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/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         kfree(priv);
 193         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 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");