linux-kernel - Re: [PATCH v3] ARM: EXYNOS: SWRESET is needed to boot secondary CPU on Exynos3250

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Date:	Thu, 25 Sep 2014 18:16:38 +0900
From:	Kukjin Kim <kgene.kim@...sung.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
CC:	Russell King <linux@....linux.org.uk>,
	Kukjin Kim <kgene.kim@...sung.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>
Subject: Re: [PATCH v3] ARM: EXYNOS: SWRESET is needed to boot secondary CPU
 on Exynos3250

On 09/24/14 21:30, Krzysztof Kozlowski wrote:
> Without software reset the secondary CPU does not power up and
> exynos_boot_secondary() ends with pen_release equal to 1. This can be
> observed in dmesg:
> 	CPU1: failed to come online
> 	Brought up 1 CPUs
> 	SMP: Total of 1 processors activated.
> 	CPU: All CPU(s) started in SVC mode.
>
> When booting the secondary CPU on Exynos3250 execute also software
> reset for core 1.
>
> Signed-off-by: Krzysztof Kozlowski<k.kozlowski@...sung.com>
> Reviewed-by: Tomasz Figa<t.figa@...sung.com>
>
> ---
>
> Changes since v2:
> 1. Rebase on Kukjin's for-next tree from 24th of September
> (v3.17-rc3-97-gbcf20e084a4b)
>
> Changes since v1:
> 1. Removed inline keyword and change if statement to early return as
>     Tomasz suggested.
> 2. Added reviewed-by Tomasz Figa.
> ---
>   arch/arm/mach-exynos/platsmp.c  | 23 +++++++++++++++++++++++
>   arch/arm/mach-exynos/regs-pmu.h |  2 ++
>   2 files changed, 25 insertions(+)
>
> diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
> index 41ae28d69e6f..8543064dc445 100644
> --- a/arch/arm/mach-exynos/platsmp.c
> +++ b/arch/arm/mach-exynos/platsmp.c
> @@ -121,6 +121,26 @@ static inline void __iomem *cpu_boot_reg(int cpu)
>   }
>
>   /*
> + * Set wake up by local power mode and execute software reset for given core.
> + *
> + * Currently this is needed only when booting secondary CPU on Exynos3250.
> + */
> +static void exynos_core_restart(u32 core_id)
> +{
> +	u32 val;
> +
> +	if (!of_machine_is_compatible("samsung,exynos3250"))
> +		return;
> +
> +	val = pmu_raw_readl(EXYNOS_ARM_CORE_STATUS(core_id));
> +	val |= S5P_CORE_WAKEUP_FROM_LOCAL_CFG;
> +	pmu_raw_writel(val, EXYNOS_ARM_CORE_STATUS(core_id));
> +
> +	pr_info("CPU%u: Software reset\n", core_id);
> +	pmu_raw_writel(EXYNOS_CORE_PO_RESET(core_id), EXYNOS_SWRESET);
> +}
> +
> +/*
>    * Write pen_release in a way that is guaranteed to be visible to all
>    * observers, irrespective of whether they're taking part in coherency
>    * or not.  This is necessary for the hotplug code to work reliably.
> @@ -196,6 +216,9 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
>   			return -ETIMEDOUT;
>   		}
>   	}
> +
> +	exynos_core_restart(core_id);
> +
>   	/*
>   	 * Send the secondary CPU a soft interrupt, thereby causing
>   	 * the boot monitor to read the system wide flags register,
> diff --git a/arch/arm/mach-exynos/regs-pmu.h b/arch/arm/mach-exynos/regs-pmu.h
> index 30c03017aa6a..4ea5e320c6d1 100644
> --- a/arch/arm/mach-exynos/regs-pmu.h
> +++ b/arch/arm/mach-exynos/regs-pmu.h
> @@ -21,6 +21,7 @@
>   #define S5P_USE_STANDBY_WFI0			(1<<  16)
>   #define S5P_USE_STANDBY_WFE0			(1<<  24)
>
> +#define EXYNOS_CORE_PO_RESET(n)			((1<<  4)<<  n)
>   #define EXYNOS_WAKEUP_FROM_LOWPWR		(1<<  28)
>   #define EXYNOS_SWRESET				0x0400
>   #define EXYNOS5440_SWRESET			0x00C4
> @@ -125,6 +126,7 @@
>   #define S5P_PAD_RET_EBIB_OPTION			0x31A8
>
>   #define S5P_CORE_LOCAL_PWR_EN			0x3
> +#define S5P_CORE_WAKEUP_FROM_LOCAL_CFG		(0x3<<  8)
>
>   /* Only for EXYNOS4210 */
>   #define S5P_CMU_CLKSTOP_LCD1_LOWPWR	0x1154

Applied, thanks.

- Kukjin
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