tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Common code to handle map devices which are simple RAM
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/mtd/mtd.h>
16#include <linux/mtd/map.h>
17
18
19static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
20static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
21static int mapram_erase (struct mtd_info *, struct erase_info *);
22static void mapram_nop (struct mtd_info *);
23static struct mtd_info *map_ram_probe(struct map_info *map);
24static int mapram_point (struct mtd_info *mtd, loff_t from, size_t len,
25 size_t *retlen, void **virt, resource_size_t *phys);
26static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len);
27
28
29static struct mtd_chip_driver mapram_chipdrv = {
30 .probe = map_ram_probe,
31 .name = "map_ram",
32 .module = THIS_MODULE
33};
34
35static struct mtd_info *map_ram_probe(struct map_info *map)
36{
37 struct mtd_info *mtd;
38
39 /* Check the first byte is RAM */
40#if 0
41 map_write8(map, 0x55, 0);
42 if (map_read8(map, 0) != 0x55)
43 return NULL;
44
45 map_write8(map, 0xAA, 0);
46 if (map_read8(map, 0) != 0xAA)
47 return NULL;
48
49 /* Check the last byte is RAM */
50 map_write8(map, 0x55, map->size-1);
51 if (map_read8(map, map->size-1) != 0x55)
52 return NULL;
53
54 map_write8(map, 0xAA, map->size-1);
55 if (map_read8(map, map->size-1) != 0xAA)
56 return NULL;
57#endif
58 /* OK. It seems to be RAM. */
59
60 mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
61 if (!mtd)
62 return NULL;
63
64 map->fldrv = &mapram_chipdrv;
65 mtd->priv = map;
66 mtd->name = map->name;
67 mtd->type = MTD_RAM;
68 mtd->size = map->size;
69 mtd->_erase = mapram_erase;
70 mtd->_read = mapram_read;
71 mtd->_write = mapram_write;
72 mtd->_panic_write = mapram_write;
73 mtd->_point = mapram_point;
74 mtd->_sync = mapram_nop;
75 mtd->_unpoint = mapram_unpoint;
76 mtd->flags = MTD_CAP_RAM;
77 mtd->writesize = 1;
78
79 mtd->erasesize = PAGE_SIZE;
80 while(mtd->size & (mtd->erasesize - 1))
81 mtd->erasesize >>= 1;
82
83 __module_get(THIS_MODULE);
84 return mtd;
85}
86
87static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len,
88 size_t *retlen, void **virt, resource_size_t *phys)
89{
90 struct map_info *map = mtd->priv;
91
92 if (!map->virt)
93 return -EINVAL;
94 *virt = map->virt + from;
95 if (phys)
96 *phys = map->phys + from;
97 *retlen = len;
98 return 0;
99}
100
101static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
102{
103 return 0;
104}
105
106static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
107{
108 struct map_info *map = mtd->priv;
109
110 map_copy_from(map, buf, from, len);
111 *retlen = len;
112 return 0;
113}
114
115static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
116{
117 struct map_info *map = mtd->priv;
118
119 map_copy_to(map, to, buf, len);
120 *retlen = len;
121 return 0;
122}
123
124static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
125{
126 /* Yeah, it's inefficient. Who cares? It's faster than a _real_
127 flash erase. */
128 struct map_info *map = mtd->priv;
129 map_word allff;
130 unsigned long i;
131
132 allff = map_word_ff(map);
133 for (i=0; i<instr->len; i += map_bankwidth(map))
134 map_write(map, allff, instr->addr + i);
135 return 0;
136}
137
138static void mapram_nop(struct mtd_info *mtd)
139{
140 /* Nothing to see here */
141}
142
143static int __init map_ram_init(void)
144{
145 register_mtd_chip_driver(&mapram_chipdrv);
146 return 0;
147}
148
149static void __exit map_ram_exit(void)
150{
151 unregister_mtd_chip_driver(&mapram_chipdrv);
152}
153
154module_init(map_ram_init);
155module_exit(map_ram_exit);
156
157MODULE_LICENSE("GPL");
158MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
159MODULE_DESCRIPTION("MTD chip driver for RAM chips");