drivers/mtd/chips/map_ram.c

   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 1.22 2005/01/05 18:05:12 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 #include <linux/init.h>
  15 #include <linux/mtd/mtd.h>
  16 #include <linux/mtd/map.h>
  17 #include <linux/mtd/compatmac.h>
  18
  19
  20 static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  21 static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  22 static int mapram_erase (struct mtd_info *, struct erase_info *);
  23 static void mapram_nop (struct mtd_info *);
  24 static struct mtd_info *map_ram_probe(struct map_info *map);
  25
  26
  27 static struct mtd_chip_driver mapram_chipdrv = {
  28         .probe  = map_ram_probe,
  29         .name   = "map_ram",
  30         .module = THIS_MODULE
  31 };
  32
  33 static 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->read = mapram_read;
  69         mtd->write = mapram_write;
  70         mtd->sync = mapram_nop;
  71         mtd->flags = MTD_CAP_RAM;
  72         mtd->writesize = 1;
  73
  74         mtd->erasesize = PAGE_SIZE;
  75         while(mtd->size & (mtd->erasesize - 1))
  76                 mtd->erasesize >>= 1;
  77
  78         __module_get(THIS_MODULE);
  79         return mtd;
  80 }
  81
  82
  83 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
  84 {
  85         struct map_info *map = mtd->priv;
  86
  87         map_copy_from(map, buf, from, len);
  88         *retlen = len;
  89         return 0;
  90 }
  91
  92 static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
  93 {
  94         struct map_info *map = mtd->priv;
  95
  96         map_copy_to(map, to, buf, len);
  97         *retlen = len;
  98         return 0;
  99 }
 100
 101 static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
 102 {
 103         /* Yeah, it's inefficient. Who cares? It's faster than a _real_
 104            flash erase. */
 105         struct map_info *map = mtd->priv;
 106         map_word allff;
 107         unsigned long i;
 108
 109         allff = map_word_ff(map);
 110
 111         for (i=0; i<instr->len; i += map_bankwidth(map))
 112                 map_write(map, allff, instr->addr + i);
 113
 114         instr->state = MTD_ERASE_DONE;
 115
 116         mtd_erase_callback(instr);
 117
 118         return 0;
 119 }
 120
 121 static void mapram_nop(struct mtd_info *mtd)
 122 {
 123         /* Nothing to see here */
 124 }
 125
 126 static int __init map_ram_init(void)
 127 {
 128         register_mtd_chip_driver(&mapram_chipdrv);
 129         return 0;
 130 }
 131
 132 static void __exit map_ram_exit(void)
 133 {
 134         unregister_mtd_chip_driver(&mapram_chipdrv);
 135 }
 136
 137 module_init(map_ram_init);
 138 module_exit(map_ram_exit);
 139
 140 MODULE_LICENSE("GPL");
 141 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 142 MODULE_DESCRIPTION("MTD chip driver for RAM chips");