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/*
 * Common code to handle map devices which are simple RAM
 * (C) 2000 Red Hat. GPL'd.
 * $Id: map_ram.c,v 1.1.1.1 2004-04-15 01:52:10 phoenix Exp $
 */
 
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/io.h>
#include <asm/byteorder.h>
#include <linux/errno.h>
#include <linux/slab.h>
 
#include <linux/mtd/map.h>
 
 
static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
static int mapram_erase (struct mtd_info *, struct erase_info *);
static void mapram_nop (struct mtd_info *);
static struct mtd_info *map_ram_probe(struct map_info *map);
 
 
static struct mtd_chip_driver mapram_chipdrv = {
	probe: map_ram_probe,
	name: "map_ram",
	module: THIS_MODULE
};
 
static struct mtd_info *map_ram_probe(struct map_info *map)
{
	struct mtd_info *mtd;
 
	/* Check the first byte is RAM */
#if 0
	map->write8(map, 0x55, 0);
	if (map->read8(map, 0) != 0x55)
		return NULL;
 
	map->write8(map, 0xAA, 0);
	if (map->read8(map, 0) != 0xAA)
		return NULL;
 
	/* Check the last byte is RAM */
	map->write8(map, 0x55, map->size-1);
	if (map->read8(map, map->size-1) != 0x55)
		return NULL;
 
	map->write8(map, 0xAA, map->size-1);
	if (map->read8(map, map->size-1) != 0xAA)
		return NULL;
#endif
	/* OK. It seems to be RAM. */
 
	mtd = kmalloc(sizeof(*mtd), GFP_KERNEL);
	if (!mtd)
		return NULL;
 
	memset(mtd, 0, sizeof(*mtd));
 
	map->fldrv = &mapram_chipdrv;
	mtd->priv = map;
	mtd->name = map->name;
	mtd->type = MTD_RAM;
	mtd->size = map->size;
	mtd->erase = mapram_erase;
	mtd->read = mapram_read;
	mtd->write = mapram_write;
	mtd->sync = mapram_nop;
	mtd->flags = MTD_CAP_RAM | MTD_VOLATILE;
 
	mtd->erasesize = PAGE_SIZE;
 	while(mtd->size & (mtd->erasesize - 1))
		mtd->erasesize >>= 1;
 
	MOD_INC_USE_COUNT;
	return mtd;
}
 
 
static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
{
	struct map_info *map = (struct map_info *)mtd->priv;
 
	map->copy_from(map, buf, from, len);
	*retlen = len;
	return 0;
}
 
static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
{
	struct map_info *map = (struct map_info *)mtd->priv;
 
	map->copy_to(map, to, buf, len);
	*retlen = len;
	return 0;
}
 
static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
{
	/* Yeah, it's inefficient. Who cares? It's faster than a _real_
	   flash erase. */
	struct map_info *map = (struct map_info *)mtd->priv;
	unsigned long i;
 
	for (i=0; i<instr->len; i++)
		map->write8(map, 0xFF, instr->addr + i);
 
	if (instr->callback)
		instr->callback(instr);
 
	return 0;
}
 
static void mapram_nop(struct mtd_info *mtd)
{
	/* Nothing to see here */
}
 
int __init map_ram_init(void)
{
	register_mtd_chip_driver(&mapram_chipdrv);
	return 0;
}
 
static void __exit map_ram_exit(void)
{
	unregister_mtd_chip_driver(&mapram_chipdrv);
}
 
module_init(map_ram_init);
module_exit(map_ram_exit);
 
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("MTD chip driver for RAM chips");