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Commit 8def3103 authored by Sudeep Holla's avatar Sudeep Holla
Browse files

cpufreq: arm_big_little: add SCPI interface driver 



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: default avatarSudeep Holla <sudeep.holla@arm.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
parent 9490f01e

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -9155,6 +9155,7 @@ L: linux-arm-kernel@lists.infradead.org 
S:	Maintained

F:	Documentation/devicetree/bindings/arm/arm,scpi.txt

F:	drivers/clk/clk-scpi.c

F:	drivers/cpufreq/scpi-cpufreq.c

F:	drivers/firmware/arm_scpi.c

F:	include/linux/scpi_protocol.h

drivers/cpufreq/Kconfig.arm

+10 −0
Original line number Diff line number Diff line
@@ -199,6 +199,16 @@ config ARM_SA1100_CPUFREQ 
config ARM_SA1110_CPUFREQ

	bool



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_SPEAR_CPUFREQ

	bool "SPEAr CPUFreq support"

	depends on PLAT_SPEAR

drivers/cpufreq/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ obj-$(CONFIG_ARM_S3C64XX_CPUFREQ) += s3c64xx-cpufreq.o 
obj-$(CONFIG_ARM_S5PV210_CPUFREQ)	+= s5pv210-cpufreq.o

obj-$(CONFIG_ARM_SA1100_CPUFREQ)	+= sa1100-cpufreq.o

obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o

obj-$(CONFIG_ARM_SCPI_CPUFREQ)		+= scpi-cpufreq.o

obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o

obj-$(CONFIG_ARM_TEGRA20_CPUFREQ)	+= tegra20-cpufreq.o

obj-$(CONFIG_ARM_TEGRA124_CPUFREQ)	+= tegra124-cpufreq.o

drivers/cpufreq/scpi-cpufreq.c

0 → 100644
+124 −0
Original line number Diff line number Diff line 
/*

 * System Control and Power Interface (SCPI) based 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 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@arm.com>");

MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");

MODULE_LICENSE("GPL v2");