ARM: sunxi: Add support for uart0 on port F (mmc0)

Allwinner SoCs provide uart0 muxed with mmc0, which can then be used
with a micro SD breakout board. On the A23, this is the only way to
use uart0.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
diff --git a/arch/arm/cpu/armv7/sunxi/board.c b/arch/arm/cpu/armv7/sunxi/board.c
index 436df8c..7d10f10 100644
--- a/arch/arm/cpu/armv7/sunxi/board.c
+++ b/arch/arm/cpu/armv7/sunxi/board.c
@@ -50,7 +50,16 @@
 
 int gpio_init(void)
 {
-#if CONFIG_CONS_INDEX == 1 && (defined(CONFIG_SUN4I) || defined(CONFIG_SUN7I))
+#if CONFIG_CONS_INDEX == 1 && defined(CONFIG_UART0_PORT_F)
+#if defined(CONFIG_SUN4I) || defined(CONFIG_SUN7I)
+	/* disable GPB22,23 as uart0 tx,rx to avoid conflict */
+	sunxi_gpio_set_cfgpin(SUNXI_GPB(22), SUNXI_GPIO_INPUT);
+	sunxi_gpio_set_cfgpin(SUNXI_GPB(23), SUNXI_GPIO_INPUT);
+#endif
+	sunxi_gpio_set_cfgpin(SUNXI_GPF(2), SUNXI_GPF2_UART0_TX);
+	sunxi_gpio_set_cfgpin(SUNXI_GPF(4), SUNXI_GPF4_UART0_RX);
+	sunxi_gpio_set_pull(SUNXI_GPF(4), 1);
+#elif CONFIG_CONS_INDEX == 1 && (defined(CONFIG_SUN4I) || defined(CONFIG_SUN7I))
 	sunxi_gpio_set_cfgpin(SUNXI_GPB(22), SUN4I_GPB22_UART0_TX);
 	sunxi_gpio_set_cfgpin(SUNXI_GPB(23), SUN4I_GPB23_UART0_RX);
 	sunxi_gpio_set_pull(SUNXI_GPB(23), SUNXI_GPIO_PULL_UP);