228 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * System Control and Power Interface (SCPI) based CPUFreq Interface driver4 *5 * Copyright (C) 2015 ARM Ltd.6 * Sudeep Holla <sudeep.holla@arm.com>7 */8 9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt10 11#include <linux/clk.h>12#include <linux/cpu.h>13#include <linux/cpufreq.h>14#include <linux/cpumask.h>15#include <linux/export.h>16#include <linux/module.h>17#include <linux/platform_device.h>18#include <linux/pm_opp.h>19#include <linux/scpi_protocol.h>20#include <linux/slab.h>21#include <linux/types.h>22 23struct scpi_data {24 struct clk *clk;25 struct device *cpu_dev;26};27 28static struct scpi_ops *scpi_ops;29 30static unsigned int scpi_cpufreq_get_rate(unsigned int cpu)31{32 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);33 struct scpi_data *priv = policy->driver_data;34 unsigned long rate = clk_get_rate(priv->clk);35 36 return rate / 1000;37}38 39static int40scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)41{42 u64 rate = policy->freq_table[index].frequency * 1000;43 struct scpi_data *priv = policy->driver_data;44 int ret;45 46 ret = clk_set_rate(priv->clk, rate);47 48 if (ret)49 return ret;50 51 if (clk_get_rate(priv->clk) != rate)52 return -EIO;53 54 return 0;55}56 57static int58scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)59{60 int cpu, domain, tdomain;61 struct device *tcpu_dev;62 63 domain = scpi_ops->device_domain_id(cpu_dev);64 if (domain < 0)65 return domain;66 67 for_each_possible_cpu(cpu) {68 if (cpu == cpu_dev->id)69 continue;70 71 tcpu_dev = get_cpu_device(cpu);72 if (!tcpu_dev)73 continue;74 75 tdomain = scpi_ops->device_domain_id(tcpu_dev);76 if (tdomain == domain)77 cpumask_set_cpu(cpu, cpumask);78 }79 80 return 0;81}82 83static int scpi_cpufreq_init(struct cpufreq_policy *policy)84{85 int ret;86 unsigned int latency;87 struct device *cpu_dev;88 struct scpi_data *priv;89 struct cpufreq_frequency_table *freq_table;90 91 cpu_dev = get_cpu_device(policy->cpu);92 if (!cpu_dev) {93 pr_err("failed to get cpu%d device\n", policy->cpu);94 return -ENODEV;95 }96 97 ret = scpi_ops->add_opps_to_device(cpu_dev);98 if (ret) {99 dev_warn(cpu_dev, "failed to add opps to the device\n");100 return ret;101 }102 103 ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus);104 if (ret) {105 dev_warn(cpu_dev, "failed to get sharing cpumask\n");106 return ret;107 }108 109 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);110 if (ret) {111 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",112 __func__, ret);113 return ret;114 }115 116 ret = dev_pm_opp_get_opp_count(cpu_dev);117 if (ret <= 0) {118 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");119 ret = -EPROBE_DEFER;120 goto out_free_opp;121 }122 123 priv = kzalloc(sizeof(*priv), GFP_KERNEL);124 if (!priv) {125 ret = -ENOMEM;126 goto out_free_opp;127 }128 129 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);130 if (ret) {131 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);132 goto out_free_priv;133 }134 135 priv->cpu_dev = cpu_dev;136 priv->clk = clk_get(cpu_dev, NULL);137 if (IS_ERR(priv->clk)) {138 dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n",139 __func__, cpu_dev->id);140 ret = PTR_ERR(priv->clk);141 goto out_free_cpufreq_table;142 }143 144 policy->driver_data = priv;145 policy->freq_table = freq_table;146 147 /* scpi allows DVFS request for any domain from any CPU */148 policy->dvfs_possible_from_any_cpu = true;149 150 latency = scpi_ops->get_transition_latency(cpu_dev);151 if (!latency)152 latency = CPUFREQ_ETERNAL;153 154 policy->cpuinfo.transition_latency = latency;155 156 policy->fast_switch_possible = false;157 158 return 0;159 160out_free_cpufreq_table:161 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);162out_free_priv:163 kfree(priv);164out_free_opp:165 dev_pm_opp_remove_all_dynamic(cpu_dev);166 167 return ret;168}169 170static void scpi_cpufreq_exit(struct cpufreq_policy *policy)171{172 struct scpi_data *priv = policy->driver_data;173 174 clk_put(priv->clk);175 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);176 dev_pm_opp_remove_all_dynamic(priv->cpu_dev);177 kfree(priv);178}179 180static struct cpufreq_driver scpi_cpufreq_driver = {181 .name = "scpi-cpufreq",182 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |183 CPUFREQ_NEED_INITIAL_FREQ_CHECK |184 CPUFREQ_IS_COOLING_DEV,185 .verify = cpufreq_generic_frequency_table_verify,186 .attr = cpufreq_generic_attr,187 .get = scpi_cpufreq_get_rate,188 .init = scpi_cpufreq_init,189 .exit = scpi_cpufreq_exit,190 .target_index = scpi_cpufreq_set_target,191 .register_em = cpufreq_register_em_with_opp,192};193 194static int scpi_cpufreq_probe(struct platform_device *pdev)195{196 int ret;197 198 scpi_ops = get_scpi_ops();199 if (!scpi_ops)200 return -EIO;201 202 ret = cpufreq_register_driver(&scpi_cpufreq_driver);203 if (ret)204 dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n",205 __func__, ret);206 return ret;207}208 209static void scpi_cpufreq_remove(struct platform_device *pdev)210{211 cpufreq_unregister_driver(&scpi_cpufreq_driver);212 scpi_ops = NULL;213}214 215static struct platform_driver scpi_cpufreq_platdrv = {216 .driver = {217 .name = "scpi-cpufreq",218 },219 .probe = scpi_cpufreq_probe,220 .remove_new = scpi_cpufreq_remove,221};222module_platform_driver(scpi_cpufreq_platdrv);223 224MODULE_ALIAS("platform:scpi-cpufreq");225MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");226MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");227MODULE_LICENSE("GPL v2");228