gpio: add support for 74x164 serial-in/parallel-out 8-bit shift register

Add support for generic 74x164 serial-in/parallel-out 8-bits shift
register.  This driver can be used as a GPIO output expander.

[akpm@linux-foundation.org: remove unused local `refresh']
Signed-off-by: Miguel Gaio <miguel.gaio@efixo.com>
Signed-off-by: Juhos Gabor <juhosg@openwrt.org>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index e47ef94..bc7b0fc 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -344,6 +344,14 @@
 	  SPI driver for Freescale MC33880 high-side/low-side switch.
 	  This provides GPIO interface supporting inputs and outputs.
 
+config GPIO_74X164
+	tristate "74x164 serial-in/parallel-out 8-bits shift register"
+	depends on SPI_MASTER
+	help
+	  Platform driver for 74x164 compatible serial-in/parallel-out
+	  8-outputs shift registers. This driver can be used to provide access
+	  to more gpio outputs.
+
 comment "AC97 GPIO expanders:"
 
 config GPIO_UCB1400