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/*  dv-m68hc11spi.c -- Simulation of the 68HC11 SPI

    Copyright (C) 2000, 2002, 2003, 2007, 2008, 2009, 2010

    Free Software Foundation, Inc.

    Written by Stephane Carrez (stcarrez@nerim.fr)

    (From a driver model Contributed by Cygnus Solutions.)

    This file is part of the program GDB, the GNU debugger.

    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 "dv-sockser.h"

#include "sim-assert.h"

/* DEVICE

        m68hc11spi - m68hc11 SPI interface

   DESCRIPTION

        Implements the m68hc11 Synchronous Serial Peripheral Interface

        described in the m68hc11 user guide (Chapter 8 in pink book).

        The SPI I/O controller is directly connected to the CPU

        interrupt.  The simulator implements:

            - SPI clock emulation

            - Data transfer

            - Write collision detection

   PROPERTIES

        None

   PORTS

   reset (input)

        Reset port. This port is only used to simulate a reset of the SPI

        I/O controller. It should be connected to the RESET output of the cpu.

   */

/* port ID's */

enum

{

  RESET_PORT

};

static const struct hw_port_descriptor m68hc11spi_ports[] =

{

  { "reset", RESET_PORT, 0, input_port, },

  { NULL, },

};

/* SPI */

struct m68hc11spi

{

  /* Information about next character to be transmited.  */

  unsigned char tx_char;

  int           tx_bit;

  unsigned char mode;

  unsigned char rx_char;

  unsigned char rx_clear_scsr;

  unsigned char clk_pin;

  /* SPI clock rate (twice the real clock).  */

  unsigned int clock;

  /* Periodic SPI event.  */

  struct hw_event* spi_event;

};

/* Finish off the partially created hw device.  Attach our local

   callbacks.  Wire up our port names etc */

static hw_io_read_buffer_method m68hc11spi_io_read_buffer;

static hw_io_write_buffer_method m68hc11spi_io_write_buffer;

static hw_port_event_method m68hc11spi_port_event;

static hw_ioctl_method m68hc11spi_ioctl;

#define M6811_SPI_FIRST_REG (M6811_SPCR)

#define M6811_SPI_LAST_REG  (M6811_SPDR)

static void

attach_m68hc11spi_regs (struct hw *me,

                        struct m68hc11spi *controller)

{

  hw_attach_address (hw_parent (me), M6811_IO_LEVEL, io_map,

                     M6811_SPI_FIRST_REG,

                     M6811_SPI_LAST_REG - M6811_SPI_FIRST_REG + 1,

                     me);

}

static void

m68hc11spi_finish (struct hw *me)

{

  struct m68hc11spi *controller;

  controller = HW_ZALLOC (me, struct m68hc11spi);

  set_hw_data (me, controller);

  set_hw_io_read_buffer (me, m68hc11spi_io_read_buffer);

  set_hw_io_write_buffer (me, m68hc11spi_io_write_buffer);

  set_hw_ports (me, m68hc11spi_ports);

  set_hw_port_event (me, m68hc11spi_port_event);

#ifdef set_hw_ioctl

  set_hw_ioctl (me, m68hc11spi_ioctl);

#else

  me->to_ioctl = m68hc11spi_ioctl;

#endif

  /* Attach ourself to our parent bus.  */

  attach_m68hc11spi_regs (me, controller);

  /* Initialize to reset state.  */

  controller->spi_event = NULL;

  controller->rx_clear_scsr = 0;

}

/* An event arrives on an interrupt port */

static void

m68hc11spi_port_event (struct hw *me,

                       int my_port,

                       struct hw *source,

                       int source_port,

                       int level)

{

  SIM_DESC sd;

  struct m68hc11spi *controller;

  sim_cpu* cpu;

  unsigned8 val;

  controller = hw_data (me);

  sd         = hw_system (me);

  cpu        = STATE_CPU (sd, 0);

  switch (my_port)

    {

    case RESET_PORT:

      {

        HW_TRACE ((me, "SPI reset"));

        /* Reset the state of SPI registers.  */

        controller->rx_clear_scsr = 0;

        if (controller->spi_event)

          {

            hw_event_queue_deschedule (me, controller->spi_event);

            controller->spi_event = 0;

          }

        val = 0;

        m68hc11spi_io_write_buffer (me, &val, io_map,

                                    (unsigned_word) M6811_SPCR, 1);

        break;

      }

    default:

      hw_abort (me, "Event on unknown port %d", my_port);

      break;

    }

}

static void

set_bit_port (struct hw *me, sim_cpu *cpu, int port, int mask, int value)

{

  uint8 val;

  if (value)

    val = cpu->ios[port] | mask;

  else

    val = cpu->ios[port] & ~mask;

  /* Set the new value and post an event to inform other devices

     that pin 'port' changed.  */

  m68hc11cpu_set_port (me, cpu, port, val);

}

/* When a character is sent/received by the SPI, the PD2..PD5 line

   are driven by the following signals:

              B7        B6

      -----+---------+--------+---/-+-------

 MOSI      |    |    |   |    |     |

 MISO      +---------+--------+---/-+

                ____      ___

 CLK    _______/    \____/   \__                CPOL=0, CPHA=0

        _______      ____     __

               \____/    \___/                  CPOL=1, CPHA=0

           ____      ____     __

        __/    \____/    \___/                  CPOL=0, CPHA=1

        __      ____      ___

          \____/    \____/   \__                CPOL=1, CPHA=1

 SS ___                                 ____

       \__________________________//___/

 MISO = PD2

 MOSI = PD3

 SCK  = PD4

 SS   = PD5

*/

#define SPI_START_BYTE 0

#define SPI_START_BIT  1

#define SPI_MIDDLE_BIT 2

void

m68hc11spi_clock (struct hw *me, void *data)

{

  SIM_DESC sd;

  struct m68hc11spi* controller;

  sim_cpu *cpu;

  int check_interrupt = 0;

  controller = hw_data (me);

  sd         = hw_system (me);

  cpu        = STATE_CPU (sd, 0);

  /* Cleanup current event.  */

  if (controller->spi_event)

    {

      hw_event_queue_deschedule (me, controller->spi_event);

      controller->spi_event = 0;

    }

  /* Change a bit of data at each two SPI event.  */

  if (controller->mode == SPI_START_BIT)

    {

      /* Reflect the bit value on bit 2 of port D.  */

      set_bit_port (me, cpu, M6811_PORTD, (1 << 2),

                    (controller->tx_char & (1 << controller->tx_bit)));

      controller->tx_bit--;

      controller->mode = SPI_MIDDLE_BIT;

    }

  else if (controller->mode == SPI_MIDDLE_BIT)

    {

      controller->mode = SPI_START_BIT;

    }

  if (controller->mode == SPI_START_BYTE)

    {

      /* Start a new SPI transfer.  */

      /* TBD: clear SS output.  */

      controller->mode = SPI_START_BIT;

      controller->tx_bit = 7;

      set_bit_port (me, cpu, M6811_PORTD, (1 << 4), ~controller->clk_pin);

    }

  else

    {

      /* Change the SPI clock at each event on bit 4 of port D.  */

      controller->clk_pin = ~controller->clk_pin;

      set_bit_port (me, cpu, M6811_PORTD, (1 << 4), controller->clk_pin);

    }

  /* Transmit is now complete for this byte.  */

  if (controller->mode == SPI_START_BIT && controller->tx_bit < 0)

    {

      controller->rx_clear_scsr = 0;

      cpu->ios[M6811_SPSR] |= M6811_SPIF;

      if (cpu->ios[M6811_SPCR] & M6811_SPIE)

        check_interrupt = 1;

    }

  else

    {

      controller->spi_event = hw_event_queue_schedule (me, controller->clock,

                                                       m68hc11spi_clock,

                                                       NULL);

    }

  if (check_interrupt)

    interrupts_update_pending (&cpu->cpu_interrupts);

}

/* Flags of the SPCR register.  */

io_reg_desc spcr_desc[] = {

  { M6811_SPIE, "SPIE ", "Serial Peripheral Interrupt Enable" },

  { M6811_SPE,  "SPE  ",  "Serial Peripheral System Enable" },

  { M6811_DWOM, "DWOM ", "Port D Wire-OR mode option" },

  { M6811_MSTR, "MSTR ", "Master Mode Select" },

  { M6811_CPOL, "CPOL ", "Clock Polarity" },

  { M6811_CPHA, "CPHA ", "Clock Phase" },

  { M6811_SPR1, "SPR1 ", "SPI Clock Rate Select" },

  { M6811_SPR0, "SPR0 ", "SPI Clock Rate Select" },

  { 0,  0, 0 }

};

/* Flags of the SPSR register.  */

io_reg_desc spsr_desc[] = {

  { M6811_SPIF, "SPIF ", "SPI Transfer Complete flag" },

  { M6811_WCOL, "WCOL ", "Write Collision" },

  { M6811_MODF, "MODF ", "Mode Fault" },

  { 0,  0, 0 }

};

static void

m68hc11spi_info (struct hw *me)

{

  SIM_DESC sd;

  uint16 base = 0;

  sim_cpu *cpu;

  struct m68hc11spi *controller;

  uint8 val;

  sd = hw_system (me);

  cpu = STATE_CPU (sd, 0);

  controller = hw_data (me);

  sim_io_printf (sd, "M68HC11 SPI:\n");

  base = cpu_get_io_base (cpu);

  val = cpu->ios[M6811_SPCR];

  print_io_byte (sd, "SPCR", spcr_desc, val, base + M6811_SPCR);

  sim_io_printf (sd, "\n");

  val = cpu->ios[M6811_SPSR];

  print_io_byte (sd, "SPSR", spsr_desc, val, base + M6811_SPSR);

  sim_io_printf (sd, "\n");

  if (controller->spi_event)

    {

      signed64 t;

      sim_io_printf (sd, "  SPI has %d bits to send\n",

                     controller->tx_bit + 1);

      t = hw_event_remain_time (me, controller->spi_event);

      sim_io_printf (sd, "  SPI current bit-cycle finished in %s\n",

                     cycle_to_string (cpu, t, PRINT_TIME | PRINT_CYCLE));

      t += (controller->tx_bit + 1) * 2 * controller->clock;

      sim_io_printf (sd, "  SPI operation finished in %s\n",

                     cycle_to_string (cpu, t, PRINT_TIME | PRINT_CYCLE));

    }

}

static int

m68hc11spi_ioctl (struct hw *me,

                  hw_ioctl_request request,

                  va_list ap)

{

  m68hc11spi_info (me);

  return 0;

}

/* generic read/write */

static unsigned

m68hc11spi_io_read_buffer (struct hw *me,

                           void *dest,

                           int space,

                           unsigned_word base,

                           unsigned nr_bytes)

{

  SIM_DESC sd;

  struct m68hc11spi *controller;

  sim_cpu *cpu;

  unsigned8 val;

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

  sd  = hw_system (me);

  cpu = STATE_CPU (sd, 0);

  controller = hw_data (me);

  switch (base)

    {

    case M6811_SPSR:

      controller->rx_clear_scsr = cpu->ios[M6811_SCSR]

        & (M6811_SPIF | M6811_WCOL | M6811_MODF);

    case M6811_SPCR:

      val = cpu->ios[base];

      break;

    case M6811_SPDR:

      if (controller->rx_clear_scsr)

        {

          cpu->ios[M6811_SPSR] &= ~controller->rx_clear_scsr;

          controller->rx_clear_scsr = 0;

          interrupts_update_pending (&cpu->cpu_interrupts);

        }

      val = controller->rx_char;

      break;

    default:

      return 0;

    }

  *((unsigned8*) dest) = val;

  return 1;

}

static unsigned

m68hc11spi_io_write_buffer (struct hw *me,

                            const void *source,

                            int space,

                            unsigned_word base,

                            unsigned nr_bytes)

{

  SIM_DESC sd;

  struct m68hc11spi *controller;

  sim_cpu *cpu;

  unsigned8 val;

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

  sd  = hw_system (me);

  cpu = STATE_CPU (sd, 0);

  controller = hw_data (me);

  val = *((const unsigned8*) source);

  switch (base)

    {

    case M6811_SPCR:

      cpu->ios[M6811_SPCR] = val;

      /* The SPI clock rate is 2, 4, 16, 32 of the internal CPU clock.

         We have to drive the clock pin and need a 2x faster clock.  */

      switch (val & (M6811_SPR1 | M6811_SPR0))

        {

        case 0:

          controller->clock = 1;

          break;

        case 1:

          controller->clock = 2;

          break;

        case 2:

          controller->clock = 8;

          break;

        default:

          controller->clock = 16;

          break;

        }

      /* Set the clock pin.  */

      if ((val & M6811_CPOL)

          && (controller->spi_event == 0

              || ((val & M6811_CPHA) && controller->mode == 1)))

        controller->clk_pin = 1;

      else

        controller->clk_pin = 0;

      set_bit_port (me, cpu, M6811_PORTD, (1 << 4), controller->clk_pin);

      break;

      /* Can't write to SPSR.  */

    case M6811_SPSR:

      break;

    case M6811_SPDR:

      if (!(cpu->ios[M6811_SPCR] & M6811_SPE))

        {

          return 0;

        }

      if (controller->rx_clear_scsr)

        {

          cpu->ios[M6811_SPSR] &= ~controller->rx_clear_scsr;

          controller->rx_clear_scsr = 0;

          interrupts_update_pending (&cpu->cpu_interrupts);

        }

      /* If transfer is taking place, a write to SPDR

         generates a collision.  */

      if (controller->spi_event)

        {

          cpu->ios[M6811_SPSR] |= M6811_WCOL;

          break;

        }

      /* Refuse the write if there was no read of SPSR.  */

      /* ???? TBD. */

      /* Prepare to send a byte.  */

      controller->tx_char = val;

      controller->mode   = SPI_START_BYTE;

      /* Toggle clock pin internal value when CPHA is 0 so that

         it will really change in the middle of a bit.  */

      if (!(cpu->ios[M6811_SPCR] & M6811_CPHA))

        controller->clk_pin = ~controller->clk_pin;

      cpu->ios[M6811_SPDR] = val;

      /* Activate transmission.  */

      m68hc11spi_clock (me, NULL);

      break;

    default:

      return 0;

    }

  return nr_bytes;

}

const struct hw_descriptor dv_m68hc11spi_descriptor[] = {

  { "m68hc11spi", m68hc11spi_finish },

  { "m68hc12spi", m68hc11spi_finish },

  { NULL },

};