linux-kernel - Re: [PATCH v3 3/3] arm: kernel: implement cpuidle

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Date:	Tue, 14 Jul 2015 11:34:21 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Jisheng Zhang <jszhang@...vell.com>
Cc:	will.deacon@....com, mark.rutland@....com,
	daniel.lezcano@...aro.org, Catalin.Marinas@....com,
	Lorenzo.Pieralisi@....com, galak@...eaurora.org,
	agross@...eaurora.org, davidb@...eaurora.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] arm: kernel: implement cpuidle_ops with psci
 backend

On Thu, Jul 09, 2015 at 04:31:25PM +0800, Jisheng Zhang wrote:
> This patch implements cpuidle_ops using psci. After this patch, we can
> use cpuidle-arm.c with psci backend for both arm and arm64.
> 
> Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
> ---
>  arch/arm/kernel/Makefile       |  1 +
>  arch/arm/kernel/psci_cpuidle.c | 19 +++++++++++++++++++
>  2 files changed, 20 insertions(+)
>  create mode 100644 arch/arm/kernel/psci_cpuidle.c
> 
> diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
> index 3b995f5..96383d8 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -91,6 +91,7 @@ obj-$(CONFIG_ARM_VIRT_EXT)	+= hyp-stub.o
>  ifeq ($(CONFIG_ARM_PSCI),y)
>  obj-y				+= psci-call.o
>  obj-$(CONFIG_SMP)		+= psci_smp.o
> +obj-$(CONFIG_CPU_IDLE)		+= psci_cpuidle.o
>  endif
>  
>  extra-y := $(head-y) vmlinux.lds
> diff --git a/arch/arm/kernel/psci_cpuidle.c b/arch/arm/kernel/psci_cpuidle.c
> new file mode 100644
> index 0000000..e7146d2
> --- /dev/null
> +++ b/arch/arm/kernel/psci_cpuidle.c
> @@ -0,0 +1,19 @@
> +/*
> + * Copyright (C) 2015 Marvell Technology Group Ltd.
> + * Author: Jisheng Zhang <jszhang@...vell.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/cpuidle.h>
> +#include <linux/psci.h>
> +
> +#include <asm/cpuidle.h>
> +
> +static struct cpuidle_ops psci_cpuidle_ops __initdata = {
> +	.suspend = cpu_psci_cpu_suspend,
> +	.init = cpu_psci_cpu_init_idle,
> +};
> +CPUIDLE_METHOD_OF_DECLARE(psci_cpuidle, "psci", &psci_cpuidle_ops);

Is there any reason this can't live in the drivers sub-tree?  Is there
anything specific to 32-bit ARM about this?

It looks to me like the right thing to do is to have it as part of
drivers/firmware/psci.c.

We don't do this for other stuff - we don't have IRQ_CHIP_OF_DECLARE
stuff in arch/arm but have the IRQ chip drivers in drivers/irqchip.
We keep it all togehter in drivers/irqchip, even when the IRQ chip
driver is only useful on ARM.

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