[PATCH v2 43/48] usb: gadget: udc: add usb_gadget_ep_match_desc() function

[Robert Baldyga]

Add function matching endpoint with ep descriptor. This function checks if
hardware endponit can fulfill requirements requested in descriptor. This
function can be used by UDC drivers in match_ep() callback to avoid writing
lots of repetitive code.

Signed-off-by: Robert Baldyga <r.baldyga at samsung.com>
---
 drivers/usb/gadget/udc/udc-core.c | 69 +++++++++++++++++++++++++++++++++++++++
 include/linux/usb/gadget.h        |  8 +++++
 2 files changed, 77 insertions(+)

diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
index d69c355..2dff8df 100644
--- a/drivers/usb/gadget/udc/udc-core.c
+++ b/drivers/usb/gadget/udc/udc-core.c
@@ -129,6 +129,75 @@ EXPORT_SYMBOL_GPL(usb_gadget_giveback_request);
 
 /* ------------------------------------------------------------------------- */
 
+int usb_gadget_ep_match_desc(struct usb_gadget *gadget,
+		struct usb_ep *ep, struct usb_endpoint_descriptor *desc,
+		struct usb_ss_ep_comp_descriptor *ep_comp)
+{
+	u8              type;
+	u16             max;
+	int             num_req_streams = 0;
+
+	/* endpoint already claimed? */
+	if (ep->claimed)
+		return 0;
+
+	type = usb_endpoint_type(desc);
+	max = 0x7ff & usb_endpoint_maxp(desc);
+
+	if (usb_endpoint_dir_in(desc) && !ep->caps.dir_in)
+		return 0;
+	else if (!ep->caps.dir_out)
+		return 0;
+
+	if (max > ep->maxpacket_limit)
+		return 0;
+
+	/* "high bandwidth" works only at high speed */
+	if (!gadget_is_dualspeed(gadget) && usb_endpoint_maxp(desc) & (3<<11))
+		return 0;
+
+	switch (type) {
+	case USB_ENDPOINT_XFER_CONTROL:
+		/* only support ep0 for portable CONTROL traffic */
+		return 0;
+	case USB_ENDPOINT_XFER_ISOC:
+		if (!ep->caps.type_iso)
+			return 0;
+		/* ISO:  limit 1023 bytes full speed, 1024 high/super speed */
+		if (!gadget_is_dualspeed(gadget) && max > 1023)
+			return 0;
+		break;
+	case USB_ENDPOINT_XFER_BULK:
+		if (!ep->caps.type_bulk)
+			return 0;
+		if (ep_comp && gadget_is_superspeed(gadget)) {
+			/* Get the number of required streams from the
+			 * EP companion descriptor and see if the EP
+			 * matches it
+			 */
+			num_req_streams = ep_comp->bmAttributes & 0x1f;
+			if (num_req_streams > ep->max_streams)
+				return 0;
+		}
+		break;
+	case USB_ENDPOINT_XFER_INT:
+		/* Bulk endpoints handle interrupt transfers,
+		 * except the toggle-quirky iso-synch kind
+		 */
+		if (!ep->caps.type_int && !ep->caps.type_bulk)
+			return 0;
+		/* INT:  limit 64 bytes full speed, 1024 high/super speed */
+		if (!gadget_is_dualspeed(gadget) && max > 64)
+			return 0;
+		break;
+	}
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(usb_gadget_ep_match_desc);
+
+/* ------------------------------------------------------------------------- */
+
 static void usb_gadget_state_work(struct work_struct *work)
 {
 	struct usb_gadget *gadget = work_to_gadget(work);
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 0041bb9..77e2c1e 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -1079,6 +1079,14 @@ extern void usb_gadget_giveback_request(struct usb_ep *ep,
 
 /*-------------------------------------------------------------------------*/
 
+/* utility to check if endpoint caps match descriptor needs */
+
+extern int usb_gadget_ep_match_desc(struct usb_gadget *gadget,
+		struct usb_ep *ep, struct usb_endpoint_descriptor *desc,
+		struct usb_ss_ep_comp_descriptor *ep_comp);
+
+/*-------------------------------------------------------------------------*/
+
 /* utility to update vbus status for udc core, it may be scheduled */
 extern void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status);
 
-- 
1.9.1