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1da177e4 LT |
1 | /* |
2 | * Common code to handle absent "placeholder" devices | |
3 | * Copyright 2001 Resilience Corporation <ebrower@resilience.com> | |
1da177e4 LT |
4 | * |
5 | * This map driver is used to allocate "placeholder" MTD | |
1f948b43 TG |
6 | * devices on systems that have socketed/removable media. |
7 | * Use of this driver as a fallback preserves the expected | |
1da177e4 LT |
8 | * registration of MTD device nodes regardless of probe outcome. |
9 | * A usage example is as follows: | |
10 | * | |
11 | * my_dev[i] = do_map_probe("cfi", &my_map[i]); | |
12 | * if(NULL == my_dev[i]) { | |
13 | * my_dev[i] = do_map_probe("map_absent", &my_map[i]); | |
14 | * } | |
15 | * | |
16 | * Any device 'probed' with this driver will return -ENODEV | |
17 | * upon open. | |
18 | */ | |
19 | ||
20 | #include <linux/module.h> | |
21 | #include <linux/types.h> | |
22 | #include <linux/kernel.h> | |
23 | #include <linux/errno.h> | |
24 | #include <linux/slab.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/mtd/mtd.h> | |
27 | #include <linux/mtd/map.h> | |
1da177e4 LT |
28 | |
29 | static int map_absent_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *); | |
30 | static int map_absent_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *); | |
31 | static int map_absent_erase (struct mtd_info *, struct erase_info *); | |
32 | static void map_absent_sync (struct mtd_info *); | |
33 | static struct mtd_info *map_absent_probe(struct map_info *map); | |
34 | static void map_absent_destroy (struct mtd_info *); | |
35 | ||
36 | ||
37 | static struct mtd_chip_driver map_absent_chipdrv = { | |
38 | .probe = map_absent_probe, | |
39 | .destroy = map_absent_destroy, | |
40 | .name = "map_absent", | |
41 | .module = THIS_MODULE | |
42 | }; | |
43 | ||
44 | static struct mtd_info *map_absent_probe(struct map_info *map) | |
45 | { | |
46 | struct mtd_info *mtd; | |
47 | ||
95b93a0c | 48 | mtd = kzalloc(sizeof(*mtd), GFP_KERNEL); |
1da177e4 LT |
49 | if (!mtd) { |
50 | return NULL; | |
51 | } | |
52 | ||
1da177e4 LT |
53 | map->fldrv = &map_absent_chipdrv; |
54 | mtd->priv = map; | |
55 | mtd->name = map->name; | |
56 | mtd->type = MTD_ABSENT; | |
57 | mtd->size = map->size; | |
58 | mtd->erase = map_absent_erase; | |
59 | mtd->read = map_absent_read; | |
60 | mtd->write = map_absent_write; | |
61 | mtd->sync = map_absent_sync; | |
62 | mtd->flags = 0; | |
17ffc7ba AB |
63 | mtd->erasesize = PAGE_SIZE; |
64 | mtd->writesize = 1; | |
1da177e4 LT |
65 | |
66 | __module_get(THIS_MODULE); | |
67 | return mtd; | |
68 | } | |
69 | ||
70 | ||
71 | static int map_absent_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) | |
72 | { | |
73 | *retlen = 0; | |
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 | { | |
79 | *retlen = 0; | |
1f948b43 | 80 | return -ENODEV; |
1da177e4 LT |
81 | } |
82 | ||
83 | static int map_absent_erase(struct mtd_info *mtd, struct erase_info *instr) | |
84 | { | |
85 | return -ENODEV; | |
86 | } | |
87 | ||
88 | static void map_absent_sync(struct mtd_info *mtd) | |
89 | { | |
90 | /* nop */ | |
91 | } | |
92 | ||
93 | static void map_absent_destroy(struct mtd_info *mtd) | |
94 | { | |
95 | /* nop */ | |
96 | } | |
97 | ||
98 | static int __init map_absent_init(void) | |
99 | { | |
100 | register_mtd_chip_driver(&map_absent_chipdrv); | |
101 | return 0; | |
102 | } | |
103 | ||
104 | static void __exit map_absent_exit(void) | |
105 | { | |
106 | unregister_mtd_chip_driver(&map_absent_chipdrv); | |
107 | } | |
108 | ||
109 | module_init(map_absent_init); | |
110 | module_exit(map_absent_exit); | |
111 | ||
112 | MODULE_LICENSE("GPL"); | |
113 | MODULE_AUTHOR("Resilience Corporation - Eric Brower <ebrower@resilience.com>"); | |
114 | MODULE_DESCRIPTION("Placeholder MTD chip driver for 'absent' chips"); |