157 lines
3.6 KiB
C
157 lines
3.6 KiB
C
/*
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* Common code to handle map devices which are simple RAM
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* (C) 2000 Red Hat. GPL'd.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <asm/io.h>
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#include <asm/byteorder.h>
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/map.h>
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static int mapram_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
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static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
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static int mapram_erase (struct mtd_info *, struct erase_info *);
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static void mapram_nop (struct mtd_info *);
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static struct mtd_info *map_ram_probe(struct map_info *map);
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static unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
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unsigned long, unsigned long);
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static struct mtd_chip_driver mapram_chipdrv = {
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.probe = map_ram_probe,
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.name = "map_ram",
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.module = THIS_MODULE
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};
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static struct mtd_info *map_ram_probe(struct map_info *map)
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{
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struct mtd_info *mtd;
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/* Check the first byte is RAM */
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#if 0
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map_write8(map, 0x55, 0);
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if (map_read8(map, 0) != 0x55)
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return NULL;
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map_write8(map, 0xAA, 0);
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if (map_read8(map, 0) != 0xAA)
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return NULL;
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/* Check the last byte is RAM */
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map_write8(map, 0x55, map->size-1);
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if (map_read8(map, map->size-1) != 0x55)
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return NULL;
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map_write8(map, 0xAA, map->size-1);
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if (map_read8(map, map->size-1) != 0xAA)
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return NULL;
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#endif
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/* OK. It seems to be RAM. */
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mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
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if (!mtd)
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return NULL;
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map->fldrv = &mapram_chipdrv;
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mtd->priv = map;
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mtd->name = map->name;
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mtd->type = MTD_RAM;
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mtd->size = map->size;
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mtd->erase = mapram_erase;
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mtd->get_unmapped_area = mapram_unmapped_area;
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mtd->read = mapram_read;
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mtd->write = mapram_write;
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mtd->sync = mapram_nop;
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mtd->flags = MTD_CAP_RAM;
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mtd->writesize = 1;
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mtd->erasesize = PAGE_SIZE;
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while(mtd->size & (mtd->erasesize - 1))
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mtd->erasesize >>= 1;
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__module_get(THIS_MODULE);
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return mtd;
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}
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/*
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* Allow NOMMU mmap() to directly map the device (if not NULL)
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* - return the address to which the offset maps
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* - return -ENOSYS to indicate refusal to do the mapping
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*/
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static unsigned long mapram_unmapped_area(struct mtd_info *mtd,
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unsigned long len,
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unsigned long offset,
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unsigned long flags)
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{
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struct map_info *map = mtd->priv;
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return (unsigned long) map->virt + offset;
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}
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static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
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{
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struct map_info *map = mtd->priv;
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map_copy_from(map, buf, from, len);
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*retlen = len;
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return 0;
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}
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static int mapram_write (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
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{
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struct map_info *map = mtd->priv;
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map_copy_to(map, to, buf, len);
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*retlen = len;
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return 0;
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}
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static int mapram_erase (struct mtd_info *mtd, struct erase_info *instr)
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{
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/* Yeah, it's inefficient. Who cares? It's faster than a _real_
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flash erase. */
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struct map_info *map = mtd->priv;
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map_word allff;
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unsigned long i;
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allff = map_word_ff(map);
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for (i=0; i<instr->len; i += map_bankwidth(map))
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map_write(map, allff, instr->addr + i);
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instr->state = MTD_ERASE_DONE;
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mtd_erase_callback(instr);
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return 0;
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}
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static void mapram_nop(struct mtd_info *mtd)
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{
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/* Nothing to see here */
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}
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static int __init map_ram_init(void)
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{
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register_mtd_chip_driver(&mapram_chipdrv);
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return 0;
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}
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static void __exit map_ram_exit(void)
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{
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unregister_mtd_chip_driver(&mapram_chipdrv);
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}
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module_init(map_ram_init);
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module_exit(map_ram_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
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MODULE_DESCRIPTION("MTD chip driver for RAM chips");
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