Thomas Gleixner | 09c434b | 2019-05-19 13:08:20 +0100 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
| 3 | * Common code to handle absent "placeholder" devices |
| 4 | * Copyright 2001 Resilience Corporation <ebrower@resilience.com> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 5 | * |
| 6 | * This map driver is used to allocate "placeholder" MTD |
Thomas Gleixner | 1f948b4 | 2005-11-07 11:15:37 +0000 | [diff] [blame] | 7 | * devices on systems that have socketed/removable media. |
| 8 | * Use of this driver as a fallback preserves the expected |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | * registration of MTD device nodes regardless of probe outcome. |
| 10 | * A usage example is as follows: |
| 11 | * |
| 12 | * my_dev[i] = do_map_probe("cfi", &my_map[i]); |
| 13 | * if(NULL == my_dev[i]) { |
| 14 | * my_dev[i] = do_map_probe("map_absent", &my_map[i]); |
| 15 | * } |
| 16 | * |
| 17 | * Any device 'probed' with this driver will return -ENODEV |
| 18 | * upon open. |
| 19 | */ |
| 20 | |
| 21 | #include <linux/module.h> |
| 22 | #include <linux/types.h> |
| 23 | #include <linux/kernel.h> |
| 24 | #include <linux/errno.h> |
| 25 | #include <linux/slab.h> |
| 26 | #include <linux/init.h> |
| 27 | #include <linux/mtd/mtd.h> |
| 28 | #include <linux/mtd/map.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | |
| 30 | static int map_absent_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *); |
| 31 | static int map_absent_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *); |
| 32 | static int map_absent_erase (struct mtd_info *, struct erase_info *); |
| 33 | static void map_absent_sync (struct mtd_info *); |
| 34 | static struct mtd_info *map_absent_probe(struct map_info *map); |
| 35 | static void map_absent_destroy (struct mtd_info *); |
| 36 | |
| 37 | |
| 38 | static struct mtd_chip_driver map_absent_chipdrv = { |
| 39 | .probe = map_absent_probe, |
| 40 | .destroy = map_absent_destroy, |
| 41 | .name = "map_absent", |
| 42 | .module = THIS_MODULE |
| 43 | }; |
| 44 | |
| 45 | static struct mtd_info *map_absent_probe(struct map_info *map) |
| 46 | { |
| 47 | struct mtd_info *mtd; |
| 48 | |
Burman Yan | 95b93a0 | 2006-11-15 21:10:29 +0200 | [diff] [blame] | 49 | mtd = kzalloc(sizeof(*mtd), GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | if (!mtd) { |
| 51 | return NULL; |
| 52 | } |
| 53 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | map->fldrv = &map_absent_chipdrv; |
| 55 | mtd->priv = map; |
| 56 | mtd->name = map->name; |
| 57 | mtd->type = MTD_ABSENT; |
| 58 | mtd->size = map->size; |
Artem Bityutskiy | 3c3c10b | 2012-01-30 14:58:32 +0200 | [diff] [blame] | 59 | mtd->_erase = map_absent_erase; |
| 60 | mtd->_read = map_absent_read; |
| 61 | mtd->_write = map_absent_write; |
| 62 | mtd->_sync = map_absent_sync; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | mtd->flags = 0; |
Artem B. Bityutskiy | 17ffc7b | 2006-06-22 18:15:48 +0400 | [diff] [blame] | 64 | mtd->erasesize = PAGE_SIZE; |
| 65 | mtd->writesize = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | |
| 67 | __module_get(THIS_MODULE); |
| 68 | return mtd; |
| 69 | } |
| 70 | |
| 71 | |
| 72 | static int map_absent_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) |
| 73 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | return -ENODEV; |
| 75 | } |
| 76 | |
| 77 | static int map_absent_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf) |
| 78 | { |
Thomas Gleixner | 1f948b4 | 2005-11-07 11:15:37 +0000 | [diff] [blame] | 79 | return -ENODEV; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 80 | } |
| 81 | |
| 82 | static int map_absent_erase(struct mtd_info *mtd, struct erase_info *instr) |
| 83 | { |
| 84 | return -ENODEV; |
| 85 | } |
| 86 | |
| 87 | static void map_absent_sync(struct mtd_info *mtd) |
| 88 | { |
| 89 | /* nop */ |
| 90 | } |
| 91 | |
| 92 | static void map_absent_destroy(struct mtd_info *mtd) |
| 93 | { |
| 94 | /* nop */ |
| 95 | } |
| 96 | |
| 97 | static int __init map_absent_init(void) |
| 98 | { |
| 99 | register_mtd_chip_driver(&map_absent_chipdrv); |
| 100 | return 0; |
| 101 | } |
| 102 | |
| 103 | static void __exit map_absent_exit(void) |
| 104 | { |
| 105 | unregister_mtd_chip_driver(&map_absent_chipdrv); |
| 106 | } |
| 107 | |
| 108 | module_init(map_absent_init); |
| 109 | module_exit(map_absent_exit); |
| 110 | |
| 111 | MODULE_LICENSE("GPL"); |
| 112 | MODULE_AUTHOR("Resilience Corporation - Eric Brower <ebrower@resilience.com>"); |
| 113 | MODULE_DESCRIPTION("Placeholder MTD chip driver for 'absent' chips"); |