3 files changed, 32 insertions, 0 deletions
diff --git a/hw/usb-bus.c b/hw/usb-bus.c
index b75383458..5c05ed580 100644
--- a/hw/usb-bus.c
+++ b/hw/usb-bus.c
@@ -74,6 +74,15 @@ static int usb_device_init(USBDevice *dev)
     return 0;
 }
 
+USBDevice *usb_device_find_device(USBDevice *dev, uint8_t addr)
+{
+    USBDeviceClass *klass = USB_DEVICE_GET_CLASS(dev);
+    if (klass->find_device) {
+        return klass->find_device(dev, addr);
+    }
+    return NULL;
+}
+
 static void usb_device_handle_destroy(USBDevice *dev)
 {
     USBDeviceClass *klass = USB_DEVICE_GET_CLASS(dev);
diff --git a/hw/usb.c b/hw/usb.c
index 0c261644e..bacdc81bf 100644
--- a/hw/usb.c
+++ b/hw/usb.c
@@ -295,6 +295,19 @@ int set_usb_string(uint8_t *buf, const char *str)
     return q - buf;
 }
 
+USBDevice *usb_find_device(USBPort *port, uint8_t addr)
+{
+    USBDevice *dev = port->dev;
+
+    if (dev == NULL || !dev->attached || dev->state != USB_STATE_DEFAULT) {
+        return NULL;
+    }
+    if (dev->addr == addr) {
+        return dev;
+    }
+    return usb_device_find_device(dev, addr);
+}
+
 /* Hand over a packet to a device for processing.  Return value
    USB_RET_ASYNC indicates the processing isn't finished yet, the
    driver will call usb_packet_complete() when done processing it. */
diff --git a/hw/usb.h b/hw/usb.h
index 61271768b..1beb4b32a 100644
--- a/hw/usb.h
+++ b/hw/usb.h
@@ -229,6 +229,12 @@ typedef struct USBDeviceClass {
     int (*init)(USBDevice *dev);
 
     /*
+     * Walk (enabled) downstream ports, check for a matching device.
+     * Only hubs implement this.
+     */
+    USBDevice *(*find_device)(USBDevice *dev, uint8_t addr);
+
+    /*
      * Process USB packet.
      * Called by the HC (Host Controller).
      *
@@ -332,6 +338,8 @@ void usb_packet_copy(USBPacket *p, void *ptr, size_t bytes);
 void usb_packet_skip(USBPacket *p, size_t bytes);
 void usb_packet_cleanup(USBPacket *p);
 
+USBDevice *usb_find_device(USBPort *port, uint8_t addr);
+
 int usb_handle_packet(USBDevice *dev, USBPacket *p);
 void usb_packet_complete(USBDevice *dev, USBPacket *p);
 void usb_cancel_packet(USBPacket * p);
@@ -446,6 +454,8 @@ extern const VMStateDescription vmstate_usb_device;
     .offset     = vmstate_offset_value(_state, _field, USBDevice),   \
 }
 
+USBDevice *usb_device_find_device(USBDevice *dev, uint8_t addr);
+
 int usb_device_handle_packet(USBDevice *dev, USBPacket *p);
 
 void usb_device_cancel_packet(USBDevice *dev, USBPacket *p);