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 static unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
  25                                           unsigned long, unsigned long);
  26
  27
  28 static struct mtd_chip_driver mapram_chipdrv = {
  29         .probe  = map_ram_probe,
  30         .name   = "map_ram",
  31         .module = THIS_MODULE
  32 };
  33
  34 static 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->get_unmapped_area = mapram_unmapped_area;
  70         mtd->read = mapram_read;
  71         mtd->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  */
  90 static 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
  99 static 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
 108 static 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
 117 static 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
 127         for (i=0; i<instr->len; i += map_bankwidth(map))
 128                 map_write(map, allff, instr->addr + i);
 129
 130         instr->state = MTD_ERASE_DONE;
 131
 132         mtd_erase_callback(instr);
 133
 134         return 0;
 135 }
 136
 137 static void mapram_nop(struct mtd_info *mtd)
 138 {
 139         /* Nothing to see here */
 140 }
 141
 142 static int __init map_ram_init(void)
 143 {
 144         register_mtd_chip_driver(&mapram_chipdrv);
 145         return 0;
 146 }
 147
 148 static void __exit map_ram_exit(void)
 149 {
 150         unregister_mtd_chip_driver(&mapram_chipdrv);
 151 }
 152
 153 module_init(map_ram_init);
 154 module_exit(map_ram_exit);
 155
 156 MODULE_LICENSE("GPL");
 157 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 158 MODULE_DESCRIPTION("MTD chip driver for RAM chips");