[PATCH] ArmPkg/ArmSmcPsciResetSystemLib: add support for warm reboot

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

PSCI SYSTEM_RESET is specified as a cold reboot, which does not
preserve the contents of DRAM. In version 1.1, a new reset method
was introduced that allows a warm reboot to be requested.

This is especially relevant for capsule update, given that it will
invoke a warm reboot before processing the capsule, under the
assumption that the capsule will still be in memory when the PEI
phase is reentered.

So wire up the [rather inaccurately named] EnterS3WithImmediateWake()
entry point that the capsule update runtime uses to the new PSCI 1.1
warm reboot. Note that many PSCI implementations will not support this
yet, so fall back to a cold reboot if warm reboot fails.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

I don't actually need this code for Synquacer, but given that I had
already wrote it, we may just as well merge it.

 ArmPkg/Include/IndustryStandard/ArmStdSmc.h                        | 10 +++++++---
 ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c | 14 ++++++++++++--
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/ArmPkg/Include/IndustryStandard/ArmStdSmc.h b/ArmPkg/Include/IndustryStandard/ArmStdSmc.h
index 593a3ce729ce..41b086947eaa 100644
--- a/ArmPkg/Include/IndustryStandard/ArmStdSmc.h
+++ b/ArmPkg/Include/IndustryStandard/ArmStdSmc.h
@@ -57,10 +57,12 @@
 #define ARM_SMC_ID_PSCI_MIGRATE_AARCH32        0x84000005
 #define ARM_SMC_ID_PSCI_SYSTEM_OFF             0x84000008
 #define ARM_SMC_ID_PSCI_SYSTEM_RESET           0x84000009
+#define ARM_SMC_ID_PSCI_SYSTEM_RESET2_AARCH64  0xc4000012
+#define ARM_SMC_ID_PSCI_SYSTEM_RESET2_AARCH32  0x84000012
 
-/* The current PSCI version is:  0.2 */
-#define ARM_SMC_PSCI_VERSION_MAJOR  0
-#define ARM_SMC_PSCI_VERSION_MINOR  2
+/* The current PSCI version is:  1.1 */
+#define ARM_SMC_PSCI_VERSION_MAJOR  1
+#define ARM_SMC_PSCI_VERSION_MINOR  1
 #define ARM_SMC_PSCI_VERSION  \
   ((ARM_SMC_PSCI_VERSION_MAJOR << 16) | ARM_SMC_PSCI_VERSION_MINOR)
 
@@ -93,4 +95,6 @@
 #define ARM_SMC_ID_PSCI_AFFINITY_INFO_OFF         1
 #define ARM_SMC_ID_PSCI_AFFINITY_INFO_ON_PENDING  2
 
+#define ARM_SMC_ID_PSCI_SYSTEM_RESET2_WARM  0
+
 #endif
diff --git a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
index d6d26bce5009..ffd726554c0f 100644
--- a/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
+++ b/ArmPkg/Library/ArmSmcPsciResetSystemLib/ArmSmcPsciResetSystemLib.c
@@ -55,7 +55,17 @@ ResetWarm (
   VOID
   )
 {
-  // Map a warm reset into a cold reset
+  ARM_SMC_ARGS ArmSmcArgs;
+
+#if defined(MDE_CPU_AARCH64)
+  ArmSmcArgs.Arg0 = ARM_SMC_ID_PSCI_SYSTEM_RESET2_AARCH64;
+#else
+  ArmSmcArgs.Arg0 = ARM_SMC_ID_PSCI_SYSTEM_RESET2_AARCH32;
+#endif
+  ArmSmcArgs.Arg1 = ARM_SMC_ID_PSCI_SYSTEM_RESET2_WARM;
+  ArmCallSmc (&ArmSmcArgs);
+
+  // Fall back to cold reset if unsupported
   ResetCold ();
 }
 
@@ -89,7 +99,7 @@ EnterS3WithImmediateWake (
   VOID
   )
 {
-  // Not implemented
+  ResetWarm ();
 }
 
 /**
-- 
2.11.0