From dde2dd64f07041c2ccc23dc7a5a846e667b7bb1a Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Wed, 6 Jun 2018 14:32:42 +0200
Subject: ArmPkg/ArmSmcPsciResetSystemLib: implement fallback for warm reboot

Implement ResetSystemLib's EnterS3WithImmediateWake() routine using
a jump back to the PEI entry point with interrupts and MMU+caches
disabled. This is only possible at boot time, when we are sure that
the current CPU is the only one up and running. Also, it depends on
the platform whether the PEI code is preserved in memory (it may be
copied to DRAM rather than execute in place), so also add a feature
PCD to selectively enable this feature.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
---
 .../ArmSmcPsciResetSystemLib.c                      | 21 +++++++++++++++++++--
 .../ArmSmcPsciResetSystemLib.inf                    |  9 +++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

(limited to 'ArmPkg/Library/ArmSmcPsciResetSystemLib')

diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
index d6d26bc..10ceafd 100644
--- a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
@@ -15,10 +15,13 @@
 
 #include <PiDxe.h>
 
+#include <Library/ArmMmuLib.h>
+#include <Library/ArmSmcLib.h>
 #include <Library/BaseLib.h>
 #include <Library/DebugLib.h>
 #include <Library/ResetSystemLib.h>
-#include <Library/ArmSmcLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiRuntimeLib.h>
 
 #include <IndustryStandard/ArmStdSmc.h>
 
@@ -89,7 +92,21 @@ EnterS3WithImmediateWake (
   VOID
   )
 {
-  // Not implemented
+  VOID (*Reset)(VOID);
+
+  if (FeaturePcdGet (PcdArmReenterPeiForCapsuleWarmReboot) &&
+      !EfiAtRuntime ()) {
+    //
+    // At boot time, we are the only core running, so we can implement the
+    // immediate wake (which is used by capsule update) by disabling the MMU
+    // and interrupts, and jumping to the PEI entry point.
+    //
+    Reset = (VOID (*)(VOID))(UINTN)FixedPcdGet64 (PcdFvBaseAddress);
+
+    gBS->RaiseTPL (TPL_HIGH_LEVEL);
+    ArmDisableMmu ();
+    Reset ();
+  }
 }
 
 /**
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
index 5a1ee97..19021cd 100644
--- a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.inf
@@ -30,6 +30,15 @@
   MdePkg/MdePkg.dec
 
 [LibraryClasses]
+  ArmMmuLib
   ArmSmcLib
   BaseLib
   DebugLib
+  UefiBootServicesTableLib
+  UefiRuntimeLib
+
+[FeaturePcd]
+  gArmTokenSpaceGuid.PcdArmReenterPeiForCapsuleWarmReboot
+
+[FixedPcd]
+  gArmTokenSpaceGuid.PcdFvBaseAddress
-- 
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