[PATCH] USB: add notifier functions to the USB core for devices and busses

This should let us get rid of all of the different hooks in the USB core for
when something has changed.

Also, some other parts of the kernel have wanted to know this kind of
information at times.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 120 insertions, 0 deletions

diff --git a/drivers/usb/core/notify.c b/drivers/usb/core/notify.c
new file mode 100644
index 000000000000..37da059eced7
--- /dev/null
+++ b/drivers/usb/core/notify.c
@@ -0,0 +1,120 @@
+/*
+ * All the USB notify logic
+ *
+ * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
+ *
+ * notifier functions originally based on those in kernel/sys.c
+ * but fixed up to not be so broken.
+ *
+ */
+
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/notifier.h>
+#ifdef CONFIG_USB_DEBUG
+	#define DEBUG
+#else
+	#undef DEBUG
+#endif
+#include <linux/usb.h>
+
+#include "usb.h"
+
+
+static struct notifier_block *usb_notifier_list;
+static DECLARE_MUTEX(usb_notifier_lock);
+
+static void usb_notifier_chain_register(struct notifier_block **list,
+					struct notifier_block *n)
+{
+	down(&usb_notifier_lock);
+	while (*list) {
+		if (n->priority > (*list)->priority)
+			break;
+		list = &((*list)->next);
+	}
+	n->next = *list;
+	*list = n;
+	up(&usb_notifier_lock);
+}
+
+static void usb_notifier_chain_unregister(struct notifier_block **nl,
+				   struct notifier_block *n)
+{
+	down(&usb_notifier_lock);
+	while ((*nl)!=NULL) {
+		if ((*nl)==n) {
+			*nl = n->next;
+			goto exit;
+		}
+		nl=&((*nl)->next);
+	}
+exit:
+	up(&usb_notifier_lock);
+}
+
+static int usb_notifier_call_chain(struct notifier_block **n,
+				   unsigned long val, void *v)
+{
+	int ret=NOTIFY_DONE;
+	struct notifier_block *nb = *n;
+
+	down(&usb_notifier_lock);
+	while (nb) {
+		ret = nb->notifier_call(nb,val,v);
+		if (ret&NOTIFY_STOP_MASK) {
+			goto exit;
+		}
+		nb = nb->next;
+	}
+exit:
+	up(&usb_notifier_lock);
+	return ret;
+}
+
+/**
+ * usb_register_notify - register a notifier callback whenever a usb change happens
+ * @nb: pointer to the notifier block for the callback events.
+ *
+ * These changes are either USB devices or busses being added or removed.
+ */
+void usb_register_notify(struct notifier_block *nb)
+{
+	usb_notifier_chain_register(&usb_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(usb_register_notify);
+
+/**
+ * usb_unregister_notify - unregister a notifier callback
+ * @nb: pointer to the notifier block for the callback events.
+ *
+ * usb_register_notifier() must have been previously called for this function
+ * to work properly.
+ */
+void usb_unregister_notify(struct notifier_block *nb)
+{
+	usb_notifier_chain_unregister(&usb_notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(usb_unregister_notify);
+
+
+void usb_notify_add_device(struct usb_device *udev)
+{
+	usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev);
+}
+
+void usb_notify_remove_device(struct usb_device *udev)
+{
+	usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_REMOVE, udev);
+}
+
+void usb_notify_add_bus(struct usb_bus *ubus)
+{
+	usb_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus);
+}
+
+void usb_notify_remove_bus(struct usb_bus *ubus)
+{
+	usb_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus);
+}