LXR linux/drivers/mtd/chips/map

   1/*
   2 * Common code to handle map devices which are simple RAM
   3 * (C) 2000 Red Hat. GPL'd.
   4 */
   5
   6#include <linux/module.h>
   7#include <linux/types.h>
   8#include <linux/kernel.h>
   9#include <asm/io.h>
  10#include <asm/byteorder.h>
  11#include <linux/errno.h>
  12#include <linux/slab.h>
  13#include <linux/init.h>
  14#include <linux/mtd/mtd.h>
  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);
  23static int mapram_point (struct mtd_info *mtd, loff_t from, size_t len,
  24                         size_t *retlen, void **virt, resource_size_t *phys);
  25static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len);
  26
  27
  28static struct mtd_chip_driver mapram_chipdrv = {
  29        .probe  = map_ram_probe,
  30        .name   = "map_ram",
  31        .module = THIS_MODULE
  32};
  33
  34static struct mtd_info *map_ram_probe(struct map_info *map)
  35{
  36        struct mtd_info *mtd;
  37
  38        /* Check the first byte is RAM */
  39#if 0
  40        map_write8(map, 0x55, 0);
  41        if (map_read8(map, 0) != 0x55)
  42                return NULL;
  43
  44        map_write8(map, 0xAA, 0);
  45        if (map_read8(map, 0) != 0xAA)
  46                return NULL;
  47
  48        /* Check the last byte is RAM */
  49        map_write8(map, 0x55, map->size-1);
  50        if (map_read8(map, map->size-1) != 0x55)
  51                return NULL;
  52
  53        map_write8(map, 0xAA, map->size-1);
  54        if (map_read8(map, map->size-1) != 0xAA)
  55                return NULL;
  56#endif
  57        /* OK. It seems to be RAM. */
  58
  59        mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
  60        if (!mtd)
  61                return NULL;
  62
  63        map->fldrv = &mapram_chipdrv;
  64        mtd->priv = map;
  65        mtd->name = map->name;
  66        mtd->type = MTD_RAM;
  67        mtd->size = map->size;
  68        mtd->_erase = mapram_erase;
  69        mtd->_read = mapram_read;
  70        mtd->_write = mapram_write;
  71        mtd->_panic_write = mapram_write;
  72        mtd->_point = mapram_point;
  73        mtd->_sync = mapram_nop;
  74        mtd->_unpoint = mapram_unpoint;
  75        mtd->flags = MTD_CAP_RAM;
  76        mtd->writesize = 1;
  77
  78        mtd->erasesize = PAGE_SIZE;
  79        while(mtd->size & (mtd->erasesize - 1))
  80                mtd->erasesize >>= 1;
  81
  82        __module_get(THIS_MODULE);
  83        return mtd;
  84}
  85
  86static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len,
  87                        size_t *retlen, void **virt, resource_size_t *phys)
  88{
  89        struct map_info *map = mtd->priv;
  90
  91        if (!map->virt)
  92                return -EINVAL;
  93        *virt = map->virt + from;
  94        if (phys)
  95                *phys = map->phys + from;
  96        *retlen = len;
  97        return 0;
  98}
  99
 100static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
 101{
 102        return 0;
 103}
 104
 105static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
 106{
 107        struct map_info *map = mtd->priv;
 108
 109        map_copy_from(map, buf, from, len);
 110        *retlen = len;
 111        return 0;
 112}
 113
 114static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
 115{
 116        struct map_info *map = mtd->priv;
 117
 118        map_copy_to(map, to, buf, len);
 119        *retlen = len;
 120        return 0;
 121}
 122
 123static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
 124{
 125        /* Yeah, it's inefficient. Who cares? It's faster than a _real_
 126           flash erase. */
 127        struct map_info *map = mtd->priv;
 128        map_word allff;
 129        unsigned long i;
 130
 131        allff = map_word_ff(map);
 132        for (i=0; i<instr->len; i += map_bankwidth(map))
 133                map_write(map, allff, instr->addr + i);
 134        return 0;
 135}
 136
 137static void mapram_nop(struct mtd_info *mtd)
 138{
 139        /* Nothing to see here */
 140}
 141
 142static int __init map_ram_init(void)
 143{
 144        register_mtd_chip_driver(&mapram_chipdrv);
 145        return 0;
 146}
 147
 148static void __exit map_ram_exit(void)
 149{
 150        unregister_mtd_chip_driver(&mapram_chipdrv);
 151}
 152
 153module_init(map_ram_init);
 154module_exit(map_ram_exit);
 155
 156MODULE_LICENSE("GPL");
 157MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 158MODULE_DESCRIPTION("MTD chip driver for RAM chips");
 159