114 lines
2.8 KiB
C
114 lines
2.8 KiB
C
/*
|
|
* Common code to handle absent "placeholder" devices
|
|
* Copyright 2001 Resilience Corporation <ebrower@resilience.com>
|
|
*
|
|
* This map driver is used to allocate "placeholder" MTD
|
|
* devices on systems that have socketed/removable media.
|
|
* Use of this driver as a fallback preserves the expected
|
|
* registration of MTD device nodes regardless of probe outcome.
|
|
* A usage example is as follows:
|
|
*
|
|
* my_dev[i] = do_map_probe("cfi", &my_map[i]);
|
|
* if(NULL == my_dev[i]) {
|
|
* my_dev[i] = do_map_probe("map_absent", &my_map[i]);
|
|
* }
|
|
*
|
|
* Any device 'probed' with this driver will return -ENODEV
|
|
* upon open.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/types.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/init.h>
|
|
#include <linux/mtd/mtd.h>
|
|
#include <linux/mtd/map.h>
|
|
|
|
static int map_absent_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
|
|
static int map_absent_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
|
|
static int map_absent_erase (struct mtd_info *, struct erase_info *);
|
|
static void map_absent_sync (struct mtd_info *);
|
|
static struct mtd_info *map_absent_probe(struct map_info *map);
|
|
static void map_absent_destroy (struct mtd_info *);
|
|
|
|
|
|
static struct mtd_chip_driver map_absent_chipdrv = {
|
|
.probe = map_absent_probe,
|
|
.destroy = map_absent_destroy,
|
|
.name = "map_absent",
|
|
.module = THIS_MODULE
|
|
};
|
|
|
|
static struct mtd_info *map_absent_probe(struct map_info *map)
|
|
{
|
|
struct mtd_info *mtd;
|
|
|
|
mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
|
|
if (!mtd) {
|
|
return NULL;
|
|
}
|
|
|
|
map->fldrv = &map_absent_chipdrv;
|
|
mtd->priv = map;
|
|
mtd->name = map->name;
|
|
mtd->type = MTD_ABSENT;
|
|
mtd->size = map->size;
|
|
mtd->erase = map_absent_erase;
|
|
mtd->read = map_absent_read;
|
|
mtd->write = map_absent_write;
|
|
mtd->sync = map_absent_sync;
|
|
mtd->flags = 0;
|
|
mtd->erasesize = PAGE_SIZE;
|
|
mtd->writesize = 1;
|
|
|
|
__module_get(THIS_MODULE);
|
|
return mtd;
|
|
}
|
|
|
|
|
|
static int map_absent_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
|
|
{
|
|
*retlen = 0;
|
|
return -ENODEV;
|
|
}
|
|
|
|
static int map_absent_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf)
|
|
{
|
|
*retlen = 0;
|
|
return -ENODEV;
|
|
}
|
|
|
|
static int map_absent_erase(struct mtd_info *mtd, struct erase_info *instr)
|
|
{
|
|
return -ENODEV;
|
|
}
|
|
|
|
static void map_absent_sync(struct mtd_info *mtd)
|
|
{
|
|
/* nop */
|
|
}
|
|
|
|
static void map_absent_destroy(struct mtd_info *mtd)
|
|
{
|
|
/* nop */
|
|
}
|
|
|
|
static int __init map_absent_init(void)
|
|
{
|
|
register_mtd_chip_driver(&map_absent_chipdrv);
|
|
return 0;
|
|
}
|
|
|
|
static void __exit map_absent_exit(void)
|
|
{
|
|
unregister_mtd_chip_driver(&map_absent_chipdrv);
|
|
}
|
|
|
|
module_init(map_absent_init);
|
|
module_exit(map_absent_exit);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Resilience Corporation - Eric Brower <ebrower@resilience.com>");
|
|
MODULE_DESCRIPTION("Placeholder MTD chip driver for 'absent' chips");
|