drivers/cpufreq/scpi-cpufreq.c

   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");