Re: [RFC/PATCH 1/6] cpuidle: renesas: Add CPUIdle Driver for Renesas SoCs

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 03/04/2015 05:55 AM, Keita Kobayashi wrote:
> This patch adds a cpuidle driver for Renesas SoCs.
>
> Signed-off-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
> ---
>   drivers/cpuidle/Kconfig.arm                   |   8 ++
>   drivers/cpuidle/Makefile                      |   1 +
>   drivers/cpuidle/cpuidle-renesas.c             | 118 ++++++++++++++++++++++++++
>   include/linux/platform_data/renesas-cpuidle.h |  24 ++++++
>   4 files changed, 151 insertions(+)
>   create mode 100644 drivers/cpuidle/cpuidle-renesas.c
>   create mode 100644 include/linux/platform_data/renesas-cpuidle.h
>
> diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
> index 8e07c94..01cb8cc 100644
> --- a/drivers/cpuidle/Kconfig.arm
> +++ b/drivers/cpuidle/Kconfig.arm
> @@ -64,3 +64,11 @@ config ARM_MVEBU_V7_CPUIDLE
>   	depends on ARCH_MVEBU
>   	help
>   	  Select this to enable cpuidle on Armada 370, 38x and XP processors.
> +
> +config ARM_RENESAS_CPUIDLE
> +	bool "CPU Idle Driver for the renesas SoCs"
> +	depends on ARCH_SHMOBILE_MULTI
> +	select ARM_CPU_SUSPEND
> +	select CPU_IDLE_MULTIPLE_DRIVERS
> +	help
> +	  Select this to enable cpuidle for renesas SoCs
> diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
> index 4d177b9..c718906 100644
> --- a/drivers/cpuidle/Makefile
> +++ b/drivers/cpuidle/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_ARM_ZYNQ_CPUIDLE)		+= cpuidle-zynq.o
>   obj-$(CONFIG_ARM_U8500_CPUIDLE)         += cpuidle-ux500.o
>   obj-$(CONFIG_ARM_AT91_CPUIDLE)          += cpuidle-at91.o
>   obj-$(CONFIG_ARM_EXYNOS_CPUIDLE)        += cpuidle-exynos.o
> +obj-$(CONFIG_ARM_RENESAS_CPUIDLE)	+= cpuidle-renesas.o
>
>   ###############################################################################
>   # MIPS drivers
> diff --git a/drivers/cpuidle/cpuidle-renesas.c b/drivers/cpuidle/cpuidle-renesas.c
> new file mode 100644
> index 0000000..b469e95
> --- /dev/null
> +++ b/drivers/cpuidle/cpuidle-renesas.c
> @@ -0,0 +1,118 @@
> +/*
> + * CPUIdle support code for Renesas ARM
> + *
> + *  Copyright (C) 2014 Renesas Electronics Corporation
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + */
> +
> +#include <linux/cpuidle.h>
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +#include <linux/platform_data/renesas-cpuidle.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm.h>
> +#include <linux/suspend.h>
> +#include <asm/cpuidle.h>
> +#include <asm/proc-fns.h>
> +#include <asm/smp_plat.h>
> +
> +static struct cpuidle_driver renesas_cpuidle_default_driver = {
> +	.name			= "renesas_default_cpuidle",
> +	.owner			= THIS_MODULE,
> +	.states[0]		= ARM_CPUIDLE_WFI_STATE,
> +	.safe_state_index	= 0, /* C1 */
> +	.state_count		= 1,
> +};
> +
> +static struct renesas_cpuidle_driver default_driver = {
> +	.target_cpu	= -1, /* default */
> +	.renesas_drv	= &renesas_cpuidle_default_driver,
> +};
> +
> +static struct renesas_cpuidle cpuidle_data = {
> +	.num_drvs	= 1,
> +	.rcd		= &default_driver,
> +};
> +
> +static int __init renesas_idle_driver_init(struct device *dev,
> +				struct renesas_cpuidle_driver *rcd)
> +{
> +	struct cpumask *cpumask = NULL;
> +	int cpu;
> +
> +	for_each_online_cpu(cpu) {
> +		if (smp_cpuid_part(cpu) == rcd->target_cpu ||
> +		    rcd->target_cpu == -1) { /* default */
> +			if (!cpumask) {
> +				cpumask = devm_kzalloc(dev,
> +					  cpumask_size(), GFP_KERNEL);
> +				if (!cpumask)
> +					return -ENOMEM;
> +			}
> +			cpumask_set_cpu(cpu, cpumask);
> +			rcd->renesas_drv->cpumask = cpumask;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int renesas_cpuidle_probe(struct platform_device *pdev)
> +{
> +	struct renesas_cpuidle *pd = pdev->dev.platform_data;
> +	struct renesas_cpuidle_driver *rcd;
> +	int i, j, ret;
> +
> +	if (!pd->num_drvs || !pd->rcd)
> +		pd = &cpuidle_data;
> +
> +	for (i = 0; i < pd->num_drvs; i++) {
> +		rcd = pd->rcd + i;
> +		ret = renesas_idle_driver_init(&pdev->dev, rcd);
> +		if (ret)
> +			goto out_uninit_driver;
> +
> +		if (!rcd->renesas_drv->cpumask)
> +			continue;
> +
> +		ret = cpuidle_register(rcd->renesas_drv, NULL);
> +		if (ret) {
> +			dev_err(&pdev->dev,
> +				"failed to register cpuidle driver\n");
> +			goto out_uninit_driver;
> +		}
> +	}
> +
> +	return 0;
> +
> +out_uninit_driver:
> +	for (j = 0; j < i; j++) {
> +		rcd = pd->rcd + j;
> +
> +		if (!rcd->renesas_drv->cpumask)
> +			continue;
> +
> +		cpuidle_unregister(rcd->renesas_drv);
> +	}
> +
> +	return ret;
> +}

The initialization looks very complex. Can you explain why and what the 
code is doing ?

> +static struct platform_driver renesas_cpuidle_driver = {
> +	.probe	= renesas_cpuidle_probe,
> +	.driver	= {
> +		.name = "cpuidle-renesas",
> +		.owner = THIS_MODULE,
> +	},
> +};
> +
> +module_platform_driver(renesas_cpuidle_driver);
> +
> +MODULE_DESCRIPTION("Renesas cpuidle driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/platform_data/renesas-cpuidle.h b/include/linux/platform_data/renesas-cpuidle.h
> new file mode 100644
> index 0000000..9446215
> --- /dev/null
> +++ b/include/linux/platform_data/renesas-cpuidle.h
> @@ -0,0 +1,24 @@
> +/*
> + * renesas-cpuidle.h -- CPUIdle support code for Renesas ARM
> + *
> + *  Copyright (C) 2014 Renesas Electronics Corporation
> + *
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License.  See the file "COPYING" in the main directory of this archive
> + * for more details.
> + */
> +
> +#ifndef __RENESAS_CPUIDLE_H__
> +#define __RENESAS_CPUIDLE_H__
> +
> +struct renesas_cpuidle_driver {
> +	unsigned int		target_cpu;
> +	struct cpuidle_driver	*renesas_drv;
> +};
> +
> +struct renesas_cpuidle {
> +	unsigned int		num_drvs;
> +	struct renesas_cpuidle_driver *rcd;
> +};
> +
> +#endif /* __RENESAS_CPUIDLE_H__ */
>


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