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