rockchip: add timer driver

some rockchip soc will not include lib/timer.c in SPL stage,
so implement timer driver for some soc can use us delay function in SPL.

Signed-off-by: Lin Huang <hl@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/include/asm/arch-rockchip/timer.h b/arch/arm/include/asm/arch-rockchip/timer.h
new file mode 100644
index 0000000..1d044bb
--- /dev/null
+++ b/arch/arm/include/asm/arch-rockchip/timer.h
@@ -0,0 +1,22 @@
+/*
+ * (C) Copyright 2015 Rockchip Electronics Co., Ltd
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#ifndef __ASM_ARCH_TIMER_H
+#define __ASM_ARCH_TIMER_H
+
+struct rk_timer {
+	unsigned int timer_load_count0;
+	unsigned int timer_load_count1;
+	unsigned int timer_curr_value0;
+	unsigned int timer_curr_value1;
+	unsigned int timer_ctrl_reg;
+	unsigned int timer_int_status;
+};
+
+void rockchip_timer_init(void);
+void rockchip_udelay(unsigned int usec);
+
+#endif