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/drivers/mtd/chips/map_ram.c

https://bitbucket.org/ndreys/linux-sunxi
C | 157 lines | 111 code | 31 blank | 15 comment | 10 complexity | 7652a7cb926b4f96ff630c7a1610f52d MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  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
126	for (i=0; i<instr->len; i += map_bankwidth(map))
127		map_write(map, allff, instr->addr + i);
128
129	instr->state = MTD_ERASE_DONE;
130
131	mtd_erase_callback(instr);
132
133	return 0;
134}
135
136static void mapram_nop(struct mtd_info *mtd)
137{
138	/* Nothing to see here */
139}
140
141static int __init map_ram_init(void)
142{
143	register_mtd_chip_driver(&mapram_chipdrv);
144	return 0;
145}
146
147static void __exit map_ram_exit(void)
148{
149	unregister_mtd_chip_driver(&mapram_chipdrv);
150}
151
152module_init(map_ram_init);
153module_exit(map_ram_exit);
154
155MODULE_LICENSE("GPL");
156MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
157MODULE_DESCRIPTION("MTD chip driver for RAM chips");