pinctrl: Add pinctrl-aspeed-g4 driver

A subset of the pins and functions are exposed. The selection of
functions and pins is driven by the development of OpenBMC[1] on the
AST2400 SoC, particularly around booting the OpenPOWER Palmetto
development machine.

[1] https://github.com/openbmc/docs

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/aspeed/Kconfig

@@ -6,3 +6,11 @@ config PINCTRL_ASPEED
 	select PINCONF
 	select GENERIC_PINCONF
 	select REGMAP_MMIO
+
+config PINCTRL_ASPEED_G4
+	bool "Aspeed G4 SoC pin control"
+	depends on (MACH_ASPEED_G4 || COMPILE_TEST) && OF
+	select PINCTRL_ASPEED
+	help
+	  Say Y here to enable pin controller support for Aspeed's 4th
+	  generation SoCs. GPIO is provided by a separate GPIO driver.

drivers/pinctrl/aspeed/Makefile

@@ -2,3 +2,4 @@
 
 ccflags-y += -Woverride-init
 obj-$(CONFIG_PINCTRL_ASPEED)	+= pinctrl-aspeed.o
+obj-$(CONFIG_PINCTRL_ASPEED_G4)	+= pinctrl-aspeed-g4.o