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/*
* 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");
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