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

From: [email-masked] (Krzysztof Kozlowski)
Date: Wed, 02 Sep 2015 09:15:11 +0900

On 01.09.2015 23:17, Chanho Park wrote:
> 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.
> 
> [1]:http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/350632.html
> [2]:https://patchwork.kernel.org/patch/6782891/
> 
> Cc: Kevin Hilman <[email-masked]>
> Cc: Javier Martinez Canillas <[email-masked]>
> Cc: Krzysztof Kozlowski <[email-masked]>
> Tested-by: Kevin Hilman <[email-masked]>
> Signed-off-by: Chanho Park <[email-masked]>
> ---
> 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(-)

Thanks for updating the patch. Remaining minor nit about comment style
(/* on first line) can be fixed while applying.

The patch works good, after disabling bL switcher I have 8 cores running:

Tested on Odroid XU4:
Reviewed-by: Krzysztof Kozlowski <[email-masked]>
Tested-by: Krzysztof Kozlowski <[email-masked]>

It's 4.3 merge window so the patch will go probably to v4.4.

Best regards,
Krzysztof

> 
> 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),
> +					EXYNOS_SWRESET);
> +		}
> +	}
> +
>  	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)				\
> +	((EXYNOS5420_KFC_CORE_RESET0 | EXYNOS5420_KFC_ETM_RESET0) << (_nr))
> +
>  #define EXYNOS5420_BB_CON1					0x0784
>  #define EXYNOS5420_BB_SEL_EN					BIT(31)
>  #define EXYNOS5420_BB_PMOS_EN					BIT(7)
>