1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Common code to handle map devices which are simple RAM 4 * (C) 2000 Red Hat. 5 */ 6 7 #include <linux/module.h> 8 #include <linux/types.h> 9 #include <linux/kernel.h> 10 #include <asm/io.h> 11 #include <asm/byteorder.h> 12 #include <linux/errno.h> 13 #include <linux/slab.h> 14 #include <linux/init.h> 15 #include <linux/mtd/mtd.h> 16 #include <linux/mtd/map.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 int mapram_point (struct mtd_info *mtd, loff_t from, size_t len, 25 size_t *retlen, void **virt, resource_size_t *phys); 26 static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len); 27 28 29 static struct mtd_chip_driver mapram_chipdrv = { 30 .probe = map_ram_probe, 31 .name = "map_ram", 32 .module = THIS_MODULE 33 }; 34 35 static struct mtd_info *map_ram_probe(struct map_info *map) 36 { 37 struct mtd_info *mtd; 38 39 /* Check the first byte is RAM */ 40 #if 0 41 map_write8(map, 0x55, 0); 42 if (map_read8(map, 0) != 0x55) 43 return NULL; 44 45 map_write8(map, 0xAA, 0); 46 if (map_read8(map, 0) != 0xAA) 47 return NULL; 48 49 /* Check the last byte is RAM */ 50 map_write8(map, 0x55, map->size-1); 51 if (map_read8(map, map->size-1) != 0x55) 52 return NULL; 53 54 map_write8(map, 0xAA, map->size-1); 55 if (map_read8(map, map->size-1) != 0xAA) 56 return NULL; 57 #endif 58 /* OK. It seems to be RAM. */ 59 60 mtd = kzalloc(sizeof(*mtd), GFP_KERNEL); 61 if (!mtd) 62 return NULL; 63 64 map->fldrv = &mapram_chipdrv; 65 mtd->priv = map; 66 mtd->name = map->name; 67 mtd->type = MTD_RAM; 68 mtd->size = map->size; 69 mtd->_erase = mapram_erase; 70 mtd->_read = mapram_read; 71 mtd->_write = mapram_write; 72 mtd->_panic_write = mapram_write; 73 mtd->_sync = mapram_nop; 74 mtd->flags = MTD_CAP_RAM; 75 mtd->writesize = 1; 76 77 /* Disable direct access when NO_XIP is set */ 78 if (map->phys != NO_XIP) { 79 mtd->_point = mapram_point; 80 mtd->_unpoint = mapram_unpoint; 81 } 82 83 mtd->erasesize = PAGE_SIZE; 84 while(mtd->size & (mtd->erasesize - 1)) 85 mtd->erasesize >>= 1; 86 87 __module_get(THIS_MODULE); 88 return mtd; 89 } 90 91 static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len, 92 size_t *retlen, void **virt, resource_size_t *phys) 93 { 94 struct map_info *map = mtd->priv; 95 96 if (!map->virt) 97 return -EINVAL; 98 *virt = map->virt + from; 99 if (phys) 100 *phys = map->phys + from; 101 *retlen = len; 102 return 0; 103 } 104 105 static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len) 106 { 107 return 0; 108 } 109 110 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) 111 { 112 struct map_info *map = mtd->priv; 113 114 map_copy_from(map, buf, from, len); 115 *retlen = len; 116 return 0; 117 } 118 119 static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf) 120 { 121 struct map_info *map = mtd->priv; 122 123 map_copy_to(map, to, buf, len); 124 *retlen = len; 125 return 0; 126 } 127 128 static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr) 129 { 130 /* Yeah, it's inefficient. Who cares? It's faster than a _real_ 131 flash erase. */ 132 struct map_info *map = mtd->priv; 133 map_word allff; 134 unsigned long i; 135 136 allff = map_word_ff(map); 137 for (i=0; i<instr->len; i += map_bankwidth(map)) 138 map_write(map, allff, instr->addr + i); 139 return 0; 140 } 141 142 static void mapram_nop(struct mtd_info *mtd) 143 { 144 /* Nothing to see here */ 145 } 146 147 static int __init map_ram_init(void) 148 { 149 register_mtd_chip_driver(&mapram_chipdrv); 150 return 0; 151 } 152 153 static void __exit map_ram_exit(void) 154 { 155 unregister_mtd_chip_driver(&mapram_chipdrv); 156 } 157 158 module_init(map_ram_init); 159 module_exit(map_ram_exit); 160 161 MODULE_LICENSE("GPL"); 162 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 163 MODULE_DESCRIPTION("MTD chip driver for RAM chips"); 164