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  */
   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 #include <linux/mtd/compatmac.h>
  17
  18
  19 static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  20 static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  21 static int mapram_erase (struct mtd_info *, struct erase_info *);
  22 static void mapram_nop (struct mtd_info *);
  23 static struct mtd_info *map_ram_probe(struct map_info *map);
  24
  25
  26 static struct mtd_chip_driver mapram_chipdrv = {
  27         .probe  = map_ram_probe,
  28         .name   = "map_ram",
  29         .module = THIS_MODULE
  30 };
  31
  32 static struct mtd_info *map_ram_probe(struct map_info *map)
  33 {
  34         struct mtd_info *mtd;
  35
  36         /* Check the first byte is RAM */
  37 #if 0
  38         map_write8(map, 0x55, 0);
  39         if (map_read8(map, 0) != 0x55)
  40                 return NULL;
  41
  42         map_write8(map, 0xAA, 0);
  43         if (map_read8(map, 0) != 0xAA)
  44                 return NULL;
  45
  46         /* Check the last byte is RAM */
  47         map_write8(map, 0x55, map->size-1);
  48         if (map_read8(map, map->size-1) != 0x55)
  49                 return NULL;
  50
  51         map_write8(map, 0xAA, map->size-1);
  52         if (map_read8(map, map->size-1) != 0xAA)
  53                 return NULL;
  54 #endif
  55         /* OK. It seems to be RAM. */
  56
  57         mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
  58         if (!mtd)
  59                 return NULL;
  60
  61         map->fldrv = &mapram_chipdrv;
  62         mtd->priv = map;
  63         mtd->name = map->name;
  64         mtd->type = MTD_RAM;
  65         mtd->size = map->size;
  66         mtd->erase = mapram_erase;
  67         mtd->read = mapram_read;
  68         mtd->write = mapram_write;
  69         mtd->sync = mapram_nop;
  70         mtd->flags = MTD_CAP_RAM;
  71         mtd->writesize = 1;
  72
  73         mtd->erasesize = PAGE_SIZE;
  74         while(mtd->size & (mtd->erasesize - 1))
  75                 mtd->erasesize >>= 1;
  76
  77         __module_get(THIS_MODULE);
  78         return mtd;
  79 }
  80
  81
  82 static 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 = mtd->priv;
  85
  86         map_copy_from(map, buf, from, len);
  87         *retlen = len;
  88         return 0;
  89 }
  90
  91 static 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 = mtd->priv;
  94
  95         map_copy_to(map, to, buf, len);
  96         *retlen = len;
  97         return 0;
  98 }
  99
 100 static 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 = mtd->priv;
 105         map_word allff;
 106         unsigned long i;
 107
 108         allff = map_word_ff(map);
 109
 110         for (i=0; i<instr->len; i += map_bankwidth(map))
 111                 map_write(map, allff, instr->addr + i);
 112
 113         instr->state = MTD_ERASE_DONE;
 114
 115         mtd_erase_callback(instr);
 116
 117         return 0;
 118 }
 119
 120 static void mapram_nop(struct mtd_info *mtd)
 121 {
 122         /* Nothing to see here */
 123 }
 124
 125 static int __init map_ram_init(void)
 126 {
 127         register_mtd_chip_driver(&mapram_chipdrv);
 128         return 0;
 129 }
 130
 131 static void __exit map_ram_exit(void)
 132 {
 133         unregister_mtd_chip_driver(&mapram_chipdrv);
 134 }
 135
 136 module_init(map_ram_init);
 137 module_exit(map_ram_exit);
 138
 139 MODULE_LICENSE("GPL");
 140 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 141 MODULE_DESCRIPTION("MTD chip driver for RAM chips");