[PATCH v2 2/2] dt-bindings: Document "UntrustedDevice" property for PCI devices

[Rajat Jain <rajatja@google.com>]

Add the new "UntrustedDevice" property for PCI devices. This property
is optional and can be applied to any PCI device.

Signed-off-by: Rajat Jain <rajatja@google.com>
---
v2: Initial version (added documentation based on comments)
v1: Does not exist.

 Documentation/devicetree/bindings/pci/pci.txt | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt
index 6a8f2874a24d..bc1ba10f51e1 100644
--- a/Documentation/devicetree/bindings/pci/pci.txt
+++ b/Documentation/devicetree/bindings/pci/pci.txt
@@ -82,3 +82,38 @@ pcie@10000000 {
 		external-facing;
 	};
 };
+
+PCI Device Properties
+---------------------
+Following optional properties may be present for any PCI device:
+
+- UntrustedDevice:
+   When present, this property is an indicator that this PCI device (and
+   any downstream devices) are to be treated as untrusted by the kernel.
+   The kernel can, for example, use this information to isolate such
+   devices using a strict DMA protection via the IOMMU.
+
+   Example device tree node:
+	pcie@0008 {
+		/* PCI device 00:01.0 is an untrusted device */
+		reg = <0x00000800 0 0 0 0>;
+		UntrustedDevice = <1>;
+	};
+
+   Example ACPI node:
+	Scope (\_SB.PCI0.WFA3)
+	    {
+	        Name (_DSD, Package (0x02)  // _DSD: Device-Specific Data
+	        {
+	            ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device
+	Properties for _DSD */,
+	            Package (0x01)
+	            {
+	                Package (0x02)
+	                {
+	                    "UntrustedDevice",
+	                    One
+	                }
+	            }
+	        })
+	    }
-- 
2.35.0.rc2.247.g8bbb082509-goog