Add symbolic definitions for USB delays.
diff --git a/src/usb-ohci.c b/src/usb-ohci.c
index 2d33fa9..8ebd340 100644
--- a/src/usb-ohci.c
+++ b/src/usb-ohci.c
@@ -25,7 +25,7 @@
     // Do reset
     writel(&cntl->ohci.regs->control, OHCI_USB_RESET | oldrwc);
     readl(&cntl->ohci.regs->control); // flush writes
-    msleep(50);
+    msleep(USB_TIME_DRSTR);
 
     // Do software init (min 10us, max 2ms)
     u64 end = calc_future_tsc_usec(10);
@@ -96,7 +96,8 @@
         // No devices connected
         goto shutdown;
 
-    msleep(60);    // XXX - should poll instead of using timer.
+    // XXX - should poll instead of using timer.
+    msleep(USB_TIME_DRSTR + USB_TIME_RSTRCY);
 
     totalcount = 0;
     for (i=0; i<ports; i++) {
diff --git a/src/usb-uhci.c b/src/usb-uhci.c
index 950ec6a..b09b17a 100644
--- a/src/usb-uhci.c
+++ b/src/usb-uhci.c
@@ -106,10 +106,10 @@
         outw(USBPORTSC_PR, cntl->uhci.iobase + USBPORTSC1);
     if (port2 & USBPORTSC_CCS)
         outw(USBPORTSC_PR, cntl->uhci.iobase + USBPORTSC2);
-    msleep(50);
+    msleep(USB_TIME_DRSTR);
     outw(0, cntl->uhci.iobase + USBPORTSC1);
     outw(0, cntl->uhci.iobase + USBPORTSC2);
-    msleep(10);
+    msleep(USB_TIME_RSTRCY);
 
     // Configure ports
     int totalcount = 0;
diff --git a/src/usb.c b/src/usb.c
index 3d59faf..7d4520e 100644
--- a/src/usb.c
+++ b/src/usb.c
@@ -125,7 +125,7 @@
     int ret = send_default_control(endp, &req, NULL);
     if (ret)
         return 0;
-    msleep(2);
+    msleep(USB_TIME_SETADDR_RECOVERY);
 
     cntl->maxaddr++;
     return mkendp(cntl, cntl->maxaddr, 0, endp2speed(endp), endp2maxsize(endp));
diff --git a/src/usb.h b/src/usb.h
index 8b9c5f1..e4d0a66 100644
--- a/src/usb.h
+++ b/src/usb.h
@@ -75,6 +75,15 @@
  * usb structs and flags
  ****************************************************************/
 
+// USB mandated timings (in ms)
+#define USB_TIME_SIGATT 100
+#define USB_TIME_ATTDB  100
+#define USB_TIME_DRST   10
+#define USB_TIME_DRSTR  50
+#define USB_TIME_RSTRCY 10
+
+#define USB_TIME_SETADDR_RECOVERY 2
+
 #define USB_PID_OUT                     0xe1
 #define USB_PID_IN                      0x69
 #define USB_PID_SETUP                   0x2d