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 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
  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  */
  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");