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"); 159