Add power-domain binding documentation for the NVIDIA PMC driver in
order to support generic power-domains.

Signed-off-by: Jon Hunter <redacted>

---

Please note that I have been debating whether I add this
"nvidia,powergate-clock-disable" property or just leave the clocks
disabled by default. Some downstream kernels leave the clocks enabled
for the audio power-domain because the clocks required for powering up
the power-domain are needed by all modules within the power-domain.
However are the same time there are other power-domains that may need
to be on, but not always clocked and so having the ability to specify if
the clocks should be disabled seems useful. However, I can also remove
this and just have the appropriate devices turn on the clocks as well.
---
 .../bindings/arm/tegra/nvidia,tegra20-pmc.txt      | 61 ++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt
index 838e1a69ec0a..8e4641db51a9 100644
--- a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt
+++ b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt

@@ -1,5 +1,7 @@
 NVIDIA Tegra Power Management Controller (PMC)
 
+== Power Management Controller Node ==
+
 The PMC block interacts with an external Power Management Unit. The PMC
 mostly controls the entry and exit of the system from different sleep
 modes. It provides power-gating controllers for SoC and CPU power-islands.

@@ -69,6 +71,10 @@ Optional properties for hardware-triggered thermal reset (inside 'i2c-thermtrip'
                      Defaults to 0. Valid values are described in section 12.5.2
                      "Pinmux Support" of the Tegra4 Technical Reference Manual.
 
+Optional nodes:
+- pm-domains : This node contains a hierarchy of PM domain nodes, which should
+	       match the power-domains on the Tegra SoC.
+