[PATCHv2] ARM: EXYNOS: reset Little cores when cpu is up

Chanho Park parkch98 at gmail.com
Tue Sep 1 07:17:03 PDT 2015

The cpu booting of exynos5422 has been still broken since we discussed
it in last year[1]. This patch is inspired from Odroid XU3
code (Actually, it was from samsung exynos vendor kernel)[2]. This weird
reset code was founded exynos5420 octa cores series SoCs and only
required for the first boot core is the Little core (Cortex A7).
Some of the exynos5420 boards and all of the exynos5422 boards will require
this code.

There is two ways to check the little core is the first cpu. One is
checking GPG2CON[1] GPIO value and the other is checking the cluster
number of the first cpu. I selected the latter because it's more easier
than the former.


Cc: Kevin Hilman <khilman at kernel.org>
Cc: Javier Martinez Canillas <javier at osg.samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski at samsung.com>
Tested-by: Kevin Hilman <khilman at linaro.org>
Signed-off-by: Chanho Park <parkch98 at gmail.com>
Changes from v1:
 .kfc to Little (Cortex A7) and eagle to big (Cortex A15)
 .append comments about waiting SPARE2 register

Changes since RFC:
 .drop checking soc_is_exynos5800 to extend this codes to
exynos5420/5422 boards.
 .kfc cores will be reset only if the cpu0 is kfc core.
 .Rebase top of the kukjin's for-next branch

 arch/arm/mach-exynos/mcpm-exynos.c | 25 ++++++++++++++++++++++++-
 arch/arm/mach-exynos/regs-pmu.h    |  6 ++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-exynos/mcpm-exynos.c b/arch/arm/mach-exynos/mcpm-exynos.c
index 9bdf547..8926621 100644
--- a/arch/arm/mach-exynos/mcpm-exynos.c
+++ b/arch/arm/mach-exynos/mcpm-exynos.c
@@ -20,6 +20,7 @@
 #include <asm/cputype.h>
 #include <asm/cp15.h>
 #include <asm/mcpm.h>
+#include <asm/smp_plat.h>
 #include "regs-pmu.h"
 #include "common.h"
@@ -70,7 +71,29 @@ static int exynos_cpu_powerup(unsigned int cpu, unsigned int cluster)
 		cluster >= EXYNOS5420_NR_CLUSTERS)
 		return -EINVAL;
-	exynos_cpu_power_up(cpunr);
+	if (!exynos_cpu_power_state(cpunr)) {
+		exynos_cpu_power_up(cpunr);
+		/* This assumes the cluster number of the big cores(Cortex A15)
+		 * is 0 and the Little cores(Cortex A7) is 1.
+		 * When the system was booted from the Little core,
+		 * they should be reset during power up cpu.
+		 */
+		if (cluster &&
+		    cluster == MPIDR_AFFINITY_LEVEL(cpu_logical_map(0), 1)) {
+			/* Before we reset the Little cores, we should wait
+			 * the SPARE2 register is set to 1 because the init
+			 * codes of the iROM will set the register after
+			 * initialization.
+			 */
+			while (!pmu_raw_readl(S5P_PMU_SPARE2))
+				udelay(10);
+			pmu_raw_writel(EXYNOS5420_KFC_CORE_RESET(cpu),
+		}
+	}
 	return 0;
diff --git a/arch/arm/mach-exynos/regs-pmu.h b/arch/arm/mach-exynos/regs-pmu.h
index b761433..fba9068 100644
--- a/arch/arm/mach-exynos/regs-pmu.h
+++ b/arch/arm/mach-exynos/regs-pmu.h
@@ -513,6 +513,12 @@ static inline unsigned int exynos_pmu_cpunr(unsigned int mpidr)
 #define SPREAD_ENABLE						0xF
 #define SPREAD_USE_STANDWFI					0xF
+#define EXYNOS5420_KFC_CORE_RESET0				BIT(8)
+#define EXYNOS5420_KFC_ETM_RESET0				BIT(20)
+#define EXYNOS5420_KFC_CORE_RESET(_nr)				\
 #define EXYNOS5420_BB_CON1					0x0784
 #define EXYNOS5420_BB_SEL_EN					BIT(31)
 #define EXYNOS5420_BB_PMOS_EN					BIT(7)

More information about the linux-arm-kernel mailing list