From f5a31b4f4ea8daaa0d337d5a2322ddb1912083fc Mon Sep 17 00:00:00 2001
From: Qi Feng <qi.feng@arm.com>
Date: Wed, 26 May 2021 17:52:01 +0800
Subject: [PATCH] Allow --enable-psci to choose between smc and hvc

According to Armv8-R AArch64 manual [1], Armv8-R AArch64 does not
support smc:

- Pseudocode for AArch64.CheckForSMCUndefOrTrap has this snippet:

      if !HaveEL(EL3) || PSTATE.EL == EL0 then
          UNDEFINED;

  And Armv8-R AArch64 does not have EL3.

- In the document of HCR_EL2 TSC bit:
  If EL3 is not implemented and HCR_EL2.NV is 0, it is IMPLEMENTATION
  DEFINED whether this bit is:
  - RES0.
  - Implemented with the functionality as described in HCR_EL2.TSC.

So hvc is needed in this situation. And due to the lack of libfdt, the
psci method cannot be modified at runtime.

To use smc, use --enable-psci or --enable-psci=smc.
To use hvc, use --enable-psci=hvc.

[1]: https://developer.arm.com/documentation/ddi0600/latest/

Issue-Id: SCM-2654
Upstream-Status: Pending
Signed-off-by: Qi Feng <qi.feng@arm.com>
Change-Id: Ib8afabdad2d98bc37371d165bbb6f1f9b88bfc87

Upstream-Status: Pending
Signed-off-by: Huifeng Zhang <Huifeng.Zhang@arm.com>
---
 Makefile.am  | 10 +++++-----
 configure.ac | 14 +++++++++-----
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index f941b07..88a27de 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -50,11 +50,11 @@ endif
 if PSCI
 ARCH_OBJ	+= psci.o
 COMMON_OBJ	+= psci.o
-PSCI_NODE	:= psci {				\
-			compatible = \"arm,psci\";	\
-			method = \"smc\";		\
-			cpu_on = <$(PSCI_CPU_ON)>;	\
-			cpu_off = <$(PSCI_CPU_OFF)>;	\
+PSCI_NODE	:= psci {						\
+			compatible = \"arm,psci\";			\
+			method = \"$(PSCI_METHOD)\";			\
+			cpu_on = <$(PSCI_CPU_ON)>;			\
+			cpu_off = <$(PSCI_CPU_OFF)>;			\
 		   };
 CPU_NODES	:= $(shell perl -I $(SCRIPT_DIR) $(SCRIPT_DIR)/addpsci.pl $(KERNEL_DTB))
 else
diff --git a/configure.ac b/configure.ac
index 9e3b722..53e51be 100644
--- a/configure.ac
+++ b/configure.ac
@@ -83,13 +83,17 @@ AS_IF([test "x$X_IMAGE" != "x"],
 # Allow a user to pass --enable-psci
 AC_ARG_ENABLE([psci],
 	AS_HELP_STRING([--disable-psci], [disable the psci boot method]),
-	[USE_PSCI=$enableval], [USE_PSCI="yes"])
-AM_CONDITIONAL([PSCI], [test "x$USE_PSCI" = "xyes"])
-AS_IF([test "x$USE_PSCI" = "xyes"], [], [USE_PSCI=no])
-
-AS_IF([test "x$USE_PSCI" != "xyes" -a "x$KERNEL_ES" = "x32"],
+	[case "${enableval}" in
+		yes|smc) USE_PSCI=smc ;;
+		hvc) USE_PSCI=hvc ;;
+		*) AC_MSG_ERROR([Bad value "${enableval}" for --enable-psci. Use "smc" or "hvc"]) ;;
+	esac], [USE_PSCI="yes"])
+AM_CONDITIONAL([PSCI], [test "x$USE_PSCI" = "xyes" -o "x$USE_PSCI" = "xsmc" -o "x$USE_PSCI" = "xhvc"])
+
+AS_IF([test "x$USE_PSCI" = "xno" -a "x$KERNEL_ES" = "x32"],
 	[AC_MSG_ERROR([With an AArch32 kernel, boot method must be PSCI.])]
 )
+AC_SUBST([PSCI_METHOD], [$USE_PSCI])
 
 # Allow a user to pass --with-initrd
 AC_ARG_WITH([initrd],