summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/chips/map_ram.c
blob: afb43d5e178269d33443a59a439245263cb263c0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
/*
 * Common code to handle map devices which are simple RAM
 * (C) 2000 Red Hat. GPL'd.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/io.h>
#include <asm/byteorder.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>


static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
static int mapram_erase (struct mtd_info *, struct erase_info *);
static void mapram_nop (struct mtd_info *);
static struct mtd_info *map_ram_probe(struct map_info *map);
static unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
					  unsigned long, unsigned long);


static struct mtd_chip_driver mapram_chipdrv = {
	.probe	= map_ram_probe,
	.name	= "map_ram",
	.module	= THIS_MODULE
};

static struct mtd_info *map_ram_probe(struct map_info *map)
{
	struct mtd_info *mtd;

	/* Check the first byte is RAM */
#if 0
	map_write8(map, 0x55, 0);
	if (map_read8(map, 0) != 0x55)
		return NULL;

	map_write8(map, 0xAA, 0);
	if (map_read8(map, 0) != 0xAA)
		return NULL;

	/* Check the last byte is RAM */
	map_write8(map, 0x55, map->size-1);
	if (map_read8(map, map->size-1) != 0x55)
		return NULL;

	map_write8(map, 0xAA, map->size-1);
	if (map_read8(map, map->size-1) != 0xAA)
		return NULL;
#endif
	/* OK. It seems to be RAM. */

	mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
	if (!mtd)
		return NULL;

	map->fldrv = &mapram_chipdrv;
	mtd->priv = map;
	mtd->name = map->name;
	mtd->type = MTD_RAM;
	mtd->size = map->size;
	mtd->_erase = mapram_erase;
	mtd->_get_unmapped_area = mapram_unmapped_area;
	mtd->_read = mapram_read;
	mtd->_write = mapram_write;
	mtd->_panic_write = mapram_write;
	mtd->_sync = mapram_nop;
	mtd->flags = MTD_CAP_RAM;
	mtd->writesize = 1;

	mtd->erasesize = PAGE_SIZE;
 	while(mtd->size & (mtd->erasesize - 1))
		mtd->erasesize >>= 1;

	__module_get(THIS_MODULE);
	return mtd;
}


/*
 * Allow NOMMU mmap() to directly map the device (if not NULL)
 * - return the address to which the offset maps
 * - return -ENOSYS to indicate refusal to do the mapping
 */
static unsigned long mapram_unmapped_area(struct mtd_info *mtd,
					  unsigned long len,
					  unsigned long offset,
					  unsigned long flags)
{
	struct map_info *map = mtd->priv;
	return (unsigned long) map->virt + offset;
}

static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
{
	struct map_info *map = mtd->priv;

	map_copy_from(map, buf, from, len);
	*retlen = len;
	return 0;
}

static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
{
	struct map_info *map = mtd->priv;

	map_copy_to(map, to, buf, len);
	*retlen = len;
	return 0;
}

static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
{
	/* Yeah, it's inefficient. Who cares? It's faster than a _real_
	   flash erase. */
	struct map_info *map = mtd->priv;
	map_word allff;
	unsigned long i;

	allff = map_word_ff(map);
	for (i=0; i<instr->len; i += map_bankwidth(map))
		map_write(map, allff, instr->addr + i);
	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);
	return 0;
}

static void mapram_nop(struct mtd_info *mtd)
{
	/* Nothing to see here */
}

static int __init map_ram_init(void)
{
	register_mtd_chip_driver(&mapram_chipdrv);
	return 0;
}

static void __exit map_ram_exit(void)
{
	unregister_mtd_chip_driver(&mapram_chipdrv);
}

module_init(map_ram_init);
module_exit(map_ram_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("MTD chip driver for RAM chips");