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 
15 static DEFINE_SPINLOCK(chip_drvs_lock);
16 static LIST_HEAD(chip_drvs_list);
17 
register_mtd_chip_driver(struct mtd_chip_driver * drv)18 void 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 
unregister_mtd_chip_driver(struct mtd_chip_driver * drv)25 void 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 
get_mtd_chip_driver(const char * name)32 static 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 
do_map_probe(const char * name,struct map_info * map)55 struct 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  */
map_destroy(struct mtd_info * mtd)83 void 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 
95 EXPORT_SYMBOL(register_mtd_chip_driver);
96 EXPORT_SYMBOL(unregister_mtd_chip_driver);
97 EXPORT_SYMBOL(do_map_probe);
98 EXPORT_SYMBOL(map_destroy);
99 
100 MODULE_LICENSE("GPL");
101 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
102 MODULE_DESCRIPTION("Core routines for registering and invoking MTD chip drivers");
103