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/*  Lattice Mico32 UART model.

    Contributed by Jon Beniston <jon@beniston.com>

   Copyright (C) 2009, 2010 Free Software Foundation, Inc.

   This file is part of GDB.

   This program 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.

   This program 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 should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "sim-main.h"

#include "hw-main.h"

#include "sim-assert.h"

#include <stdio.h>

#include <sys/time.h>

struct lm32uart

{

  unsigned base;                /* Base address of this UART.  */

  unsigned limit;               /* Limit address of this UART.  */

  unsigned char rbr;

  unsigned char thr;

  unsigned char ier;

  unsigned char iir;

  unsigned char lcr;

  unsigned char mcr;

  unsigned char lsr;

  unsigned char msr;

  unsigned char div;

  struct hw_event *event;

};

/* UART registers.  */

#define LM32_UART_RBR           0x0

#define LM32_UART_THR           0x0

#define LM32_UART_IER           0x4

#define LM32_UART_IIR           0x8

#define LM32_UART_LCR           0xc

#define LM32_UART_MCR           0x10

#define LM32_UART_LSR           0x14

#define LM32_UART_MSR           0x18

#define LM32_UART_DIV           0x1c

#define LM32_UART_IER_RX_INT    0x1

#define LM32_UART_IER_TX_INT    0x2

#define MICOUART_IIR_TXRDY      0x2

#define MICOUART_IIR_RXRDY      0x4

#define LM32_UART_LSR_RX_RDY    0x01

#define LM32_UART_LSR_TX_RDY    0x20

#define LM32_UART_LCR_WLS_MASK  0x3

#define LM32_UART_LCR_WLS_5     0x0

#define LM32_UART_LCR_WLS_6     0x1

#define LM32_UART_LCR_WLS_7     0x2

#define LM32_UART_LCR_WLS_8     0x3

/* UART ports.  */

enum

{

  INT_PORT

};

static const struct hw_port_descriptor lm32uart_ports[] = {

  {"int", INT_PORT, 0, output_port},

  {}

};

static void

do_uart_tx_event (struct hw *me, void *data)

{

  struct lm32uart *uart = hw_data (me);

  char c;

  /* Generate interrupt when transmission is complete.  */

  if (uart->ier & LM32_UART_IER_TX_INT)

    {

      /* Generate interrupt */

      hw_port_event (me, INT_PORT, 1);

    }

  /* Indicate which interrupt has occured.  */

  uart->iir = MICOUART_IIR_TXRDY;

  /* Indicate THR is empty.  */

  uart->lsr |= LM32_UART_LSR_TX_RDY;

  /* Output the character in the THR.  */

  c = (char) uart->thr;

  /* WLS field in LCR register specifies the number of bits to output.  */

  switch (uart->lcr & LM32_UART_LCR_WLS_MASK)

    {

    case LM32_UART_LCR_WLS_5:

      c &= 0x1f;

      break;

    case LM32_UART_LCR_WLS_6:

      c &= 0x3f;

      break;

    case LM32_UART_LCR_WLS_7:

      c &= 0x7f;

      break;

    }

  printf ("%c", c);

}

static unsigned

lm32uart_io_write_buffer (struct hw *me,

                          const void *source,

                          int space, unsigned_word base, unsigned nr_bytes)

{

  struct lm32uart *uart = hw_data (me);

  int uart_reg;

  const unsigned char *source_bytes = source;

  int value = 0;

  HW_TRACE ((me, "write to 0x%08lx length %d with 0x%x", (long) base,

             (int) nr_bytes, value));

  if (nr_bytes == 4)

    value = (source_bytes[0] << 24)

      | (source_bytes[1] << 16) | (source_bytes[2] << 8) | (source_bytes[3]);

  else

    hw_abort (me, "write of unsupported number of bytes: %d.", nr_bytes);

  uart_reg = base - uart->base;

  switch (uart_reg)

    {

    case LM32_UART_THR:

      /* Buffer the character to output.  */

      uart->thr = value;

      /* Indicate the THR is full.  */

      uart->lsr &= ~LM32_UART_LSR_TX_RDY;

      /* deassert interrupt when IER is loaded.  */

      uart->iir &= ~MICOUART_IIR_TXRDY;

      /* schedule an event to output the character.  */

      hw_event_queue_schedule (me, 1, do_uart_tx_event, 0);

      break;

    case LM32_UART_IER:

      uart->ier = value;

      if ((value & LM32_UART_IER_TX_INT)

          && (uart->lsr & LM32_UART_LSR_TX_RDY))

        {

          /* hw_event_queue_schedule (me, 1, do_uart_tx_event, 0); */

          uart->lsr |= LM32_UART_LSR_TX_RDY;

          uart->iir |= MICOUART_IIR_TXRDY;

          hw_port_event (me, INT_PORT, 1);

        }

      else if ((value & LM32_UART_IER_TX_INT) == 0)

        {

          hw_port_event (me, INT_PORT, 0);

        }

      break;

    case LM32_UART_IIR:

      uart->iir = value;

      break;

    case LM32_UART_LCR:

      uart->lcr = value;

      break;

    case LM32_UART_MCR:

      uart->mcr = value;

      break;

    case LM32_UART_LSR:

      uart->lsr = value;

      break;

    case LM32_UART_MSR:

      uart->msr = value;

      break;

    case LM32_UART_DIV:

      uart->div = value;

      break;

    default:

      hw_abort (me, "write to invalid register address: 0x%x.", uart_reg);

    }

  return nr_bytes;

}

static unsigned

lm32uart_io_read_buffer (struct hw *me,

                         void *dest,

                         int space, unsigned_word base, unsigned nr_bytes)

{

  struct lm32uart *uart = hw_data (me);

  int uart_reg;

  int value;

  unsigned char *dest_bytes = dest;

  fd_set fd;

  struct timeval tv;

  HW_TRACE ((me, "read 0x%08lx length %d", (long) base, (int) nr_bytes));

  uart_reg = base - uart->base;

  switch (uart_reg)

    {

    case LM32_UART_RBR:

      value = getchar ();

      uart->lsr &= ~LM32_UART_LSR_RX_RDY;

      break;

    case LM32_UART_IER:

      value = uart->ier;

      break;

    case LM32_UART_IIR:

      value = uart->iir;

      break;

    case LM32_UART_LCR:

      value = uart->lcr;

      break;

    case LM32_UART_MCR:

      value = uart->mcr;

      break;

    case LM32_UART_LSR:

      /* Check to see if any data waiting in stdin.  */

      FD_ZERO (&fd);

      FD_SET (fileno (stdin), &fd);

      tv.tv_sec = 0;

      tv.tv_usec = 1;

      if (select (fileno (stdin) + 1, &fd, NULL, NULL, &tv))

        uart->lsr |= LM32_UART_LSR_RX_RDY;

      value = uart->lsr;

      break;

    case LM32_UART_MSR:

      value = uart->msr;

      break;

    case LM32_UART_DIV:

      value = uart->div;

      break;

    default:

      hw_abort (me, "read from invalid register address: 0x%x.", uart_reg);

    }

  if (nr_bytes == 4)

    {

      dest_bytes[0] = value >> 24;

      dest_bytes[1] = value >> 16;

      dest_bytes[2] = value >> 8;

      dest_bytes[3] = value;

    }

  else

    hw_abort (me, "read of unsupported number of bytes: %d", nr_bytes);

  return nr_bytes;

}

static void

attach_lm32uart_regs (struct hw *me, struct lm32uart *uart)

{

  unsigned_word attach_address;

  int attach_space;

  unsigned attach_size;

  reg_property_spec reg;

  if (hw_find_property (me, "reg") == NULL)

    hw_abort (me, "Missing \"reg\" property");

  if (!hw_find_reg_array_property (me, "reg", 0, &reg))

    hw_abort (me, "\"reg\" property must contain three addr/size entries");

  hw_unit_address_to_attach_address (hw_parent (me),

                                     &reg.address,

                                     &attach_space, &attach_address, me);

  uart->base = attach_address;

  hw_unit_size_to_attach_size (hw_parent (me), &reg.size, &attach_size, me);

  uart->limit = attach_address + (attach_size - 1);

  hw_attach_address (hw_parent (me),

                     0, attach_space, attach_address, attach_size, me);

}

static void

lm32uart_finish (struct hw *me)

{

  struct lm32uart *uart;

  int i;

  uart = HW_ZALLOC (me, struct lm32uart);

  set_hw_data (me, uart);

  set_hw_io_read_buffer (me, lm32uart_io_read_buffer);

  set_hw_io_write_buffer (me, lm32uart_io_write_buffer);

  set_hw_ports (me, lm32uart_ports);

  /* Attach ourself to our parent bus.  */

  attach_lm32uart_regs (me, uart);

  /* Initialize the UART.  */

  uart->rbr = 0;

  uart->thr = 0;

  uart->ier = 0;

  uart->iir = 0;

  uart->lcr = 0;

  uart->mcr = 0;

  uart->lsr = LM32_UART_LSR_TX_RDY;

  uart->msr = 0;

  uart->div = 0;         /* By setting to zero, characters are output immediately.  */

}

const struct hw_descriptor dv_lm32uart_descriptor[] = {

  {"lm32uart", lm32uart_finish,},

  {NULL},

};