1 /* 2 * System Control and Power Interface (SCPI) based CPUFreq Interface driver 3 * 4 * It provides necessary ops to arm_big_little cpufreq driver. 5 * 6 * Copyright (C) 2015 ARM Ltd. 7 * Sudeep Holla <sudeep.holla@arm.com> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 * 13 * This program is distributed "as is" WITHOUT ANY WARRANTY of any 14 * kind, whether express or implied; without even the implied warranty 15 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/clk.h> 22 #include <linux/cpu.h> 23 #include <linux/cpufreq.h> 24 #include <linux/cpumask.h> 25 #include <linux/cpu_cooling.h> 26 #include <linux/export.h> 27 #include <linux/module.h> 28 #include <linux/of_platform.h> 29 #include <linux/pm_opp.h> 30 #include <linux/scpi_protocol.h> 31 #include <linux/slab.h> 32 #include <linux/types.h> 33 34 struct scpi_data { 35 struct clk *clk; 36 struct device *cpu_dev; 37 struct thermal_cooling_device *cdev; 38 }; 39 40 static struct scpi_ops *scpi_ops; 41 42 static unsigned int scpi_cpufreq_get_rate(unsigned int cpu) 43 { 44 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); 45 struct scpi_data *priv = policy->driver_data; 46 unsigned long rate = clk_get_rate(priv->clk); 47 48 return rate / 1000; 49 } 50 51 static int 52 scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index) 53 { 54 unsigned long freq = policy->freq_table[index].frequency; 55 struct scpi_data *priv = policy->driver_data; 56 u64 rate = freq * 1000; 57 int ret; 58 59 ret = clk_set_rate(priv->clk, rate); 60 61 if (ret) 62 return ret; 63 64 if (clk_get_rate(priv->clk) != rate) 65 return -EIO; 66 67 arch_set_freq_scale(policy->related_cpus, freq, 68 policy->cpuinfo.max_freq); 69 70 return 0; 71 } 72 73 static int 74 scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 75 { 76 int cpu, domain, tdomain; 77 struct device *tcpu_dev; 78 79 domain = scpi_ops->device_domain_id(cpu_dev); 80 if (domain < 0) 81 return domain; 82 83 for_each_possible_cpu(cpu) { 84 if (cpu == cpu_dev->id) 85 continue; 86 87 tcpu_dev = get_cpu_device(cpu); 88 if (!tcpu_dev) 89 continue; 90 91 tdomain = scpi_ops->device_domain_id(tcpu_dev); 92 if (tdomain == domain) 93 cpumask_set_cpu(cpu, cpumask); 94 } 95 96 return 0; 97 } 98 99 static int scpi_cpufreq_init(struct cpufreq_policy *policy) 100 { 101 int ret; 102 unsigned int latency; 103 struct device *cpu_dev; 104 struct scpi_data *priv; 105 struct cpufreq_frequency_table *freq_table; 106 107 cpu_dev = get_cpu_device(policy->cpu); 108 if (!cpu_dev) { 109 pr_err("failed to get cpu%d device\n", policy->cpu); 110 return -ENODEV; 111 } 112 113 ret = scpi_ops->add_opps_to_device(cpu_dev); 114 if (ret) { 115 dev_warn(cpu_dev, "failed to add opps to the device\n"); 116 return ret; 117 } 118 119 ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus); 120 if (ret) { 121 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 122 return ret; 123 } 124 125 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus); 126 if (ret) { 127 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 128 __func__, ret); 129 return ret; 130 } 131 132 ret = dev_pm_opp_get_opp_count(cpu_dev); 133 if (ret <= 0) { 134 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); 135 ret = -EPROBE_DEFER; 136 goto out_free_opp; 137 } 138 139 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 140 if (!priv) { 141 ret = -ENOMEM; 142 goto out_free_opp; 143 } 144 145 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 146 if (ret) { 147 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 148 goto out_free_priv; 149 } 150 151 priv->cpu_dev = cpu_dev; 152 priv->clk = clk_get(cpu_dev, NULL); 153 if (IS_ERR(priv->clk)) { 154 dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n", 155 __func__, cpu_dev->id); 156 ret = PTR_ERR(priv->clk); 157 goto out_free_cpufreq_table; 158 } 159 160 policy->driver_data = priv; 161 policy->freq_table = freq_table; 162 163 /* scpi allows DVFS request for any domain from any CPU */ 164 policy->dvfs_possible_from_any_cpu = true; 165 166 latency = scpi_ops->get_transition_latency(cpu_dev); 167 if (!latency) 168 latency = CPUFREQ_ETERNAL; 169 170 policy->cpuinfo.transition_latency = latency; 171 172 policy->fast_switch_possible = false; 173 return 0; 174 175 out_free_cpufreq_table: 176 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table); 177 out_free_priv: 178 kfree(priv); 179 out_free_opp: 180 dev_pm_opp_cpumask_remove_table(policy->cpus); 181 182 return ret; 183 } 184 185 static int scpi_cpufreq_exit(struct cpufreq_policy *policy) 186 { 187 struct scpi_data *priv = policy->driver_data; 188 189 cpufreq_cooling_unregister(priv->cdev); 190 clk_put(priv->clk); 191 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 192 kfree(priv); 193 dev_pm_opp_cpumask_remove_table(policy->related_cpus); 194 195 return 0; 196 } 197 198 static void scpi_cpufreq_ready(struct cpufreq_policy *policy) 199 { 200 struct scpi_data *priv = policy->driver_data; 201 202 priv->cdev = of_cpufreq_cooling_register(policy); 203 } 204 205 static struct cpufreq_driver scpi_cpufreq_driver = { 206 .name = "scpi-cpufreq", 207 .flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 208 CPUFREQ_NEED_INITIAL_FREQ_CHECK, 209 .verify = cpufreq_generic_frequency_table_verify, 210 .attr = cpufreq_generic_attr, 211 .get = scpi_cpufreq_get_rate, 212 .init = scpi_cpufreq_init, 213 .exit = scpi_cpufreq_exit, 214 .ready = scpi_cpufreq_ready, 215 .target_index = scpi_cpufreq_set_target, 216 }; 217 218 static int scpi_cpufreq_probe(struct platform_device *pdev) 219 { 220 int ret; 221 222 scpi_ops = get_scpi_ops(); 223 if (!scpi_ops) 224 return -EIO; 225 226 ret = cpufreq_register_driver(&scpi_cpufreq_driver); 227 if (ret) 228 dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n", 229 __func__, ret); 230 return ret; 231 } 232 233 static int scpi_cpufreq_remove(struct platform_device *pdev) 234 { 235 cpufreq_unregister_driver(&scpi_cpufreq_driver); 236 scpi_ops = NULL; 237 return 0; 238 } 239 240 static struct platform_driver scpi_cpufreq_platdrv = { 241 .driver = { 242 .name = "scpi-cpufreq", 243 }, 244 .probe = scpi_cpufreq_probe, 245 .remove = scpi_cpufreq_remove, 246 }; 247 module_platform_driver(scpi_cpufreq_platdrv); 248 249 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 250 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver"); 251 MODULE_LICENSE("GPL v2"); 252