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