USB: otg: add notifier support

The notifier will be used to communicate usb events
to other drivers like the charger chip.

This can be used as source of information to kick
usb charger detection as described by the USB
Battery Charging Specification 1.1 and/or to
pass bMaxPower field of selected usb_configuration
to charger chip in order to use that information
as input current on the charging profile
setup.

Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/usb/otg.h

@@ -9,6 +9,8 @@
 #ifndef __LINUX_USB_OTG_H
 #define __LINUX_USB_OTG_H
 
+#include <linux/notifier.h>
+
 /* OTG defines lots of enumeration states before device reset */
 enum usb_otg_state {
 	OTG_STATE_UNDEFINED = 0,
@@ -33,6 +35,14 @@ enum usb_otg_state {
 	OTG_STATE_A_VBUS_ERR,
 };
 
+enum usb_xceiv_events {
+	USB_EVENT_NONE,         /* no events or cable disconnected */
+	USB_EVENT_VBUS,         /* vbus valid event */
+	USB_EVENT_ID,           /* id was grounded */
+	USB_EVENT_CHARGER,      /* usb dedicated charger */
+	USB_EVENT_ENUMERATED,   /* gadget driver enumerated */
+};
+
 #define USB_OTG_PULLUP_ID		(1 << 0)
 #define USB_OTG_PULLDOWN_DP		(1 << 1)
 #define USB_OTG_PULLDOWN_DM		(1 << 2)
@@ -70,6 +80,9 @@ struct otg_transceiver {
 	struct otg_io_access_ops	*io_ops;
 	void __iomem			*io_priv;
 
+	/* for notification of usb_xceiv_events */
+	struct blocking_notifier_head	notifier;
+
 	/* to pass extra port status to the root hub */
 	u16			port_status;
 	u16			port_change;
@@ -203,6 +216,18 @@ otg_start_srp(struct otg_transceiver *otg)
 	return otg->start_srp(otg);
 }
 
+/* notifiers */
+static inline int
+otg_register_notifier(struct otg_transceiver *otg, struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&otg->notifier, nb);
+}
+
+static inline void
+otg_unregister_notifier(struct otg_transceiver *otg, struct notifier_block *nb)
+{
+	blocking_notifier_chain_unregister(&otg->notifier, nb);
+}
 
 /* for OTG controller drivers (and maybe other stuff) */
 extern int usb_bus_start_enum(struct usb_bus *bus, unsigned port_num);