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 unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
  24                                          unsigned long, unsigned long);
  25
  26
  27static struct mtd_chip_driver mapram_chipdrv = {
  28        .probe  = map_ram_probe,
  29        .name   = "map_ram",
  30        .module = THIS_MODULE
  31};
  32
  33static struct mtd_info *map_ram_probe(struct map_info *map)
  34{
  35        struct mtd_info *mtd;
  36
  37        /* Check the first byte is RAM */
  38#if 0
  39        map_write8(map, 0x55, 0);
  40        if (map_read8(map, 0) != 0x55)
  41                return NULL;
  42
  43        map_write8(map, 0xAA, 0);
  44        if (map_read8(map, 0) != 0xAA)
  45                return NULL;
  46
  47        /* Check the last byte is RAM */
  48        map_write8(map, 0x55, map->size-1);
  49        if (map_read8(map, map->size-1) != 0x55)
  50                return NULL;
  51
  52        map_write8(map, 0xAA, map->size-1);
  53        if (map_read8(map, map->size-1) != 0xAA)
  54                return NULL;
  55#endif
  56        /* OK. It seems to be RAM. */
  57
  58        mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
  59        if (!mtd)
  60                return NULL;
  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->_get_unmapped_area = mapram_unmapped_area;
  69        mtd->_read = mapram_read;
  70        mtd->_write = mapram_write;
  71        mtd->_panic_write = mapram_write;
  72        mtd->_sync = mapram_nop;
  73        mtd->flags = MTD_CAP_RAM;
  74        mtd->writesize = 1;
  75
  76        mtd->erasesize = PAGE_SIZE;
  77        while(mtd->size & (mtd->erasesize - 1))
  78                mtd->erasesize >>= 1;
  79
  80        __module_get(THIS_MODULE);
  81        return mtd;
  82}
  83
  84
  85/*
  86 * Allow NOMMU mmap() to directly map the device (if not NULL)
  87 * - return the address to which the offset maps
  88 * - return -ENOSYS to indicate refusal to do the mapping
  89 */
  90static unsigned long mapram_unmapped_area(struct mtd_info *mtd,
  91                                          unsigned long len,
  92                                          unsigned long offset,
  93                                          unsigned long flags)
  94{
  95        struct map_info *map = mtd->priv;
  96        return (unsigned long) map->virt + offset;
  97}
  98
  99static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
 100{
 101        struct map_info *map = mtd->priv;
 102
 103        map_copy_from(map, buf, from, len);
 104        *retlen = len;
 105        return 0;
 106}
 107
 108static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
 109{
 110        struct map_info *map = mtd->priv;
 111
 112        map_copy_to(map, to, buf, len);
 113        *retlen = len;
 114        return 0;
 115}
 116
 117static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
 118{
 119        /* Yeah, it's inefficient. Who cares? It's faster than a _real_
 120           flash erase. */
 121        struct map_info *map = mtd->priv;
 122        map_word allff;
 123        unsigned long i;
 124
 125        allff = map_word_ff(map);
 126        for (i=0; i<instr->len; i += map_bankwidth(map))
 127                map_write(map, allff, instr->addr + i);
 128        instr->state = MTD_ERASE_DONE;
 129        mtd_erase_callback(instr);
 130        return 0;
 131}
 132
 133static void mapram_nop(struct mtd_info *mtd)
 134{
 135        /* Nothing to see here */
 136}
 137
 138static int __init map_ram_init(void)
 139{
 140        register_mtd_chip_driver(&mapram_chipdrv);
 141        return 0;
 142}
 143
 144static void __exit map_ram_exit(void)
 145{
 146        unregister_mtd_chip_driver(&mapram_chipdrv);
 147}
 148
 149module_init(map_ram_init);
 150module_exit(map_ram_exit);
 151
 152MODULE_LICENSE("GPL");
 153MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 154MODULE_DESCRIPTION("MTD chip driver for RAM chips");
 155