[PATCH 2/3] ArmVirtPkg/FdtPL011SerialPortLib: take DT node 'status' property into account

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

In some cases, (e.g., when running QEMU with TrustZone emulation), the
DT may contain DT nodes whose status is set to 'secure'. Similarly, the
status may be set to 'disabled' if the consumer of the DT image is expected
to treat it as if it weren't there.

So check whether a 'status' property is present, and if so, ignore the node
if the status is not 'okay'.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmVirtPkg/Library/FdtPL011SerialPortLib/EarlyFdtPL011SerialPortLib.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ArmVirtPkg/Library/FdtPL011SerialPortLib/EarlyFdtPL011SerialPortLib.c b/ArmVirtPkg/Library/FdtPL011SerialPortLib/EarlyFdtPL011SerialPortLib.c
index c458abb622d9..e28750f3b4c4 100644
--- a/ArmVirtPkg/Library/FdtPL011SerialPortLib/EarlyFdtPL011SerialPortLib.c
+++ b/ArmVirtPkg/Library/FdtPL011SerialPortLib/EarlyFdtPL011SerialPortLib.c
@@ -66,6 +66,7 @@ SerialPortGetBaseAddress (
   INT32               Node, Prev;
   INT32               Len;
   CONST CHAR8         *Compatible;
+  CONST CHAR8         *NodeStatus;
   CONST CHAR8         *CompatibleItem;
   CONST UINT64        *RegProperty;
   UINTN               UartBase;
@@ -98,6 +99,11 @@ SerialPortGetBaseAddress (
       CompatibleItem += 1 + AsciiStrLen (CompatibleItem)) {
 
       if (AsciiStrCmp (CompatibleItem, "arm,pl011") == 0) {
+        NodeStatus = fdt_getprop (DeviceTreeBase, Node, "status", &Len);
+        if (NodeStatus != NULL && AsciiStrCmp (NodeStatus, "okay") != 0) {
+          continue;
+        }
+
         RegProperty = fdt_getprop (DeviceTreeBase, Node, "reg", &Len);
         if (Len != 16) {
           return 0;
-- 
2.9.3