1 /* 2 * All the USB notify logic 3 * 4 * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de> 5 * 6 * notifier functions originally based on those in kernel/sys.c 7 * but fixed up to not be so broken. 8 * 9 */ 10 11 12 #include <linux/config.h> 13 #include <linux/kernel.h> 14 #include <linux/notifier.h> 15 #include <linux/usb.h> 16 #include "usb.h" 17 18 19 static struct notifier_block *usb_notifier_list; 20 static DECLARE_MUTEX(usb_notifier_lock); 21 22 static void usb_notifier_chain_register(struct notifier_block **list, 23 struct notifier_block *n) 24 { 25 down(&usb_notifier_lock); 26 while (*list) { 27 if (n->priority > (*list)->priority) 28 break; 29 list = &((*list)->next); 30 } 31 n->next = *list; 32 *list = n; 33 up(&usb_notifier_lock); 34 } 35 36 static void usb_notifier_chain_unregister(struct notifier_block **nl, 37 struct notifier_block *n) 38 { 39 down(&usb_notifier_lock); 40 while ((*nl)!=NULL) { 41 if ((*nl)==n) { 42 *nl = n->next; 43 goto exit; 44 } 45 nl=&((*nl)->next); 46 } 47 exit: 48 up(&usb_notifier_lock); 49 } 50 51 static int usb_notifier_call_chain(struct notifier_block **n, 52 unsigned long val, void *v) 53 { 54 int ret=NOTIFY_DONE; 55 struct notifier_block *nb = *n; 56 57 down(&usb_notifier_lock); 58 while (nb) { 59 ret = nb->notifier_call(nb,val,v); 60 if (ret&NOTIFY_STOP_MASK) { 61 goto exit; 62 } 63 nb = nb->next; 64 } 65 exit: 66 up(&usb_notifier_lock); 67 return ret; 68 } 69 70 /** 71 * usb_register_notify - register a notifier callback whenever a usb change happens 72 * @nb: pointer to the notifier block for the callback events. 73 * 74 * These changes are either USB devices or busses being added or removed. 75 */ 76 void usb_register_notify(struct notifier_block *nb) 77 { 78 usb_notifier_chain_register(&usb_notifier_list, nb); 79 } 80 EXPORT_SYMBOL_GPL(usb_register_notify); 81 82 /** 83 * usb_unregister_notify - unregister a notifier callback 84 * @nb: pointer to the notifier block for the callback events. 85 * 86 * usb_register_notifier() must have been previously called for this function 87 * to work properly. 88 */ 89 void usb_unregister_notify(struct notifier_block *nb) 90 { 91 usb_notifier_chain_unregister(&usb_notifier_list, nb); 92 } 93 EXPORT_SYMBOL_GPL(usb_unregister_notify); 94 95 96 void usb_notify_add_device(struct usb_device *udev) 97 { 98 usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev); 99 } 100 101 void usb_notify_remove_device(struct usb_device *udev) 102 { 103 usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_REMOVE, udev); 104 } 105 106 void usb_notify_add_bus(struct usb_bus *ubus) 107 { 108 usb_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus); 109 } 110 111 void usb_notify_remove_bus(struct usb_bus *ubus) 112 { 113 usb_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus); 114 } 115