usb: ci_udc: complete ep0 direction handling

handle_setup() currently assumes that the response to a Setup transaction
will be an OUT transaction, and any subsequent packet (if any) will be an
IN transaction. This appears to be valid in many cases; both USB
enumeration and Mass Storage work OK with this restriction. However, DFU
uses ep0 to transfer data in both directions. This renders the assumption
invalid; when sending data from device to host, the Data Stage is an IN
transaction, and the Status Stage is an OUT transaction. Enhance
handle_setup() to deduce the correct direction for the USB transactions
based on Setup transaction data.

ep0's request object only needs to be automatically re-queued when the
Data Stage completes, in order to implement the Status Stage. Once the
Status Stage transaction is complete, there is no need to re-queue the
USB request, so don't do that.

Don't sent USB request completion callbacks for Status Stage transactions.
These were queued by ci_udc itself, and only serve to confuse the USB
function code. For example, f_dfu attempts to interpret the 0-length data
buffers for Status Stage transactions as DFU packets. These buffers
contain stale data from the previous transaction. This causes f_dfu to
complain about a sequence number mismatch.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

2 files changed, 42 insertions, 7 deletions

diff --git a/drivers/usb/gadget/ci_udc.c b/drivers/usb/gadget/ci_udc.c
index 03ad231..6dc20c6 100644
--- a/drivers/usb/gadget/ci_udc.c
+++ b/drivers/usb/gadget/ci_udc.c
@@ -428,6 +428,17 @@ static int ci_ep_queue(struct usb_ep *ep,
 	return 0;
 }
 
+static void flip_ep0_direction(void)
+{
+	if (ep0_desc.bEndpointAddress == USB_DIR_IN) {
+		DBG("%s: Flipping ep0 ot OUT\n", __func__);
+		ep0_desc.bEndpointAddress = 0;
+	} else {
+		DBG("%s: Flipping ep0 ot IN\n", __func__);
+		ep0_desc.bEndpointAddress = USB_DIR_IN;
+	}
+}
+
 static void handle_ep_complete(struct ci_ep *ep)
 {
 	struct ept_queue_item *item;
@@ -436,8 +447,6 @@ static void handle_ep_complete(struct ci_ep *ep)
 
 	num = ep->desc->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
 	in = (ep->desc->bEndpointAddress & USB_DIR_IN) != 0;
-	if (num == 0)
-		ep0_desc.bEndpointAddress = 0;
 	item = ci_get_qtd(num, in);
 	ci_invalidate_qtd(num);
 
@@ -458,11 +467,18 @@ static void handle_ep_complete(struct ci_ep *ep)
 
 	DBG("ept%d %s req %p, complete %x\n",
 	    num, in ? "in" : "out", ci_req, len);
-	ci_req->req.complete(&ep->ep, &ci_req->req);
-	if (num == 0) {
+	if (num != 0 || controller.ep0_data_phase)
+		ci_req->req.complete(&ep->ep, &ci_req->req);
+	if (num == 0 && controller.ep0_data_phase) {
+		/*
+		 * Data Stage is complete, so flip ep0 dir for Status Stage,
+		 * which always transfers a packet in the opposite direction.
+		 */
+		DBG("%s: flip ep0 dir for Status Stage\n", __func__);
+		flip_ep0_direction();
+		controller.ep0_data_phase = false;
 		ci_req->req.length = 0;
 		usb_ep_queue(&ep->ep, &ci_req->req, 0);
-		ep0_desc.bEndpointAddress = USB_DIR_IN;
 	}
 }
 
@@ -491,8 +507,26 @@ static void handle_setup(void)
 #else
 	writel(EPT_RX(0), &udc->epstat);
 #endif
-	DBG("handle setup %s, %x, %x index %x value %x\n", reqname(r.bRequest),
-	    r.bRequestType, r.bRequest, r.wIndex, r.wValue);
+	DBG("handle setup %s, %x, %x index %x value %x length %x\n",
+	    reqname(r.bRequest), r.bRequestType, r.bRequest, r.wIndex,
+	    r.wValue, r.wLength);
+
+	/* Set EP0 dir for Data Stage based on Setup Stage data */
+	if (r.bRequestType & USB_DIR_IN) {
+		DBG("%s: Set ep0 to IN for Data Stage\n", __func__);
+		ep0_desc.bEndpointAddress = USB_DIR_IN;
+	} else {
+		DBG("%s: Set ep0 to OUT for Data Stage\n", __func__);
+		ep0_desc.bEndpointAddress = 0;
+	}
+	if (r.wLength) {
+		controller.ep0_data_phase = true;
+	} else {
+		/* 0 length -> no Data Stage. Flip dir for Status Stage */
+		DBG("%s: 0 length: flip ep0 dir for Status Stage\n", __func__);
+		flip_ep0_direction();
+		controller.ep0_data_phase = false;
+	}
 
 	list_del_init(&ci_req->queue);
 	ci_ep->req_primed = false;
diff --git a/drivers/usb/gadget/ci_udc.h b/drivers/usb/gadget/ci_udc.h
index 7d76af8..c214402 100644
--- a/drivers/usb/gadget/ci_udc.h
+++ b/drivers/usb/gadget/ci_udc.h
@@ -98,6 +98,7 @@ struct ci_ep {
 struct ci_drv {
 	struct usb_gadget		gadget;
 	struct ci_req			*ep0_req;
+	bool				ep0_data_phase;
 	struct usb_gadget_driver	*driver;
 	struct ehci_ctrl		*ctrl;
 	struct ept_queue_head		*epts;