pinctrl: Add STM32 MCUs support

This patch adds pinctrl and GPIO support to STMicroelectronic's STM32
family of MCUs.

While it only supports STM32F429 for now, it has been designed to enable
support of other MCUs of the family (e.g. STM32F746).

Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/stm32/Kconfig b/drivers/pinctrl/stm32/Kconfig
new file mode 100644
index 0000000..0f28841
--- /dev/null
+++ b/drivers/pinctrl/stm32/Kconfig
@@ -0,0 +1,16 @@
+if ARCH_STM32 || COMPILE_TEST
+
+config PINCTRL_STM32
+	bool
+	depends on OF
+	select PINMUX
+	select GENERIC_PINCONF
+	select GPIOLIB
+
+config PINCTRL_STM32F429
+	bool "STMicroelectronics STM32F429 pin control" if COMPILE_TEST && !MACH_STM32F429
+	depends on OF
+	default MACH_STM32F429
+	select PINCTRL_STM32
+
+endif