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 #ifdef CONFIG_USB_DEBUG 16 #define DEBUG 17 #else 18 #undef DEBUG 19 #endif 20 #include <linux/usb.h> 21 22 #include "usb.h" 23 24 25 static struct notifier_block *usb_notifier_list; 26 static DECLARE_MUTEX(usb_notifier_lock); 27 28 static void usb_notifier_chain_register(struct notifier_block **list, 29 struct notifier_block *n) 30 { 31 down(&usb_notifier_lock); 32 while (*list) { 33 if (n->priority > (*list)->priority) 34 break; 35 list = &((*list)->next); 36 } 37 n->next = *list; 38 *list = n; 39 up(&usb_notifier_lock); 40 } 41 42 static void usb_notifier_chain_unregister(struct notifier_block **nl, 43 struct notifier_block *n) 44 { 45 down(&usb_notifier_lock); 46 while ((*nl)!=NULL) { 47 if ((*nl)==n) { 48 *nl = n->next; 49 goto exit; 50 } 51 nl=&((*nl)->next); 52 } 53 exit: 54 up(&usb_notifier_lock); 55 } 56 57 static int usb_notifier_call_chain(struct notifier_block **n, 58 unsigned long val, void *v) 59 { 60 int ret=NOTIFY_DONE; 61 struct notifier_block *nb = *n; 62 63 down(&usb_notifier_lock); 64 while (nb) { 65 ret = nb->notifier_call(nb,val,v); 66 if (ret&NOTIFY_STOP_MASK) { 67 goto exit; 68 } 69 nb = nb->next; 70 } 71 exit: 72 up(&usb_notifier_lock); 73 return ret; 74 } 75 76 /** 77 * usb_register_notify - register a notifier callback whenever a usb change happens 78 * @nb: pointer to the notifier block for the callback events. 79 * 80 * These changes are either USB devices or busses being added or removed. 81 */ 82 void usb_register_notify(struct notifier_block *nb) 83 { 84 usb_notifier_chain_register(&usb_notifier_list, nb); 85 } 86 EXPORT_SYMBOL_GPL(usb_register_notify); 87 88 /** 89 * usb_unregister_notify - unregister a notifier callback 90 * @nb: pointer to the notifier block for the callback events. 91 * 92 * usb_register_notifier() must have been previously called for this function 93 * to work properly. 94 */ 95 void usb_unregister_notify(struct notifier_block *nb) 96 { 97 usb_notifier_chain_unregister(&usb_notifier_list, nb); 98 } 99 EXPORT_SYMBOL_GPL(usb_unregister_notify); 100 101 102 void usb_notify_add_device(struct usb_device *udev) 103 { 104 usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev); 105 } 106 107 void usb_notify_remove_device(struct usb_device *udev) 108 { 109 usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_REMOVE, udev); 110 } 111 112 void usb_notify_add_bus(struct usb_bus *ubus) 113 { 114 usb_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus); 115 } 116 117 void usb_notify_remove_bus(struct usb_bus *ubus) 118 { 119 usb_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus); 120 } 121