WCH RISC-V SWD physical interface TDF signal validation

build/scripts/Targets/TargetDescriptionFiles/Services/ValidationService.php

@@ -736,6 +736,9 @@ class ValidationService
         }
 
         if ($enumValue === TargetPhysicalInterface::SDI) {
+            $singleWireVariant = $containsSignal('SWIO');
+
+            if (!$singleWireVariant) {
                 if (!$containsSignal('SWDIO')) {
                     $failures[] = 'Missing SWDIO signal';
                 }
@@ -744,6 +747,7 @@ class ValidationService
                     $failures[] = 'Missing SWCLK signal';
                 }
             }
+        }
 
         foreach ($physicalInterface->signals as $signal) {
             $failures = array_merge($failures, $this->validateSignal($signal, $tdf));