1/*
2 * Common code to handle map devices which are simple RAM
3 * (C) 2000 Red Hat. GPL'd.
4 */
5
6#include <linux/module.h>
7#include <linux/types.h>
8#include <linux/kernel.h>
9#include <asm/io.h>
10#include <asm/byteorder.h>
11#include <linux/errno.h>
12#include <linux/slab.h>
13#include <linux/init.h>
14#include <linux/mtd/mtd.h>
15#include <linux/mtd/map.h>
16
17
18static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
19static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
20static int mapram_erase (struct mtd_info *, struct erase_info *);
21static void mapram_nop (struct mtd_info *);
22static struct mtd_info *map_ram_probe(struct map_info *map);
23static unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
24					  unsigned long, unsigned long);
25
26
27static struct mtd_chip_driver mapram_chipdrv = {
28	.probe	= map_ram_probe,
29	.name	= "map_ram",
30	.module	= THIS_MODULE
31};
32
33static 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->_get_unmapped_area = mapram_unmapped_area;
69	mtd->_read = mapram_read;
70	mtd->_write = mapram_write;
71	mtd->_sync = mapram_nop;
72	mtd->flags = MTD_CAP_RAM;
73	mtd->writesize = 1;
74
75	mtd->erasesize = PAGE_SIZE;
76 	while(mtd->size & (mtd->erasesize - 1))
77		mtd->erasesize >>= 1;
78
79	__module_get(THIS_MODULE);
80	return mtd;
81}
82
83
84/*
85 * Allow NOMMU mmap() to directly map the device (if not NULL)
86 * - return the address to which the offset maps
87 * - return -ENOSYS to indicate refusal to do the mapping
88 */
89static unsigned long mapram_unmapped_area(struct mtd_info *mtd,
90					  unsigned long len,
91					  unsigned long offset,
92					  unsigned long flags)
93{
94	struct map_info *map = mtd->priv;
95	return (unsigned long) map->virt + offset;
96}
97
98static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
99{
100	struct map_info *map = mtd->priv;
101
102	map_copy_from(map, buf, from, len);
103	*retlen = len;
104	return 0;
105}
106
107static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
108{
109	struct map_info *map = mtd->priv;
110
111	map_copy_to(map, to, buf, len);
112	*retlen = len;
113	return 0;
114}
115
116static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
117{
118	/* Yeah, it's inefficient. Who cares? It's faster than a _real_
119	   flash erase. */
120	struct map_info *map = mtd->priv;
121	map_word allff;
122	unsigned long i;
123
124	allff = map_word_ff(map);
125	for (i=0; i<instr->len; i += map_bankwidth(map))
126		map_write(map, allff, instr->addr + i);
127	instr->state = MTD_ERASE_DONE;
128	mtd_erase_callback(instr);
129	return 0;
130}
131
132static void mapram_nop(struct mtd_info *mtd)
133{
134	/* Nothing to see here */
135}
136
137static int __init map_ram_init(void)
138{
139	register_mtd_chip_driver(&mapram_chipdrv);
140	return 0;
141}
142
143static void __exit map_ram_exit(void)
144{
145	unregister_mtd_chip_driver(&mapram_chipdrv);
146}
147
148module_init(map_ram_init);
149module_exit(map_ram_exit);
150
151MODULE_LICENSE("GPL");
152MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
153MODULE_DESCRIPTION("MTD chip driver for RAM chips");
154