pinctrl: pinctrl-microchip-sgpio: Add pinctrl driver for Microsemi Serial GPIO

This adds a pinctrl driver for the Microsemi/Microchip Serial GPIO
(SGPIO) device used in various SoC's.

The driver is added as a pinctrl driver, albeit only having just GPIO
support currently. The hardware supports other functions that will be
added following.
Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
Link: https://lore.kernel.org/r/20201113145151.68900-3-lars.povlsen@microchip.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

MAINTAINERS

@@ -2117,6 +2117,7 @@ L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Supported
 T:	git git://github.com/microchip-ung/linux-upstream.git
 F:	arch/arm64/boot/dts/microchip/
+F:	drivers/pinctrl/pinctrl-microchip-sgpio.c
 N:	sparx5
 
 ARM/MIOA701 MACHINE SUPPORT

drivers/pinctrl/Kconfig

@@ -374,6 +374,22 @@ config PINCTRL_OCELOT
 	select OF_GPIO
 	select REGMAP_MMIO
 
+config PINCTRL_MICROCHIP_SGPIO
+	bool "Pinctrl driver for Microsemi/Microchip Serial GPIO"
+	depends on HAS_IOMEM
+	select GPIOLIB
+	select GENERIC_PINCONF
+	select GENERIC_PINCTRL_GROUPS
+	select GENERIC_PINMUX_FUNCTIONS
+	help
+	  Support for the serial GPIO interface used on Microsemi and
+	  Microchip SoC's. By using a serial interface, the SIO
+	  controller significantly extends the number of available
+	  GPIOs with a minimum number of additional pins on the
+	  device. The primary purpose of the SIO controller is to
+	  connect control signals from SFP modules and to act as an
+	  LED controller.
+
 source "drivers/pinctrl/actions/Kconfig"
 source "drivers/pinctrl/aspeed/Kconfig"
 source "drivers/pinctrl/bcm/Kconfig"

drivers/pinctrl/Makefile

@@ -46,6 +46,7 @@ obj-$(CONFIG_PINCTRL_ZYNQ)	+= pinctrl-zynq.o
 obj-$(CONFIG_PINCTRL_INGENIC)	+= pinctrl-ingenic.o
 obj-$(CONFIG_PINCTRL_RK805)	+= pinctrl-rk805.o
 obj-$(CONFIG_PINCTRL_OCELOT)	+= pinctrl-ocelot.o
+obj-$(CONFIG_PINCTRL_MICROCHIP_SGPIO)	+= pinctrl-microchip-sgpio.o
 obj-$(CONFIG_PINCTRL_EQUILIBRIUM)   += pinctrl-equilibrium.o
 
 obj-y				+= actions/