dm: implement a Timer uclass

Implement a Timer uclass to work with lib/time.c.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Acked-by: Simon Glass <sjg@chromium.org>

include/timer.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+/*
+ * Get the current timer count
+ *
+ * @dev: The Timer device
+ * @count: pointer that returns the current timer count
+ * @return: 0 if OK, -ve on error
+ */
+int timer_get_count(struct udevice *dev, unsigned long *count);
+/*
+ * Get the timer input clock frequency
+ *
+ * @dev: The Timer device
+ * @return: the timer input clock frequency
+ */
+unsigned long timer_get_rate(struct udevice *dev);
+
+/*
+ * struct timer_ops - Driver model Timer operations
+ *
+ * The uclass interface is implemented by all Timer devices which use
+ * driver model.
+ */
+struct timer_ops {
+	/*
+	 * Get the current timer count
+	 *
+	 * @dev: The Timer device
+	 * @count: pointer that returns the current timer count
+	 * @return: 0 if OK, -ve on error
+	 */
+	int (*get_count)(struct udevice *dev, unsigned long *count);
+};
+
+/*
+ * struct timer_dev_priv - information about a device used by the uclass
+ *
+ * @clock_rate: the timer input clock frequency
+ */
+struct timer_dev_priv {
+	unsigned long clock_rate;
+};
+
+#endif	/* _TIMER_H_ */