1 /*
2 * Common code to handle map devices which are simple RAM
3 * (C) 2000 Red Hat. GPL'd.
4 * $Id: map_ram.c,v 1.22 2005/01/05 18:05:12 dwmw2 Exp $
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 #include <linux/mtd/compatmac.h>
18
19
20 static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
21 static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
22 static int mapram_erase (struct mtd_info *, struct erase_info *);
23 static void mapram_nop (struct mtd_info *);
24 static struct mtd_info *map_ram_probe(struct map_info *map);
25
26
27 static struct mtd_chip_driver mapram_chipdrv = {
28 .probe = map_ram_probe,
29 .name = "map_ram",
30 .module = THIS_MODULE
31 };
32
33 static struct mtd_info *map_ram_probe(struct map_info *map)
34 {
35 struct mtd_info *mtd;
36
37 /* Check the first byte is RAM */
38 #if 0
39 map_write8(map, 0x55, 0);
40 if (map_read8(map, 0) != 0x55)
41 return NULL;
42
43 map_write8(map, 0xAA, 0);
44 if (map_read8(map, 0) != 0xAA)
45 return NULL;
46
47 /* Check the last byte is RAM */
48 map_write8(map, 0x55, map->size-1);
49 if (map_read8(map, map->size-1) != 0x55)
50 return NULL;
51
52 map_write8(map, 0xAA, map->size-1);
53 if (map_read8(map, map->size-1) != 0xAA)
54 return NULL;
55 #endif
56 /* OK. It seems to be RAM. */
57
58 mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
59 if (!mtd)
60 return NULL;
61
62 map->fldrv = &mapram_chipdrv;
63 mtd->priv = map;
64 mtd->name = map->name;
65 mtd->type = MTD_RAM;
66 mtd->size = map->size;
67 mtd->erase = mapram_erase;
68 mtd->read = mapram_read;
69 mtd->write = mapram_write;
70 mtd->sync = mapram_nop;
71 mtd->flags = MTD_CAP_RAM;
72 mtd->writesize = 1;
73
74 mtd->erasesize = PAGE_SIZE;
75 while(mtd->size & (mtd->erasesize - 1))
76 mtd->erasesize >>= 1;
77
78 __module_get(THIS_MODULE);
79 return mtd;
80 }
81
82
83 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
84 {
85 struct map_info *map = mtd->priv;
86
87 map_copy_from(map, buf, from, len);
88 *retlen = len;
89 return 0;
90 }
91
92 static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
93 {
94 struct map_info *map = mtd->priv;
95
96 map_copy_to(map, to, buf, len);
97 *retlen = len;
98 return 0;
99 }
100
101 static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
102 {
103 /* Yeah, it's inefficient. Who cares? It's faster than a _real_
104 flash erase. */
105 struct map_info *map = mtd->priv;
106 map_word allff;
107 unsigned long i;
108
109 allff = map_word_ff(map);
110
111 for (i=0; i<instr->len; i += map_bankwidth(map))
112 map_write(map, allff, instr->addr + i);
113
114 instr->state = MTD_ERASE_DONE;
115
116 mtd_erase_callback(instr);
117
118 return 0;
119 }
120
121 static void mapram_nop(struct mtd_info *mtd)
122 {
123 /* Nothing to see here */
124 }
125
126 static int __init map_ram_init(void)
127 {
128 register_mtd_chip_driver(&mapram_chipdrv);
129 return 0;
130 }
131
132 static void __exit map_ram_exit(void)
133 {
134 unregister_mtd_chip_driver(&mapram_chipdrv);
135 }
136
137 module_init(map_ram_init);
138 module_exit(map_ram_exit);
139
140 MODULE_LICENSE("GPL");
141 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
142 MODULE_DESCRIPTION("MTD chip driver for RAM chips");
143
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