[edk2-platform][PATCH v1 1/1] ArmPlatformPkg/PL011UartLib : Fix SetControl() SCT conformance

[edk2-platform][PATCH v1 1/1] ArmPlatformPkg/PL011UartLib : Fix SetControl() SCT conformance

[Samer El-Haj-Mahmoud]

REF: https://github.com/pftf/RPi4/issues/87

The PL011UartLib SetControl() is failing the SCT test for
SerialIoBBTestConformance (00605CBC-3965-4B61-A254-2B2B723172EA),
which is trying to set bits that are not supported per UEFI spec.

Add proper argument check for valid bits, and confirm that test passes.

Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@arm.com>
---
 ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c b/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c
index 3c58a0f39acb..ec6056f5fdfd 100644
--- a/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c
+++ b/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c
@@ -269,6 +269,21 @@ PL011UartSetControl (
 {
   UINT32  Bits;
 
+
+  //
+  // Per UEFI spec, the control bits that can be set are :
+  //     EFI_SERIAL_DATA_TERMINAL_READY
+  //     EFI_SERIAL_REQUEST_TO_SEND
+  //     EFI_SERIAL_HARDWARE_LOOPBACK_ENABLE
+  //     EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE
+  //     EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE
+  //
+  if ((Control & (~(EFI_SERIAL_REQUEST_TO_SEND | EFI_SERIAL_DATA_TERMINAL_READY |
+                    EFI_SERIAL_HARDWARE_LOOPBACK_ENABLE | EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE |
+                    EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE))) != 0) {
+    return EFI_UNSUPPORTED;
+  }
+
   if ((Control & mInvalidControlBits) != 0) {
     return RETURN_UNSUPPORTED;
   }
-- 
2.25.1