linux-kernel - [PATCHv3 4/7] ARM: EXYNOS: Enter a15 lowpower mode for Exynos3250 based on Cortex-a7

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Message-id: <1397783728-6193-5-git-send-email-cw00.choi@samsung.com>
Date:	Fri, 18 Apr 2014 10:15:25 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux@....linux.org.uk, ben-linux@...ff.org, kgene.kim@...sung.com,
	t.figa@...sung.com, arnd@...db.de, olof@...om.net,
	marc.zyngier@....com, thomas.abraham@...aro.org,
	kyungmin.park@...sung.com, cw00.choi@...sung.com,
	sw0312.kim@...sung.com, hyunhee.kim@...sung.com,
	yj44.cho@...sung.com, chanho61.park@...sung.com,
	sajjan.linux@...il.com, tushar.behera@...aro.org,
	sachin.kamat@...aro.org, linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org
Subject: [PATCHv3 4/7] ARM: EXYNOS: Enter a15 lowpower mode for Exynos3250
 based on Cortex-a7

This patch decide proper lowpower mode of either a15 or a9 according to own ID
from Main ID register.

Cc: Arnd Bergmann <arnd@...db.de>
Cc: Marc Zynigier <marc.zyngier@....com>
Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
---
 arch/arm/mach-exynos/hotplug.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c
index 5eead53..acf3119 100644
--- a/arch/arm/mach-exynos/hotplug.c
+++ b/arch/arm/mach-exynos/hotplug.c
@@ -135,16 +135,21 @@ void __ref exynos_cpu_die(unsigned int cpu)
 	int primary_part = 0;
 
 	/*
-	 * we're ready for shutdown now, so do it.
-	 * Exynos4 is A9 based while Exynos5 is A15; check the CPU part
-	 * number by reading the Main ID register and then perform the
-	 * appropriate sequence for entering low power.
+	 * Prepare the CPU for shutting down. The required sequence of
+	 * operations depends on core type. CPUID part number can be used to
+	 * determine the right way.
 	 */
-	asm("mrc p15, 0, %0, c0, c0, 0" : "=r"(primary_part) : : "cc");
-	if ((primary_part & 0xfff0) == 0xc0f0)
+	primary_part = read_cpuid_part_number();
+
+	switch (primary_part) {
+	case ARM_CPU_PART_CORTEX_A7:
+	case ARM_CPU_PART_CORTEX_A15:
 		cpu_enter_lowpower_a15();
-	else
+		break;
+	default:
 		cpu_enter_lowpower_a9();
+		break;
+	}
 
 	platform_do_lowpower(cpu, &spurious);
 
-- 
1.8.0

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