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/export.h> 26 #include <linux/module.h> 27 #include <linux/of_platform.h> 28 #include <linux/pm_opp.h> 29 #include <linux/scpi_protocol.h> 30 #include <linux/slab.h> 31 #include <linux/types.h> 32 33 struct scpi_data { 34 struct clk *clk; 35 struct device *cpu_dev; 36 }; 37 38 static struct scpi_ops *scpi_ops; 39 40 static unsigned int scpi_cpufreq_get_rate(unsigned int cpu) 41 { 42 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); 43 struct scpi_data *priv = policy->driver_data; 44 unsigned long rate = clk_get_rate(priv->clk); 45 46 return rate / 1000; 47 } 48 49 static int 50 scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index) 51 { 52 unsigned long freq = policy->freq_table[index].frequency; 53 struct scpi_data *priv = policy->driver_data; 54 u64 rate = freq * 1000; 55 int ret; 56 57 ret = clk_set_rate(priv->clk, rate); 58 59 if (ret) 60 return ret; 61 62 if (clk_get_rate(priv->clk) != rate) 63 return -EIO; 64 65 arch_set_freq_scale(policy->related_cpus, freq, 66 policy->cpuinfo.max_freq); 67 68 return 0; 69 } 70 71 static int 72 scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 73 { 74 int cpu, domain, tdomain; 75 struct device *tcpu_dev; 76 77 domain = scpi_ops->device_domain_id(cpu_dev); 78 if (domain < 0) 79 return domain; 80 81 for_each_possible_cpu(cpu) { 82 if (cpu == cpu_dev->id) 83 continue; 84 85 tcpu_dev = get_cpu_device(cpu); 86 if (!tcpu_dev) 87 continue; 88 89 tdomain = scpi_ops->device_domain_id(tcpu_dev); 90 if (tdomain == domain) 91 cpumask_set_cpu(cpu, cpumask); 92 } 93 94 return 0; 95 } 96 97 static int scpi_cpufreq_init(struct cpufreq_policy *policy) 98 { 99 int ret; 100 unsigned int latency; 101 struct device *cpu_dev; 102 struct scpi_data *priv; 103 struct cpufreq_frequency_table *freq_table; 104 105 cpu_dev = get_cpu_device(policy->cpu); 106 if (!cpu_dev) { 107 pr_err("failed to get cpu%d device\n", policy->cpu); 108 return -ENODEV; 109 } 110 111 ret = scpi_ops->add_opps_to_device(cpu_dev); 112 if (ret) { 113 dev_warn(cpu_dev, "failed to add opps to the device\n"); 114 return ret; 115 } 116 117 ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus); 118 if (ret) { 119 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 120 return ret; 121 } 122 123 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus); 124 if (ret) { 125 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 126 __func__, ret); 127 return ret; 128 } 129 130 ret = dev_pm_opp_get_opp_count(cpu_dev); 131 if (ret <= 0) { 132 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); 133 ret = -EPROBE_DEFER; 134 goto out_free_opp; 135 } 136 137 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 138 if (!priv) { 139 ret = -ENOMEM; 140 goto out_free_opp; 141 } 142 143 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 144 if (ret) { 145 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 146 goto out_free_priv; 147 } 148 149 priv->cpu_dev = cpu_dev; 150 priv->clk = clk_get(cpu_dev, NULL); 151 if (IS_ERR(priv->clk)) { 152 dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n", 153 __func__, cpu_dev->id); 154 ret = PTR_ERR(priv->clk); 155 goto out_free_cpufreq_table; 156 } 157 158 policy->driver_data = priv; 159 policy->freq_table = freq_table; 160 161 /* scpi allows DVFS request for any domain from any CPU */ 162 policy->dvfs_possible_from_any_cpu = true; 163 164 latency = scpi_ops->get_transition_latency(cpu_dev); 165 if (!latency) 166 latency = CPUFREQ_ETERNAL; 167 168 policy->cpuinfo.transition_latency = latency; 169 170 policy->fast_switch_possible = false; 171 172 dev_pm_opp_of_register_em(policy->cpus); 173 174 return 0; 175 176 out_free_cpufreq_table: 177 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table); 178 out_free_priv: 179 kfree(priv); 180 out_free_opp: 181 dev_pm_opp_remove_all_dynamic(cpu_dev); 182 183 return ret; 184 } 185 186 static int scpi_cpufreq_exit(struct cpufreq_policy *policy) 187 { 188 struct scpi_data *priv = policy->driver_data; 189 190 clk_put(priv->clk); 191 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 192 dev_pm_opp_remove_all_dynamic(priv->cpu_dev); 193 kfree(priv); 194 195 return 0; 196 } 197 198 static struct cpufreq_driver scpi_cpufreq_driver = { 199 .name = "scpi-cpufreq", 200 .flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 201 CPUFREQ_NEED_INITIAL_FREQ_CHECK | 202 CPUFREQ_IS_COOLING_DEV, 203 .verify = cpufreq_generic_frequency_table_verify, 204 .attr = cpufreq_generic_attr, 205 .get = scpi_cpufreq_get_rate, 206 .init = scpi_cpufreq_init, 207 .exit = scpi_cpufreq_exit, 208 .target_index = scpi_cpufreq_set_target, 209 }; 210 211 static int scpi_cpufreq_probe(struct platform_device *pdev) 212 { 213 int ret; 214 215 scpi_ops = get_scpi_ops(); 216 if (!scpi_ops) 217 return -EIO; 218 219 ret = cpufreq_register_driver(&scpi_cpufreq_driver); 220 if (ret) 221 dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n", 222 __func__, ret); 223 return ret; 224 } 225 226 static int scpi_cpufreq_remove(struct platform_device *pdev) 227 { 228 cpufreq_unregister_driver(&scpi_cpufreq_driver); 229 scpi_ops = NULL; 230 return 0; 231 } 232 233 static struct platform_driver scpi_cpufreq_platdrv = { 234 .driver = { 235 .name = "scpi-cpufreq", 236 }, 237 .probe = scpi_cpufreq_probe, 238 .remove = scpi_cpufreq_remove, 239 }; 240 module_platform_driver(scpi_cpufreq_platdrv); 241 242 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 243 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver"); 244 MODULE_LICENSE("GPL v2"); 245