1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * System Control and Power Interface (SCPI) based CPUFreq Interface driver 4 * 5 * Copyright (C) 2015 ARM Ltd. 6 * Sudeep Holla <sudeep.holla@arm.com> 7 */ 8 9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 10 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 23 struct scpi_data { 24 struct clk *clk; 25 struct device *cpu_dev; 26 }; 27 28 static struct scpi_ops *scpi_ops; 29 30 static 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 39 static int 40 scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index) 41 { 42 unsigned long freq_khz = policy->freq_table[index].frequency; 43 struct scpi_data *priv = policy->driver_data; 44 unsigned long rate = freq_khz * 1000; 45 int ret; 46 47 ret = clk_set_rate(priv->clk, rate); 48 49 if (ret) 50 return ret; 51 52 if (clk_get_rate(priv->clk) / 1000 != freq_khz) 53 return -EIO; 54 55 return 0; 56 } 57 58 static int 59 scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 60 { 61 int cpu, domain, tdomain; 62 struct device *tcpu_dev; 63 64 domain = scpi_ops->device_domain_id(cpu_dev); 65 if (domain < 0) 66 return domain; 67 68 for_each_present_cpu(cpu) { 69 if (cpu == cpu_dev->id) 70 continue; 71 72 tcpu_dev = get_cpu_device(cpu); 73 if (!tcpu_dev) 74 continue; 75 76 tdomain = scpi_ops->device_domain_id(tcpu_dev); 77 if (tdomain == domain) 78 cpumask_set_cpu(cpu, cpumask); 79 } 80 81 return 0; 82 } 83 84 static int scpi_cpufreq_init(struct cpufreq_policy *policy) 85 { 86 int ret; 87 unsigned int latency; 88 struct device *cpu_dev; 89 struct scpi_data *priv; 90 struct cpufreq_frequency_table *freq_table; 91 92 cpu_dev = get_cpu_device(policy->cpu); 93 if (!cpu_dev) { 94 pr_err("failed to get cpu%d device\n", policy->cpu); 95 return -ENODEV; 96 } 97 98 ret = scpi_ops->add_opps_to_device(cpu_dev); 99 if (ret) { 100 dev_warn(cpu_dev, "failed to add opps to the device\n"); 101 return ret; 102 } 103 104 ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus); 105 if (ret) { 106 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 107 return ret; 108 } 109 110 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus); 111 if (ret) { 112 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 113 __func__, ret); 114 return ret; 115 } 116 117 ret = dev_pm_opp_get_opp_count(cpu_dev); 118 if (ret <= 0) { 119 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); 120 ret = -EPROBE_DEFER; 121 goto out_free_opp; 122 } 123 124 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 125 if (!priv) { 126 ret = -ENOMEM; 127 goto out_free_opp; 128 } 129 130 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 131 if (ret) { 132 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 133 goto out_free_priv; 134 } 135 136 priv->cpu_dev = cpu_dev; 137 priv->clk = clk_get(cpu_dev, NULL); 138 if (IS_ERR(priv->clk)) { 139 dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n", 140 __func__, cpu_dev->id); 141 ret = PTR_ERR(priv->clk); 142 goto out_free_cpufreq_table; 143 } 144 145 policy->driver_data = priv; 146 policy->freq_table = freq_table; 147 148 /* scpi allows DVFS request for any domain from any CPU */ 149 policy->dvfs_possible_from_any_cpu = true; 150 151 latency = scpi_ops->get_transition_latency(cpu_dev); 152 if (!latency) 153 latency = CPUFREQ_ETERNAL; 154 155 policy->cpuinfo.transition_latency = latency; 156 157 policy->fast_switch_possible = false; 158 159 return 0; 160 161 out_free_cpufreq_table: 162 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table); 163 out_free_priv: 164 kfree(priv); 165 out_free_opp: 166 dev_pm_opp_remove_all_dynamic(cpu_dev); 167 168 return ret; 169 } 170 171 static void scpi_cpufreq_exit(struct cpufreq_policy *policy) 172 { 173 struct scpi_data *priv = policy->driver_data; 174 175 clk_put(priv->clk); 176 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 177 dev_pm_opp_remove_all_dynamic(priv->cpu_dev); 178 kfree(priv); 179 } 180 181 static struct cpufreq_driver scpi_cpufreq_driver = { 182 .name = "scpi-cpufreq", 183 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 184 CPUFREQ_NEED_INITIAL_FREQ_CHECK | 185 CPUFREQ_IS_COOLING_DEV, 186 .verify = cpufreq_generic_frequency_table_verify, 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 }; 193 194 static 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 } 208 209 static void scpi_cpufreq_remove(struct platform_device *pdev) 210 { 211 cpufreq_unregister_driver(&scpi_cpufreq_driver); 212 scpi_ops = NULL; 213 } 214 215 static struct platform_driver scpi_cpufreq_platdrv = { 216 .driver = { 217 .name = "scpi-cpufreq", 218 }, 219 .probe = scpi_cpufreq_probe, 220 .remove = scpi_cpufreq_remove, 221 }; 222 module_platform_driver(scpi_cpufreq_platdrv); 223 224 MODULE_ALIAS("platform:scpi-cpufreq"); 225 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 226 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver"); 227 MODULE_LICENSE("GPL v2"); 228