1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Common code to handle map devices which are simple ROM 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/of.h> 16 #include <linux/mtd/mtd.h> 17 #include <linux/mtd/map.h> 18 19 static int maprom_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *); 20 static int maprom_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *); 21 static void maprom_nop (struct mtd_info *); 22 static struct mtd_info *map_rom_probe(struct map_info *map); 23 static int maprom_erase (struct mtd_info *mtd, struct erase_info *info); 24 static int maprom_point (struct mtd_info *mtd, loff_t from, size_t len, 25 size_t *retlen, void **virt, resource_size_t *phys); 26 static int maprom_unpoint(struct mtd_info *mtd, loff_t from, size_t len); 27 28 29 static struct mtd_chip_driver maprom_chipdrv = { 30 .probe = map_rom_probe, 31 .name = "map_rom", 32 .module = THIS_MODULE 33 }; 34 35 static unsigned int default_erasesize(struct map_info *map) 36 { 37 const __be32 *erase_size = NULL; 38 39 erase_size = of_get_property(map->device_node, "erase-size", NULL); 40 41 return !erase_size ? map->size : be32_to_cpu(*erase_size); 42 } 43 44 static struct mtd_info *map_rom_probe(struct map_info *map) 45 { 46 struct mtd_info *mtd; 47 48 mtd = kzalloc(sizeof(*mtd), GFP_KERNEL); 49 if (!mtd) 50 return NULL; 51 52 map->fldrv = &maprom_chipdrv; 53 mtd->priv = map; 54 mtd->name = map->name; 55 mtd->type = MTD_ROM; 56 mtd->size = map->size; 57 mtd->_point = maprom_point; 58 mtd->_unpoint = maprom_unpoint; 59 mtd->_read = maprom_read; 60 mtd->_write = maprom_write; 61 mtd->_sync = maprom_nop; 62 mtd->_erase = maprom_erase; 63 mtd->flags = MTD_CAP_ROM; 64 mtd->erasesize = default_erasesize(map); 65 mtd->writesize = 1; 66 mtd->writebufsize = 1; 67 68 __module_get(THIS_MODULE); 69 return mtd; 70 } 71 72 73 static int maprom_point(struct mtd_info *mtd, loff_t from, size_t len, 74 size_t *retlen, void **virt, resource_size_t *phys) 75 { 76 struct map_info *map = mtd->priv; 77 78 if (!map->virt) 79 return -EINVAL; 80 *virt = map->virt + from; 81 if (phys) 82 *phys = map->phys + from; 83 *retlen = len; 84 return 0; 85 } 86 87 static int maprom_unpoint(struct mtd_info *mtd, loff_t from, size_t len) 88 { 89 return 0; 90 } 91 92 static int maprom_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) 93 { 94 struct map_info *map = mtd->priv; 95 96 map_copy_from(map, buf, from, len); 97 *retlen = len; 98 return 0; 99 } 100 101 static void maprom_nop(struct mtd_info *mtd) 102 { 103 /* Nothing to see here */ 104 } 105 106 static int maprom_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf) 107 { 108 return -EROFS; 109 } 110 111 static int maprom_erase (struct mtd_info *mtd, struct erase_info *info) 112 { 113 /* We do our best 8) */ 114 return -EROFS; 115 } 116 117 static int __init map_rom_init(void) 118 { 119 register_mtd_chip_driver(&maprom_chipdrv); 120 return 0; 121 } 122 123 static void __exit map_rom_exit(void) 124 { 125 unregister_mtd_chip_driver(&maprom_chipdrv); 126 } 127 128 module_init(map_rom_init); 129 module_exit(map_rom_exit); 130 131 MODULE_LICENSE("GPL"); 132 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 133 MODULE_DESCRIPTION("MTD chip driver for ROM chips"); 134