linux-old/drivers/mtd/chips/map_ram.c
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   1/*
   2 * Common code to handle map devices which are simple RAM
   3 * (C) 2000 Red Hat. GPL'd.
   4 * $Id: map_ram.c,v 1.14 2001/10/02 15:05:12 dwmw2 Exp $
   5 */
   6
   7#include <linux/module.h>
   8#include <linux/types.h>
   9#include <linux/kernel.h>
  10#include <asm/io.h>
  11#include <asm/byteorder.h>
  12#include <linux/errno.h>
  13#include <linux/slab.h>
  14
  15#include <linux/mtd/map.h>
  16
  17
  18static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  19static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  20static int mapram_erase (struct mtd_info *, struct erase_info *);
  21static void mapram_nop (struct mtd_info *);
  22static struct mtd_info *map_ram_probe(struct map_info *map);
  23
  24
  25static struct mtd_chip_driver mapram_chipdrv = {
  26        probe: map_ram_probe,
  27        name: "map_ram",
  28        module: THIS_MODULE
  29};
  30
  31static struct mtd_info *map_ram_probe(struct map_info *map)
  32{
  33        struct mtd_info *mtd;
  34
  35        /* Check the first byte is RAM */
  36#if 0
  37        map->write8(map, 0x55, 0);
  38        if (map->read8(map, 0) != 0x55)
  39                return NULL;
  40
  41        map->write8(map, 0xAA, 0);
  42        if (map->read8(map, 0) != 0xAA)
  43                return NULL;
  44
  45        /* Check the last byte is RAM */
  46        map->write8(map, 0x55, map->size-1);
  47        if (map->read8(map, map->size-1) != 0x55)
  48                return NULL;
  49
  50        map->write8(map, 0xAA, map->size-1);
  51        if (map->read8(map, map->size-1) != 0xAA)
  52                return NULL;
  53#endif
  54        /* OK. It seems to be RAM. */
  55
  56        mtd = kmalloc(sizeof(*mtd), GFP_KERNEL);
  57        if (!mtd)
  58                return NULL;
  59
  60        memset(mtd, 0, sizeof(*mtd));
  61
  62        map->fldrv = &mapram_chipdrv;
  63        mtd->priv = map;
  64        mtd->name = map->name;
  65        mtd->type = MTD_RAM;
  66        mtd->size = map->size;
  67        mtd->erase = mapram_erase;
  68        mtd->read = mapram_read;
  69        mtd->write = mapram_write;
  70        mtd->sync = mapram_nop;
  71        mtd->flags = MTD_CAP_RAM | MTD_VOLATILE;
  72
  73        mtd->erasesize = PAGE_SIZE;
  74        while(mtd->size & (mtd->erasesize - 1))
  75                mtd->erasesize >>= 1;
  76
  77        MOD_INC_USE_COUNT;
  78        return mtd;
  79}
  80
  81
  82static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
  83{
  84        struct map_info *map = (struct map_info *)mtd->priv;
  85
  86        map->copy_from(map, buf, from, len);
  87        *retlen = len;
  88        return 0;
  89}
  90
  91static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
  92{
  93        struct map_info *map = (struct map_info *)mtd->priv;
  94
  95        map->copy_to(map, to, buf, len);
  96        *retlen = len;
  97        return 0;
  98}
  99
 100static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
 101{
 102        /* Yeah, it's inefficient. Who cares? It's faster than a _real_
 103           flash erase. */
 104        struct map_info *map = (struct map_info *)mtd->priv;
 105        unsigned long i;
 106
 107        for (i=0; i<instr->len; i++)
 108                map->write8(map, 0xFF, instr->addr + i);
 109
 110        if (instr->callback)
 111                instr->callback(instr);
 112
 113        return 0;
 114}
 115
 116static void mapram_nop(struct mtd_info *mtd)
 117{
 118        /* Nothing to see here */
 119}
 120
 121int __init map_ram_init(void)
 122{
 123        register_mtd_chip_driver(&mapram_chipdrv);
 124        return 0;
 125}
 126
 127static void __exit map_ram_exit(void)
 128{
 129        unregister_mtd_chip_driver(&mapram_chipdrv);
 130}
 131
 132module_init(map_ram_init);
 133module_exit(map_ram_exit);
 134
 135MODULE_LICENSE("GPL");
 136MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 137MODULE_DESCRIPTION("MTD chip driver for RAM chips");
 138