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// SPDX-License-Identifier: GPL-2.0
/*
* Common code to handle map devices which are simple RAM
* (C) 2000 Red Hat.
*/
#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/init.h>
#include <linux/mtd/mtd.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 int mapram_point (struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, void **virt, resource_size_t *phys);
static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len);
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 = kzalloc(sizeof(*mtd), GFP_KERNEL);
if (!mtd)
return NULL;
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->_panic_write = mapram_write;
mtd->_sync = mapram_nop;
mtd->flags = MTD_CAP_RAM;
mtd->writesize = 1;
/* Disable direct access when NO_XIP is set */
if (map->phys != NO_XIP) {
mtd->_point = mapram_point;
mtd->_unpoint = mapram_unpoint;
}
mtd->erasesize = PAGE_SIZE;
while(mtd->size & (mtd->erasesize - 1))
mtd->erasesize >>= 1;
__module_get(THIS_MODULE);
return mtd;
}
static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, void **virt, resource_size_t *phys)
{
struct map_info *map = mtd->priv;
if (!map->virt)
return -EINVAL;
*virt = map->virt + from;
if (phys)
*phys = map->phys + from;
*retlen = len;
return 0;
}
static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
{
return 0;
}
static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
{
struct map_info *map = 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 = 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 = mtd->priv;
map_word allff;
unsigned long i;
allff = map_word_ff(map);
for (i=0; i<instr->len; i += map_bankwidth(map))
map_write(map, allff, instr->addr + i);
return 0;
}
static void mapram_nop(struct mtd_info *mtd)
{
/* Nothing to see here */
}
static 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");
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