cpu: Add initial support for Allwinner A10 SoC

Add minimal support needed to get a bootblock capable of initialising
a serial console.

Change-Id: I50dd85544549baf9c5ea0aa3b4296972136c02a4
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/4549
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/allwinner/a10/pinmux.c

@@ -0,0 +1,30 @@
+/*
+ * Helpers to multiplex and configure pins on Allwinner SoCs
+ *
+ * Copyright (C) 2013  Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ * Subject to the GNU GPL v2, or (at your option) any later version.
+ */
+
+#include "gpio.h"
+
+#include <arch/io.h>
+
+static struct a10_gpio *const gpio = (void *)GPIO_BASE;
+
+void gpio_set_func(u8 port, u8 pin, u8 pad_func)
+{
+	u8 reg, bit;
+	u32 reg32;
+
+	if ((port > GPS))
+		return;
+
+	pin &= 0x1f;
+	reg = pin / 8;
+	bit = (pin % 8) * 4;
+
+	reg32 = read32(&gpio->port[port].cfg[reg]);
+	reg32 &= ~(0xf << bit);
+	reg32 |= (pad_func & 0xf) << bit;
+	write32(reg32, &gpio->port[port].cfg[reg]);
+}