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113 lines
2.8 KiB
113 lines
2.8 KiB
// 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 <[email protected]> |
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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 <[email protected]>"); |
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MODULE_DESCRIPTION("Placeholder MTD chip driver for 'absent' chips");
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