usb: add pipelining option to usb endpoints

With this patch applied USB drivers can enable pipelining per endpoint.
With pipelining enabled the usb core will continue submitting packets
even when there are still async transfers in flight instead of passing
them on one by one.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/usb.c

@@ -323,7 +323,7 @@ int usb_handle_packet(USBDevice *dev, USBPacket *p)
     assert(p->state == USB_PACKET_SETUP);
     assert(p->ep != NULL);
 
-    if (QTAILQ_EMPTY(&p->ep->queue)) {
+    if (QTAILQ_EMPTY(&p->ep->queue) || p->ep->pipeline) {
         ret = usb_process_one(p);
         if (ret == USB_RET_ASYNC) {
             usb_packet_set_state(p, USB_PACKET_ASYNC);
@@ -468,6 +468,7 @@ void usb_ep_init(USBDevice *dev)
     dev->ep_ctl.type = USB_ENDPOINT_XFER_CONTROL;
     dev->ep_ctl.ifnum = 0;
     dev->ep_ctl.dev = dev;
+    dev->ep_ctl.pipeline = false;
     QTAILQ_INIT(&dev->ep_ctl.queue);
     for (ep = 0; ep < USB_MAX_ENDPOINTS; ep++) {
         dev->ep_in[ep].nr = ep + 1;
@@ -480,6 +481,8 @@ void usb_ep_init(USBDevice *dev)
         dev->ep_out[ep].ifnum = 0;
         dev->ep_in[ep].dev = dev;
         dev->ep_out[ep].dev = dev;
+        dev->ep_in[ep].pipeline = false;
+        dev->ep_out[ep].pipeline = false;
         QTAILQ_INIT(&dev->ep_in[ep].queue);
         QTAILQ_INIT(&dev->ep_out[ep].queue);
     }
@@ -593,3 +596,9 @@ int usb_ep_get_max_packet_size(USBDevice *dev, int pid, int ep)
     struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
     return uep->max_packet_size;
 }
+
+void usb_ep_set_pipeline(USBDevice *dev, int pid, int ep, bool enabled)
+{
+    struct USBEndpoint *uep = usb_ep_get(dev, pid, ep);
+    uep->pipeline = enabled;
+}

hw/usb.h

@@ -177,6 +177,7 @@ struct USBEndpoint {
     uint8_t type;
     uint8_t ifnum;
     int max_packet_size;
+    bool pipeline;
     USBDevice *dev;
     QTAILQ_HEAD(, USBPacket) queue;
 };
@@ -364,6 +365,7 @@ void usb_ep_set_ifnum(USBDevice *dev, int pid, int ep, uint8_t ifnum);
 void usb_ep_set_max_packet_size(USBDevice *dev, int pid, int ep,
                                 uint16_t raw);
 int usb_ep_get_max_packet_size(USBDevice *dev, int pid, int ep);
+void usb_ep_set_pipeline(USBDevice *dev, int pid, int ep, bool enabled);
 
 void usb_attach(USBPort *port);
 void usb_detach(USBPort *port);