[PATCH v2 5/5] cpufreq: arm_big_little: add SCPI interface driver
Rafael J. Wysocki
rjw at rjwysocki.net
Thu May 14 15:03:12 PDT 2015
On Thursday, May 14, 2015 04:42:35 PM Sudeep Holla wrote:
> On some ARM based systems, a separate Cortex-M based System Control
> Processor(SCP) provides the overall power, clock, reset and system
> control including CPU DVFS. SCPI Message Protocol is used to
> communicate with the SCPI.
>
> This patch adds a interface driver for adding OPPs and registering
> the arm_big_little cpufreq driver for such systems.
>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> Cc: Viresh Kumar <viresh.kumar at linaro.org>
> Cc: "Rafael J. Wysocki" <rjw at rjwysocki.net>
> Cc: linux-pm at vger.kernel.org
> ---
> drivers/cpufreq/Kconfig.arm | 9 +++
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/scpi-cpufreq.c | 124 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 134 insertions(+)
> create mode 100644 drivers/cpufreq/scpi-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 611cb09239eb..6419b17b89dd 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 adds the CPUfreq driver support for ARM big.LITTLE platforms
> + using SCPI protocol for CPU power management.
> +
> + This driver uses SCPI Message Protocol driver to interact with the
> + firmware providing the CPU DVFS functionality.
>
> 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..443570801229
> --- /dev/null
> +++ b/drivers/cpufreq/scpi-cpufreq.c
> @@ -0,0 +1,124 @@
> +/*
> + * SCPI CPUFreq Interface driver
It would be good to expand the TLA here IMO.
The rest I'm leaving to Viresh. :-)
> + *
> + * It provides necessary ops to arm_big_little cpufreq driver.
> + *
> + * Copyright (C) 2015 ARM Ltd.
> + * Sudeep Holla <sudeep.holla at 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 struct scpi_dvfs_info *scpi_get_dvfs_info(struct device *cpu_dev)
> +{
> + u8 domain = topology_physical_package_id(cpu_dev->id);
> +
> + if (domain < 0)
> + return ERR_PTR(-EINVAL);
> + return scpi_ops->dvfs_get_info(domain);
> +}
> +
> +static int scpi_opp_table_ops(struct device *cpu_dev, bool remove)
> +{
> + int idx, ret = 0;
> + struct scpi_opp *opp;
> + struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
> +
> + if (IS_ERR(info))
> + return PTR_ERR(info);
> +
> + if (!info->opps)
> + return -EIO;
> +
> + for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
> + if (remove)
> + dev_pm_opp_remove(cpu_dev, opp->freq);
> + else
> + 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);
> + while (idx-- > 0)
> + dev_pm_opp_remove(cpu_dev, (--opp)->freq);
> + return ret;
> + }
> + }
> + return ret;
> +}
> +
> +static int scpi_get_transition_latency(struct device *cpu_dev)
> +{
> + struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
> +
> + if (IS_ERR(info))
> + return PTR_ERR(info);
> + return info->latency;
> +}
> +
> +static int scpi_init_opp_table(struct device *cpu_dev)
> +{
> + return scpi_opp_table_ops(cpu_dev, false);
> +}
> +
> +static void scpi_free_opp_table(struct device *cpu_dev)
> +{
> + scpi_opp_table_ops(cpu_dev, true);
> +}
> +
> +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,
> + .free_opp_table = scpi_free_opp_table,
> +};
> +
> +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);
> + scpi_ops = NULL;
> + 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_AUTHOR("Sudeep Holla <sudeep.holla at arm.com>");
> +MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
> +MODULE_LICENSE("GPL v2");
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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