gpio MIPS/OCTEON: Add a driver for OCTEON's on-chip GPIO pins.

The SOCs in the OCTEON family have 16 (or in some cases 20) on-chip
GPIO pins, this driver handles them all.  Configuring the pins as
interrupt sources is handled elsewhere (OCTEON's irq handling code).

Signed-off-by: David Daney <david.daney@cavium.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/5633/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b2450ba..b21b7a2 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -193,6 +193,14 @@
 	select GPIO_GENERIC
 	select GENERIC_IRQ_CHIP
 
+config GPIO_OCTEON
+	tristate "Cavium OCTEON GPIO"
+	depends on GPIOLIB && CAVIUM_OCTEON_SOC
+	default y
+	help
+	  Say yes here to support the on-chip GPIO lines on the OCTEON
+	  family of SOCs.
+
 config GPIO_PL061
 	bool "PrimeCell PL061 GPIO support"
 	depends on ARM && ARM_AMBA