drivers/cpufreq/cpufreq-dt.c

   1 /*
   2  * Copyright (C) 2012 Freescale Semiconductor, Inc.
   3  *
   4  * Copyright (C) 2014 Linaro.
   5  * Viresh Kumar <viresh.kumar@linaro.org>
   6  *
   7  * The OPP code in function set_target() is reused from
   8  * drivers/cpufreq/omap-cpufreq.c
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  16
  17 #include <linux/clk.h>
  18 #include <linux/cpu.h>
  19 #include <linux/cpu_cooling.h>
  20 #include <linux/cpufreq.h>
  21 #include <linux/cpufreq-dt.h>
  22 #include <linux/cpumask.h>
  23 #include <linux/err.h>
  24 #include <linux/module.h>
  25 #include <linux/of.h>
  26 #include <linux/pm_opp.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/regulator/consumer.h>
  29 #include <linux/slab.h>
  30 #include <linux/thermal.h>
  31
  32 struct private_data {
  33         struct device *cpu_dev;
  34         struct regulator *cpu_reg;
  35         struct thermal_cooling_device *cdev;
  36         unsigned int voltage_tolerance; /* in percentage */
  37 };
  38
  39 static int set_target(struct cpufreq_policy *policy, unsigned int index)
  40 {
  41         struct dev_pm_opp *opp;
  42         struct cpufreq_frequency_table *freq_table = policy->freq_table;
  43         struct clk *cpu_clk = policy->clk;
  44         struct private_data *priv = policy->driver_data;
  45         struct device *cpu_dev = priv->cpu_dev;
  46         struct regulator *cpu_reg = priv->cpu_reg;
  47         unsigned long volt = 0, volt_old = 0, tol = 0;
  48         unsigned int old_freq, new_freq;
  49         long freq_Hz, freq_exact;
  50         int ret;
  51
  52         freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
  53         if (freq_Hz <= 0)
  54                 freq_Hz = freq_table[index].frequency * 1000;
  55
  56         freq_exact = freq_Hz;
  57         new_freq = freq_Hz / 1000;
  58         old_freq = clk_get_rate(cpu_clk) / 1000;
  59
  60         if (!IS_ERR(cpu_reg)) {
  61                 unsigned long opp_freq;
  62
  63                 rcu_read_lock();
  64                 opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
  65                 if (IS_ERR(opp)) {
  66                         rcu_read_unlock();
  67                         dev_err(cpu_dev, "failed to find OPP for %ld\n",
  68                                 freq_Hz);
  69                         return PTR_ERR(opp);
  70                 }
  71                 volt = dev_pm_opp_get_voltage(opp);
  72                 opp_freq = dev_pm_opp_get_freq(opp);
  73                 rcu_read_unlock();
  74                 tol = volt * priv->voltage_tolerance / 100;
  75                 volt_old = regulator_get_voltage(cpu_reg);
  76                 dev_dbg(cpu_dev, "Found OPP: %ld kHz, %ld uV\n",
  77                         opp_freq / 1000, volt);
  78         }
  79
  80         dev_dbg(cpu_dev, "%u MHz, %ld mV --> %u MHz, %ld mV\n",
  81                 old_freq / 1000, (volt_old > 0) ? volt_old / 1000 : -1,
  82                 new_freq / 1000, volt ? volt / 1000 : -1);
  83
  84         /* scaling up?  scale voltage before frequency */
  85         if (!IS_ERR(cpu_reg) && new_freq > old_freq) {
  86                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
  87                 if (ret) {
  88                         dev_err(cpu_dev, "failed to scale voltage up: %d\n",
  89                                 ret);
  90                         return ret;
  91                 }
  92         }
  93
  94         ret = clk_set_rate(cpu_clk, freq_exact);
  95         if (ret) {
  96                 dev_err(cpu_dev, "failed to set clock rate: %d\n", ret);
  97                 if (!IS_ERR(cpu_reg) && volt_old > 0)
  98                         regulator_set_voltage_tol(cpu_reg, volt_old, tol);
  99                 return ret;
 100         }
 101
 102         /* scaling down?  scale voltage after frequency */
 103         if (!IS_ERR(cpu_reg) && new_freq < old_freq) {
 104                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
 105                 if (ret) {
 106                         dev_err(cpu_dev, "failed to scale voltage down: %d\n",
 107                                 ret);
 108                         clk_set_rate(cpu_clk, old_freq * 1000);
 109                 }
 110         }
 111
 112         return ret;
 113 }
 114
 115 static int allocate_resources(int cpu, struct device **cdev,
 116                               struct regulator **creg, struct clk **cclk)
 117 {
 118         struct device *cpu_dev;
 119         struct regulator *cpu_reg;
 120         struct clk *cpu_clk;
 121         int ret = 0;
 122         char *reg_cpu0 = "cpu0", *reg_cpu = "cpu", *reg;
 123
 124         cpu_dev = get_cpu_device(cpu);
 125         if (!cpu_dev) {
 126                 pr_err("failed to get cpu%d device\n", cpu);
 127                 return -ENODEV;
 128         }
 129
 130         /* Try "cpu0" for older DTs */
 131         if (!cpu)
 132                 reg = reg_cpu0;
 133         else
 134                 reg = reg_cpu;
 135
 136 try_again:
 137         cpu_reg = regulator_get_optional(cpu_dev, reg);
 138         if (IS_ERR(cpu_reg)) {
 139                 /*
 140                  * If cpu's regulator supply node is present, but regulator is
 141                  * not yet registered, we should try defering probe.
 142                  */
 143                 if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
 144                         dev_dbg(cpu_dev, "cpu%d regulator not ready, retry\n",
 145                                 cpu);
 146                         return -EPROBE_DEFER;
 147                 }
 148
 149                 /* Try with "cpu-supply" */
 150                 if (reg == reg_cpu0) {
 151                         reg = reg_cpu;
 152                         goto try_again;
 153                 }
 154
 155                 dev_dbg(cpu_dev, "no regulator for cpu%d: %ld\n",
 156                         cpu, PTR_ERR(cpu_reg));
 157         }
 158
 159         cpu_clk = clk_get(cpu_dev, NULL);
 160         if (IS_ERR(cpu_clk)) {
 161                 /* put regulator */
 162                 if (!IS_ERR(cpu_reg))
 163                         regulator_put(cpu_reg);
 164
 165                 ret = PTR_ERR(cpu_clk);
 166
 167                 /*
 168                  * If cpu's clk node is present, but clock is not yet
 169                  * registered, we should try defering probe.
 170                  */
 171                 if (ret == -EPROBE_DEFER)
 172                         dev_dbg(cpu_dev, "cpu%d clock not ready, retry\n", cpu);
 173                 else
 174                         dev_err(cpu_dev, "failed to get cpu%d clock: %d\n", cpu,
 175                                 ret);
 176         } else {
 177                 *cdev = cpu_dev;
 178                 *creg = cpu_reg;
 179                 *cclk = cpu_clk;
 180         }
 181
 182         return ret;
 183 }
 184
 185 static int cpufreq_init(struct cpufreq_policy *policy)
 186 {
 187         struct cpufreq_dt_platform_data *pd;
 188         struct cpufreq_frequency_table *freq_table;
 189         struct thermal_cooling_device *cdev;
 190         struct device_node *np;
 191         struct private_data *priv;
 192         struct device *cpu_dev;
 193         struct regulator *cpu_reg;
 194         struct clk *cpu_clk;
 195         unsigned long min_uV = ~0, max_uV = 0;
 196         unsigned int transition_latency;
 197         int ret;
 198
 199         ret = allocate_resources(policy->cpu, &cpu_dev, &cpu_reg, &cpu_clk);
 200         if (ret) {
 201                 pr_err("%s: Failed to allocate resources\n: %d", __func__, ret);
 202                 return ret;
 203         }
 204
 205         np = of_node_get(cpu_dev->of_node);
 206         if (!np) {
 207                 dev_err(cpu_dev, "failed to find cpu%d node\n", policy->cpu);
 208                 ret = -ENOENT;
 209                 goto out_put_reg_clk;
 210         }
 211
 212         /* OPPs might be populated at runtime, don't check for error here */
 213         of_init_opp_table(cpu_dev);
 214
 215         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 216         if (!priv) {
 217                 ret = -ENOMEM;
 218                 goto out_put_node;
 219         }
 220
 221         of_property_read_u32(np, "voltage-tolerance", &priv->voltage_tolerance);
 222
 223         if (of_property_read_u32(np, "clock-latency", &transition_latency))
 224                 transition_latency = CPUFREQ_ETERNAL;
 225
 226         if (!IS_ERR(cpu_reg)) {
 227                 unsigned long opp_freq = 0;
 228
 229                 /*
 230                  * Disable any OPPs where the connected regulator isn't able to
 231                  * provide the specified voltage and record minimum and maximum
 232                  * voltage levels.
 233                  */
 234                 while (1) {
 235                         struct dev_pm_opp *opp;
 236                         unsigned long opp_uV, tol_uV;
 237
 238                         rcu_read_lock();
 239                         opp = dev_pm_opp_find_freq_ceil(cpu_dev, &opp_freq);
 240                         if (IS_ERR(opp)) {
 241                                 rcu_read_unlock();
 242                                 break;
 243                         }
 244                         opp_uV = dev_pm_opp_get_voltage(opp);
 245                         rcu_read_unlock();
 246
 247                         tol_uV = opp_uV * priv->voltage_tolerance / 100;
 248                         if (regulator_is_supported_voltage(cpu_reg, opp_uV,
 249                                                            opp_uV + tol_uV)) {
 250                                 if (opp_uV < min_uV)
 251                                         min_uV = opp_uV;
 252                                 if (opp_uV > max_uV)
 253                                         max_uV = opp_uV;
 254                         } else {
 255                                 dev_pm_opp_disable(cpu_dev, opp_freq);
 256                         }
 257
 258                         opp_freq++;
 259                 }
 260
 261                 ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
 262                 if (ret > 0)
 263                         transition_latency += ret * 1000;
 264         }
 265
 266         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 267         if (ret) {
 268                 pr_err("failed to init cpufreq table: %d\n", ret);
 269                 goto out_free_priv;
 270         }
 271
 272         /*
 273          * For now, just loading the cooling device;
 274          * thermal DT code takes care of matching them.
 275          */
 276         if (of_find_property(np, "#cooling-cells", NULL)) {
 277                 cdev = of_cpufreq_cooling_register(np, cpu_present_mask);
 278                 if (IS_ERR(cdev))
 279                         dev_err(cpu_dev,
 280                                 "running cpufreq without cooling device: %ld\n",
 281                                 PTR_ERR(cdev));
 282                 else
 283                         priv->cdev = cdev;
 284         }
 285
 286         priv->cpu_dev = cpu_dev;
 287         priv->cpu_reg = cpu_reg;
 288         policy->driver_data = priv;
 289
 290         policy->clk = cpu_clk;
 291         ret = cpufreq_table_validate_and_show(policy, freq_table);
 292         if (ret) {
 293                 dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
 294                         ret);
 295                 goto out_cooling_unregister;
 296         }
 297
 298         policy->cpuinfo.transition_latency = transition_latency;
 299
 300         pd = cpufreq_get_driver_data();
 301         if (!pd || !pd->independent_clocks)
 302                 cpumask_setall(policy->cpus);
 303
 304         of_node_put(np);
 305
 306         return 0;
 307
 308 out_cooling_unregister:
 309         cpufreq_cooling_unregister(priv->cdev);
 310         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
 311 out_free_priv:
 312         kfree(priv);
 313 out_put_node:
 314         of_node_put(np);
 315 out_put_reg_clk:
 316         clk_put(cpu_clk);
 317         if (!IS_ERR(cpu_reg))
 318                 regulator_put(cpu_reg);
 319
 320         return ret;
 321 }
 322
 323 static int cpufreq_exit(struct cpufreq_policy *policy)
 324 {
 325         struct private_data *priv = policy->driver_data;
 326
 327         cpufreq_cooling_unregister(priv->cdev);
 328         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 329         clk_put(policy->clk);
 330         if (!IS_ERR(priv->cpu_reg))
 331                 regulator_put(priv->cpu_reg);
 332         kfree(priv);
 333
 334         return 0;
 335 }
 336
 337 static struct cpufreq_driver dt_cpufreq_driver = {
 338         .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 339         .verify = cpufreq_generic_frequency_table_verify,
 340         .target_index = set_target,
 341         .get = cpufreq_generic_get,
 342         .init = cpufreq_init,
 343         .exit = cpufreq_exit,
 344         .name = "cpufreq-dt",
 345         .attr = cpufreq_generic_attr,
 346 };
 347
 348 static int dt_cpufreq_probe(struct platform_device *pdev)
 349 {
 350         struct device *cpu_dev;
 351         struct regulator *cpu_reg;
 352         struct clk *cpu_clk;
 353         int ret;
 354
 355         /*
 356          * All per-cluster (CPUs sharing clock/voltages) initialization is done
 357          * from ->init(). In probe(), we just need to make sure that clk and
 358          * regulators are available. Else defer probe and retry.
 359          *
 360          * FIXME: Is checking this only for CPU0 sufficient ?
 361          */
 362         ret = allocate_resources(0, &cpu_dev, &cpu_reg, &cpu_clk);
 363         if (ret)
 364                 return ret;
 365
 366         clk_put(cpu_clk);
 367         if (!IS_ERR(cpu_reg))
 368                 regulator_put(cpu_reg);
 369
 370         dt_cpufreq_driver.driver_data = dev_get_platdata(&pdev->dev);
 371
 372         ret = cpufreq_register_driver(&dt_cpufreq_driver);
 373         if (ret)
 374                 dev_err(cpu_dev, "failed register driver: %d\n", ret);
 375
 376         return ret;
 377 }
 378
 379 static int dt_cpufreq_remove(struct platform_device *pdev)
 380 {
 381         cpufreq_unregister_driver(&dt_cpufreq_driver);
 382         return 0;
 383 }
 384
 385 static struct platform_driver dt_cpufreq_platdrv = {
 386         .driver = {
 387                 .name   = "cpufreq-dt",
 388                 .owner  = THIS_MODULE,
 389         },
 390         .probe          = dt_cpufreq_probe,
 391         .remove         = dt_cpufreq_remove,
 392 };
 393 module_platform_driver(dt_cpufreq_platdrv);
 394
 395 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
 396 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 397 MODULE_DESCRIPTION("Generic cpufreq driver");
 398 MODULE_LICENSE("GPL");