root/drivers/thermal/devfreq_cooling.c

DEFINITIONS

1. partition_enable_opps
2. devfreq_cooling_get_max_state
3. devfreq_cooling_get_cur_state
4. devfreq_cooling_set_cur_state
5. freq_get_state
6. get_voltage
7. get_static_power
8. get_dynamic_power
9. get_total_power
10. devfreq_cooling_get_requested_power
11. devfreq_cooling_state2power
12. devfreq_cooling_power2state
13. devfreq_cooling_gen_tables
14. of_devfreq_cooling_register_power
15. of_devfreq_cooling_register
16. devfreq_cooling_register
17. devfreq_cooling_unregister

   1 /*
   2  * devfreq_cooling: Thermal cooling device implementation for devices using
   3  *                  devfreq
   4  *
   5  * Copyright (C) 2014-2015 ARM Limited
   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  * TODO:
  17  *    - If OPPs are added or removed after devfreq cooling has
  18  *      registered, the devfreq cooling won't react to it.
  19  */
  20 
  21 #include <linux/devfreq.h>
  22 #include <linux/devfreq_cooling.h>
  23 #include <linux/export.h>
  24 #include <linux/idr.h>
  25 #include <linux/slab.h>
  26 #include <linux/pm_opp.h>
  27 #include <linux/thermal.h>
  28 
  29 #include <trace/events/thermal.h>
  30 
  31 #define SCALE_ERROR_MITIGATION 100
  32 
  33 static DEFINE_IDA(devfreq_ida);
  34 
  35 /**
  36  * struct devfreq_cooling_device - Devfreq cooling device
  37  * @id:         unique integer value corresponding to each
  38  *              devfreq_cooling_device registered.
  39  * @cdev:       Pointer to associated thermal cooling device.
  40  * @devfreq:    Pointer to associated devfreq device.
  41  * @cooling_state:      Current cooling state.
  42  * @power_table:        Pointer to table with maximum power draw for each
  43  *                      cooling state. State is the index into the table, and
  44  *                      the power is in mW.
  45  * @freq_table: Pointer to a table with the frequencies sorted in descending
  46  *              order.  You can index the table by cooling device state
  47  * @freq_table_size:    Size of the @freq_table and @power_table
  48  * @power_ops:  Pointer to devfreq_cooling_power, used to generate the
  49  *              @power_table.
  50  * @res_util:   Resource utilization scaling factor for the power.
  51  *              It is multiplied by 100 to minimize the error. It is used
  52  *              for estimation of the power budget instead of using
  53  *              'utilization' (which is 'busy_time / 'total_time').
  54  *              The 'res_util' range is from 100 to (power_table[state] * 100)
  55  *              for the corresponding 'state'.
  56  */
  57 struct devfreq_cooling_device {
  58         int id;
  59         struct thermal_cooling_device *cdev;
  60         struct devfreq *devfreq;
  61         unsigned long cooling_state;
  62         u32 *power_table;
  63         u32 *freq_table;
  64         size_t freq_table_size;
  65         struct devfreq_cooling_power *power_ops;
  66         u32 res_util;
  67         int capped_state;
  68 };
  69 
  70 /**
  71  * partition_enable_opps() - disable all opps above a given state
  72  * @dfc:        Pointer to devfreq we are operating on
  73  * @cdev_state: cooling device state we're setting
  74  *
  75  * Go through the OPPs of the device, enabling all OPPs until
  76  * @cdev_state and disabling those frequencies above it.
  77  */
  78 static int partition_enable_opps(struct devfreq_cooling_device *dfc,
  79                                  unsigned long cdev_state)
  80 {
  81         int i;
  82         struct device *dev = dfc->devfreq->dev.parent;
  83 
  84         for (i = 0; i < dfc->freq_table_size; i++) {
  85                 struct dev_pm_opp *opp;
  86                 int ret = 0;
  87                 unsigned int freq = dfc->freq_table[i];
  88                 bool want_enable = i >= cdev_state ? true : false;
  89 
  90                 opp = dev_pm_opp_find_freq_exact(dev, freq, !want_enable);
  91 
  92                 if (PTR_ERR(opp) == -ERANGE)
  93                         continue;
  94                 else if (IS_ERR(opp))
  95                         return PTR_ERR(opp);
  96 
  97                 dev_pm_opp_put(opp);
  98 
  99                 if (want_enable)
 100                         ret = dev_pm_opp_enable(dev, freq);
 101                 else
 102                         ret = dev_pm_opp_disable(dev, freq);
 103 
 104                 if (ret)
 105                         return ret;
 106         }
 107 
 108         return 0;
 109 }
 110 
 111 static int devfreq_cooling_get_max_state(struct thermal_cooling_device *cdev,
 112                                          unsigned long *state)
 113 {
 114         struct devfreq_cooling_device *dfc = cdev->devdata;
 115 
 116         *state = dfc->freq_table_size - 1;
 117 
 118         return 0;
 119 }
 120 
 121 static int devfreq_cooling_get_cur_state(struct thermal_cooling_device *cdev,
 122                                          unsigned long *state)
 123 {
 124         struct devfreq_cooling_device *dfc = cdev->devdata;
 125 
 126         *state = dfc->cooling_state;
 127 
 128         return 0;
 129 }
 130 
 131 static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
 132                                          unsigned long state)
 133 {
 134         struct devfreq_cooling_device *dfc = cdev->devdata;
 135         struct devfreq *df = dfc->devfreq;
 136         struct device *dev = df->dev.parent;
 137         int ret;
 138 
 139         if (state == dfc->cooling_state)
 140                 return 0;
 141 
 142         dev_dbg(dev, "Setting cooling state %lu\n", state);
 143 
 144         if (state >= dfc->freq_table_size)
 145                 return -EINVAL;
 146 
 147         ret = partition_enable_opps(dfc, state);
 148         if (ret)
 149                 return ret;
 150 
 151         dfc->cooling_state = state;
 152 
 153         return 0;
 154 }
 155 
 156 /**
 157  * freq_get_state() - get the cooling state corresponding to a frequency
 158  * @dfc:        Pointer to devfreq cooling device
 159  * @freq:       frequency in Hz
 160  *
 161  * Return: the cooling state associated with the @freq, or
 162  * THERMAL_CSTATE_INVALID if it wasn't found.
 163  */
 164 static unsigned long
 165 freq_get_state(struct devfreq_cooling_device *dfc, unsigned long freq)
 166 {
 167         int i;
 168 
 169         for (i = 0; i < dfc->freq_table_size; i++) {
 170                 if (dfc->freq_table[i] == freq)
 171                         return i;
 172         }
 173 
 174         return THERMAL_CSTATE_INVALID;
 175 }
 176 
 177 static unsigned long get_voltage(struct devfreq *df, unsigned long freq)
 178 {
 179         struct device *dev = df->dev.parent;
 180         unsigned long voltage;
 181         struct dev_pm_opp *opp;
 182 
 183         opp = dev_pm_opp_find_freq_exact(dev, freq, true);
 184         if (PTR_ERR(opp) == -ERANGE)
 185                 opp = dev_pm_opp_find_freq_exact(dev, freq, false);
 186 
 187         if (IS_ERR(opp)) {
 188                 dev_err_ratelimited(dev, "Failed to find OPP for frequency %lu: %ld\n",
 189                                     freq, PTR_ERR(opp));
 190                 return 0;
 191         }
 192 
 193         voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */
 194         dev_pm_opp_put(opp);
 195 
 196         if (voltage == 0) {
 197                 dev_err_ratelimited(dev,
 198                                     "Failed to get voltage for frequency %lu\n",
 199                                     freq);
 200         }
 201 
 202         return voltage;
 203 }
 204 
 205 /**
 206  * get_static_power() - calculate the static power
 207  * @dfc:        Pointer to devfreq cooling device
 208  * @freq:       Frequency in Hz
 209  *
 210  * Calculate the static power in milliwatts using the supplied
 211  * get_static_power().  The current voltage is calculated using the
 212  * OPP library.  If no get_static_power() was supplied, assume the
 213  * static power is negligible.
 214  */
 215 static unsigned long
 216 get_static_power(struct devfreq_cooling_device *dfc, unsigned long freq)
 217 {
 218         struct devfreq *df = dfc->devfreq;
 219         unsigned long voltage;
 220 
 221         if (!dfc->power_ops->get_static_power)
 222                 return 0;
 223 
 224         voltage = get_voltage(df, freq);
 225 
 226         if (voltage == 0)
 227                 return 0;
 228 
 229         return dfc->power_ops->get_static_power(df, voltage);
 230 }
 231 
 232 /**
 233  * get_dynamic_power - calculate the dynamic power
 234  * @dfc:        Pointer to devfreq cooling device
 235  * @freq:       Frequency in Hz
 236  * @voltage:    Voltage in millivolts
 237  *
 238  * Calculate the dynamic power in milliwatts consumed by the device at
 239  * frequency @freq and voltage @voltage.  If the get_dynamic_power()
 240  * was supplied as part of the devfreq_cooling_power struct, then that
 241  * function is used.  Otherwise, a simple power model (Pdyn = Coeff *
 242  * Voltage^2 * Frequency) is used.
 243  */
 244 static unsigned long
 245 get_dynamic_power(struct devfreq_cooling_device *dfc, unsigned long freq,
 246                   unsigned long voltage)
 247 {
 248         u64 power;
 249         u32 freq_mhz;
 250         struct devfreq_cooling_power *dfc_power = dfc->power_ops;
 251 
 252         if (dfc_power->get_dynamic_power)
 253                 return dfc_power->get_dynamic_power(dfc->devfreq, freq,
 254                                                     voltage);
 255 
 256         freq_mhz = freq / 1000000;
 257         power = (u64)dfc_power->dyn_power_coeff * freq_mhz * voltage * voltage;
 258         do_div(power, 1000000000);
 259 
 260         return power;
 261 }
 262 
 263 
 264 static inline unsigned long get_total_power(struct devfreq_cooling_device *dfc,
 265                                             unsigned long freq,
 266                                             unsigned long voltage)
 267 {
 268         return get_static_power(dfc, freq) + get_dynamic_power(dfc, freq,
 269                                                                voltage);
 270 }
 271 
 272 
 273 static int devfreq_cooling_get_requested_power(struct thermal_cooling_device *cdev,
 274                                                struct thermal_zone_device *tz,
 275                                                u32 *power)
 276 {
 277         struct devfreq_cooling_device *dfc = cdev->devdata;
 278         struct devfreq *df = dfc->devfreq;
 279         struct devfreq_dev_status *status = &df->last_status;
 280         unsigned long state;
 281         unsigned long freq = status->current_frequency;
 282         unsigned long voltage;
 283         u32 dyn_power = 0;
 284         u32 static_power = 0;
 285         int res;
 286 
 287         state = freq_get_state(dfc, freq);
 288         if (state == THERMAL_CSTATE_INVALID) {
 289                 res = -EAGAIN;
 290                 goto fail;
 291         }
 292 
 293         if (dfc->power_ops->get_real_power) {
 294                 voltage = get_voltage(df, freq);
 295                 if (voltage == 0) {
 296                         res = -EINVAL;
 297                         goto fail;
 298                 }
 299 
 300                 res = dfc->power_ops->get_real_power(df, power, freq, voltage);
 301                 if (!res) {
 302                         state = dfc->capped_state;
 303                         dfc->res_util = dfc->power_table[state];
 304                         dfc->res_util *= SCALE_ERROR_MITIGATION;
 305 
 306                         if (*power > 1)
 307                                 dfc->res_util /= *power;
 308                 } else {
 309                         goto fail;
 310                 }
 311         } else {
 312                 dyn_power = dfc->power_table[state];
 313 
 314                 /* Scale dynamic power for utilization */
 315                 dyn_power *= status->busy_time;
 316                 dyn_power /= status->total_time;
 317                 /* Get static power */
 318                 static_power = get_static_power(dfc, freq);
 319 
 320                 *power = dyn_power + static_power;
 321         }
 322 
 323         trace_thermal_power_devfreq_get_power(cdev, status, freq, dyn_power,
 324                                               static_power, *power);
 325 
 326         return 0;
 327 fail:
 328         /* It is safe to set max in this case */
 329         dfc->res_util = SCALE_ERROR_MITIGATION;
 330         return res;
 331 }
 332 
 333 static int devfreq_cooling_state2power(struct thermal_cooling_device *cdev,
 334                                        struct thermal_zone_device *tz,
 335                                        unsigned long state,
 336                                        u32 *power)
 337 {
 338         struct devfreq_cooling_device *dfc = cdev->devdata;
 339         unsigned long freq;
 340         u32 static_power;
 341 
 342         if (state >= dfc->freq_table_size)
 343                 return -EINVAL;
 344 
 345         freq = dfc->freq_table[state];
 346         static_power = get_static_power(dfc, freq);
 347 
 348         *power = dfc->power_table[state] + static_power;
 349         return 0;
 350 }
 351 
 352 static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
 353                                        struct thermal_zone_device *tz,
 354                                        u32 power, unsigned long *state)
 355 {
 356         struct devfreq_cooling_device *dfc = cdev->devdata;
 357         struct devfreq *df = dfc->devfreq;
 358         struct devfreq_dev_status *status = &df->last_status;
 359         unsigned long freq = status->current_frequency;
 360         unsigned long busy_time;
 361         s32 dyn_power;
 362         u32 static_power;
 363         s32 est_power;
 364         int i;
 365 
 366         if (dfc->power_ops->get_real_power) {
 367                 /* Scale for resource utilization */
 368                 est_power = power * dfc->res_util;
 369                 est_power /= SCALE_ERROR_MITIGATION;
 370         } else {
 371                 static_power = get_static_power(dfc, freq);
 372 
 373                 dyn_power = power - static_power;
 374                 dyn_power = dyn_power > 0 ? dyn_power : 0;
 375 
 376                 /* Scale dynamic power for utilization */
 377                 busy_time = status->busy_time ?: 1;
 378                 est_power = (dyn_power * status->total_time) / busy_time;
 379         }
 380 
 381         /*
 382          * Find the first cooling state that is within the power
 383          * budget for dynamic power.
 384          */
 385         for (i = 0; i < dfc->freq_table_size - 1; i++)
 386                 if (est_power >= dfc->power_table[i])
 387                         break;
 388 
 389         *state = i;
 390         dfc->capped_state = i;
 391         trace_thermal_power_devfreq_limit(cdev, freq, *state, power);
 392         return 0;
 393 }
 394 
 395 static struct thermal_cooling_device_ops devfreq_cooling_ops = {
 396         .get_max_state = devfreq_cooling_get_max_state,
 397         .get_cur_state = devfreq_cooling_get_cur_state,
 398         .set_cur_state = devfreq_cooling_set_cur_state,
 399 };
 400 
 401 /**
 402  * devfreq_cooling_gen_tables() - Generate power and freq tables.
 403  * @dfc: Pointer to devfreq cooling device.
 404  *
 405  * Generate power and frequency tables: the power table hold the
 406  * device's maximum power usage at each cooling state (OPP).  The
 407  * static and dynamic power using the appropriate voltage and
 408  * frequency for the state, is acquired from the struct
 409  * devfreq_cooling_power, and summed to make the maximum power draw.
 410  *
 411  * The frequency table holds the frequencies in descending order.
 412  * That way its indexed by cooling device state.
 413  *
 414  * The tables are malloced, and pointers put in dfc.  They must be
 415  * freed when unregistering the devfreq cooling device.
 416  *
 417  * Return: 0 on success, negative error code on failure.
 418  */
 419 static int devfreq_cooling_gen_tables(struct devfreq_cooling_device *dfc)
 420 {
 421         struct devfreq *df = dfc->devfreq;
 422         struct device *dev = df->dev.parent;
 423         int ret, num_opps;
 424         unsigned long freq;
 425         u32 *power_table = NULL;
 426         u32 *freq_table;
 427         int i;
 428 
 429         num_opps = dev_pm_opp_get_opp_count(dev);
 430 
 431         if (dfc->power_ops) {
 432                 power_table = kcalloc(num_opps, sizeof(*power_table),
 433                                       GFP_KERNEL);
 434                 if (!power_table)
 435                         return -ENOMEM;
 436         }
 437 
 438         freq_table = kcalloc(num_opps, sizeof(*freq_table),
 439                              GFP_KERNEL);
 440         if (!freq_table) {
 441                 ret = -ENOMEM;
 442                 goto free_power_table;
 443         }
 444 
 445         for (i = 0, freq = ULONG_MAX; i < num_opps; i++, freq--) {
 446                 unsigned long power, voltage;
 447                 struct dev_pm_opp *opp;
 448 
 449                 opp = dev_pm_opp_find_freq_floor(dev, &freq);
 450                 if (IS_ERR(opp)) {
 451                         ret = PTR_ERR(opp);
 452                         goto free_tables;
 453                 }
 454 
 455                 voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */
 456                 dev_pm_opp_put(opp);
 457 
 458                 if (dfc->power_ops) {
 459                         if (dfc->power_ops->get_real_power)
 460                                 power = get_total_power(dfc, freq, voltage);
 461                         else
 462                                 power = get_dynamic_power(dfc, freq, voltage);
 463 
 464                         dev_dbg(dev, "Power table: %lu MHz @ %lu mV: %lu = %lu mW\n",
 465                                 freq / 1000000, voltage, power, power);
 466 
 467                         power_table[i] = power;
 468                 }
 469 
 470                 freq_table[i] = freq;
 471         }
 472 
 473         if (dfc->power_ops)
 474                 dfc->power_table = power_table;
 475 
 476         dfc->freq_table = freq_table;
 477         dfc->freq_table_size = num_opps;
 478 
 479         return 0;
 480 
 481 free_tables:
 482         kfree(freq_table);
 483 free_power_table:
 484         kfree(power_table);
 485 
 486         return ret;
 487 }
 488 
 489 /**
 490  * of_devfreq_cooling_register_power() - Register devfreq cooling device,
 491  *                                      with OF and power information.
 492  * @np: Pointer to OF device_node.
 493  * @df: Pointer to devfreq device.
 494  * @dfc_power:  Pointer to devfreq_cooling_power.
 495  *
 496  * Register a devfreq cooling device.  The available OPPs must be
 497  * registered on the device.
 498  *
 499  * If @dfc_power is provided, the cooling device is registered with the
 500  * power extensions.  For the power extensions to work correctly,
 501  * devfreq should use the simple_ondemand governor, other governors
 502  * are not currently supported.
 503  */
 504 struct thermal_cooling_device *
 505 of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
 506                                   struct devfreq_cooling_power *dfc_power)
 507 {
 508         struct thermal_cooling_device *cdev;
 509         struct devfreq_cooling_device *dfc;
 510         char dev_name[THERMAL_NAME_LENGTH];
 511         int err;
 512 
 513         dfc = kzalloc(sizeof(*dfc), GFP_KERNEL);
 514         if (!dfc)
 515                 return ERR_PTR(-ENOMEM);
 516 
 517         dfc->devfreq = df;
 518 
 519         if (dfc_power) {
 520                 dfc->power_ops = dfc_power;
 521 
 522                 devfreq_cooling_ops.get_requested_power =
 523                         devfreq_cooling_get_requested_power;
 524                 devfreq_cooling_ops.state2power = devfreq_cooling_state2power;
 525                 devfreq_cooling_ops.power2state = devfreq_cooling_power2state;
 526         }
 527 
 528         err = devfreq_cooling_gen_tables(dfc);
 529         if (err)
 530                 goto free_dfc;
 531 
 532         err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);
 533         if (err < 0)
 534                 goto free_tables;
 535         dfc->id = err;
 536 
 537         snprintf(dev_name, sizeof(dev_name), "thermal-devfreq-%d", dfc->id);
 538 
 539         cdev = thermal_of_cooling_device_register(np, dev_name, dfc,
 540                                                   &devfreq_cooling_ops);
 541         if (IS_ERR(cdev)) {
 542                 err = PTR_ERR(cdev);
 543                 dev_err(df->dev.parent,
 544                         "Failed to register devfreq cooling device (%d)\n",
 545                         err);
 546                 goto release_ida;
 547         }
 548 
 549         dfc->cdev = cdev;
 550 
 551         return cdev;
 552 
 553 release_ida:
 554         ida_simple_remove(&devfreq_ida, dfc->id);
 555 free_tables:
 556         kfree(dfc->power_table);
 557         kfree(dfc->freq_table);
 558 free_dfc:
 559         kfree(dfc);
 560 
 561         return ERR_PTR(err);
 562 }
 563 EXPORT_SYMBOL_GPL(of_devfreq_cooling_register_power);
 564 
 565 /**
 566  * of_devfreq_cooling_register() - Register devfreq cooling device,
 567  *                                with OF information.
 568  * @np: Pointer to OF device_node.
 569  * @df: Pointer to devfreq device.
 570  */
 571 struct thermal_cooling_device *
 572 of_devfreq_cooling_register(struct device_node *np, struct devfreq *df)
 573 {
 574         return of_devfreq_cooling_register_power(np, df, NULL);
 575 }
 576 EXPORT_SYMBOL_GPL(of_devfreq_cooling_register);
 577 
 578 /**
 579  * devfreq_cooling_register() - Register devfreq cooling device.
 580  * @df: Pointer to devfreq device.
 581  */
 582 struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df)
 583 {
 584         return of_devfreq_cooling_register(NULL, df);
 585 }
 586 EXPORT_SYMBOL_GPL(devfreq_cooling_register);
 587 
 588 /**
 589  * devfreq_cooling_unregister() - Unregister devfreq cooling device.
 590  * @dfc: Pointer to devfreq cooling device to unregister.
 591  */
 592 void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
 593 {
 594         struct devfreq_cooling_device *dfc;
 595 
 596         if (!cdev)
 597                 return;
 598 
 599         dfc = cdev->devdata;
 600 
 601         thermal_cooling_device_unregister(dfc->cdev);
 602         ida_simple_remove(&devfreq_ida, dfc->id);
 603         kfree(dfc->power_table);
 604         kfree(dfc->freq_table);
 605 
 606         kfree(dfc);
 607 }
 608 EXPORT_SYMBOL_GPL(devfreq_cooling_unregister);