diff options
Diffstat (limited to 'drivers/mtd/chips/map_absent.c')
| -rw-r--r-- | drivers/mtd/chips/map_absent.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/drivers/mtd/chips/map_absent.c b/drivers/mtd/chips/map_absent.c new file mode 100644 index 000000000000..c6c83833cc32 --- /dev/null +++ b/drivers/mtd/chips/map_absent.c @@ -0,0 +1,117 @@ +/* + * Common code to handle absent "placeholder" devices + * Copyright 2001 Resilience Corporation <ebrower@resilience.com> + * $Id: map_absent.c,v 1.5 2004/11/16 18:29:00 dwmw2 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/init.h> +#include <linux/mtd/mtd.h> +#include <linux/mtd/map.h> +#include <linux/mtd/compatmac.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; + + __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"); |