dev_s *dev)
  {
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
  
    /* Disable all UART interrupts */
  
    up_disableuartint(priv, NULL);
  
    /* Detach the UART interrupts */
  
    (void)irq_detach(priv->rcvirq);
    (void)irq_detach(priv->xmtirq);
  }
  
  /****************************************************************************
   * Name: up_recvinterrupt
   *
   * Description:
   *   This is the UART receive interrupt handler.  It will be invoked when an
   *   interrupt received on the 'irq'  It should call uart_receivechar to
   *   perform the appropriate data transfer.  The interrupt handling logic
   *   must be able to map the 'irq' number into the approprite up_dev_s
   *   structure in order to call these functions.
   *
   ****************************************************************************/
  
  static int up_rcvinterrupt(int irq, void *context)
  {
    struct uart_dev_s *dev = NULL;
  
  #ifdef CONFIG_M16C_UART0
    if (irq == g_uart0priv.rcvirq)
      {
        dev = &g_uart0port;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART1
    if (irq == g_uart1priv.rcvirq)
      {
        dev = &g_uart1port;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART2
    if (irq = g_uart2priv.rcvirq)
      {
        dev = &g_uart2port;
      }
    else
  #endif
      {
        PANIC();
      }
  
    /* Handle incoming, receive bytes (RDRF: Receive Data Register Full) */
  
    uart_recvchars(dev);
    return OK;
  }
  
  /****************************************************************************
   * Name: up_receive
   *
   * Description:
   *   Called (usually) from the interrupt level to receive one character from
   *   the UART.  Error bits associated with the receipt are provided in the
   *   return 'status'.
   *
   ****************************************************************************/
  
  static int up_receive(struct uart_dev_s *dev, unsigned int *status)
  {
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
    uint16_t rb;
  
    /* Read the character from the readbuffer */
  
    rb = up_serialin16(priv, M16C_UART_RB);
  
    /* Return the received byte with the receive status */
  
    *status = rb;
  
    /* Return the received character (up to 9 bits) */
  
    return (int)(rb & 0x01ff);
  }
  
  /****************************************************************************
   * Name: m16c_rxint, up_rxint
   *
   * Description:
   *   Call to enable or disable RX interrupts
   *
   ****************************************************************************/
  
  static void m16c_rxint(struct up_dev_s *dev, bool enable)
  {
    irqstate_t flags;
    uint16_t   regaddr;
    uint8_t    regvalue;
  
    /* Disable interrupts to prevent asynchronous accesses */
  
    flags = enter_critical_section();
  
    /* Pick the SxTIC register and enable interrupt priority */
  
  #ifdef CONFIG_M16C_UART0
    if (dev->uartno == 0)
      {
        regaddr  = M16C_S0RIC;
        regvalue = M16C_S0R_PRIO;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART1
    if (dev->uartno == 1)
      {
        regaddr  = M16C_S1RIC;
        regvalue = M16C_S1R_PRIO;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART2
    if (dev->uartno == 2)
      {
        regaddr  = M16C_S2RIC;
        regvalue = M16C_S2R_PRIO;
      }
    else
  #endif
      {
        _err("ERROR: Invalid UART #\n");
        return;
      }
  
    /* Are we enabling or disabling? */
  
    if (enable)
      {
  #ifndef CONFIG_SUPPRESS_SERIAL_INTS
        putreg8(regvalue, regaddr);
  #endif
        dev->enables |= M16C_RXENABLED;
      }
    else
      {
        putreg8(0, regaddr);
        dev->enables = ~M16C_RXENABLED;
      }
  
    asm ("\tnop\n\tnop\n\tnop"); /* Three NOPs -- probably not necessary here */
    leave_critical_section(flags);
  }
  
  static void up_rxint(struct uart_dev_s *dev, bool enable)
  {
    m16c_rxint((struct up_dev_s*)dev->priv, enable);
  }
  
  /****************************************************************************
   * Name: up_rxavailable
   *
   * Description:
   *   Return true if the RDR is not empty
   *
   ****************************************************************************/
  
  static bool up_rxavailable(struct uart_dev_s *dev)
  {
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
  
    /* Return true if there is data available in the read buffer */
  
    return ((up_serialin(priv, M16C_UART_C1) & UART_C1_RI) != 0);
  }
  
  /****************************************************************************
   * Name: up_xmtvinterrupt
   *
   * Description:
   *   This is the UART receive interrupt handler.  It will be invoked
   *   when an interrupt received on the 'irq'  It should call
   *   uart_transmitchars or uart_receivechar to perform the
   *   appropriate data transfers.  The interrupt handling logic\
   *   must be able to map the 'irq' number into the approprite
   *   up_dev_s structure in order to call these functions.
   *
   ****************************************************************************/
  
  static int up_xmtinterrupt(int irq, void *context)
  {
    struct uart_dev_s *dev = NULL;
  
  #ifdef CONFIG_M16C_UART0
    if (irq == g_uart0priv.xmtirq)
      {
        dev = &g_uart0port;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART1
    if (irq == g_uart1priv.xmtirq)
      {
        dev = &g_uart1port;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART2
    if (irq == g_uart2priv.xmtirq)
      {
        dev = &g_uart1port;
      }
    else
  #endif
      {
        PANIC();
      }
  
    /* Handle outgoing, transmit bytes */
  
    uart_xmitchars(dev);
    return OK;
  }
  
  /****************************************************************************
   * Name: up_send
   *
   * Description:
   *   This method will send one byte on the UART
   *
   ****************************************************************************/
  
  static void up_send(struct uart_dev_s *dev, int ch)
  {
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
  
    /* Write the data to the transmit buffer */
  
    up_serialout16(priv, M16C_UART_TB, (uint16_t)ch);
  }
  
  /****************************************************************************
   * Name: m16c_txint, up_txint
   *
   * Description:
   *   Call to enable or disable TX interrupts
   *
   ****************************************************************************/
  
  static void m16c_txint(struct up_dev_s *dev, bool enable)
  {
    irqstate_t flags;
    uint16_t   regaddr;
    uint8_t    regvalue;
  
    /* Disable interrupts to prevent asynchronous accesses */
  
    flags = enter_critical_section();
  
    /* Pick the SxTIC register and enable interrupt priority */
  
  #ifdef CONFIG_M16C_UART0
    if (dev->uartno == 0)
      {
        regaddr  = M16C_S0TIC;
        regvalue = M16C_S0T_PRIO;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART1
    if (dev->uartno == 1)
      {
        regaddr  = M16C_S1TIC;
        regvalue = M16C_S1T_PRIO;
      }
    else
  #endif
  #ifdef CONFIG_M16C_UART2
    if (dev->uartno == 2)
      {
        regaddr  = M16C_S2TIC;
        regvalue = M16C_S2T_PRIO;
      }
    else
  #endif
      {
        _err("ERROR: Invalid UART #\n");
        return;
      }
  
    /* Are we enabling or disabling? */
  
    if (enable)
      {
  #ifndef CONFIG_SUPPRESS_SERIAL_INTS
        putreg8(regvalue, regaddr);
  #endif
        dev->enables |= M16C_TXENABLED;
      }
    else
      {
        putreg8(0, regaddr);
        dev->enables = ~M16C_TXENABLED;
      }
  
    asm ("\tnop\n\tnop\n\tnop"); /* Three NOPs -- probably not necessary here */
    leave_critical_section(flags);
  }
  
  static void up_txint(struct uart_dev_s *dev, bool enable)
  {
    m16c_txint((struct up_dev_s*)dev->priv, enable);
  }
  
  /****************************************************************************
   * Name: up_txready
   *
   * Description:
   *   Return true if the TDR is empty
   *
   ****************************************************************************/
  
  static bool up_txready(struct uart_dev_s *dev)
  {
    struct up_dev_s *priv = (struct up_dev_s*)dev->priv;
    return ((up_serialin(priv, M16C_UART_C1) & UART_C1_TI) != 0);
  }
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_earlyconsoleinit
   *
   * Description:
   *   Performs the low level UART initialization early in
   *   debug so that the serial console will be available
   *   during bootup.  This must be called before up_consoleinit.
   *
   ****************************************************************************/
  
  void up_earlyconsoleinit(void)
  {
    /* NOTE:  All GPIO configuration for the UARTs was performed in
     * up_lowsetup
     */
  
    /* Disable all UARTs */
  
  #ifdef TTYS0_DEV
    up_disableuartint(TTYS0_DEV.priv, NULL);
  #ifdef TTYS1_DEV
    up_disableuartint(TTYS1_DEV.priv, NULL);
  #ifdef TTYS2_DEV
    up_disableuartint(TTYS2_DEV.priv, NULL);
  #endif
  #endif
  #endif
  
    /* Configuration whichever one is the console */
  
  #ifdef HAVE_SERIALCONSOLE
    CONSOLE_DEV.isconsole = true;
    up_setup(&CONSOLE_DEV);
  #endif
  }
  
  /****************************************************************************
   * Name: up_consoleinit
   *
   * Description:
   *   Register serial console and serial ports.  This assumes
   *   that up_earlyconsoleinit was called previously.
   *
   ****************************************************************************/
  
  void up_consoleinit(void)
  {
    /* Register the console */
  
  #ifdef HAVE_SERIALCONSOLE
    (void)uart_register("/dev/console", &CONSOLE_DEV);
  #endif
  
    /* Register all UARTs */
  
  #ifdef TTYS0_DEV
    (void)uart_register("/dev/ttyS0", &TTYS0_DEV);
  #ifdef TTYS1_DEV
    (void)uart_register("/dev/ttyS1", &TTYS1_DEV);
  #ifdef TTYS2_DEV
    (void)uart_register("/dev/ttyS2", &TTYS2_DEV);
  #endif
  #endif
  #endif
  }
  
  /****************************************************************************
   * Name: up_putc
   *
   * Description:
   *   Provide priority, low-level access to support OS debug  writes
   *
   ****************************************************************************/
  
  int up_putc(int ch)
  {
  #ifdef HAVE_SERIALCONSOLE
    struct up_dev_s *priv = (struct up_dev_s*)CONSOLE_DEV.priv;
    uint8_t  ucon;
  
    up_disableuartint(priv, &ucon);
  
    /* Check for LF */
  
    if (ch == '\n')
      {
        /* Add CR */
  
        up_waittxready(priv);
        up_serialout16(priv, M16C_UART_TB, (uint16_t)'\r');
      }
  
    up_waittxready(priv);
    up_serialout16(priv, M16C_UART_TB, (uint16_t)ch);
  
    up_waittxready(priv);
    up_restoreuartint(priv, ucon);
  #endif
    return ch;
  }
  
  #else /* USE_SERIALDRIVER */
  
  /****************************************************************************
   * Name: up_putc
   *
   * Description:
   *   Provide priority, low-level access to support OS debug writes
   *
   ****************************************************************************/
  
  int up_putc(int ch)
  {
  #ifdef HAVE_SERIALCONSOLE
    /* Check for LF */
  
    if (ch == '\n')
      {
        /* Add CR */
  
        up_lowputc('\r');
      }
  
    up_lowputc(ch);
  #endif
    return ch;
  }
  
  #endif /* USE_SERIALDRIVER */
  #elif defined(CONFIG_UART0_SERIAL_CONSOLE) || defined(CONFIG_UART1_SERIAL_CONSOLE)|| defined(CONFIG_UART2_SERIAL_CONSOLE)
  #    error "A serial console selected, but corresponding UART not enabled"
  #endif /* CONFIG_M16C_UART0 || CONFIG_M16C_UART1 || CONFIG_M16C_UART2 */
  
  