Input: xen-kbdfront - advertise either absolute or relative coordinates

A virtualized display device is usually viewed with the vncviewer
application, either by 'xm vnc domU' or with vncviewer localhost:port.
vncviewer and the RFB protocol provides absolute coordinates to the
virtual display. These coordinates are either passed through to a PV
guest or converted to relative coordinates for a HVM guest.

A PV guest receives these coordinates and passes them to the kernels
evdev driver. There it can be picked up by applications such as the
xorg-input drivers. Using absolute coordinates avoids issues such as
guest mouse pointer not tracking host mouse pointer due to wrong mouse
acceleration settings in the guests X display.

Advertise either absolute or relative coordinates to the input system
and the evdev driver, depending on what dom0 provides. The xorg-input
driver prefers relative coordinates even if a devices provides both.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/xen-kbdfront.c

@@ -110,7 +110,7 @@ static irqreturn_t input_handler(int rq, void *dev_id)
 static int __devinit xenkbd_probe(struct xenbus_device *dev,
 				  const struct xenbus_device_id *id)
 {
-	int ret, i;
+	int ret, i, abs;
 	struct xenkbd_info *info;
 	struct input_dev *kbd, *ptr;
 
@@ -128,6 +128,11 @@ static int __devinit xenkbd_probe(struct xenbus_device *dev,
 	if (!info->page)
 		goto error_nomem;
 
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-abs-pointer", "%d", &abs) < 0)
+		abs = 0;
+	if (abs)
+		xenbus_printf(XBT_NIL, dev->nodename, "request-abs-pointer", "1");
+
 	/* keyboard */
 	kbd = input_allocate_device();
 	if (!kbd)
@@ -137,11 +142,12 @@ static int __devinit xenkbd_probe(struct xenbus_device *dev,
 	kbd->id.bustype = BUS_PCI;
 	kbd->id.vendor = 0x5853;
 	kbd->id.product = 0xffff;
-	kbd->evbit[0] = BIT(EV_KEY);
+
+	__set_bit(EV_KEY, kbd->evbit);
 	for (i = KEY_ESC; i < KEY_UNKNOWN; i++)
-		set_bit(i, kbd->keybit);
+		__set_bit(i, kbd->keybit);
 	for (i = KEY_OK; i < KEY_MAX; i++)
-		set_bit(i, kbd->keybit);
+		__set_bit(i, kbd->keybit);
 
 	ret = input_register_device(kbd);
 	if (ret) {
@@ -160,12 +166,20 @@ static int __devinit xenkbd_probe(struct xenbus_device *dev,
 	ptr->id.bustype = BUS_PCI;
 	ptr->id.vendor = 0x5853;
 	ptr->id.product = 0xfffe;
-	ptr->evbit[0] = BIT(EV_KEY) | BIT(EV_REL) | BIT(EV_ABS);
-	for (i = BTN_LEFT; i <= BTN_TASK; i++)
-		set_bit(i, ptr->keybit);
-	ptr->relbit[0] = BIT(REL_X) | BIT(REL_Y) | BIT(REL_WHEEL);
+
+	if (abs) {
+		__set_bit(EV_ABS, ptr->evbit);
 		input_set_abs_params(ptr, ABS_X, 0, XENFB_WIDTH, 0, 0);
 		input_set_abs_params(ptr, ABS_Y, 0, XENFB_HEIGHT, 0, 0);
+	} else {
+		input_set_capability(ptr, EV_REL, REL_X);
+		input_set_capability(ptr, EV_REL, REL_Y);
+	}
+	input_set_capability(ptr, EV_REL, REL_WHEEL);
+
+	__set_bit(EV_KEY, ptr->evbit);
+	for (i = BTN_LEFT; i <= BTN_TASK; i++)
+		__set_bit(i, ptr->keybit);
 
 	ret = input_register_device(ptr);
 	if (ret) {
@@ -272,7 +286,7 @@ static void xenkbd_backend_changed(struct xenbus_device *dev,
 				   enum xenbus_state backend_state)
 {
 	struct xenkbd_info *info = dev_get_drvdata(&dev->dev);
-	int ret, val;
+	int val;
 
 	switch (backend_state) {
 	case XenbusStateInitialising:
@@ -285,16 +299,6 @@ static void xenkbd_backend_changed(struct xenbus_device *dev,
 
 	case XenbusStateInitWait:
 InitWait:
-		ret = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
-				   "feature-abs-pointer", "%d", &val);
-		if (ret < 0)
-			val = 0;
-		if (val) {
-			ret = xenbus_printf(XBT_NIL, info->xbdev->nodename,
-					    "request-abs-pointer", "1");
-			if (ret)
-				pr_warning("can't request abs-pointer\n");
-		}
 		xenbus_switch_state(dev, XenbusStateConnected);
 		break;