linux-kernel - [PATCH V3] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available

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Message-Id: <1557501373-24436-1-git-send-email-olekstysh@gmail.com>
Date:   Fri, 10 May 2019 18:16:13 +0300
From:   Oleksandr Tyshchenko <olekstysh@...il.com>
To:     linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     julien.grall@....com, horms@...ge.net.au, magnus.damm@...il.com,
        linux@...linux.org.uk, biju.das@...renesas.com,
        geert@...ux-m68k.org,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
Subject: [PATCH V3] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>

If PSCI is available then most likely we are running on PSCI-enabled
U-Boot which, we assume, has already taken care of resetting CNTVOFF
before switching to non-secure mode and we don't need to.

Please note, an extra check to prevent secure_cntvoff_init() from
being called for secondary CPUs in headsmp-apmu.S is not needed,
as SMP code for APMU based system is not executed if PSCI is in use.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
CC: Julien Grall <julien.grall@....com>

---
   You can find previous discussions here:
   [v1] https://lkml.org/lkml/2019/4/17/810
   [v2] https://lkml.org/lkml/2019/5/3/338

   Changes in v2:
      - Clarify patch subject/description
      - Don't use CONFIG_ARM_PSCI option, check whether the PSCI is available,
        by using psci_smp_available()
      - Check whether we are running on top of Xen, by using xen_domain()

   Changes in v3:
      - Don't check for the presence of Xen
---
 arch/arm/mach-shmobile/setup-rcar-gen2.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c b/arch/arm/mach-shmobile/setup-rcar-gen2.c
index eea60b2..35dda21 100644
--- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
+++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
@@ -18,6 +18,7 @@
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
 #include <asm/mach/arch.h>
+#include <asm/psci.h>
 #include <asm/secure_cntvoff.h>
 #include "common.h"
 #include "rcar-gen2.h"
@@ -63,7 +64,13 @@ void __init rcar_gen2_timer_init(void)
 	void __iomem *base;
 	u32 freq;
 
-	secure_cntvoff_init();
+	/*
+	 * If PSCI is available then most likely we are running on PSCI-enabled
+	 * U-Boot which, we assume, has already taken care of resetting CNTVOFF
+	 * before switching to non-secure mode and we don't need to.
+	 */
+	if (!psci_smp_available())
+		secure_cntvoff_init();
 
 	if (of_machine_is_compatible("renesas,r8a7745") ||
 	    of_machine_is_compatible("renesas,r8a77470") ||
-- 
2.7.4