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/*  dv-nvram.c -- Generic driver for a non volatile ram (battery saved)

    Copyright (C) 1999, 2000, 2007, 2008, 2009, 2010

    Free Software Foundation, Inc.

    Written by Stephane Carrez (stcarrez@worldnet.fr)

    (From a driver model Contributed by Cygnus Solutions.)

    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 <unistd.h>

#include <fcntl.h>

#include <errno.h>

/* DEVICE

        nvram - Non Volatile Ram

   DESCRIPTION

        Implements a generic battery saved CMOS ram. This ram device does

        not contain any realtime clock and does not generate any interrupt.

        The ram content is loaded from a file and saved when it is changed.

        It is intended to be generic.

   PROPERTIES

   reg <base> <length>

        Base and size of the non-volatile ram bank.

   file <path>

        Path where the memory must be saved or loaded when we start.

   mode {map | save-modified | save-all}

        Controls how to load and save the memory content.

           map            The file is mapped in memory

           save-modified  The simulator keeps an open file descriptor to

                          the file and saves portion of memory which are

                          modified.

           save-all       The simulator saves the complete memory each time

                          it's modified (it does not keep an open file

                          descriptor).

   PORTS

        None.

   NOTES

        This device is independent of the Motorola 68hc11.

   */

/* static functions */

/* Control of how to access the ram and save its content.  */

enum nvram_mode

{

  /* Save the complete ram block each time it's changed.

     We don't keep an open file descriptor.  This should be

     ok for small memory banks.  */

  NVRAM_SAVE_ALL,

  /* Save only the memory bytes which are modified.

     This mode means that we have to keep an open file

     descriptor (O_RDWR).  It's good for middle sized memory banks.  */

  NVRAM_SAVE_MODIFIED,

  /* Map file in memory (not yet implemented).

     This mode is suitable for large memory banks.  We don't allocate

     a buffer to represent the ram, instead it's mapped in memory

     with mmap.  */

  NVRAM_MAP_FILE

};

struct nvram

{

  address_word    base_address; /* Base address of ram.  */

  unsigned        size;         /* Size of ram.  */

  unsigned8       *data;        /* Pointer to ram memory.  */

  const char      *file_name;   /* Path of ram file.  */

  int             fd;           /* File description of opened ram file.  */

  enum nvram_mode mode;         /* How load/save ram file.  */

};

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

   callbacks.  Wire up our port names etc.  */

static hw_io_read_buffer_method  nvram_io_read_buffer;

static hw_io_write_buffer_method nvram_io_write_buffer;

static void

attach_nvram_regs (struct hw *me, struct nvram *controller)

{

  unsigned_word attach_address;

  int attach_space;

  unsigned attach_size;

  reg_property_spec reg;

  int result, oerrno;

  /* Get ram bank description (base and size).  */

  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 one addr/size entry");

  hw_unit_address_to_attach_address (hw_parent (me),

                                     &reg.address,

                                     &attach_space,

                                     &attach_address,

                                     me);

  hw_unit_size_to_attach_size (hw_parent (me),

                               &reg.size,

                               &attach_size, me);

  hw_attach_address (hw_parent (me), 0,

                     attach_space, attach_address, attach_size,

                     me);

  controller->mode         = NVRAM_SAVE_ALL;

  controller->base_address = attach_address;

  controller->size         = attach_size;

  controller->fd           = -1;

  /* Get the file where the ram content must be loaded/saved.  */

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

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

  controller->file_name = hw_find_string_property (me, "file");

  /* Get the mode which defines how to save the memory.  */

  if(hw_find_property (me, "mode") != NULL)

    {

      const char *value = hw_find_string_property (me, "mode");

      if (strcmp (value, "map") == 0)

        controller->mode = NVRAM_MAP_FILE;

      else if (strcmp (value, "save-modified") == 0)

        controller->mode = NVRAM_SAVE_MODIFIED;

      else if (strcmp (value, "save-all") == 0)

        controller->mode = NVRAM_SAVE_ALL;

      else

        hw_abort (me, "illegal value for mode parameter `%s': "

                  "use map, save-modified or save-all", value);

    }

  /* Initialize the ram by loading/mapping the file in memory.

     If the file does not exist, create and give it some content.  */

  switch (controller->mode)

    {

    case NVRAM_MAP_FILE:

      hw_abort (me, "'map' mode is not yet implemented, use 'save-modified'");

      break;

    case NVRAM_SAVE_MODIFIED:

    case NVRAM_SAVE_ALL:

      controller->data = (char*) hw_malloc (me, attach_size);

      if (controller->data == 0)

        hw_abort (me, "Not enough memory, try to use the mode 'map'");

      memset (controller->data, 0, attach_size);

      controller->fd = open (controller->file_name, O_RDWR);

      if (controller->fd < 0)

        {

          controller->fd = open (controller->file_name,

                                 O_RDWR | O_CREAT, 0644);

          if (controller->fd < 0)

            hw_abort (me, "Cannot open or create file '%s'",

                      controller->file_name);

          result = write (controller->fd, controller->data, attach_size);

          if (result != attach_size)

            {

              oerrno = errno;

              hw_free (me, controller->data);

              close (controller->fd);

              errno = oerrno;

              hw_abort (me, "Failed to save the ram content");

            }

        }

      else

        {

          result = read (controller->fd, controller->data, attach_size);

          if (result != attach_size)

            {

              oerrno = errno;

              hw_free (me, controller->data);

              close (controller->fd);

              errno = oerrno;

              hw_abort (me, "Failed to load the ram content");

            }

        }

      if (controller->mode == NVRAM_SAVE_ALL)

        {

          close (controller->fd);

          controller->fd = -1;

        }

      break;

    default:

      break;

    }

}

static void

nvram_finish (struct hw *me)

{

  struct nvram *controller;

  controller = HW_ZALLOC (me, struct nvram);

  set_hw_data (me, controller);

  set_hw_io_read_buffer (me, nvram_io_read_buffer);

  set_hw_io_write_buffer (me, nvram_io_write_buffer);

  /* Attach ourself to our parent bus.  */

  attach_nvram_regs (me, controller);

}

/* generic read/write */

static unsigned

nvram_io_read_buffer (struct hw *me,

                      void *dest,

                      int space,

                      unsigned_word base,

                      unsigned nr_bytes)

{

  struct nvram *controller = hw_data (me);

  HW_TRACE ((me, "read 0x%08lx %d [%ld]",

             (long) base, (int) nr_bytes,

             (long) (base - controller->base_address)));

  base -= controller->base_address;

  if (base + nr_bytes > controller->size)

    nr_bytes = controller->size - base;

  memcpy (dest, &controller->data[base], nr_bytes);

  return nr_bytes;

}

static unsigned

nvram_io_write_buffer (struct hw *me,

                       const void *source,

                       int space,

                       unsigned_word base,

                       unsigned nr_bytes)

{

  struct nvram *controller = hw_data (me);

  HW_TRACE ((me, "write 0x%08lx %d [%ld]",

             (long) base, (int) nr_bytes,

             (long) (base - controller->base_address)));

  base -= controller->base_address;

  if (base + nr_bytes > controller->size)

    nr_bytes = controller->size - base;

  switch (controller->mode)

    {

    case NVRAM_SAVE_ALL:

      {

        int fd, result, oerrno;

        fd = open (controller->file_name, O_WRONLY, 0644);

        if (fd < 0)

          {

            return 0;

          }

        memcpy (&controller->data[base], source, nr_bytes);

        result = write (fd, controller->data, controller->size);

        oerrno = errno;

        close (fd);

        errno = oerrno;

        if (result != controller->size)

          {

            return 0;

          }

        return nr_bytes;

      }

    case NVRAM_SAVE_MODIFIED:

      {

        off_t pos;

        int result;

        pos = lseek (controller->fd, (off_t) base, SEEK_SET);

        if (pos != (off_t) base)

          return 0;

        result = write (controller->fd, source, nr_bytes);

        if (result < 0)

          return 0;

        nr_bytes = result;

        break;

      }

    default:

      break;

    }

  memcpy (&controller->data[base], source, nr_bytes);

  return nr_bytes;

}

const struct hw_descriptor dv_nvram_descriptor[] = {

  { "nvram", nvram_finish, },

  { NULL },

};