commit a5b1832e1d1d5f917fd6971478bf2e0d05bd868a
author Alexander Graf <agraf@suse.de> Tue Aug 16 21:08:46 2016 +0200
committer Alexander Graf <agraf@suse.de> Tue Oct 18 09:08:08 2016 +0200
tree c5be0a47dee5c0719f1370960f73614ce06802da
parent 7725609ba1b066d3d8734a3f839d57849acf800b

arm: Disable HVC PSCI calls by default

All systems that are running on armv8 are running bare metal with firmware
that implements PSCI running in EL3. That means we don't really need to expose
the hypercall variants of them.

This patch leaves the code in, but makes the code explicit enough to have the
compiler optimize it out. With this we don't need to worry about hvc vs smc
calling convention when calling psci helper functions.

Signed-off-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/arm/cpu/armv8/fwcall.c

diff --git a/arch/arm/cpu/armv8/fwcall.c b/arch/arm/cpu/armv8/fwcall.c
index 079e250..6bb68f2 100644
--- a/arch/arm/cpu/armv8/fwcall.c
+++ b/arch/arm/cpu/armv8/fwcall.c
@@ -17,7 +17,7 @@
  * x0~x7: input arguments
  * x0~x3: output arguments
  */
-void hvc_call(struct pt_regs *args)
+static void hvc_call(struct pt_regs *args)
 {
 	asm volatile(
 		"ldr x0, %0\n"
@@ -75,13 +75,21 @@
 		  "x16", "x17");
 }
 
-void __noreturn psci_system_reset(bool conduit_smc)
+/*
+ * For now, all systems we support run at least in EL2 and thus
+ * trigger PSCI calls to EL3 using SMC. If anyone ever wants to
+ * use PSCI on U-Boot running below a hypervisor, please detect
+ * this and set the flag accordingly.
+ */
+static const bool use_smc_for_psci = true;
+
+void __noreturn psci_system_reset(void)
 {
 	struct pt_regs regs;
 
 	regs.regs[0] = ARM_PSCI_0_2_FN_SYSTEM_RESET;
 
-	if (conduit_smc)
+	if (use_smc_for_psci)
 		smc_call(&regs);
 	else
 		hvc_call(&regs);