[PATCH v4 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.

Signed-off-by: Patrick Venture <venture@xxxxxxxxxx>
---
Changes for v4:
- None
Changes for v3:
- None
Changes for v2:
- Added comment about syscon required parameter.
---
 .../bindings/misc/aspeed-p2a-ctrl.txt         | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt

diff --git a/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
new file mode 100644
index 000000000000..1092d62d1c92
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
@@ -0,0 +1,32 @@
+======================================================================
+Device tree bindings for Aspeed AST2400/AST2500 PCI-to-AHB Bridge Control Driver
+======================================================================
+
+The bridge is available on platforms with the VGA enabled on the Aspeed device.
+In this case, the host has access to a 64KiB window into all of the BMC's
+memory.  The BMC can disable this bridge.  If the bridge is enabled, the host
+has read access to all the regions of memory, however the host only has read
+and write access depending on a register controlled by the BMC.
+
+Required properties:
+===================
+
+ - compatible: must be one of:
+	- "aspeed,ast2400-p2a-ctrl"
+	- "aspeed,ast2500-p2a-ctrl"
+
+ - syscon: handle to syscon device node controlling PCI.
+
+Optional properties:
+===================
+
+- memory-region: A phandle to a reserved_memory region to be used for the PCI
+		to AHB mapping
+
+Example:
+
+p2a: p2a-control@1e6e2000 {
+	compatible = "aspeed,ast2400-p2a-ctrl";
+	memory-region = <&reserved_memory>;
+	syscon = <&syscon>;
+};
-- 
2.21.0.rc2.261.ga7da99ff1b-goog