// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Common code to handle absent "placeholder" devices
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* Copyright 2001 Resilience Corporation <ebrower@resilience.com>
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*
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* This map driver is used to allocate "placeholder" MTD
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* devices on systems that have socketed/removable media.
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* Use of this driver as a fallback preserves the expected
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* registration of MTD device nodes regardless of probe outcome.
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* A usage example is as follows:
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*
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* my_dev[i] = do_map_probe("cfi", &my_map[i]);
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* if(NULL == my_dev[i]) {
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* my_dev[i] = do_map_probe("map_absent", &my_map[i]);
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* }
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*
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* Any device 'probed' with this driver will return -ENODEV
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* upon open.
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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 <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 map_absent_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
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static int map_absent_write (struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
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static int map_absent_erase (struct mtd_info *, struct erase_info *);
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static void map_absent_sync (struct mtd_info *);
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static struct mtd_info *map_absent_probe(struct map_info *map);
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static void map_absent_destroy (struct mtd_info *);
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static struct mtd_chip_driver map_absent_chipdrv = {
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.probe = map_absent_probe,
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.destroy = map_absent_destroy,
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.name = "map_absent",
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.module = THIS_MODULE
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};
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static struct mtd_info *map_absent_probe(struct map_info *map)
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{
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struct mtd_info *mtd;
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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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}
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map->fldrv = &map_absent_chipdrv;
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mtd->priv = map;
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mtd->name = map->name;
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mtd->type = MTD_ABSENT;
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mtd->size = map->size;
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mtd->_erase = map_absent_erase;
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mtd->_read = map_absent_read;
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mtd->_write = map_absent_write;
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mtd->_sync = map_absent_sync;
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mtd->flags = 0;
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mtd->erasesize = PAGE_SIZE;
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mtd->writesize = 1;
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__module_get(THIS_MODULE);
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return mtd;
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}
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static int map_absent_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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return -ENODEV;
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}
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static int map_absent_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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return -ENODEV;
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}
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static int map_absent_erase(struct mtd_info *mtd, struct erase_info *instr)
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{
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return -ENODEV;
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}
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static void map_absent_sync(struct mtd_info *mtd)
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{
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/* nop */
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}
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static void map_absent_destroy(struct mtd_info *mtd)
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{
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/* nop */
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}
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static int __init map_absent_init(void)
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{
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register_mtd_chip_driver(&map_absent_chipdrv);
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return 0;
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}
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static void __exit map_absent_exit(void)
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{
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unregister_mtd_chip_driver(&map_absent_chipdrv);
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}
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module_init(map_absent_init);
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module_exit(map_absent_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Resilience Corporation - Eric Brower <ebrower@resilience.com>");
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MODULE_DESCRIPTION("Placeholder MTD chip driver for 'absent' chips");
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