usb: fix port reset

commit 891fb2cd removed the implicit
detach before (re-)attaching in usb_attach().  Some usb host controllers
used that behavior though to do a port reset by a detach+attach
sequence.

This patch establishes old behavior by adding a new usb_reset() function
for port resets and putting it into use, thereby also unifying port
reset behavior of all host controllers.  The patch also adds asserts to
usb_attach() and usb_detach() to make sure the calls are symmetrical.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/usb-ehci.c

@@ -880,6 +880,7 @@ static void ehci_reset(void *opaque)
         }
         if (devs[i] && devs[i]->attached) {
             usb_attach(&s->ports[i]);
+            usb_send_msg(devs[i], USB_MSG_RESET);
         }
     }
     ehci_queues_rip_all(s);
@@ -978,8 +979,7 @@ static void handle_port_status_write(EHCIState *s, int port, uint32_t val)
     if (!(val & PORTSC_PRESET) &&(*portsc & PORTSC_PRESET)) {
         trace_usb_ehci_port_reset(port, 0);
         if (dev && dev->attached) {
-            usb_attach(&s->ports[port]);
-            usb_send_msg(dev, USB_MSG_RESET);
+            usb_reset(&s->ports[port]);
             *portsc &= ~PORTSC_CSC;
         }
 

hw/usb-ohci.c

@@ -449,7 +449,7 @@ static void ohci_reset(void *opaque)
         port = &ohci->rhport[i];
         port->ctrl = 0;
         if (port->port.dev && port->port.dev->attached) {
-            usb_attach(&port->port);
+            usb_reset(&port->port);
         }
       }
     if (ohci->async_td) {

hw/usb-uhci.c

@@ -341,7 +341,7 @@ static void uhci_reset(void *opaque)
         port = &s->ports[i];
         port->ctrl = 0x0080;
         if (port->port.dev && port->port.dev->attached) {
-            usb_attach(&port->port);
+            usb_reset(&port->port);
         }
     }
 

hw/usb.c

@@ -33,6 +33,7 @@ void usb_attach(USBPort *port)
 
     assert(dev != NULL);
     assert(dev->attached);
+    assert(dev->state == USB_STATE_NOTATTACHED);
     port->ops->attach(port);
     usb_send_msg(dev, USB_MSG_ATTACH);
 }
@@ -42,10 +43,21 @@ void usb_detach(USBPort *port)
     USBDevice *dev = port->dev;
 
     assert(dev != NULL);
+    assert(dev->state != USB_STATE_NOTATTACHED);
     port->ops->detach(port);
     usb_send_msg(dev, USB_MSG_DETACH);
 }
 
+void usb_reset(USBPort *port)
+{
+    USBDevice *dev = port->dev;
+
+    assert(dev != NULL);
+    usb_detach(port);
+    usb_attach(port);
+    usb_send_msg(dev, USB_MSG_RESET);
+}
+
 void usb_wakeup(USBDevice *dev)
 {
     if (dev->remote_wakeup && dev->port && dev->port->ops->wakeup) {

hw/usb.h

@@ -306,6 +306,7 @@ void usb_cancel_packet(USBPacket * p);
 
 void usb_attach(USBPort *port);
 void usb_detach(USBPort *port);
+void usb_reset(USBPort *port);
 void usb_wakeup(USBDevice *dev);
 int usb_generic_handle_packet(USBDevice *s, USBPacket *p);
 void usb_generic_async_ctrl_complete(USBDevice *s, USBPacket *p);