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 static int mapram_point (struct mtd_info *mtd, loff_t from, size_t len, 26 size_t *retlen, void **virt, resource_size_t *phys); 27 static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len); 28 29 30 static struct mtd_chip_driver mapram_chipdrv = { 31 .probe = map_ram_probe, 32 .name = "map_ram", 33 .module = THIS_MODULE 34 }; 35 36 static struct mtd_info *map_ram_probe(struct map_info *map) 37 { 38 struct mtd_info *mtd; 39 40 /* Check the first byte is RAM */ 41 #if 0 42 map_write8(map, 0x55, 0); 43 if (map_read8(map, 0) != 0x55) 44 return NULL; 45 46 map_write8(map, 0xAA, 0); 47 if (map_read8(map, 0) != 0xAA) 48 return NULL; 49 50 /* Check the last byte is RAM */ 51 map_write8(map, 0x55, map->size-1); 52 if (map_read8(map, map->size-1) != 0x55) 53 return NULL; 54 55 map_write8(map, 0xAA, map->size-1); 56 if (map_read8(map, map->size-1) != 0xAA) 57 return NULL; 58 #endif 59 /* OK. It seems to be RAM. */ 60 61 mtd = kzalloc(sizeof(*mtd), GFP_KERNEL); 62 if (!mtd) 63 return NULL; 64 65 map->fldrv = &mapram_chipdrv; 66 mtd->priv = map; 67 mtd->name = map->name; 68 mtd->type = MTD_RAM; 69 mtd->size = map->size; 70 mtd->_erase = mapram_erase; 71 mtd->_get_unmapped_area = mapram_unmapped_area; 72 mtd->_read = mapram_read; 73 mtd->_write = mapram_write; 74 mtd->_panic_write = mapram_write; 75 mtd->_point = mapram_point; 76 mtd->_sync = mapram_nop; 77 mtd->_unpoint = mapram_unpoint; 78 mtd->flags = MTD_CAP_RAM; 79 mtd->writesize = 1; 80 81 mtd->erasesize = PAGE_SIZE; 82 while(mtd->size & (mtd->erasesize - 1)) 83 mtd->erasesize >>= 1; 84 85 __module_get(THIS_MODULE); 86 return mtd; 87 } 88 89 90 /* 91 * Allow NOMMU mmap() to directly map the device (if not NULL) 92 * - return the address to which the offset maps 93 * - return -ENOSYS to indicate refusal to do the mapping 94 */ 95 static unsigned long mapram_unmapped_area(struct mtd_info *mtd, 96 unsigned long len, 97 unsigned long offset, 98 unsigned long flags) 99 { 100 struct map_info *map = mtd->priv; 101 return (unsigned long) map->virt + offset; 102 } 103 104 static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len, 105 size_t *retlen, void **virt, resource_size_t *phys) 106 { 107 struct map_info *map = mtd->priv; 108 109 if (!map->virt) 110 return -EINVAL; 111 *virt = map->virt + from; 112 if (phys) 113 *phys = map->phys + from; 114 *retlen = len; 115 return 0; 116 } 117 118 static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len) 119 { 120 return 0; 121 } 122 123 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) 124 { 125 struct map_info *map = mtd->priv; 126 127 map_copy_from(map, buf, from, len); 128 *retlen = len; 129 return 0; 130 } 131 132 static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf) 133 { 134 struct map_info *map = mtd->priv; 135 136 map_copy_to(map, to, buf, len); 137 *retlen = len; 138 return 0; 139 } 140 141 static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr) 142 { 143 /* Yeah, it's inefficient. Who cares? It's faster than a _real_ 144 flash erase. */ 145 struct map_info *map = mtd->priv; 146 map_word allff; 147 unsigned long i; 148 149 allff = map_word_ff(map); 150 for (i=0; i<instr->len; i += map_bankwidth(map)) 151 map_write(map, allff, instr->addr + i); 152 instr->state = MTD_ERASE_DONE; 153 mtd_erase_callback(instr); 154 return 0; 155 } 156 157 static void mapram_nop(struct mtd_info *mtd) 158 { 159 /* Nothing to see here */ 160 } 161 162 static int __init map_ram_init(void) 163 { 164 register_mtd_chip_driver(&mapram_chipdrv); 165 return 0; 166 } 167 168 static void __exit map_ram_exit(void) 169 { 170 unregister_mtd_chip_driver(&mapram_chipdrv); 171 } 172 173 module_init(map_ram_init); 174 module_exit(map_ram_exit); 175 176 MODULE_LICENSE("GPL"); 177 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 178 MODULE_DESCRIPTION("MTD chip driver for RAM chips"); 179