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