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NOMMU: Present backing device capabilities for MTD chardevs

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Present backing device capabilities for MTD character device files to allow
NOMMU mmap to do direct mapping where possible.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Bernd Schmidt <bernd.schmidt@analog.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
David Howells
2009-02-12 10:40:00 +00:00
committed by David Woodhouse
parent 9ce969082e
commit 402d326519
10 changed files with 215 additions and 2 deletions
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17
drivers/mtd/chips/map_ram.c
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@@ -21,6 +21,8 @@ static int mapram_write (struct mtd_info *, loff_t, size_t, size_t *, const u_ch
static int mapram_erase (struct mtd_info *, struct erase_info *);
static void mapram_nop (struct mtd_info *);
static struct mtd_info *map_ram_probe(struct map_info *map);
static unsigned long mapram_unmapped_area(struct mtd_info *, unsigned long,
unsigned long, unsigned long);
static struct mtd_chip_driver mapram_chipdrv = {
@@ -64,6 +66,7 @@ static struct mtd_info *map_ram_probe(struct map_info *map)
mtd->type = MTD_RAM;
mtd->size = map->size;
mtd->erase = mapram_erase;
mtd->get_unmapped_area = mapram_unmapped_area;
mtd->read = mapram_read;
mtd->write = mapram_write;
mtd->sync = mapram_nop;
@@ -79,6 +82,20 @@ static struct mtd_info *map_ram_probe(struct map_info *map)
}
/*
* Allow NOMMU mmap() to directly map the device (if not NULL)
* - return the address to which the offset maps
* - return -ENOSYS to indicate refusal to do the mapping
*/
static unsigned long mapram_unmapped_area(struct mtd_info *mtd,
unsigned long len,
unsigned long offset,
unsigned long flags)
{
struct map_info *map = mtd->priv;
return (unsigned long) map->virt + offset;
}
static int mapram_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
{
struct map_info *map = mtd->priv;