dm: Add a demonstration/example driver

As an example of how to write a uclass and a driver, provide a demo version
of each, accessible through the 'demo' command.

To use these with driver model, define CONFIG_CMD_DEMO and CONFIG_DM_DEMO.

The two demo drivers are enabled with CONFIG_DM_DEMO_SIMPLE and
CONFIG_DM_DEMO_SHAPE.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Pavel Herrmann <morpheus.ibis@gmail.com>
Signed-off-by: Viktor Křivák <viktor.krivak@gmail.com>
Signed-off-by: Tomas Hlavacek <tmshlvck@gmail.com>
diff --git a/include/dm-demo.h b/include/dm-demo.h
new file mode 100644
index 0000000..6e38d3c
--- /dev/null
+++ b/include/dm-demo.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2013 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __DM_DEMO_H
+#define __DM_DEMO_H
+
+#include <dm.h>
+
+/**
+ * struct dm_demo_pdata - configuration data for demo instance
+ *
+ * @colour: Color of the demo
+ * @sides: Numbers of sides
+ * @default_char: Default ASCII character to output (65 = 'A')
+ */
+struct dm_demo_pdata {
+	const char *colour;
+	int sides;
+	int default_char;
+};
+
+struct demo_ops {
+	int (*hello)(struct device *dev, int ch);
+	int (*status)(struct device *dev, int *status);
+};
+
+int demo_hello(struct device *dev, int ch);
+int demo_status(struct device *dev, int *status);
+int demo_list(void);
+
+int demo_parse_dt(struct device *dev);
+
+#endif