1 files changed, 80 insertions, 0 deletions
diff --git a/DynamicTablesPkg/Library/Common/SsdtPcieSupportLib/SsdtPcieOscTemplate.asl b/DynamicTablesPkg/Library/Common/SsdtPcieSupportLib/SsdtPcieOscTemplate.asl
new file mode 100644
index 0000000000..feaf56b533
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+++ b/DynamicTablesPkg/Library/Common/SsdtPcieSupportLib/SsdtPcieOscTemplate.asl
@@ -0,0 +1,80 @@
+/** @file
+  SSDT Pci Osc (Operating System Capabilities)
+
+  Copyright (c) 2021, Arm Limited. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+  @par Reference(s):
+  - PCI Firmware Specification - Revision 3.3
+  - ACPI 6.4 specification:
+   - s6.2.13 "_PRT (PCI Routing Table)"
+   - s6.1.1 "_ADR (Address)"
+  - linux kernel code
+**/
+
+DefinitionBlock ("SsdtPciOsc.aml", "SSDT", 2, "ARMLTD", "PCI-OSC", 1) {
+
+  // This table is just a template and is never installed as a table.
+  // Pci devices are dynamically created at runtime as:
+  // ASL:
+  // Device (PCIx) {
+  //   ...
+  // }
+  // and the _OSC method available below is appended to the PCIx device as:
+  // ASL:
+  // Device (PCIx) {
+  //   ...
+  //   Method (_OSC, 4 {
+  //    ...
+  //   })
+  // }
+  Method (_OSC, 4) {
+    //
+    // OS Control Handoff
+    //
+    Name (SUPP, Zero) // PCI _OSC Support Field value
+    Name (CTRL, Zero) // PCI _OSC Control Field value
+
+    // Create DWord-addressable fields from the Capabilities Buffer
+    CreateDWordField (Arg3, 0, CDW1)
+    CreateDWordField (Arg3, 4, CDW2)
+    CreateDWordField (Arg3, 8, CDW3)
+
+    // Check for proper UUID
+    If (LEqual (Arg0,ToUUID ("33DB4D5B-1FF7-401C-9657-7441C03DD766"))) {
+
+      // Save Capabilities DWord2 & 3
+      Store (CDW2, SUPP)
+      Store (CDW3, CTRL)
+
+      // Only allow native hot plug control if OS supports:
+      // * ASPM
+      // * Clock PM
+      // * MSI/MSI-X
+      If (LNotEqual (And (SUPP, 0x16), 0x16)) {
+        And (CTRL, 0x1E, CTRL) // Mask bit 0 (and undefined bits)
+      }
+
+      // Always allow native PME, AER (no dependencies)
+
+      // Never allow SHPC (no SHPC controller in this system)
+      And (CTRL, 0x1D, CTRL)
+
+      If (LNotEqual (Arg1, One)) {  // Unknown revision
+        Or (CDW1, 0x08, CDW1)
+      }
+
+      If (LNotEqual (CDW3, CTRL)) {  // Capabilities bits were masked
+        Or (CDW1, 0x10, CDW1)
+      }
+
+      // Update DWORD3 in the buffer
+      Store (CTRL,CDW3)
+      Return (Arg3)
+    } Else {
+      Or (CDW1, 4, CDW1) // Unrecognized UUID
+      Return (Arg3)
+    } // If
+  } // _OSC
+}