arc: add architecture header files

These are header files used by ARC700 architecture.

Also note that "arch-arc700/hardware.h" is only required for compilation of
"designware_i2c" driver which refers to "asm/arch/hardware.h".
It would be good to fix mentioned driver sometime soon but it will cause
changes in ARM board configs that use "designware_i2c".

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Francois Bedard <fbedard@synopsys.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Heiko Schocher <hs@denx.de>

arch/arc/include/asm/cache.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2013-2014 Synopsys, Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __ASM_ARC_CACHE_H
+#define __ASM_ARC_CACHE_H
+
+#include <config.h>
+
+/*
+ * The current upper bound for ARC L1 data cache line sizes is 128 bytes.
+ * We use that value for aligning DMA buffers unless the board config has
+ * specified an alternate cache line size.
+ */
+#ifdef CONFIG_SYS_CACHELINE_SIZE
+#define ARCH_DMA_MINALIGN	CONFIG_SYS_CACHELINE_SIZE
+#else
+#define ARCH_DMA_MINALIGN	128
+#endif
+
+#endif /* __ASM_ARC_CACHE_H */