Add callback that is called by epautoconf to allow UDC driver match the
best endpoint for specific descriptor. It's intended to supply mechanism
which allows to get rid of chip-specific endpoint matching code from
epautoconf.

If gadget has set 'ep_match' callback we prefer to call it first, and
if it fails to find matching endpoint, then we try to use default matching
algorithm.

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
---
 drivers/usb/gadget/epautoconf.c | 6 ++++++
 include/linux/usb/gadget.h      | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/drivers/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
index 95e1275..f000c73 100644
--- a/drivers/usb/gadget/epautoconf.c
+++ b/drivers/usb/gadget/epautoconf.c
@@ -165,6 +165,12 @@ struct usb_ep *usb_ep_autoconfig_ss(
 
 	type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
 
+	if (gadget->ops->match_ep) {
+		ep = gadget->ops->match_ep(gadget, desc, ep_comp);
+		if (ep)
+			goto found_ep;
+	}
+
 	/* First, apply chip-specific "best usage" knowledge.
 	 * This might make a good usb_gadget_ops hook ...
 	 */
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 82b5bcb..303214b 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -534,6 +534,9 @@ struct usb_gadget_ops {
 	int	(*udc_start)(struct usb_gadget *,
 			struct usb_gadget_driver *);
 	int	(*udc_stop)(struct usb_gadget *);
+	struct usb_ep *(*match_ep)(struct usb_gadget *,
+			struct usb_endpoint_descriptor *,
+			struct usb_ss_ep_comp_descriptor *);
 };
 
 /**
-- 
1.9.1