LXR linux/drivers/platform/x86/firmware_attributes

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2
   3/* Firmware attributes class helper module */
   4
   5#include <linux/mutex.h>
   6#include <linux/device/class.h>
   7#include <linux/module.h>
   8#include "firmware_attributes_class.h"
   9
  10static DEFINE_MUTEX(fw_attr_lock);
  11static int fw_attr_inuse;
  12
  13static struct class firmware_attributes_class = {
  14        .name = "firmware-attributes",
  15};
  16
  17int fw_attributes_class_get(struct class **fw_attr_class)
  18{
  19        int err;
  20
  21        mutex_lock(&fw_attr_lock);
  22        if (!fw_attr_inuse) { /*first time class is being used*/
  23                err = class_register(&firmware_attributes_class);
  24                if (err) {
  25                        mutex_unlock(&fw_attr_lock);
  26                        return err;
  27                }
  28        }
  29        fw_attr_inuse++;
  30        *fw_attr_class = &firmware_attributes_class;
  31        mutex_unlock(&fw_attr_lock);
  32        return 0;
  33}
  34EXPORT_SYMBOL_GPL(fw_attributes_class_get);
  35
  36int fw_attributes_class_put(void)
  37{
  38        mutex_lock(&fw_attr_lock);
  39        if (!fw_attr_inuse) {
  40                mutex_unlock(&fw_attr_lock);
  41                return -EINVAL;
  42        }
  43        fw_attr_inuse--;
  44        if (!fw_attr_inuse) /* No more consumers */
  45                class_unregister(&firmware_attributes_class);
  46        mutex_unlock(&fw_attr_lock);
  47        return 0;
  48}
  49EXPORT_SYMBOL_GPL(fw_attributes_class_put);
  50
  51MODULE_AUTHOR("Mark Pearson <markpearson@lenovo.com>");
  52MODULE_LICENSE("GPL");
  53