ia64/linux-2.6.18-xen.hg

view drivers/mtd/chips/map_absent.c @ 0:831230e53067

Import 2.6.18 from kernel.org tarball.
author Ian Campbell <ian.campbell@xensource.com>
date Wed Apr 11 14:15:44 2007 +0100 (2007-04-11)
parents
children
line source
1 /*
2 * Common code to handle absent "placeholder" devices
3 * Copyright 2001 Resilience Corporation <ebrower@resilience.com>
4 * $Id: map_absent.c,v 1.6 2005/11/07 11:14:23 gleixner Exp $
5 *
6 * This map driver is used to allocate "placeholder" MTD
7 * devices on systems that have socketed/removable media.
8 * Use of this driver as a fallback preserves the expected
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 */
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>
29 #include <linux/mtd/compatmac.h>
31 static int map_absent_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
32 static int map_absent_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
33 static int map_absent_erase (struct mtd_info *, struct erase_info *);
34 static void map_absent_sync (struct mtd_info *);
35 static struct mtd_info *map_absent_probe(struct map_info *map);
36 static void map_absent_destroy (struct mtd_info *);
39 static struct mtd_chip_driver map_absent_chipdrv = {
40 .probe = map_absent_probe,
41 .destroy = map_absent_destroy,
42 .name = "map_absent",
43 .module = THIS_MODULE
44 };
46 static struct mtd_info *map_absent_probe(struct map_info *map)
47 {
48 struct mtd_info *mtd;
50 mtd = kmalloc(sizeof(*mtd), GFP_KERNEL);
51 if (!mtd) {
52 return NULL;
53 }
55 memset(mtd, 0, sizeof(*mtd));
57 map->fldrv = &map_absent_chipdrv;
58 mtd->priv = map;
59 mtd->name = map->name;
60 mtd->type = MTD_ABSENT;
61 mtd->size = map->size;
62 mtd->erase = map_absent_erase;
63 mtd->read = map_absent_read;
64 mtd->write = map_absent_write;
65 mtd->sync = map_absent_sync;
66 mtd->flags = 0;
67 mtd->erasesize = PAGE_SIZE;
68 mtd->writesize = 1;
70 __module_get(THIS_MODULE);
71 return mtd;
72 }
75 static int map_absent_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
76 {
77 *retlen = 0;
78 return -ENODEV;
79 }
81 static int map_absent_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
82 {
83 *retlen = 0;
84 return -ENODEV;
85 }
87 static int map_absent_erase(struct mtd_info *mtd, struct erase_info *instr)
88 {
89 return -ENODEV;
90 }
92 static void map_absent_sync(struct mtd_info *mtd)
93 {
94 /* nop */
95 }
97 static void map_absent_destroy(struct mtd_info *mtd)
98 {
99 /* nop */
100 }
102 static int __init map_absent_init(void)
103 {
104 register_mtd_chip_driver(&map_absent_chipdrv);
105 return 0;
106 }
108 static void __exit map_absent_exit(void)
109 {
110 unregister_mtd_chip_driver(&map_absent_chipdrv);
111 }
113 module_init(map_absent_init);
114 module_exit(map_absent_exit);
116 MODULE_LICENSE("GPL");
117 MODULE_AUTHOR("Resilience Corporation - Eric Brower <ebrower@resilience.com>");
118 MODULE_DESCRIPTION("Placeholder MTD chip driver for 'absent' chips");