DynamicTablesPkg: Exempt some _CPC field from checks

When generating _CPC objects, some fields are mandatory by spec [1].
Some fields cannot be supported by a the Juno platform, which is used
to test the _CPC generation. Therefore, rely on the
PcdDevelopmentPlatformRelaxations Pcd to either:
- warn about the missing fields and and let the OS handle the
  missing information
- consider the missing fields as an error

_CPC fields that are exempted from checks when the Pcd is set:
- PerformanceLimitedRegister
- ReferencePerformanceCounterRegister
- DeliveredPerformanceCounterRegister

[1] Cf. non-optional fields in:
    ACPI 6.5, s8.4.6.1 '_CPC (Continuous Performance Control)'

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

2 files changed, 27 insertions, 4 deletions

diff --git a/DynamicTablesPkg/Library/Common/AmlLib/AmlLib.inf b/DynamicTablesPkg/Library/Common/AmlLib/AmlLib.inf
index 6d0aa6f..f269691 100644
--- a/DynamicTablesPkg/Library/Common/AmlLib/AmlLib.inf
+++ b/DynamicTablesPkg/Library/Common/AmlLib/AmlLib.inf
@@ -71,6 +71,9 @@
   BaseLib

   MemoryAllocationLib

 

+[FixedPcd]

+  gEdkiiDynamicTablesPkgTokenSpaceGuid.PcdDevelopmentPlatformRelaxations

+

 [BuildOptions]

   *_*_*_CC_FLAGS = -DAML_HANDLE

 

diff --git a/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlCodeGen.c b/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlCodeGen.c
index 6f3f46e..22c2d59 100644
--- a/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlCodeGen.c
+++ b/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlCodeGen.c
@@ -3532,6 +3532,29 @@ AmlCreateCpcNode (
     return EFI_INVALID_PARAMETER;

   }

 

+  /// The following fields are theoretically mandatory, but not supported

+  /// by some platforms.

+  /// - PerformanceLimitedRegister

+  /// - ReferencePerformanceCounterRegister

+  /// - DeliveredPerformanceCounterRegister

+  /// Warn if BIT0 in PcdDevelopmentPlatformRelaxations is set, otherwise

+  /// return an error.

+  if (IsNullGenericAddress (&CpcInfo->PerformanceLimitedRegister) ||

+      IsNullGenericAddress (&CpcInfo->ReferencePerformanceCounterRegister) ||

+      IsNullGenericAddress (&CpcInfo->DeliveredPerformanceCounterRegister))

+  {

+    if ((PcdGet64 (PcdDevelopmentPlatformRelaxations) & BIT0) != 0) {

+      DEBUG ((

+        DEBUG_WARN,

+        "Missing PerformanceLimited|ReferencePerformanceCounter|"

+        "DeliveredPerformanceCounter field in _CPC object\n"

+        ));

+    } else {

+      ASSERT (0);

+      return EFI_INVALID_PARAMETER;

+    }

+  }

+

   if ((IsNullGenericAddress (&CpcInfo->HighestPerformanceBuffer) &&

        (CpcInfo->HighestPerformanceInteger == 0)) ||

       (IsNullGenericAddress (&CpcInfo->NominalPerformanceBuffer) &&

@@ -3540,10 +3563,7 @@ AmlCreateCpcNode (
        (CpcInfo->LowestNonlinearPerformanceInteger == 0)) ||

       (IsNullGenericAddress (&CpcInfo->LowestPerformanceBuffer) &&

        (CpcInfo->LowestPerformanceInteger == 0)) ||

-      IsNullGenericAddress (&CpcInfo->DesiredPerformanceRegister) ||

-      IsNullGenericAddress (&CpcInfo->ReferencePerformanceCounterRegister) ||

-      IsNullGenericAddress (&CpcInfo->DeliveredPerformanceCounterRegister) ||

-      IsNullGenericAddress (&CpcInfo->PerformanceLimitedRegister))

+      IsNullGenericAddress (&CpcInfo->DesiredPerformanceRegister))

   {

     ASSERT (0);

     return EFI_INVALID_PARAMETER;