usb: dwc3: ep0: introduce ep0_expect_in flag

This flag will tell us which direction we're
expecting on the next (data or status) phase.

It will help us catching errors of host going
crazy and requesting data of the wrong direction.

Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/core.h

@@ -529,6 +529,7 @@ static inline void dwc3_trb_to_nat(struct dwc3_trb_hw *hw, struct dwc3_trb *nat)
  * @three_stage_setup: set if we perform a three phase setup
  * @ep0_status_pending: ep0 status response without a req is pending
  * @ep0_bounced: true when we used bounce buffer
+ * @ep0_expect_in: true when we expect a DATA IN transfer
  * @ep0_next_event: hold the next expected event
  * @ep0state: state of endpoint zero
  * @link_state: link state
@@ -575,6 +576,7 @@ struct dwc3 {
 	unsigned		three_stage_setup:1;
 	unsigned		ep0_status_pending:1;
 	unsigned		ep0_bounced:1;
+	unsigned		ep0_expect_in:1;
 
 	enum dwc3_ep0_next	ep0_next_event;
 	enum dwc3_ep0_state	ep0state;

drivers/usb/dwc3/ep0.c

@@ -545,6 +545,8 @@ static void dwc3_ep0_inspect_setup(struct dwc3 *dwc,
 		dwc->ep0_next_event = DWC3_EP0_NRDY_DATA;
 	}
 
+	dwc->ep0_expect_in = !!(ctrl->bRequestType & USB_DIR_IN);
+
 	if ((ctrl->bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD)
 		ret = dwc3_ep0_std_request(dwc, ctrl);
 	else
@@ -758,6 +760,20 @@ static void dwc3_ep0_xfernotready(struct dwc3 *dwc,
 			return;
 		}
 
+		/*
+		 * One of the possible error cases is when Host _does_
+		 * request for Data Phase, but it does so on the wrong
+		 * direction.
+		 *
+		 * Here, we already know ep0_next_event is DATA (see above),
+		 * so we only need to check for direction.
+		 */
+		if (dwc->ep0_expect_in != event->endpoint_number) {
+			dev_vdbg(dwc->dev, "Wrong direction for Data phase\n");
+			dwc3_ep0_stall_and_restart(dwc);
+			return;
+		}
+
 		dwc3_ep0_do_control_data(dwc, event);
 		break;