text: /*  dv-nvram.c -- Generic driver for a non volatile ram (battery saved)
      Copyright (C) 1999, 2000, 2007, 2008, 2009, 2010, 2011
      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 },
  };
  
  