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
  17
  18 static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
  19 static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
  20 static int mapram_erase (struct mtd_info *, struct erase_info *);
  21 static void mapram_nop (struct mtd_info *);
  22 static struct mtd_info *map_ram_probe(struct map_info *map);
  23 static unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
  24                                           unsigned long, unsigned long);
  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->get_unmapped_area = mapram_unmapped_area;
  69         mtd->read = mapram_read;
  70         mtd->write = mapram_write;
  71         mtd->sync = mapram_nop;
  72         mtd->flags = MTD_CAP_RAM;
  73         mtd->writesize = 1;
  74
  75         mtd->erasesize = PAGE_SIZE;
  76         while(mtd->size & (mtd->erasesize - 1))
  77                 mtd->erasesize >>= 1;
  78
  79         __module_get(THIS_MODULE);
  80         return mtd;
  81 }
  82
  83
  84 /*
  85  * Allow NOMMU mmap() to directly map the device (if not NULL)
  86  * - return the address to which the offset maps
  87  * - return -ENOSYS to indicate refusal to do the mapping
  88  */
  89 static unsigned long mapram_unmapped_area(struct mtd_info *mtd,
  90                                           unsigned long len,
  91                                           unsigned long offset,
  92                                           unsigned long flags)
  93 {
  94         struct map_info *map = mtd->priv;
  95         return (unsigned long) map->virt + offset;
  96 }
  97
  98 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
  99 {
 100         struct map_info *map = mtd->priv;
 101
 102         map_copy_from(map, buf, from, len);
 103         *retlen = len;
 104         return 0;
 105 }
 106
 107 static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
 108 {
 109         struct map_info *map = mtd->priv;
 110
 111         map_copy_to(map, to, buf, len);
 112         *retlen = len;
 113         return 0;
 114 }
 115
 116 static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
 117 {
 118         /* Yeah, it's inefficient. Who cares? It's faster than a _real_
 119            flash erase. */
 120         struct map_info *map = mtd->priv;
 121         map_word allff;
 122         unsigned long i;
 123
 124         allff = map_word_ff(map);
 125
 126         for (i=0; i<instr->len; i += map_bankwidth(map))
 127                 map_write(map, allff, instr->addr + i);
 128
 129         instr->state = MTD_ERASE_DONE;
 130
 131         mtd_erase_callback(instr);
 132
 133         return 0;
 134 }
 135
 136 static void mapram_nop(struct mtd_info *mtd)
 137 {
 138         /* Nothing to see here */
 139 }
 140
 141 static int __init map_ram_init(void)
 142 {
 143         register_mtd_chip_driver(&mapram_chipdrv);
 144         return 0;
 145 }
 146
 147 static void __exit map_ram_exit(void)
 148 {
 149         unregister_mtd_chip_driver(&mapram_chipdrv);
 150 }
 151
 152 module_init(map_ram_init);
 153 module_exit(map_ram_exit);
 154
 155 MODULE_LICENSE("GPL");
 156 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 157 MODULE_DESCRIPTION("MTD chip driver for RAM chips");