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 int mapram_point (struct mtd_info *mtd, loff_t from, size_t len,
  24                          size_t *retlen, void **virt, resource_size_t *phys);
  25 static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len);
  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->_read = mapram_read;
  70         mtd->_write = mapram_write;
  71         mtd->_panic_write = mapram_write;
  72         mtd->_point = mapram_point;
  73         mtd->_sync = mapram_nop;
  74         mtd->_unpoint = mapram_unpoint;
  75         mtd->flags = MTD_CAP_RAM;
  76         mtd->writesize = 1;
  77
  78         mtd->erasesize = PAGE_SIZE;
  79         while(mtd->size & (mtd->erasesize - 1))
  80                 mtd->erasesize >>= 1;
  81
  82         __module_get(THIS_MODULE);
  83         return mtd;
  84 }
  85
  86 static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len,
  87                         size_t *retlen, void **virt, resource_size_t *phys)
  88 {
  89         struct map_info *map = mtd->priv;
  90
  91         if (!map->virt)
  92                 return -EINVAL;
  93         *virt = map->virt + from;
  94         if (phys)
  95                 *phys = map->phys + from;
  96         *retlen = len;
  97         return 0;
  98 }
  99
 100 static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
 101 {
 102         return 0;
 103 }
 104
 105 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
 106 {
 107         struct map_info *map = mtd->priv;
 108
 109         map_copy_from(map, buf, from, len);
 110         *retlen = len;
 111         return 0;
 112 }
 113
 114 static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
 115 {
 116         struct map_info *map = mtd->priv;
 117
 118         map_copy_to(map, to, buf, len);
 119         *retlen = len;
 120         return 0;
 121 }
 122
 123 static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
 124 {
 125         /* Yeah, it's inefficient. Who cares? It's faster than a _real_
 126            flash erase. */
 127         struct map_info *map = mtd->priv;
 128         map_word allff;
 129         unsigned long i;
 130
 131         allff = map_word_ff(map);
 132         for (i=0; i<instr->len; i += map_bankwidth(map))
 133                 map_write(map, allff, instr->addr + i);
 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");