chipreg.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Registration for chip drivers
  4 *
  5 */
  6
  7#include <linux/kernel.h>
  8#include <linux/module.h>
  9#include <linux/kmod.h>
 10#include <linux/spinlock.h>
 11#include <linux/slab.h>
 12#include <linux/mtd/map.h>
 13#include <linux/mtd/mtd.h>
 14
 15static DEFINE_SPINLOCK(chip_drvs_lock);
 16static LIST_HEAD(chip_drvs_list);
 17
 18void register_mtd_chip_driver(struct mtd_chip_driver *drv)
 19{
 20	spin_lock(&chip_drvs_lock);
 21	list_add(&drv->list, &chip_drvs_list);
 22	spin_unlock(&chip_drvs_lock);
 23}
 24
 25void unregister_mtd_chip_driver(struct mtd_chip_driver *drv)
 26{
 27	spin_lock(&chip_drvs_lock);
 28	list_del(&drv->list);
 29	spin_unlock(&chip_drvs_lock);
 30}
 31
 32static struct mtd_chip_driver *get_mtd_chip_driver (const char *name)
 33{
 34	struct mtd_chip_driver *ret = NULL, *this;
 35
 36	spin_lock(&chip_drvs_lock);
 37
 38	list_for_each_entry(this, &chip_drvs_list, list) {
 39		if (!strcmp(this->name, name)) {
 40			ret = this;
 41			break;
 42		}
 43	}
 44	if (ret && !try_module_get(ret->module))
 45		ret = NULL;
 46
 47	spin_unlock(&chip_drvs_lock);
 48
 49	return ret;
 50}
 51
 52	/* Hide all the horrid details, like some silly person taking
 53	   get_module_symbol() away from us, from the caller. */
 54
 55struct mtd_info *do_map_probe(const char *name, struct map_info *map)
 56{
 57	struct mtd_chip_driver *drv;
 58	struct mtd_info *ret;
 59
 60	drv = get_mtd_chip_driver(name);
 61
 62	if (!drv && !request_module("%s", name))
 63		drv = get_mtd_chip_driver(name);
 64
 65	if (!drv)
 66		return NULL;
 67
 68	ret = drv->probe(map);
 69
 70	/* We decrease the use count here. It may have been a
 71	   probe-only module, which is no longer required from this
 72	   point, having given us a handle on (and increased the use
 73	   count of) the actual driver code.
 74	*/
 75	module_put(drv->module);
 76
 77	return ret;
 78}
 79/*
 80 * Destroy an MTD device which was created for a map device.
 81 * Make sure the MTD device is already unregistered before calling this
 82 */
 83void map_destroy(struct mtd_info *mtd)
 84{
 85	struct map_info *map = mtd->priv;
 86
 87	if (map->fldrv->destroy)
 88		map->fldrv->destroy(mtd);
 89
 90	module_put(map->fldrv->module);
 91
 92	kfree(mtd);
 93}
 94
 95EXPORT_SYMBOL(register_mtd_chip_driver);
 96EXPORT_SYMBOL(unregister_mtd_chip_driver);
 97EXPORT_SYMBOL(do_map_probe);
 98EXPORT_SYMBOL(map_destroy);
 99
100MODULE_LICENSE("GPL");
101MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
102MODULE_DESCRIPTION("Core routines for registering and invoking MTD chip drivers");