drivers/mtd/chips/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
  15 static DEFINE_SPINLOCK(chip_drvs_lock);
  16 static LIST_HEAD(chip_drvs_list);
  17
  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
  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
  32 static struct mtd_chip_driver *get_mtd_chip_driver (const char *name)
  33 {
  34         struct list_head *pos;
  35         struct mtd_chip_driver *ret = NULL, *this;
  36
  37         spin_lock(&chip_drvs_lock);
  38
  39         list_for_each(pos, &chip_drvs_list) {
  40                 this = list_entry(pos, typeof(*this), list);
  41
  42                 if (!strcmp(this->name, name)) {
  43                         ret = this;
  44                         break;
  45                 }
  46         }
  47         if (ret && !try_module_get(ret->module))
  48                 ret = NULL;
  49
  50         spin_unlock(&chip_drvs_lock);
  51
  52         return ret;
  53 }
  54
  55         /* Hide all the horrid details, like some silly person taking
  56            get_module_symbol() away from us, from the caller. */
  57
  58 struct mtd_info *do_map_probe(const char *name, struct map_info *map)
  59 {
  60         struct mtd_chip_driver *drv;
  61         struct mtd_info *ret;
  62
  63         drv = get_mtd_chip_driver(name);
  64
  65         if (!drv && !request_module("%s", name))
  66                 drv = get_mtd_chip_driver(name);
  67
  68         if (!drv)
  69                 return NULL;
  70
  71         ret = drv->probe(map);
  72
  73         /* We decrease the use count here. It may have been a
  74            probe-only module, which is no longer required from this
  75            point, having given us a handle on (and increased the use
  76            count of) the actual driver code.
  77         */
  78         module_put(drv->module);
  79
  80         return ret;
  81 }
  82 /*
  83  * Destroy an MTD device which was created for a map device.
  84  * Make sure the MTD device is already unregistered before calling this
  85  */
  86 void map_destroy(struct mtd_info *mtd)
  87 {
  88         struct map_info *map = mtd->priv;
  89
  90         if (map->fldrv->destroy)
  91                 map->fldrv->destroy(mtd);
  92
  93         module_put(map->fldrv->module);
  94
  95         kfree(mtd);
  96 }
  97
  98 EXPORT_SYMBOL(register_mtd_chip_driver);
  99 EXPORT_SYMBOL(unregister_mtd_chip_driver);
 100 EXPORT_SYMBOL(do_map_probe);
 101 EXPORT_SYMBOL(map_destroy);
 102
 103 MODULE_LICENSE("GPL");
 104 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 105 MODULE_DESCRIPTION("Core routines for registering and invoking MTD chip drivers");