dt-bindings: soc: tegra-pmc: Add Tegra PMC clock bindings

Tegra PMC has 3 clocks clk_out_1, clk_out_2, and clk_out_3.

This patch documents PMC clock bindings and adds a header defining
Tegra PMC clock ids.
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.yaml

@@ -40,6 +40,15 @@ properties:
       Must contain an entry for each entry in clock-names.
       See ../clocks/clocks-bindings.txt for details.
 
+  '#clock-cells':
+    const: 1
+    description:
+      Tegra PMC has clk_out_1, clk_out_2, and clk_out_3.
+      Consumer of PMC clock should specify the desired clock by having
+      the clock ID in its "clocks" phandle cell with pmc clock provider.
+      See include/dt-bindings/soc/tegra-pmc.h for the list of Tegra PMC
+      clock IDs.
+
   '#interrupt-cells':
     const: 2
     description:
@@ -296,6 +305,7 @@ required:
   - reg
   - clock-names
   - clocks
+  - '#clock-cells'
 
 dependencies:
   "nvidia,suspend-mode": ["nvidia,core-pwr-off-time", "nvidia,cpu-pwr-off-time"]
@@ -307,12 +317,14 @@ examples:
 
     #include <dt-bindings/clock/tegra210-car.h>
     #include <dt-bindings/pinctrl/pinctrl-tegra-io-pad.h>
+    #include <dt-bindings/soc/tegra-pmc.h>
 
     tegra_pmc: pmc@7000e400 {
               compatible = "nvidia,tegra210-pmc";
               reg = <0x0 0x7000e400 0x0 0x400>;
               clocks = <&tegra_car TEGRA210_CLK_PCLK>, <&clk32k_in>;
               clock-names = "pclk", "clk32k_in";
+              #clock-cells = <1>;
 
               nvidia,invert-interrupt;
               nvidia,suspend-mode = <0>;

include/dt-bindings/soc/tegra-pmc.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2019-2020, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#ifndef _DT_BINDINGS_SOC_TEGRA_PMC_H
+#define _DT_BINDINGS_SOC_TEGRA_PMC_H
+
+#define TEGRA_PMC_CLK_OUT_1		0
+#define TEGRA_PMC_CLK_OUT_2		1
+#define TEGRA_PMC_CLK_OUT_3		2
+
+#define TEGRA_PMC_CLK_MAX		3
+
+#endif	/* _DT_BINDINGS_SOC_TEGRA_PMC_H */