mirror of https://gitee.com/openkylin/linux.git
115 lines
2.5 KiB
C
115 lines
2.5 KiB
C
/*
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* All the USB notify logic
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*
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* (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
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*
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* notifier functions originally based on those in kernel/sys.c
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* but fixed up to not be so broken.
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*
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*/
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#include <linux/config.h>
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#include <linux/kernel.h>
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#include <linux/notifier.h>
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#include <linux/usb.h>
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#include "usb.h"
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static struct notifier_block *usb_notifier_list;
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static DECLARE_MUTEX(usb_notifier_lock);
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static void usb_notifier_chain_register(struct notifier_block **list,
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struct notifier_block *n)
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{
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down(&usb_notifier_lock);
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while (*list) {
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if (n->priority > (*list)->priority)
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break;
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list = &((*list)->next);
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}
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n->next = *list;
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*list = n;
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up(&usb_notifier_lock);
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}
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static void usb_notifier_chain_unregister(struct notifier_block **nl,
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struct notifier_block *n)
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{
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down(&usb_notifier_lock);
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while ((*nl)!=NULL) {
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if ((*nl)==n) {
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*nl = n->next;
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goto exit;
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}
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nl=&((*nl)->next);
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}
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exit:
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up(&usb_notifier_lock);
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}
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static int usb_notifier_call_chain(struct notifier_block **n,
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unsigned long val, void *v)
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{
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int ret=NOTIFY_DONE;
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struct notifier_block *nb = *n;
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down(&usb_notifier_lock);
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while (nb) {
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ret = nb->notifier_call(nb,val,v);
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if (ret&NOTIFY_STOP_MASK) {
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goto exit;
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}
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nb = nb->next;
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}
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exit:
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up(&usb_notifier_lock);
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return ret;
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}
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/**
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* usb_register_notify - register a notifier callback whenever a usb change happens
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* @nb: pointer to the notifier block for the callback events.
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*
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* These changes are either USB devices or busses being added or removed.
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*/
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void usb_register_notify(struct notifier_block *nb)
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{
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usb_notifier_chain_register(&usb_notifier_list, nb);
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}
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EXPORT_SYMBOL_GPL(usb_register_notify);
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/**
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* usb_unregister_notify - unregister a notifier callback
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* @nb: pointer to the notifier block for the callback events.
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*
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* usb_register_notifier() must have been previously called for this function
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* to work properly.
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*/
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void usb_unregister_notify(struct notifier_block *nb)
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{
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usb_notifier_chain_unregister(&usb_notifier_list, nb);
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}
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EXPORT_SYMBOL_GPL(usb_unregister_notify);
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void usb_notify_add_device(struct usb_device *udev)
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{
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usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev);
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}
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void usb_notify_remove_device(struct usb_device *udev)
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{
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usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_REMOVE, udev);
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}
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void usb_notify_add_bus(struct usb_bus *ubus)
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{
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usb_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus);
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}
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void usb_notify_remove_bus(struct usb_bus *ubus)
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{
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usb_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus);
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}
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