pinctrl: add a Cirrus ep93xx SoC pin controller

Add a pin control (only multiplexing) driver for ep93xx SoC so
we can fully convert ep93xx to device tree.

This driver is capable of muxing ep9301/ep9302/ep9307/ep9312/ep9315
variants, this is chosen based on "compatible" in device tree.
Co-developed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/pinctrl/Kconfig

@@ -194,6 +194,13 @@ config PINCTRL_DIGICOLOR
 	select PINMUX
 	select GENERIC_PINCONF
 
+config PINCTRL_EP93XX
+	bool
+	depends on ARCH_EP93XX || COMPILE_TEST
+	select PINMUX
+	select GENERIC_PINCONF
+	select MFD_SYSCON
+
 config PINCTRL_EQUILIBRIUM
 	tristate "Generic pinctrl and GPIO driver for Intel Lightning Mountain SoC"
 	depends on OF && HAS_IOMEM

drivers/pinctrl/Makefile

@@ -23,6 +23,7 @@ obj-$(CONFIG_PINCTRL_DA850_PUPD) += pinctrl-da850-pupd.o
 obj-$(CONFIG_PINCTRL_DA9062)	+= pinctrl-da9062.o
 obj-$(CONFIG_PINCTRL_DIGICOLOR)	+= pinctrl-digicolor.o
 obj-$(CONFIG_PINCTRL_EQUILIBRIUM)   += pinctrl-equilibrium.o
+obj-$(CONFIG_PINCTRL_EP93XX)	+= pinctrl-ep93xx.o
 obj-$(CONFIG_PINCTRL_GEMINI)	+= pinctrl-gemini.o
 obj-$(CONFIG_PINCTRL_INGENIC)	+= pinctrl-ingenic.o
 obj-$(CONFIG_PINCTRL_K210)	+= pinctrl-k210.o