MIPS: ath79: add GPIOLIB support

This patch implements generic GPIO routines for the built-in
GPIO controllers of the Atheros AR71XX/AR724X/AR913X SoCs.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: linux-mips@linux-mips.org
Cc: Luis R. Rodriguez <lrodriguez@atheros.com>
Cc: Cliff Holden <Cliff.Holden@Atheros.com>
Cc: Kathy Giori <Kathy.Giori@Atheros.com>
Patchwork: https://patchwork.linux-mips.org/patch/1948/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/ath79/common.h b/arch/mips/ath79/common.h
index 612a6b5..561906c 100644
--- a/arch/mips/ath79/common.h
+++ b/arch/mips/ath79/common.h
@@ -23,4 +23,9 @@
 void ath79_clocks_init(void);
 void ath79_ddr_wb_flush(unsigned int reg);
 
+void ath79_gpio_function_enable(u32 mask);
+void ath79_gpio_function_disable(u32 mask);
+void ath79_gpio_function_setup(u32 set, u32 clear);
+void ath79_gpio_init(void);
+
 #endif /* __ATH79_COMMON_H */