drivers/cpufreq/scpi-cpufreq.c

   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         return 0;
 167
 168 out_free_cpufreq_table:
 169         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
 170 out_free_priv:
 171         kfree(priv);
 172 out_free_opp:
 173         dev_pm_opp_remove_all_dynamic(cpu_dev);
 174
 175         return ret;
 176 }
 177
 178 static int scpi_cpufreq_exit(struct cpufreq_policy *policy)
 179 {
 180         struct scpi_data *priv = policy->driver_data;
 181
 182         clk_put(priv->clk);
 183         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 184         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 185         kfree(priv);
 186
 187         return 0;
 188 }
 189
 190 static struct cpufreq_driver scpi_cpufreq_driver = {
 191         .name   = "scpi-cpufreq",
 192         .flags  = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 193                   CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 194                   CPUFREQ_IS_COOLING_DEV,
 195         .verify = cpufreq_generic_frequency_table_verify,
 196         .attr   = cpufreq_generic_attr,
 197         .get    = scpi_cpufreq_get_rate,
 198         .init   = scpi_cpufreq_init,
 199         .exit   = scpi_cpufreq_exit,
 200         .target_index   = scpi_cpufreq_set_target,
 201         .register_em    = cpufreq_register_em_with_opp,
 202 };
 203
 204 static int scpi_cpufreq_probe(struct platform_device *pdev)
 205 {
 206         int ret;
 207
 208         scpi_ops = get_scpi_ops();
 209         if (!scpi_ops)
 210                 return -EIO;
 211
 212         ret = cpufreq_register_driver(&scpi_cpufreq_driver);
 213         if (ret)
 214                 dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n",
 215                         __func__, ret);
 216         return ret;
 217 }
 218
 219 static int scpi_cpufreq_remove(struct platform_device *pdev)
 220 {
 221         cpufreq_unregister_driver(&scpi_cpufreq_driver);
 222         scpi_ops = NULL;
 223         return 0;
 224 }
 225
 226 static struct platform_driver scpi_cpufreq_platdrv = {
 227         .driver = {
 228                 .name   = "scpi-cpufreq",
 229         },
 230         .probe          = scpi_cpufreq_probe,
 231         .remove         = scpi_cpufreq_remove,
 232 };
 233 module_platform_driver(scpi_cpufreq_platdrv);
 234
 235 MODULE_ALIAS("platform:scpi-cpufreq");
 236 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 237 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
 238 MODULE_LICENSE("GPL v2");