From 44c385effde9d0b983713b12f9dd7afbb21712dc Mon Sep 17 00:00:00 2001
From: Star Zeng <star.zeng@intel.com>
Date: Fri, 8 Jun 2018 16:40:09 +0800
Subject: PcAtChipsetPkg PcRtc: Use new EfiLocateFirstAcpiTable()

https://bugzilla.tianocore.org/show_bug.cgi?id=967
Request to add a library function for GetAcpiTable() in order
to get ACPI table using signature as input.

After evaluation, we found there are many duplicated code to
find ACPI table by signature in different modules.

This patch updates PcatRealTimeClockRuntimeDxe to use new
EfiLocateFirstAcpiTable() and remove the duplicated code.

Cc: Younas khan <pmdyounaskhan786@gmail.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
---
 PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c | 80 +---------------------
 1 file changed, 3 insertions(+), 77 deletions(-)

diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
index 2105acf35f..7965eb8aa5 100644
--- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
+++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
@@ -1202,49 +1202,6 @@ IsWithinOneDay (
   return Adjacent;
 }
 
-/**
-  This function find ACPI table with the specified signature in RSDT or XSDT.
-
-  @param Sdt              ACPI RSDT or XSDT.
-  @param Signature        ACPI table signature.
-  @param TablePointerSize Size of table pointer: 4 or 8.
-
-  @return ACPI table or NULL if not found.
-**/
-VOID *
-ScanTableInSDT (
-  IN EFI_ACPI_DESCRIPTION_HEADER    *Sdt,
-  IN UINT32                         Signature,
-  IN UINTN                          TablePointerSize
-  )
-{
-  UINTN                          Index;
-  UINTN                          EntryCount;
-  UINTN                          EntryBase;
-  EFI_ACPI_DESCRIPTION_HEADER    *Table;
-
-  EntryCount = (Sdt->Length - sizeof (EFI_ACPI_DESCRIPTION_HEADER)) / TablePointerSize;
-
-  EntryBase = (UINTN) (Sdt + 1);
-  for (Index = 0; Index < EntryCount; Index++) {
-    //
-    // When TablePointerSize is 4 while sizeof (VOID *) is 8, make sure the upper 4 bytes are zero.
-    //
-    Table = 0;
-    CopyMem (&Table, (VOID *) (EntryBase + Index * TablePointerSize), TablePointerSize);
-
-    if (Table == NULL) {
-      continue;
-    }
-
-    if (Table->Signature == Signature) {
-      return Table;
-    }
-  }
-
-  return NULL;
-}
-
 /**
   Get the century RTC address from the ACPI FADT table.
 
@@ -1255,42 +1212,11 @@ GetCenturyRtcAddress (
   VOID
   )
 {
-  EFI_STATUS                                    Status;
-  EFI_ACPI_2_0_ROOT_SYSTEM_DESCRIPTION_POINTER  *Rsdp;
   EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE     *Fadt;
 
-  Status = EfiGetSystemConfigurationTable (&gEfiAcpiTableGuid, (VOID **) &Rsdp);
-  if (EFI_ERROR (Status)) {
-    Status = EfiGetSystemConfigurationTable (&gEfiAcpi10TableGuid, (VOID **) &Rsdp);
-  }
-
-  if (EFI_ERROR (Status) || (Rsdp == NULL)) {
-    return 0;
-  }
-
-  Fadt = NULL;
-
-  //
-  // Find FADT in XSDT
-  //
-  if (Rsdp->Revision >= EFI_ACPI_2_0_ROOT_SYSTEM_DESCRIPTION_POINTER_REVISION && Rsdp->XsdtAddress != 0) {
-    Fadt = ScanTableInSDT (
-             (EFI_ACPI_DESCRIPTION_HEADER *) (UINTN) Rsdp->XsdtAddress,
-             EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE,
-             sizeof (UINTN)
-             );
-  }
-
-  //
-  // Find FADT in RSDT
-  //
-  if (Fadt == NULL && Rsdp->RsdtAddress != 0) {
-    Fadt = ScanTableInSDT (
-             (EFI_ACPI_DESCRIPTION_HEADER *) (UINTN) Rsdp->RsdtAddress,
-             EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE,
-             sizeof (UINT32)
-             );
-  }
+  Fadt = (EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE *) EfiLocateFirstAcpiTable (
+                                                         EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE
+                                                         );
 
   if ((Fadt != NULL) &&
       (Fadt->Century > RTC_ADDRESS_REGISTER_D) && (Fadt->Century < 0x80)
-- 
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