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->_panic_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         for (i=0; i<instr->len; i += map_bankwidth(map))
 127                 map_write(map, allff, instr->addr + i);
 128         instr->state = MTD_ERASE_DONE;
 129         mtd_erase_callback(instr);
 130         return 0;
 131 }
 132
 133 static void mapram_nop(struct mtd_info *mtd)
 134 {
 135         /* Nothing to see here */
 136 }
 137
 138 static int __init map_ram_init(void)
 139 {
 140         register_mtd_chip_driver(&mapram_chipdrv);
 141         return 0;
 142 }
 143
 144 static void __exit map_ram_exit(void)
 145 {
 146         unregister_mtd_chip_driver(&mapram_chipdrv);
 147 }
 148
 149 module_init(map_ram_init);
 150 module_exit(map_ram_exit);
 151
 152 MODULE_LICENSE("GPL");
 153 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 154 MODULE_DESCRIPTION("MTD chip driver for RAM chips");