tegra: tegra124: Add a PMC syscon driver

The PMC can be modelled as a syscon peripheral. Add a driver for this
so that it can be accessed by drivers when needed. Enable it for tegra124
boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-on: Beaver, Jetson-TK1
Tested-by: Stephen Warren <swarren@nvidia.com>
diff --git a/arch/arm/mach-tegra/tegra124/pmc.c b/arch/arm/mach-tegra/tegra124/pmc.c
new file mode 100644
index 0000000..be82acf
--- /dev/null
+++ b/arch/arm/mach-tegra/tegra124/pmc.c
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2017 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <syscon.h>
+
+static const struct udevice_id tegra124_syscon_ids[] = {
+	{ .compatible = "nvidia,tegra124-pmc", .data = TEGRA_SYSCON_PMC },
+};
+
+U_BOOT_DRIVER(syscon_tegra124) = {
+	.name = "tegra124_syscon",
+	.id = UCLASS_SYSCON,
+	.of_match = tegra124_syscon_ids,
+};