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>

arch/arm/include/asm/arch-tegra/tegra.h

@@ -97,6 +97,11 @@ enum {
 	TEGRA_SOC_UNKNOWN	= -1,
 };
 
+/* Tegra system controller (SYSCON) devices */
+enum {
+	TEGRA_SYSCON_PMC,
+};
+
 #else  /* __ASSEMBLY__ */
 #define PRM_RSTCTRL		NV_PA_PMC_BASE
 #endif

arch/arm/mach-tegra/Kconfig

@@ -88,6 +88,8 @@ config TEGRA124
 	bool "Tegra124 family"
 	select TEGRA_ARMV7_COMMON
 	imply ENV_IS_IN_MMC
+	imply REGMAP
+	imply SYSCON
 
 config TEGRA210
 	bool "Tegra210 family"

arch/arm/mach-tegra/tegra124/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_SPL_BUILD) += cpu.o
 obj-y	+= clock.o
 obj-y	+= funcmux.o
 obj-y	+= pinmux.o
+obj-y	+= pmc.o
 obj-y	+= xusb-padctl.o
 obj-y	+= ../xusb-padctl-common.o
 

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,
+};