1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Common code to handle absent "placeholder" devices
4*4882a593Smuzhiyun * Copyright 2001 Resilience Corporation <ebrower@resilience.com>
5*4882a593Smuzhiyun *
6*4882a593Smuzhiyun * This map driver is used to allocate "placeholder" MTD
7*4882a593Smuzhiyun * devices on systems that have socketed/removable media.
8*4882a593Smuzhiyun * Use of this driver as a fallback preserves the expected
9*4882a593Smuzhiyun * registration of MTD device nodes regardless of probe outcome.
10*4882a593Smuzhiyun * A usage example is as follows:
11*4882a593Smuzhiyun *
12*4882a593Smuzhiyun * my_dev[i] = do_map_probe("cfi", &my_map[i]);
13*4882a593Smuzhiyun * if(NULL == my_dev[i]) {
14*4882a593Smuzhiyun * my_dev[i] = do_map_probe("map_absent", &my_map[i]);
15*4882a593Smuzhiyun * }
16*4882a593Smuzhiyun *
17*4882a593Smuzhiyun * Any device 'probed' with this driver will return -ENODEV
18*4882a593Smuzhiyun * upon open.
19*4882a593Smuzhiyun */
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun #include <linux/module.h>
22*4882a593Smuzhiyun #include <linux/types.h>
23*4882a593Smuzhiyun #include <linux/kernel.h>
24*4882a593Smuzhiyun #include <linux/errno.h>
25*4882a593Smuzhiyun #include <linux/slab.h>
26*4882a593Smuzhiyun #include <linux/init.h>
27*4882a593Smuzhiyun #include <linux/mtd/mtd.h>
28*4882a593Smuzhiyun #include <linux/mtd/map.h>
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun static int map_absent_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
31*4882a593Smuzhiyun static int map_absent_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
32*4882a593Smuzhiyun static int map_absent_erase (struct mtd_info *, struct erase_info *);
33*4882a593Smuzhiyun static void map_absent_sync (struct mtd_info *);
34*4882a593Smuzhiyun static struct mtd_info *map_absent_probe(struct map_info *map);
35*4882a593Smuzhiyun static void map_absent_destroy (struct mtd_info *);
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun static struct mtd_chip_driver map_absent_chipdrv = {
39*4882a593Smuzhiyun .probe = map_absent_probe,
40*4882a593Smuzhiyun .destroy = map_absent_destroy,
41*4882a593Smuzhiyun .name = "map_absent",
42*4882a593Smuzhiyun .module = THIS_MODULE
43*4882a593Smuzhiyun };
44*4882a593Smuzhiyun
map_absent_probe(struct map_info * map)45*4882a593Smuzhiyun static struct mtd_info *map_absent_probe(struct map_info *map)
46*4882a593Smuzhiyun {
47*4882a593Smuzhiyun struct mtd_info *mtd;
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
50*4882a593Smuzhiyun if (!mtd) {
51*4882a593Smuzhiyun return NULL;
52*4882a593Smuzhiyun }
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun map->fldrv = &map_absent_chipdrv;
55*4882a593Smuzhiyun mtd->priv = map;
56*4882a593Smuzhiyun mtd->name = map->name;
57*4882a593Smuzhiyun mtd->type = MTD_ABSENT;
58*4882a593Smuzhiyun mtd->size = map->size;
59*4882a593Smuzhiyun mtd->_erase = map_absent_erase;
60*4882a593Smuzhiyun mtd->_read = map_absent_read;
61*4882a593Smuzhiyun mtd->_write = map_absent_write;
62*4882a593Smuzhiyun mtd->_sync = map_absent_sync;
63*4882a593Smuzhiyun mtd->flags = 0;
64*4882a593Smuzhiyun mtd->erasesize = PAGE_SIZE;
65*4882a593Smuzhiyun mtd->writesize = 1;
66*4882a593Smuzhiyun
67*4882a593Smuzhiyun __module_get(THIS_MODULE);
68*4882a593Smuzhiyun return mtd;
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun
map_absent_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)72*4882a593Smuzhiyun static int map_absent_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
73*4882a593Smuzhiyun {
74*4882a593Smuzhiyun return -ENODEV;
75*4882a593Smuzhiyun }
76*4882a593Smuzhiyun
map_absent_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)77*4882a593Smuzhiyun static int map_absent_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
78*4882a593Smuzhiyun {
79*4882a593Smuzhiyun return -ENODEV;
80*4882a593Smuzhiyun }
81*4882a593Smuzhiyun
map_absent_erase(struct mtd_info * mtd,struct erase_info * instr)82*4882a593Smuzhiyun static int map_absent_erase(struct mtd_info *mtd, struct erase_info *instr)
83*4882a593Smuzhiyun {
84*4882a593Smuzhiyun return -ENODEV;
85*4882a593Smuzhiyun }
86*4882a593Smuzhiyun
map_absent_sync(struct mtd_info * mtd)87*4882a593Smuzhiyun static void map_absent_sync(struct mtd_info *mtd)
88*4882a593Smuzhiyun {
89*4882a593Smuzhiyun /* nop */
90*4882a593Smuzhiyun }
91*4882a593Smuzhiyun
map_absent_destroy(struct mtd_info * mtd)92*4882a593Smuzhiyun static void map_absent_destroy(struct mtd_info *mtd)
93*4882a593Smuzhiyun {
94*4882a593Smuzhiyun /* nop */
95*4882a593Smuzhiyun }
96*4882a593Smuzhiyun
map_absent_init(void)97*4882a593Smuzhiyun static int __init map_absent_init(void)
98*4882a593Smuzhiyun {
99*4882a593Smuzhiyun register_mtd_chip_driver(&map_absent_chipdrv);
100*4882a593Smuzhiyun return 0;
101*4882a593Smuzhiyun }
102*4882a593Smuzhiyun
map_absent_exit(void)103*4882a593Smuzhiyun static void __exit map_absent_exit(void)
104*4882a593Smuzhiyun {
105*4882a593Smuzhiyun unregister_mtd_chip_driver(&map_absent_chipdrv);
106*4882a593Smuzhiyun }
107*4882a593Smuzhiyun
108*4882a593Smuzhiyun module_init(map_absent_init);
109*4882a593Smuzhiyun module_exit(map_absent_exit);
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun MODULE_LICENSE("GPL");
112*4882a593Smuzhiyun MODULE_AUTHOR("Resilience Corporation - Eric Brower <ebrower@resilience.com>");
113*4882a593Smuzhiyun MODULE_DESCRIPTION("Placeholder MTD chip driver for 'absent' chips");
114