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/*

 * Common code to handle absent "placeholder" devices

 * Copyright 2001 Resilience Corporation <ebrower@resilience.com>

 * $Id: map_absent.c,v 1.1.1.1 2004-04-15 01:52:07 phoenix Exp $

 *

 * 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/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 = kmalloc(sizeof(*mtd), GFP_KERNEL);

        if (!mtd) {

                return NULL;

        }

        memset(mtd, 0, sizeof(*mtd));

        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;

        MOD_INC_USE_COUNT;

        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 */

}

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");