scmi-cpufreq.c
// 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/clk-provider.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/energy_model.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;
};
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);
const 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)
{
struct scmi_data *priv = policy->driver_data;
const struct scmi_perf_ops *perf_ops = handle->perf_ops;
u64 freq = policy->freq_table[index].frequency;
return perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false);
}
static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
unsigned int target_freq)
{
struct scmi_data *priv = policy->driver_data;
const struct scmi_perf_ops *perf_ops = handle->perf_ops;
if (!perf_ops->freq_set(handle, priv->domain_id,
target_freq * 1000, true))
return target_freq;
return 0;
}
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 __maybe_unused
scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
struct device *cpu_dev)
{
unsigned long Hz;
int ret, domain;
domain = handle->perf_ops->device_domain_id(cpu_dev);
if (domain < 0)
return domain;
/* Get the power cost of the performance domain. */
Hz = *KHz * 1000;
ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power);
if (ret)
return ret;
/* The EM framework specifies the frequency in KHz. */
*KHz = Hz / 1000;
return 0;
}
static int scmi_cpufreq_init(struct cpufreq_policy *policy)
{
int ret, nr_opp;
unsigned int latency;
struct device *cpu_dev;
struct scmi_data *priv;
struct cpufreq_frequency_table *freq_table;
struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
bool power_scale_mw;
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->device_opps_add(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;
}
nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
if (nr_opp <= 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;
policy->freq_table = freq_table;
/* SCMI allows DVFS request for any domain from any CPU */
policy->dvfs_possible_from_any_cpu = true;
latency = handle->perf_ops->transition_latency_get(handle, cpu_dev);
if (!latency)
latency = CPUFREQ_ETERNAL;
policy->cpuinfo.transition_latency = latency;
policy->fast_switch_possible =
handle->perf_ops->fast_switch_possible(handle, cpu_dev);
power_scale_mw = handle->perf_ops->power_scale_mw_get(handle);
em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus,
power_scale_mw);
return 0;
out_free_priv:
kfree(priv);
out_free_opp:
dev_pm_opp_remove_all_dynamic(cpu_dev);
return ret;
}
static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
{
struct scmi_data *priv = policy->driver_data;
dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
kfree(priv);
return 0;
}
static struct cpufreq_driver scmi_cpufreq_driver = {
.name = "scmi",
.flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
CPUFREQ_NEED_INITIAL_FREQ_CHECK |
CPUFREQ_IS_COOLING_DEV,
.verify = cpufreq_generic_frequency_table_verify,
.attr = cpufreq_generic_attr,
.target_index = scmi_cpufreq_set_target,
.fast_switch = scmi_cpufreq_fast_switch,
.get = scmi_cpufreq_get_rate,
.init = scmi_cpufreq_init,
.exit = scmi_cpufreq_exit,
};
static int scmi_cpufreq_probe(struct scmi_device *sdev)
{
int ret;
struct device *dev = &sdev->dev;
handle = sdev->handle;
if (!handle || !handle->perf_ops)
return -ENODEV;
#ifdef CONFIG_COMMON_CLK
/* dummy clock provider as needed by OPP if clocks property is used */
if (of_find_property(dev->of_node, "#clock-cells", NULL))
devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
#endif
ret = cpufreq_register_driver(&scmi_cpufreq_driver);
if (ret) {
dev_err(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, "cpufreq" },
{ },
};
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");