add bindings document for altera freeze bridge

Add bindings document for the Altera Freeze Bridge.  A Freeze
Bridge is used to gate traffic to/from a region of a FPGA
such that that region can be reprogrammed.  The Freeze Bridge
exist in FPGA fabric that is not currently being reconfigured.

Signed-off-by: Alan Tull <atull@opensource.altera.com>
Signed-off-by: Matthew Gerlach <mgerlach@opensource.altera.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/Documentation/devicetree/bindings/fpga/altera-freeze-bridge.txt b/Documentation/devicetree/bindings/fpga/altera-freeze-bridge.txt
new file mode 100644 (file)
index 0000000..f8e288c
--- /dev/null
+++ b/Documentation/devicetree/bindings/fpga/altera-freeze-bridge.txt
@@ -0,0 +1,23 @@
+Altera Freeze Bridge Controller Driver
+
+The Altera Freeze Bridge Controller manages one or more freeze bridges.
+The controller can freeze/disable the bridges which prevents signal
+changes from passing through the bridge.  The controller can also
+unfreeze/enable the bridges which allows traffic to pass through the
+bridge normally.
+
+Required properties:
+- compatible           : Should contain "altr,freeze-bridge-controller"
+- regs                 : base address and size for freeze bridge module
+
+Optional properties:
+- bridge-enable                : 0 if driver should disable bridge at startup
+                         1 if driver should enable bridge at startup
+                         Default is to leave bridge in current state.
+
+Example:
+       freeze-controller@100000450 {
+               compatible = "altr,freeze-bridge-controller";
+               regs = <0x1000 0x10>;
+               bridge-enable = <0>;
+       };