[Qemu-devel] [patch 2/3] support for UHCI suspend / remote wake up

[Marcelo Tosatti]

This patch enables USB UHCI global suspend/resume feature. The OS will
stop the HC once all ports are suspended. If there is activity on the
port(s), an interrupt signalling remote wakeup will be triggered.

To enable autosuspend for the USB tablet on Linux guests:

echo auto > /sys/devices/pci0000:00/0000:00:01.2/usb1/1-1/power/level

It reduces CPU consumption of an idle FC12 guest from 2.7% to 0.3%.

To enable autosuspend in Windows:

1) Enable "Allow the computer to turn off this
device to save power" checkbox in "Power Management" tab of USB Root Hub 
properties. 

2) Create a REG_BINARY (XP) or REG_DWORD (Vista/2008) key named 
SelectiveSuspendEnabled under:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB\VID_0627&PID_0001\1\Device 
Parameters

With a value of 1.

Signed-off-by: Marcelo Tosatti <address@hidden>

Index: qemu-kvm/hw/usb-hid.c
===================================================================
--- qemu-kvm.orig/hw/usb-hid.c
+++ qemu-kvm/hw/usb-hid.c
@@ -412,6 +412,9 @@ static void usb_hid_changed(USBHIDState 
 
     if (hs->datain)
         hs->datain(hs->datain_opaque);
+
+    if (hs->dev.remote_wakeup)
+        usb_remote_wakeup(&hs->dev);
 }
 
 static void usb_mouse_event(void *opaque,
Index: qemu-kvm/hw/usb-uhci.c
===================================================================
--- qemu-kvm.orig/hw/usb-uhci.c
+++ qemu-kvm/hw/usb-uhci.c
@@ -59,6 +59,7 @@
 
 #define UHCI_PORT_RESET (1 << 9)
 #define UHCI_PORT_LSDA  (1 << 8)
+#define UHCI_PORT_RD    (1 << 6)
 #define UHCI_PORT_ENC   (1 << 3)
 #define UHCI_PORT_EN    (1 << 2)
 #define UHCI_PORT_CSC   (1 << 1)
@@ -501,6 +502,7 @@ static void uhci_ioport_writew(void *opa
             port->ctrl = (port->ctrl & 0x01fb) | (val & ~0x01fb);
             /* some bits are reset when a '1' is written to them */
             port->ctrl &= ~(val & 0x000a);
+            port->ctrl &= ~(port->ctrl & 0x0040); /* clear port resume 
detected */
         }
         break;
     }
@@ -593,6 +595,23 @@ static void uhci_resume (void *opaque)
     }
 }
 
+static void uhci_event(USBPort *port, USBDevice *dev)
+{
+    USBBus *bus = usb_bus_from_device(dev);
+    UHCIState *s = container_of(bus, UHCIState, bus);
+
+    if (s->cmd & UHCI_CMD_EGSM) {
+        UHCIPort *uport = DO_UPCAST(UHCIPort, port, port);
+
+        if (uport->ctrl & UHCI_PORT_RD) {
+            return;
+        }
+
+        uport->ctrl |= UHCI_PORT_RD;
+        uhci_resume(s);
+    }
+}
+
 static void uhci_attach(USBPort *port1, USBDevice *dev)
 {
     UHCIState *s = port1->opaque;
@@ -1103,6 +1122,7 @@ static void uhci_map(PCIDevice *pci_dev,
 
 static USBPortOps uhci_port_ops = {
     .attach = uhci_attach,
+    .remote_wakeup = uhci_event,
 };
 
 static int usb_uhci_common_initfn(UHCIState *s)
Index: qemu-kvm/hw/usb.h
===================================================================
--- qemu-kvm.orig/hw/usb.h
+++ qemu-kvm/hw/usb.h
@@ -199,6 +199,7 @@ struct USBDeviceInfo {
 
 struct USBPortOps {
     void (*attach)(USBPort *port, USBDevice *dev);
+    void (*remote_wakeup)(USBPort *port, USBDevice *dev);
 };
 
 /* USB port on which a device can be connected */
@@ -253,6 +254,7 @@ static inline void usb_cancel_packet(USB
 }
 
 void usb_attach(USBPort *port, USBDevice *dev);
+void usb_remote_wakeup(USBDevice *dev);
 int usb_generic_handle_packet(USBDevice *s, USBPacket *p);
 int set_usb_string(uint8_t *buf, const char *str);
 void usb_send_msg(USBDevice *dev, int msg);
Index: qemu-kvm/hw/usb.c
===================================================================
--- qemu-kvm.orig/hw/usb.c
+++ qemu-kvm/hw/usb.c
@@ -31,6 +31,21 @@ void usb_attach(USBPort *port, USBDevice
     port->ops->attach(port, dev);
 }
 
+void usb_remote_wakeup(USBDevice *dev)
+{
+    USBBus *bus = usb_bus_from_device(dev);
+    USBPort *port;
+
+    QTAILQ_FOREACH(port, &bus->used, next) {
+        if (port->dev == dev)
+            break;
+    }
+    assert(port != NULL);
+
+    if (port->ops->remote_wakeup)
+        port->ops->remote_wakeup(port, dev);
+}
+
 /**********************/
 
 /* generic USB device helpers (you are not forced to use them when