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 unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
24 unsigned long, unsigned long);
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
map_ram_probe(struct map_info * map)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->_get_unmapped_area = mapram_unmapped_area;
69 mtd->_read = mapram_read;
70 mtd->_write = mapram_write;
71 mtd->_panic_write = mapram_write;
72 mtd->_sync = mapram_nop;
73 mtd->flags = MTD_CAP_RAM;
74 mtd->writesize = 1;
75
76 mtd->erasesize = PAGE_SIZE;
77 while(mtd->size & (mtd->erasesize - 1))
78 mtd->erasesize >>= 1;
79
80 __module_get(THIS_MODULE);
81 return mtd;
82 }
83
84
85 /*
86 * Allow NOMMU mmap() to directly map the device (if not NULL)
87 * - return the address to which the offset maps
88 * - return -ENOSYS to indicate refusal to do the mapping
89 */
mapram_unmapped_area(struct mtd_info * mtd,unsigned long len,unsigned long offset,unsigned long flags)90 static unsigned long mapram_unmapped_area(struct mtd_info *mtd,
91 unsigned long len,
92 unsigned long offset,
93 unsigned long flags)
94 {
95 struct map_info *map = mtd->priv;
96 return (unsigned long) map->virt + offset;
97 }
98
mapram_read(struct mtd_info * mtd,loff_t from,size_t len,size_t * retlen,u_char * buf)99 static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
100 {
101 struct map_info *map = mtd->priv;
102
103 map_copy_from(map, buf, from, len);
104 *retlen = len;
105 return 0;
106 }
107
mapram_write(struct mtd_info * mtd,loff_t to,size_t len,size_t * retlen,const u_char * buf)108 static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
109 {
110 struct map_info *map = mtd->priv;
111
112 map_copy_to(map, to, buf, len);
113 *retlen = len;
114 return 0;
115 }
116
mapram_erase(struct mtd_info * mtd,struct erase_info * instr)117 static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
118 {
119 /* Yeah, it's inefficient. Who cares? It's faster than a _real_
120 flash erase. */
121 struct map_info *map = mtd->priv;
122 map_word allff;
123 unsigned long i;
124
125 allff = map_word_ff(map);
126 for (i=0; i<instr->len; i += map_bankwidth(map))
127 map_write(map, allff, instr->addr + i);
128 instr->state = MTD_ERASE_DONE;
129 mtd_erase_callback(instr);
130 return 0;
131 }
132
mapram_nop(struct mtd_info * mtd)133 static void mapram_nop(struct mtd_info *mtd)
134 {
135 /* Nothing to see here */
136 }
137
map_ram_init(void)138 static int __init map_ram_init(void)
139 {
140 register_mtd_chip_driver(&mapram_chipdrv);
141 return 0;
142 }
143
map_ram_exit(void)144 static void __exit map_ram_exit(void)
145 {
146 unregister_mtd_chip_driver(&mapram_chipdrv);
147 }
148
149 module_init(map_ram_init);
150 module_exit(map_ram_exit);
151
152 MODULE_LICENSE("GPL");
153 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
154 MODULE_DESCRIPTION("MTD chip driver for RAM chips");
155