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cpufreq: add support for CPU DVFS based on SCMI message protocol

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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. SCMI Message Protocol is used to
communicate with the SCP.

This patch adds a cpufreq driver for such systems using SCMI interface
to drive CPU DVFS.

Cc: linux-pm@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
This commit is contained in:
Sudeep Holla 2017-06-18 09:38:11 +01:00
parent b23688aefb
commit 99d6bdf338
4 changed files with 259 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
MAINTAINERS
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@ -13385,7 +13385,7 @@ L: linux-arm-kernel@lists.infradead.org
S: Maintained
F: Documentation/devicetree/bindings/arm/arm,sc[mp]i.txt
F: drivers/clk/clk-sc[mp]i.c
F: drivers/cpufreq/scpi-cpufreq.c
F: drivers/cpufreq/sc[mp]i-cpufreq.c
F: drivers/firmware/arm_scpi.c
F: drivers/firmware/arm_scmi/
F: include/linux/sc[mp]i_protocol.h

11
drivers/cpufreq/Kconfig.arm
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@ -238,6 +238,17 @@ config ARM_SA1100_CPUFREQ
config ARM_SA1110_CPUFREQ
bool
config ARM_SCMI_CPUFREQ
tristate "SCMI based CPUfreq driver"
depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
select PM_OPP
help
This adds the CPUfreq driver support for ARM platforms using SCMI
protocol for CPU power management.
This driver uses SCMI 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

1
drivers/cpufreq/Makefile
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@ -75,6 +75,7 @@ obj-$(CONFIG_ARM_S3C24XX_CPUFREQ_DEBUGFS) += s3c24xx-cpufreq-debugfs.o
obj-$(CONFIG_ARM_S5PV210_CPUFREQ) += s5pv210-cpufreq.o
obj-$(CONFIG_ARM_SA1100_CPUFREQ) += sa1100-cpufreq.o
obj-$(CONFIG_ARM_SA1110_CPUFREQ) += sa1110-cpufreq.o
obj-$(CONFIG_ARM_SCMI_CPUFREQ) += scmi-cpufreq.o
obj-$(CONFIG_ARM_SCPI_CPUFREQ) += scpi-cpufreq.o
obj-$(CONFIG_ARM_SPEAR_CPUFREQ) += spear-cpufreq.o
obj-$(CONFIG_ARM_STI_CPUFREQ) += sti-cpufreq.o

246
drivers/cpufreq/scmi-cpufreq.c Normal file
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@ -0,0 +1,246 @@
// SPDX-License-Identifier: GPL-2.0
/*
* System Control and Power Interface (SCMI) based CPUFreq Interface driver
*
* Copyright (C) 2018 ARM Ltd.
* Sudeep Holla <sudeep.holla@arm.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/cpu_cooling.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>
#include <linux/scmi_protocol.h>
#include <linux/types.h>
struct scmi_data {
int domain_id;
struct device *cpu_dev;
struct thermal_cooling_device *cdev;
};
static const struct scmi_handle *handle;
static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
struct scmi_perf_ops *perf_ops = handle->perf_ops;
struct scmi_data *priv = policy->driver_data;
unsigned long rate;
int ret;
ret = perf_ops->freq_get(handle, priv->domain_id, &rate, false);
if (ret)
return 0;
return rate / 1000;
}
/*
* perf_ops->freq_set is not a synchronous, the actual OPP change will
* happen asynchronously and can get notified if the events are
* subscribed for by the SCMI firmware
*/
static int
scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
{
int ret;
struct scmi_data *priv = policy->driver_data;
struct scmi_perf_ops *perf_ops = handle->perf_ops;
u64 freq = policy->freq_table[index].frequency * 1000;
ret = perf_ops->freq_set(handle, priv->domain_id, freq, false);
if (!ret)
arch_set_freq_scale(policy->related_cpus, freq,
policy->cpuinfo.max_freq);
return ret;
}
static int
scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
{
int cpu, domain, tdomain;
struct device *tcpu_dev;
domain = handle->perf_ops->device_domain_id(cpu_dev);
if (domain < 0)
return domain;
for_each_possible_cpu(cpu) {
if (cpu == cpu_dev->id)
continue;
tcpu_dev = get_cpu_device(cpu);
if (!tcpu_dev)
continue;
tdomain = handle->perf_ops->device_domain_id(tcpu_dev);
if (tdomain == domain)
cpumask_set_cpu(cpu, cpumask);
}
return 0;
}
static int scmi_cpufreq_init(struct cpufreq_policy *policy)
{
int ret;
unsigned int latency;
struct device *cpu_dev;
struct scmi_data *priv;
struct cpufreq_frequency_table *freq_table;
cpu_dev = get_cpu_device(policy->cpu);
if (!cpu_dev) {
pr_err("failed to get cpu%d device\n", policy->cpu);
return -ENODEV;
}
ret = handle->perf_ops->add_opps_to_device(handle, cpu_dev);
if (ret) {
dev_warn(cpu_dev, "failed to add opps to the device\n");
return ret;
}
ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
if (ret) {
dev_warn(cpu_dev, "failed to get sharing cpumask\n");
return ret;
}
ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
if (ret) {
dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
__func__, ret);
return ret;
}
ret = dev_pm_opp_get_opp_count(cpu_dev);
if (ret <= 0) {
dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
ret = -EPROBE_DEFER;
goto out_free_opp;
}
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv) {
ret = -ENOMEM;
goto out_free_opp;
}
ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
if (ret) {
dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
goto out_free_priv;
}
priv->cpu_dev = cpu_dev;
priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
policy->driver_data = priv;
ret = cpufreq_table_validate_and_show(policy, freq_table);
if (ret) {
dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
ret);
goto out_free_cpufreq_table;
}
/* SCMI allows DVFS request for any domain from any CPU */
policy->dvfs_possible_from_any_cpu = true;
latency = handle->perf_ops->get_transition_latency(handle, cpu_dev);
if (!latency)
latency = CPUFREQ_ETERNAL;
policy->cpuinfo.transition_latency = latency;
return 0;
out_free_cpufreq_table:
dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
out_free_priv:
kfree(priv);
out_free_opp:
dev_pm_opp_cpumask_remove_table(policy->cpus);
return ret;
}
static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
{
struct scmi_data *priv = policy->driver_data;
cpufreq_cooling_unregister(priv->cdev);
dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
kfree(priv);
dev_pm_opp_cpumask_remove_table(policy->related_cpus);
return 0;
}
static void scmi_cpufreq_ready(struct cpufreq_policy *policy)
{
struct scmi_data *priv = policy->driver_data;
priv->cdev = of_cpufreq_cooling_register(policy);
}
static struct cpufreq_driver scmi_cpufreq_driver = {
.name = "scmi",
.flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.attr = cpufreq_generic_attr,
.target_index = scmi_cpufreq_set_target,
.get = scmi_cpufreq_get_rate,
.init = scmi_cpufreq_init,
.exit = scmi_cpufreq_exit,
.ready = scmi_cpufreq_ready,
};
static int scmi_cpufreq_probe(struct scmi_device *sdev)
{
int ret;
handle = sdev->handle;
if (!handle || !handle->perf_ops)
return -ENODEV;
ret = cpufreq_register_driver(&scmi_cpufreq_driver);
if (ret) {
dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n",
__func__, ret);
}
return ret;
}
static void scmi_cpufreq_remove(struct scmi_device *sdev)
{
cpufreq_unregister_driver(&scmi_cpufreq_driver);
}
static const struct scmi_device_id scmi_id_table[] = {
{ SCMI_PROTOCOL_PERF },
{ },
};
MODULE_DEVICE_TABLE(scmi, scmi_id_table);
static struct scmi_driver scmi_cpufreq_drv = {
.name = "scmi-cpufreq",
.probe = scmi_cpufreq_probe,
.remove = scmi_cpufreq_remove,
.id_table = scmi_id_table,
};
module_scmi_driver(scmi_cpufreq_drv);
MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
MODULE_LICENSE("GPL v2");