gpio: add Tegra186 GPIO driver

Tegra186's GPIO controller register layout is significantly different from
previous chips, so add a new driver for it. In fact, there are two
different GPIO controllers in Tegra186 that share a similar register
layout, but very different port mapping. This driver covers both.

The DT binding is already present in the Linux kernel (in linux-next via
the Tegra tree so far).

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org> # v1
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index f730744..32219ed 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -116,6 +116,14 @@
 	  Support for the GPIO controller contained in NVIDIA Tegra20 through
 	  Tegra210.
 
+config TEGRA186_GPIO
+	bool "Tegra186 GPIO driver"
+	depends on DM_GPIO
+	help
+	  Support for the GPIO controller contained in NVIDIA Tegra186. This
+	  covers both the "main" and "AON" controller instances, even though
+	  they have slightly different register layout.
+
 config GPIO_UNIPHIER
 	bool "UniPhier GPIO"
 	depends on ARCH_UNIPHIER