[usb] Allow usb_stream() to enforce a terminating short packet

Some USB endpoints require that a short packet be used to terminate
transfers, since they have no other way to determine message
boundaries.  If the message length happens to be an exact multiple of
the USB packet size, then this requires the use of an additional
zero-length packet.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/bus/usb.c

  *
  * @v ep		USB endpoint
  * @v iobuf		I/O buffer
+ * @v terminate		Terminate using a short packet
  * @ret rc		Return status code
  */
-int usb_stream ( struct usb_endpoint *ep, struct io_buffer *iobuf ) {
+int usb_stream ( struct usb_endpoint *ep, struct io_buffer *iobuf,
+		 int terminate ) {
 	struct usb_device *usb = ep->usb;
 	struct usb_port *port = usb->port;
 	int rc;
 		return rc;
 
 	/* Enqueue stream transfer */
-	if ( ( rc = ep->host->stream ( ep, iobuf ) ) != 0 ) {
+	if ( ( rc = ep->host->stream ( ep, iobuf, terminate ) ) != 0 ) {
 		DBGC ( usb, "USB %s %s could not enqueue stream transfer: %s\n",
 		       usb->name, usb_endpoint_name ( ep->address ),
 		       strerror ( rc ) );

src/drivers/net/ncm.c

 		iob_put ( iobuf, ( ring->mtu - iob_len ( iobuf ) ) );
 
 		/* Enqueue I/O buffer */
-		if ( ( rc = usb_stream ( &ring->ep, iobuf ) ) != 0 ) {
+		if ( ( rc = usb_stream ( &ring->ep, iobuf, 0 ) ) != 0 ) {
 			DBGC ( ncm, "NCM %p could not enqueue %s: %s\n", ncm,
 			       ncm_rx_name ( ncm, ring ), strerror ( rc ) );
 			/* Leave in recycled list and wait for next refill */
 	memset ( &header->desc[1], 0, sizeof ( header->desc[1] ) );
 
 	/* Enqueue I/O buffer */
-	if ( ( rc = usb_stream ( &ncm->out.ep, iobuf ) ) != 0 )
+	if ( ( rc = usb_stream ( &ncm->out.ep, iobuf, 0 ) ) != 0 )
 		return rc;
 
 	/* Increment sequence number */

src/drivers/usb/usbhub.c

 		iob_put ( iobuf, ( mtu - iob_len ( iobuf ) ) );
 
 		/* Enqueue I/O buffer */
-		if ( ( rc = usb_stream ( &hubdev->intr, iobuf ) ) != 0 ) {
+		if ( ( rc = usb_stream ( &hubdev->intr, iobuf, 0 ) ) != 0 ) {
 			DBGC ( hubdev, "HUB %s could not enqueue interrupt: "
 			       "%s\n", hubdev->name, strerror ( rc ) );
 			/* Leave in available list and wait for next refill */

src/drivers/usb/xhci.c

  *
  * @v ep		USB endpoint
  * @v iobuf		I/O buffer
+ * @v terminate		Terminate using a short packet
  * @ret rc		Return status code
  */
 static int xhci_endpoint_stream ( struct usb_endpoint *ep,
-				  struct io_buffer *iobuf ) {
+				  struct io_buffer *iobuf, int terminate ) {
 	struct xhci_endpoint *endpoint = usb_endpoint_get_hostdata ( ep );
-	union xhci_trb trb;
+	union xhci_trb trbs[ 1 /* Normal */ + 1 /* Possible zero-length */ ];
+	union xhci_trb *trb = trbs;
 	struct xhci_trb_normal *normal;
+	size_t len = iob_len ( iobuf );
 	int rc;
 
 	/* Profile stream transfers */
 	profile_start ( &xhci_stream_profiler );
 
 	/* Construct normal TRBs */
-	normal = &trb.normal;
+	memset ( &trbs, 0, sizeof ( trbs ) );
+	normal = &(trb++)->normal;
 	normal->data = cpu_to_le64 ( virt_to_phys ( iobuf->data ) );
-	normal->len = cpu_to_le32 ( iob_len ( iobuf ) );
-	normal->flags = XHCI_TRB_IOC;
+	normal->len = cpu_to_le32 ( len );
 	normal->type = XHCI_TRB_NORMAL;
+	if ( terminate && ( ( len & ( ep->mtu - 1 ) ) == 0 ) ) {
+		normal->flags = XHCI_TRB_CH;
+		normal = &(trb++)->normal;
+		normal->type = XHCI_TRB_NORMAL;
+	}
+	normal->flags = XHCI_TRB_IOC;
 
 	/* Enqueue TRBs */
-	if ( ( rc = xhci_enqueue ( &endpoint->ring, iobuf, &trb ) ) != 0 )
+	if ( ( rc = xhci_enqueue_multi ( &endpoint->ring, iobuf, trbs,
+					 ( trb - trbs ) ) ) != 0 )
 		return rc;
 
 	/* Ring the doorbell */

src/include/ipxe/usb.h

 	 *
 	 * @v ep		USB endpoint
 	 * @v iobuf		I/O buffer
+	 * @v terminate		Terminate using a short packet
 	 * @ret rc		Return status code
 	 */
-	int ( * stream ) ( struct usb_endpoint *ep,
-			   struct io_buffer *iobuf );
+	int ( * stream ) ( struct usb_endpoint *ep, struct io_buffer *iobuf,
+			   int terminate );
 };
 
 /** USB endpoint driver operations */
 extern int usb_message ( struct usb_endpoint *ep, unsigned int request,
 			 unsigned int value, unsigned int index,
 			 struct io_buffer *iobuf );
-extern int usb_stream ( struct usb_endpoint *ep, struct io_buffer *iobuf );
+extern int usb_stream ( struct usb_endpoint *ep, struct io_buffer *iobuf,
+			int terminate );
 extern void usb_complete_err ( struct usb_endpoint *ep,
 			       struct io_buffer *iobuf, int rc );