ARM: Add Gemini architecture v3

Adds support for Cortina Systems Gemini family CPUs:
http://www.cortina-systems.com/products/category/18

v3:
- fixed __io(a) to be defined as __typesafe_io(a)

v2:
- #include <asm/io.h> -> <linux/io.h>
- remove asm/system.h include
- revorked mm.c to use named initializers
- removed "empty" dma.h
- updated copyrights

Signed-off-by: Paulius Zaleckas <paulius.zaleckas@teltonika.lt>

arch/arm/mach-gemini/include/mach/entry-macro.S

@@ -0,0 +1,39 @@
+/*
+ * Low-level IRQ helper macros for Gemini platform.
+ *
+ *  Copyright (C) 2001-2006 Storlink, Corp.
+ *  Copyright (C) 2008-2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
+ *
+ * This file is licensed under  the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+#include <mach/hardware.h>
+
+#define IRQ_STATUS	0x14
+
+	.macro  disable_fiq
+	.endm
+
+	.macro  get_irqnr_preamble, base, tmp
+	.endm
+
+	.macro  arch_ret_to_user, tmp1, tmp2
+	.endm
+
+	.macro  get_irqnr_and_base, irqnr, irqstat, base, tmp
+	ldr     \irqstat, =IO_ADDRESS(GEMINI_INTERRUPT_BASE + IRQ_STATUS)
+	ldr     \irqnr, [\irqstat]
+	cmp     \irqnr, #0
+	beq     2313f
+	mov     \tmp, \irqnr
+	mov     \irqnr, #0
+2312:
+	tst     \tmp, #1
+	bne     2313f
+	add     \irqnr, \irqnr, #1
+	mov     \tmp, \tmp, lsr #1
+	cmp     \irqnr, #31
+	bcc     2312b
+2313:
+	.endm