board: add the initial support of iotdk

The initial support of iotdk which is a board based on Synopsys
ARC IoT SoC.

In this commit, it includes

* processor support
* UART driver

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>

soc/arc/snps_arc_iot/soc.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2018 Synopsys, Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @brief Board configuration macros for EM Starter kit board
+ *
+ * This header file is used to specify and describe board-level
+ * aspects for the target.
+ */
+
+#ifndef _SOC_H_
+#define _SOC_H_
+
+#include <misc/util.h>
+
+/* default system clock */
+#define SYSCLK_DEFAULT_IOSC_HZ			MHZ(16)
+
+/*
+ * UART
+ */
+#define UART_NS16550_ACCESS_IOPORT
+
+
+/* ARC EM Core IRQs */
+#define IRQ_TIMER0				16
+#define IRQ_TIMER1				17
+#include "soc_irq.h"
+
+#define BASE_ADDR_SYSCONFIG		0xF000A000
+
+#ifndef _ASMLANGUAGE
+
+
+#include <misc/util.h>
+#include <random/rand32.h>
+
+#define ARCV2_TIMER0_INT_LVL			IRQ_TIMER0
+#define ARCV2_TIMER0_INT_PRI			0
+
+#define ARCV2_TIMER1_INT_LVL			IRQ_TIMER1
+#define ARCV2_TIMER1_INT_PRI			1
+
+#define INT_ENABLE_ARC				~(0x00000001 << 8)
+#define INT_ENABLE_ARC_BIT_POS			(8)
+
+/*
+ * UARTs: UART0 & UART1 & UART2
+ */
+#define CONFIG_UART_NS16550_PORT_0_IRQ_FLAGS	0 /* Default */
+#define CONFIG_UART_NS16550_PORT_1_IRQ_FLAGS	0 /* Default */
+#define CONFIG_UART_NS16550_PORT_2_IRQ_FLAGS	0 /* Default */
+
+
+#endif /* !_ASMLANGUAGE */
+
+#endif /* _SOC_H_ */