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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_obj(*mtd);
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->_sync = mapram_nop;
74 mtd->flags = MTD_CAP_RAM;
75 mtd->writesize = 1;
76
77 /* Disable direct access when NO_XIP is set */
78 if (map->phys != NO_XIP) {
79 mtd->_point = mapram_point;
80 mtd->_unpoint = mapram_unpoint;
81 }
82
83 mtd->erasesize = PAGE_SIZE;
84 while(mtd->size & (mtd->erasesize - 1))
85 mtd->erasesize >>= 1;
86
87 __module_get(THIS_MODULE);
88 return mtd;
89}
90
91static int mapram_point(struct mtd_info *mtd, loff_t from, size_t len,
92 size_t *retlen, void **virt, resource_size_t *phys)
93{
94 struct map_info *map = mtd->priv;
95
96 if (!map->virt)
97 return -EINVAL;
98 *virt = map->virt + from;
99 if (phys)
100 *phys = map->phys + from;
101 *retlen = len;
102 return 0;
103}
104
105static int mapram_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
106{
107 return 0;
108}
109
110static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
111{
112 struct map_info *map = mtd->priv;
113
114 map_copy_from(map, buf, from, len);
115 *retlen = len;
116 return 0;
117}
118
119static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
120{
121 struct map_info *map = mtd->priv;
122
123 map_copy_to(map, to, buf, len);
124 *retlen = len;
125 return 0;
126}
127
128static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
129{
130 /* Yeah, it's inefficient. Who cares? It's faster than a _real_
131 flash erase. */
132 struct map_info *map = mtd->priv;
133 map_word allff;
134 unsigned long i;
135
136 allff = map_word_ff(map);
137 for (i=0; i<instr->len; i += map_bankwidth(map))
138 map_write(map, allff, instr->addr + i);
139 return 0;
140}
141
142static void mapram_nop(struct mtd_info *mtd)
143{
144 /* Nothing to see here */
145}
146
147static int __init map_ram_init(void)
148{
149 register_mtd_chip_driver(&mapram_chipdrv);
150 return 0;
151}
152
153static void __exit map_ram_exit(void)
154{
155 unregister_mtd_chip_driver(&mapram_chipdrv);
156}
157
158module_init(map_ram_init);
159module_exit(map_ram_exit);
160
161MODULE_LICENSE("GPL");
162MODULE_AUTHOR("David Woodhouse <[email protected]>");
163MODULE_DESCRIPTION("MTD chip driver for RAM chips");