Re: [PATCH 4/4] cpufreq: arm_big_little: add SCPI interface driver

[Viresh Kumar <viresh.kumar@linaro.org>]

On 27 April 2015 at 17:10, Sudeep Holla <sudeep.holla@arm.com> wrote:
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 4f3dbc8cf729..9e678bf1687c 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -24,6 +24,15 @@ config ARM_VEXPRESS_SPC_CPUFREQ
>            This add the CPUfreq driver support for Versatile Express
>           big.LITTLE platforms using SPC for power management.
>
> +config ARM_SCPI_CPUFREQ
> +        tristate "SCPI based CPUfreq driver"
> +       depends on ARM_BIG_LITTLE_CPUFREQ && ARM_SCPI_PROTOCOL
> +        help
> +          This add the CPUfreq driver support for ARM big.LITTLE platforms
> +         using SCPI interface for CPU power management.
> +
> +         This driver works only if firmware the supporting CPU DVFS adhere
> +         to SCPI protocol.

Wanna reword that ?

>
>  config ARM_EXYNOS_CPUFREQ
>         tristate "SAMSUNG EXYNOS CPUfreq Driver"
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index cdce92ae2e8b..02fc9f849d4b 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -79,6 +79,7 @@ obj-$(CONFIG_ARM_SA1110_CPUFREQ)      += sa1110-cpufreq.o
>  obj-$(CONFIG_ARM_SPEAR_CPUFREQ)                += spear-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA_CPUFREQ)                += tegra-cpufreq.o
>  obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ) += vexpress-spc-cpufreq.o
> +obj-$(CONFIG_ARM_SCPI_CPUFREQ)         += scpi-cpufreq.o
>
>  ##################################################################################
>  # PowerPC platform drivers
> diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
> new file mode 100644
> index 000000000000..4c2c11a9dfc6
> --- /dev/null
> +++ b/drivers/cpufreq/scpi-cpufreq.c
> @@ -0,0 +1,103 @@
> +/*
> + * SCPI CPUFreq Interface driver
> + *
> + * It provides necessary ops to arm_big_little cpufreq driver.
> + *
> + * Copyright (C) 2015 ARM Ltd.
> + * Sudeep Holla <sudeep.holla@arm.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.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/cpufreq.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_opp.h>
> +#include <linux/scpi_protocol.h>
> +#include <linux/types.h>
> +
> +#include "arm_big_little.h"
> +
> +static struct scpi_ops *scpi_ops;
> +
> +static int scpi_init_opp_table(struct device *cpu_dev)
> +{
> +       u8 domain = topology_physical_package_id(cpu_dev->id);
> +       struct scpi_dvfs_info *info;
> +       struct scpi_opp *opp;
> +       int idx, ret = 0;
> +
> +       if ((dev_pm_opp_get_opp_count(cpu_dev)) > 0)
> +               return 0;

Why, who would have added it ?

> +       info = scpi_ops->dvfs_get_info(domain);

Isn't calling this twice costly for getting the same information ?

> +       if (IS_ERR(info))
> +               return PTR_ERR(info);
> +
> +       opp = info->opps;
> +       if (!opp)
> +               return -EIO;
> +
> +       for (idx = 0; idx < info->count; idx++, opp++) {
> +               ret = dev_pm_opp_add(cpu_dev, opp->freq, opp->m_volt * 1000);
> +               if (ret) {
> +                       dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
> +                                opp->freq, opp->m_volt);

Don't you want to free earlier OPPs here ?

> +                       return ret;
> +               }
> +       }
> +       return ret;
> +}
> +
> +static int scpi_get_transition_latency(struct device *cpu_dev)
> +{
> +       u8 domain = topology_physical_package_id(cpu_dev->id);
> +       struct scpi_dvfs_info *info;
> +
> +       info = scpi_ops->dvfs_get_info(domain);
> +       if (IS_ERR(info))
> +               return PTR_ERR(info);
> +
> +       return info->latency;
> +}
> +
> +static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
> +       .name   = "scpi",
> +       .get_transition_latency = scpi_get_transition_latency,
> +       .init_opp_table = scpi_init_opp_table,

Don't want to free/remove OPPs ?

> +};
> +
> +static int scpi_cpufreq_probe(struct platform_device *pdev)
> +{
> +       scpi_ops = get_scpi_ops();
> +       if (!scpi_ops)
> +               return -EIO;
> +
> +       return bL_cpufreq_register(&scpi_cpufreq_ops);
> +}
> +
> +static int scpi_cpufreq_remove(struct platform_device *pdev)
> +{
> +       bL_cpufreq_unregister(&scpi_cpufreq_ops);
> +       return 0;
> +}
> +
> +static struct platform_driver scpi_cpufreq_platdrv = {
> +       .driver = {
> +               .name   = "scpi-cpufreq",
> +               .owner  = THIS_MODULE,
> +       },
> +       .probe          = scpi_cpufreq_probe,
> +       .remove         = scpi_cpufreq_remove,
> +};
> +module_platform_driver(scpi_cpufreq_platdrv);
> +
> +MODULE_LICENSE("GPL");

GPL V2 ?

Author/Description missing ..

> --
> 1.9.1
>