input: Add mouse support

When running a simple GUI it is useful to support a mouse. This is
similar to what is provided in UEFI's boot menu. Add a simple uclass and
a way to read the mouse position.

For sandbox add a driver that reads the position from SDL. Disable input
for the tools-only build, since it is of no use there and causes build
failures.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/input/Kconfig

@@ -100,3 +100,12 @@ config TWL4030_INPUT
 	bool "Enable TWL4030 Input controller"
 	help
 	  Enable TWL4030 Input controller
+
+config MOUSE
+	bool "Support for mice and other pointing devices"
+	default y if SANDBOX
+	help
+	  This allows U-Boot to access mouse input, typically needed for
+	  graphics boot menus and the like. The driver can provide mouse
+	  events based on user interaction and these can be used to control
+	  U-Boot's operation.

drivers/input/Makefile

@@ -15,3 +15,5 @@ obj-$(CONFIG_I8042_KEYB) += i8042.o
 obj-$(CONFIG_TEGRA_KEYBOARD) += input.o tegra-kbc.o
 obj-$(CONFIG_TWL4030_INPUT) += twl4030.o
 endif
+
+obj-$(CONFIG_MOUSE) += mouse-uclass.o

drivers/input/mouse-uclass.c

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2019 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#include <dm.h>
+#include <errno.h>
+#include <mouse.h>
+
+int mouse_get_event(struct udevice *dev, struct mouse_event *evt)
+{
+	struct mouse_ops *ops = mouse_get_ops(dev);
+	int ret;
+
+	if (!ops->get_event)
+		return -ENOSYS;
+
+	ret = ops->get_event(dev, evt);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+UCLASS_DRIVER(mouse) = {
+	.id		= UCLASS_MOUSE,
+	.name		= "mouse",
+};