[usb] Include setup packet within I/O buffer for message transfers

The USB API currently assumes that host controllers will have
immediate data buffer space available in which to store the setup
packet.  This is true for xHCI, partially true for EHCI (which happens
to have 12 bytes of padding in each transfer descriptor due to
alignment requirements), and not true at all for UHCI.

Include the setup packet within the I/O buffer passed to the host
controller's message() method, thereby eliminating the requirement for
host controllers to provide immediate data buffers.

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

1 files changed, 20 insertions, 9 deletions

diff --git a/src/drivers/bus/usb.c b/src/drivers/bus/usb.c
index f53f7461..2191867a 100644
--- a/src/drivers/bus/usb.c
+++ b/src/drivers/bus/usb.c
@@ -460,16 +460,22 @@ static int usb_endpoint_mtu ( struct usb_endpoint *ep, size_t mtu ) {
  * @v index		Index parameter
  * @v iobuf		I/O buffer
  * @ret rc		Return status code
+ *
+ * The I/O buffer must have sufficient headroom to contain a setup
+ * packet.
  */
 int usb_message ( struct usb_endpoint *ep, unsigned int request,
 		  unsigned int value, unsigned int index,
 		  struct io_buffer *iobuf ) {
 	struct usb_device *usb = ep->usb;
 	struct usb_port *port = usb->port;
-	struct usb_setup_packet packet;
+	struct usb_setup_packet *packet;
 	size_t len = iob_len ( iobuf );
 	int rc;
 
+	/* Sanity check */
+	assert ( iob_headroom ( iobuf ) >= sizeof ( *packet ) );
+
 	/* Fail immediately if device has been unplugged */
 	if ( port->speed == USB_SPEED_NONE )
 		return -ENODEV;
@@ -484,13 +490,14 @@ int usb_message ( struct usb_endpoint *ep, unsigned int request,
 		memset ( iobuf->data, 0, len );
 
 	/* Construct setup packet */
-	packet.request = cpu_to_le16 ( request );
-	packet.value = cpu_to_le16 ( value );
-	packet.index = cpu_to_le16 ( index );
-	packet.len = cpu_to_le16 ( len );
+	packet = iob_push ( iobuf, sizeof ( *packet ) );
+	packet->request = cpu_to_le16 ( request );
+	packet->value = cpu_to_le16 ( value );
+	packet->index = cpu_to_le16 ( index );
+	packet->len = cpu_to_le16 ( len );
 
 	/* Enqueue message transfer */
-	if ( ( rc = ep->host->message ( ep, &packet, iobuf ) ) != 0 ) {
+	if ( ( rc = ep->host->message ( ep, iobuf ) ) != 0 ) {
 		DBGC ( usb, "USB %s %s could not enqueue message transfer: "
 		       "%s\n", usb->name, usb_endpoint_name ( ep->address ),
 		       strerror ( rc ) );
@@ -734,19 +741,23 @@ int usb_control ( struct usb_device *usb, unsigned int request,
 		  size_t len ) {
 	struct usb_bus *bus = usb->port->hub->bus;
 	struct usb_endpoint *ep = &usb->control;
-	struct usb_control_pseudo_header *pshdr;
 	struct io_buffer *iobuf;
 	struct io_buffer *cmplt;
+	union {
+		struct usb_setup_packet setup;
+		struct usb_control_pseudo_header pshdr;
+	} *headroom;
+	struct usb_control_pseudo_header *pshdr;
 	unsigned int i;
 	int rc;
 
 	/* Allocate I/O buffer */
-	iobuf = alloc_iob ( sizeof ( *pshdr ) + len );
+	iobuf = alloc_iob ( sizeof ( *headroom ) + len );
 	if ( ! iobuf ) {
 		rc = -ENOMEM;
 		goto err_alloc;
 	}
-	iob_reserve ( iobuf, sizeof ( *pshdr ) );
+	iob_reserve ( iobuf, sizeof ( *headroom ) );
 	iob_put ( iobuf, len );
 	if ( request & USB_DIR_IN ) {
 		memset ( data, 0, len );