pinctrl: Add core support for Aspeed SoCs

The Aspeed SoCs typically provide more than 200 pins for GPIO and other
functions. The signal enabled on a pin is determined on a priority
basis, where a given pin can provide a number of different signal types.

In addition to the priority levels, the Aspeed pin controllers describe
the signal active on a pin by compound logical expressions involving
multiple operators, registers and bits. Some difficulty arises as a
pin's function bit masks for each priority level are frequently not the
same (i.e. we cannot just flip a bit to change from a high to low
priority signal), or even in the same register(s). Some configuration
bits affect multiple pins, while in other cases the signals for a bus
must each be enabled individually.

Together, these features give rise to some complexity in the
implementation. A more complete description of the complexities is
provided in the associated header file.

The patch doesn't implement pinctrl/pinmux/pinconf for any particular
Aspeed SoC, rather it adds the framework for defining pinmux
configurations.
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/Kconfig

@@ -254,6 +254,7 @@ config PINCTRL_ZYNQ
 	help
 	  This selects the pinctrl driver for Xilinx Zynq.
 
+source "drivers/pinctrl/aspeed/Kconfig"
 source "drivers/pinctrl/bcm/Kconfig"
 source "drivers/pinctrl/berlin/Kconfig"
 source "drivers/pinctrl/freescale/Kconfig"

drivers/pinctrl/Makefile

@@ -37,6 +37,7 @@ obj-$(CONFIG_PINCTRL_TB10X)	+= pinctrl-tb10x.o
 obj-$(CONFIG_PINCTRL_ST) 	+= pinctrl-st.o
 obj-$(CONFIG_PINCTRL_ZYNQ)	+= pinctrl-zynq.o
 
+obj-$(CONFIG_ARCH_ASPEED)	+= aspeed/
 obj-y				+= bcm/
 obj-$(CONFIG_PINCTRL_BERLIN)	+= berlin/
 obj-y				+= freescale/

drivers/pinctrl/aspeed/Kconfig

+config PINCTRL_ASPEED
+	bool
+	depends on (ARCH_ASPEED || COMPILE_TEST) && OF
+	depends on MFD_SYSCON
+	select PINMUX
+	select PINCONF
+	select GENERIC_PINCONF
+	select REGMAP_MMIO

drivers/pinctrl/aspeed/Makefile

+# Aspeed pinctrl support
+
+ccflags-y += -Woverride-init
+obj-$(CONFIG_PINCTRL_ASPEED)	+= pinctrl-aspeed.o