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