Test mtd ram device

[Alexander Larsson]

Since I'm playing around with the MTD stuff i needed a test device that i
can use on my normal machine. I've attached a device that just vmalloc()s
some space and registers as an mtd device. 

/ Alex
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/* 
 * mtdram - a test mtd device
 *
 * Author: Alexander Larsson <alex at cendio.se> 
 *
 * Copyright (c) 1999 Alexander Larsson <alex at cendio.se>
 *
 * This code is GPL
 *
 */

#include <linux/module.h>
#include <linux/malloc.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/vmalloc.h>
#include <linux/mtd/mapped.h>

#if LINUX_VERSION_CODE < 0x20300
#define __exit
#endif

#define MTDRAM_TOTAL_SIZE 1024*1024*2
#define MTDRAM_ERASE_SIZE 64*1024

struct ram_mtd_info {
  struct mtd_info mtd;
  char *buffer;
};

// We could store these in the mtd structure, but we only support 1 device..
static struct ram_mtd_info *mtd_info;


int
ram_erase(struct mtd_info *mtd, struct erase_info *instr)
{
  struct ram_mtd_info *priv = (struct ram_mtd_info *)mtd;

  if (instr->addr + instr->len > mtd->size)
    return -EINVAL;
	
  memset(priv->buffer + instr->addr, 0xff, instr->len);
  
  /* This'll catch a few races. Free the thing before returning :) 
   * I don't feel at all ashamed. This kind of thing is possible anyway
   * with flash, but unlikely.
   */

  instr->state = MTD_ERASE_DONE;

  if (instr->callback)
    (*(instr->callback))(instr);
  else
    kfree(instr);
  
  return 0;
}

int ram_point (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char **mtdbuf)
{
  struct ram_mtd_info *priv = (struct ram_mtd_info *)mtd;

  if (from + len > mtd->size)
    return -EINVAL;
  
  *mtdbuf = priv->buffer + from;
  *retlen = len;
  return 0;
}

void ram_unpoint (struct mtd_info *mtd, u_char *addr)
{
}

int ram_read(struct mtd_info *mtd, loff_t from, size_t len,
	     size_t *retlen, u_char *buf)
{
  struct ram_mtd_info *priv = (struct ram_mtd_info *)mtd;

  if (from + len > mtd->size)
    return -EINVAL;

  memcpy (buf, priv->buffer + from, len);

  *retlen=len;
  return 0;
}

int ram_write(struct mtd_info *mtd, loff_t to, size_t len,
	      size_t *retlen, const u_char *buf)
{
  struct ram_mtd_info *priv = (struct ram_mtd_info *)mtd;

  if (to + len > mtd->size)
    return -EINVAL;
  
  memcpy (priv->buffer + to, buf, len);

  *retlen=len;
  return 0;
}


static void __exit cleanup_mtdram()
{
  if (mtd_info) {
    del_mtd_device(&mtd_info->mtd);
    if (mtd_info->buffer)
      vfree(mtd_info->buffer);
    kfree(mtd_info);
  }
}

static int __init init_mtdram(void)
{
   // Allocate some memory
   mtd_info = (struct ram_mtd_info *)kmalloc(sizeof(struct ram_mtd_info), GFP_KERNEL);
   if (mtd_info == 0)
      return 0;
   
   memset(mtd_info, 0, sizeof(*mtd_info));

   // Setup the MTD structure
   strcpy(mtd_info->mtd.name,"mtdram test device");
   mtd_info->mtd.type = MTD_RAM;
   mtd_info->mtd.flags = MTD_CAP_RAM;
   mtd_info->mtd.size = MTDRAM_TOTAL_SIZE;
   mtd_info->mtd.erasesize = MTDRAM_ERASE_SIZE;
   mtd_info->buffer = vmalloc(MTDRAM_TOTAL_SIZE);
   if (mtd_info->buffer == NULL)
     return -ENOMEM;

   mtd_info->mtd.erase = ram_erase;
   mtd_info->mtd.point = ram_point;
   mtd_info->mtd.unpoint = ram_unpoint;
   mtd_info->mtd.read = ram_read;
   mtd_info->mtd.write = ram_write;

   if (add_mtd_device(&mtd_info->mtd)) {
     /* Clean up */
   }
   
   return 0;
}
module_init(init_mtdram);
module_exit(cleanup_mtdram);