GPIO: Add driver for 74xx-ICs with MMIO access

This patch adds driver to support GPIO functionality for 74xx-compatible
ICs with MMIO access. Compatible models include:
 1 bit:   741G125 (Input), 741G74 (Output)
 2 bits:  742G125 (Input), 7474 (Output)
 4 bits:  74125 (Input), 74175 (Output)
 6 bits:  74365 (Input), 74174 (Output)
 8 bits:  74244 (Input), 74273 (Output)
 16 bits: 741624 (Input), 7416374 (Output)

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 0959ca9..cd33134 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -112,6 +112,20 @@
 
 comment "Memory mapped GPIO drivers:"
 
+config GPIO_74XX_MMIO
+	tristate "GPIO driver for 74xx-ICs with MMIO access"
+	depends on OF_GPIO
+	select GPIO_GENERIC
+	help
+	  Say yes here to support GPIO functionality for 74xx-compatible ICs
+	  with MMIO access. Compatible models include:
+	    1 bit:	741G125 (Input), 741G74 (Output)
+	    2 bits:	742G125 (Input), 7474 (Output)
+	    4 bits:	74125 (Input), 74175 (Output)
+	    6 bits:	74365 (Input), 74174 (Output)
+	    8 bits:	74244 (Input), 74273 (Output)
+	    16 bits:	741624 (Input), 7416374 (Output)
+
 config GPIO_CLPS711X
 	tristate "CLPS711X GPIO support"
 	depends on ARCH_CLPS711X || COMPILE_TEST