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 10 static DEFINE_MUTEX(fw_attr_lock); 11 static int fw_attr_inuse; 12 13 static struct class firmware_attributes_class = { 14 .name = "firmware-attributes", 15 }; 16 17 int 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 } 34 EXPORT_SYMBOL_GPL(fw_attributes_class_get); 35 36 int 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 } 49 EXPORT_SYMBOL_GPL(fw_attributes_class_put); 50 51 MODULE_AUTHOR("Mark Pearson <markpearson@lenovo.com>"); 52 MODULE_LICENSE("GPL"); 53