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// SPDX-License-Identifier: GPL-2.0-only
/*
* System Control and Power Interface (SCPI) based CPUFreq Interface driver
*
* Copyright (C) 2015 ARM Ltd.
* Sudeep Holla <sudeep.holla@arm.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/scpi_protocol.h>
#include <linux/slab.h>
#include <linux/types.h>
struct scpi_data {
struct clk *clk;
struct device *cpu_dev;
};
static struct scpi_ops *scpi_ops;
static unsigned int scpi_cpufreq_get_rate(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
struct scpi_data *priv = policy->driver_data;
unsigned long rate = clk_get_rate(priv->clk);
return rate / 1000;
}
static int
scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
{
u64 rate = policy->freq_table[index].frequency * 1000;
struct scpi_data *priv = policy->driver_data;
int ret;
ret = clk_set_rate(priv->clk, rate);
if (ret)
return ret;
if (clk_get_rate(priv->clk) != rate)
return -EIO;
return 0;
}
static int
scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
{
int cpu, domain, tdomain;
struct device *tcpu_dev;
domain = scpi_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 = scpi_ops->device_domain_id(tcpu_dev);
if (tdomain == domain)
cpumask_set_cpu(cpu, cpumask);
}
return 0;
}
static int scpi_cpufreq_init(struct cpufreq_policy *policy)
{
int ret;
unsigned int latency;
struct device *cpu_dev;
struct scpi_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 = scpi_ops->add_opps_to_device(cpu_dev);
if (ret) {
dev_warn(cpu_dev, "failed to add opps to the device\n");
return ret;
}
ret = scpi_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->clk = clk_get(cpu_dev, NULL);
if (IS_ERR(priv->clk)) {
dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n",
__func__, cpu_dev->id);
ret = PTR_ERR(priv->clk);
goto out_free_cpufreq_table;
}
policy->driver_data = priv;
policy->freq_table = freq_table;
/* scpi allows DVFS request for any domain from any CPU */
policy->dvfs_possible_from_any_cpu = true;
latency = scpi_ops->get_transition_latency(cpu_dev);
if (!latency)
latency = CPUFREQ_ETERNAL;
policy->cpuinfo.transition_latency = latency;
policy->fast_switch_possible = false;
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_remove_all_dynamic(cpu_dev);
return ret;
}
static int scpi_cpufreq_exit(struct cpufreq_policy *policy)
{
struct scpi_data *priv = policy->driver_data;
clk_put(priv->clk);
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 scpi_cpufreq_driver = {
.name = "scpi-cpufreq",
.flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
CPUFREQ_NEED_INITIAL_FREQ_CHECK |
CPUFREQ_IS_COOLING_DEV,
.verify = cpufreq_generic_frequency_table_verify,
.attr = cpufreq_generic_attr,
.get = scpi_cpufreq_get_rate,
.init = scpi_cpufreq_init,
.exit = scpi_cpufreq_exit,
.target_index = scpi_cpufreq_set_target,
.register_em = cpufreq_register_em_with_opp,
};
static int scpi_cpufreq_probe(struct platform_device *pdev)
{
int ret;
scpi_ops = get_scpi_ops();
if (!scpi_ops)
return -EIO;
ret = cpufreq_register_driver(&scpi_cpufreq_driver);
if (ret)
dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n",
__func__, ret);
return ret;
}
static void scpi_cpufreq_remove(struct platform_device *pdev)
{
cpufreq_unregister_driver(&scpi_cpufreq_driver);
scpi_ops = NULL;
}
static struct platform_driver scpi_cpufreq_platdrv = {
.driver = {
.name = "scpi-cpufreq",
},
.probe = scpi_cpufreq_probe,
.remove_new = scpi_cpufreq_remove,
};
module_platform_driver(scpi_cpufreq_platdrv);
MODULE_ALIAS("platform:scpi-cpufreq");
MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
MODULE_LICENSE("GPL v2");
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