linux/drivers/thermal/devfreq_cooling.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * devfreq_cooling: Thermal cooling device implementation for devices using
   4 *                  devfreq
   5 *
   6 * Copyright (C) 2014-2015 ARM Limited
   7 *
   8 * TODO:
   9 *    - If OPPs are added or removed after devfreq cooling has
  10 *      registered, the devfreq cooling won't react to it.
  11 */
  12
  13#include <linux/devfreq.h>
  14#include <linux/devfreq_cooling.h>
  15#include <linux/energy_model.h>
  16#include <linux/export.h>
  17#include <linux/slab.h>
  18#include <linux/pm_opp.h>
  19#include <linux/pm_qos.h>
  20#include <linux/thermal.h>
  21
  22#include <trace/events/thermal.h>
  23
  24#define HZ_PER_KHZ              1000
  25#define SCALE_ERROR_MITIGATION  100
  26
  27/**
  28 * struct devfreq_cooling_device - Devfreq cooling device
  29 *              devfreq_cooling_device registered.
  30 * @cdev:       Pointer to associated thermal cooling device.
  31 * @devfreq:    Pointer to associated devfreq device.
  32 * @cooling_state:      Current cooling state.
  33 * @freq_table: Pointer to a table with the frequencies sorted in descending
  34 *              order.  You can index the table by cooling device state
  35 * @max_state:  It is the last index, that is, one less than the number of the
  36 *              OPPs
  37 * @power_ops:  Pointer to devfreq_cooling_power, a more precised model.
  38 * @res_util:   Resource utilization scaling factor for the power.
  39 *              It is multiplied by 100 to minimize the error. It is used
  40 *              for estimation of the power budget instead of using
  41 *              'utilization' (which is 'busy_time' / 'total_time').
  42 *              The 'res_util' range is from 100 to power * 100 for the
  43 *              corresponding 'state'.
  44 * @capped_state:       index to cooling state with in dynamic power budget
  45 * @req_max_freq:       PM QoS request for limiting the maximum frequency
  46 *                      of the devfreq device.
  47 * @em_pd:              Energy Model for the associated Devfreq device
  48 */
  49struct devfreq_cooling_device {
  50        struct thermal_cooling_device *cdev;
  51        struct devfreq *devfreq;
  52        unsigned long cooling_state;
  53        u32 *freq_table;
  54        size_t max_state;
  55        struct devfreq_cooling_power *power_ops;
  56        u32 res_util;
  57        int capped_state;
  58        struct dev_pm_qos_request req_max_freq;
  59        struct em_perf_domain *em_pd;
  60};
  61
  62static int devfreq_cooling_get_max_state(struct thermal_cooling_device *cdev,
  63                                         unsigned long *state)
  64{
  65        struct devfreq_cooling_device *dfc = cdev->devdata;
  66
  67        *state = dfc->max_state;
  68
  69        return 0;
  70}
  71
  72static int devfreq_cooling_get_cur_state(struct thermal_cooling_device *cdev,
  73                                         unsigned long *state)
  74{
  75        struct devfreq_cooling_device *dfc = cdev->devdata;
  76
  77        *state = dfc->cooling_state;
  78
  79        return 0;
  80}
  81
  82static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
  83                                         unsigned long state)
  84{
  85        struct devfreq_cooling_device *dfc = cdev->devdata;
  86        struct devfreq *df = dfc->devfreq;
  87        struct device *dev = df->dev.parent;
  88        unsigned long freq;
  89        int perf_idx;
  90
  91        if (state == dfc->cooling_state)
  92                return 0;
  93
  94        dev_dbg(dev, "Setting cooling state %lu\n", state);
  95
  96        if (state > dfc->max_state)
  97                return -EINVAL;
  98
  99        if (dfc->em_pd) {
 100                perf_idx = dfc->max_state - state;
 101                freq = dfc->em_pd->table[perf_idx].frequency * 1000;
 102        } else {
 103                freq = dfc->freq_table[state];
 104        }
 105
 106        dev_pm_qos_update_request(&dfc->req_max_freq,
 107                                  DIV_ROUND_UP(freq, HZ_PER_KHZ));
 108
 109        dfc->cooling_state = state;
 110
 111        return 0;
 112}
 113
 114/**
 115 * get_perf_idx() - get the performance index corresponding to a frequency
 116 * @em_pd:      Pointer to device's Energy Model
 117 * @freq:       frequency in kHz
 118 *
 119 * Return: the performance index associated with the @freq, or
 120 * -EINVAL if it wasn't found.
 121 */
 122static int get_perf_idx(struct em_perf_domain *em_pd, unsigned long freq)
 123{
 124        int i;
 125
 126        for (i = 0; i < em_pd->nr_perf_states; i++) {
 127                if (em_pd->table[i].frequency == freq)
 128                        return i;
 129        }
 130
 131        return -EINVAL;
 132}
 133
 134static unsigned long get_voltage(struct devfreq *df, unsigned long freq)
 135{
 136        struct device *dev = df->dev.parent;
 137        unsigned long voltage;
 138        struct dev_pm_opp *opp;
 139
 140        opp = dev_pm_opp_find_freq_exact(dev, freq, true);
 141        if (PTR_ERR(opp) == -ERANGE)
 142                opp = dev_pm_opp_find_freq_exact(dev, freq, false);
 143
 144        if (IS_ERR(opp)) {
 145                dev_err_ratelimited(dev, "Failed to find OPP for frequency %lu: %ld\n",
 146                                    freq, PTR_ERR(opp));
 147                return 0;
 148        }
 149
 150        voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */
 151        dev_pm_opp_put(opp);
 152
 153        if (voltage == 0) {
 154                dev_err_ratelimited(dev,
 155                                    "Failed to get voltage for frequency %lu\n",
 156                                    freq);
 157        }
 158
 159        return voltage;
 160}
 161
 162static void _normalize_load(struct devfreq_dev_status *status)
 163{
 164        if (status->total_time > 0xfffff) {
 165                status->total_time >>= 10;
 166                status->busy_time >>= 10;
 167        }
 168
 169        status->busy_time <<= 10;
 170        status->busy_time /= status->total_time ? : 1;
 171
 172        status->busy_time = status->busy_time ? : 1;
 173        status->total_time = 1024;
 174}
 175
 176static int devfreq_cooling_get_requested_power(struct thermal_cooling_device *cdev,
 177                                               u32 *power)
 178{
 179        struct devfreq_cooling_device *dfc = cdev->devdata;
 180        struct devfreq *df = dfc->devfreq;
 181        struct devfreq_dev_status status;
 182        unsigned long state;
 183        unsigned long freq;
 184        unsigned long voltage;
 185        int res, perf_idx;
 186
 187        mutex_lock(&df->lock);
 188        status = df->last_status;
 189        mutex_unlock(&df->lock);
 190
 191        freq = status.current_frequency;
 192
 193        if (dfc->power_ops && dfc->power_ops->get_real_power) {
 194                voltage = get_voltage(df, freq);
 195                if (voltage == 0) {
 196                        res = -EINVAL;
 197                        goto fail;
 198                }
 199
 200                res = dfc->power_ops->get_real_power(df, power, freq, voltage);
 201                if (!res) {
 202                        state = dfc->capped_state;
 203                        dfc->res_util = dfc->em_pd->table[state].power;
 204                        dfc->res_util *= SCALE_ERROR_MITIGATION;
 205
 206                        if (*power > 1)
 207                                dfc->res_util /= *power;
 208                } else {
 209                        goto fail;
 210                }
 211        } else {
 212                /* Energy Model frequencies are in kHz */
 213                perf_idx = get_perf_idx(dfc->em_pd, freq / 1000);
 214                if (perf_idx < 0) {
 215                        res = -EAGAIN;
 216                        goto fail;
 217                }
 218
 219                _normalize_load(&status);
 220
 221                /* Scale power for utilization */
 222                *power = dfc->em_pd->table[perf_idx].power;
 223                *power *= status.busy_time;
 224                *power >>= 10;
 225        }
 226
 227        trace_thermal_power_devfreq_get_power(cdev, &status, freq, *power);
 228
 229        return 0;
 230fail:
 231        /* It is safe to set max in this case */
 232        dfc->res_util = SCALE_ERROR_MITIGATION;
 233        return res;
 234}
 235
 236static int devfreq_cooling_state2power(struct thermal_cooling_device *cdev,
 237                                       unsigned long state, u32 *power)
 238{
 239        struct devfreq_cooling_device *dfc = cdev->devdata;
 240        int perf_idx;
 241
 242        if (state > dfc->max_state)
 243                return -EINVAL;
 244
 245        perf_idx = dfc->max_state - state;
 246        *power = dfc->em_pd->table[perf_idx].power;
 247
 248        return 0;
 249}
 250
 251static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
 252                                       u32 power, unsigned long *state)
 253{
 254        struct devfreq_cooling_device *dfc = cdev->devdata;
 255        struct devfreq *df = dfc->devfreq;
 256        struct devfreq_dev_status status;
 257        unsigned long freq;
 258        s32 est_power;
 259        int i;
 260
 261        mutex_lock(&df->lock);
 262        status = df->last_status;
 263        mutex_unlock(&df->lock);
 264
 265        freq = status.current_frequency;
 266
 267        if (dfc->power_ops && dfc->power_ops->get_real_power) {
 268                /* Scale for resource utilization */
 269                est_power = power * dfc->res_util;
 270                est_power /= SCALE_ERROR_MITIGATION;
 271        } else {
 272                /* Scale dynamic power for utilization */
 273                _normalize_load(&status);
 274                est_power = power << 10;
 275                est_power /= status.busy_time;
 276        }
 277
 278        /*
 279         * Find the first cooling state that is within the power
 280         * budget. The EM power table is sorted ascending.
 281         */
 282        for (i = dfc->max_state; i > 0; i--)
 283                if (est_power >= dfc->em_pd->table[i].power)
 284                        break;
 285
 286        *state = dfc->max_state - i;
 287        dfc->capped_state = *state;
 288
 289        trace_thermal_power_devfreq_limit(cdev, freq, *state, power);
 290        return 0;
 291}
 292
 293static struct thermal_cooling_device_ops devfreq_cooling_ops = {
 294        .get_max_state = devfreq_cooling_get_max_state,
 295        .get_cur_state = devfreq_cooling_get_cur_state,
 296        .set_cur_state = devfreq_cooling_set_cur_state,
 297};
 298
 299/**
 300 * devfreq_cooling_gen_tables() - Generate frequency table.
 301 * @dfc:        Pointer to devfreq cooling device.
 302 * @num_opps:   Number of OPPs
 303 *
 304 * Generate frequency table which holds the frequencies in descending
 305 * order. That way its indexed by cooling device state. This is for
 306 * compatibility with drivers which do not register Energy Model.
 307 *
 308 * Return: 0 on success, negative error code on failure.
 309 */
 310static int devfreq_cooling_gen_tables(struct devfreq_cooling_device *dfc,
 311                                      int num_opps)
 312{
 313        struct devfreq *df = dfc->devfreq;
 314        struct device *dev = df->dev.parent;
 315        unsigned long freq;
 316        int i;
 317
 318        dfc->freq_table = kcalloc(num_opps, sizeof(*dfc->freq_table),
 319                             GFP_KERNEL);
 320        if (!dfc->freq_table)
 321                return -ENOMEM;
 322
 323        for (i = 0, freq = ULONG_MAX; i < num_opps; i++, freq--) {
 324                struct dev_pm_opp *opp;
 325
 326                opp = dev_pm_opp_find_freq_floor(dev, &freq);
 327                if (IS_ERR(opp)) {
 328                        kfree(dfc->freq_table);
 329                        return PTR_ERR(opp);
 330                }
 331
 332                dev_pm_opp_put(opp);
 333                dfc->freq_table[i] = freq;
 334        }
 335
 336        return 0;
 337}
 338
 339/**
 340 * of_devfreq_cooling_register_power() - Register devfreq cooling device,
 341 *                                      with OF and power information.
 342 * @np: Pointer to OF device_node.
 343 * @df: Pointer to devfreq device.
 344 * @dfc_power:  Pointer to devfreq_cooling_power.
 345 *
 346 * Register a devfreq cooling device.  The available OPPs must be
 347 * registered on the device.
 348 *
 349 * If @dfc_power is provided, the cooling device is registered with the
 350 * power extensions.  For the power extensions to work correctly,
 351 * devfreq should use the simple_ondemand governor, other governors
 352 * are not currently supported.
 353 */
 354struct thermal_cooling_device *
 355of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
 356                                  struct devfreq_cooling_power *dfc_power)
 357{
 358        struct thermal_cooling_device *cdev;
 359        struct device *dev = df->dev.parent;
 360        struct devfreq_cooling_device *dfc;
 361        char *name;
 362        int err, num_opps;
 363
 364        dfc = kzalloc(sizeof(*dfc), GFP_KERNEL);
 365        if (!dfc)
 366                return ERR_PTR(-ENOMEM);
 367
 368        dfc->devfreq = df;
 369
 370        dfc->em_pd = em_pd_get(dev);
 371        if (dfc->em_pd) {
 372                devfreq_cooling_ops.get_requested_power =
 373                        devfreq_cooling_get_requested_power;
 374                devfreq_cooling_ops.state2power = devfreq_cooling_state2power;
 375                devfreq_cooling_ops.power2state = devfreq_cooling_power2state;
 376
 377                dfc->power_ops = dfc_power;
 378
 379                num_opps = em_pd_nr_perf_states(dfc->em_pd);
 380        } else {
 381                /* Backward compatibility for drivers which do not use IPA */
 382                dev_dbg(dev, "missing EM for cooling device\n");
 383
 384                num_opps = dev_pm_opp_get_opp_count(dev);
 385
 386                err = devfreq_cooling_gen_tables(dfc, num_opps);
 387                if (err)
 388                        goto free_dfc;
 389        }
 390
 391        if (num_opps <= 0) {
 392                err = -EINVAL;
 393                goto free_dfc;
 394        }
 395
 396        /* max_state is an index, not a counter */
 397        dfc->max_state = num_opps - 1;
 398
 399        err = dev_pm_qos_add_request(dev, &dfc->req_max_freq,
 400                                     DEV_PM_QOS_MAX_FREQUENCY,
 401                                     PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
 402        if (err < 0)
 403                goto free_table;
 404
 405        err = -ENOMEM;
 406        name = kasprintf(GFP_KERNEL, "devfreq-%s", dev_name(dev));
 407        if (!name)
 408                goto remove_qos_req;
 409
 410        cdev = thermal_of_cooling_device_register(np, name, dfc,
 411                                                  &devfreq_cooling_ops);
 412        kfree(name);
 413
 414        if (IS_ERR(cdev)) {
 415                err = PTR_ERR(cdev);
 416                dev_err(dev,
 417                        "Failed to register devfreq cooling device (%d)\n",
 418                        err);
 419                goto remove_qos_req;
 420        }
 421
 422        dfc->cdev = cdev;
 423
 424        return cdev;
 425
 426remove_qos_req:
 427        dev_pm_qos_remove_request(&dfc->req_max_freq);
 428free_table:
 429        kfree(dfc->freq_table);
 430free_dfc:
 431        kfree(dfc);
 432
 433        return ERR_PTR(err);
 434}
 435EXPORT_SYMBOL_GPL(of_devfreq_cooling_register_power);
 436
 437/**
 438 * of_devfreq_cooling_register() - Register devfreq cooling device,
 439 *                                with OF information.
 440 * @np: Pointer to OF device_node.
 441 * @df: Pointer to devfreq device.
 442 */
 443struct thermal_cooling_device *
 444of_devfreq_cooling_register(struct device_node *np, struct devfreq *df)
 445{
 446        return of_devfreq_cooling_register_power(np, df, NULL);
 447}
 448EXPORT_SYMBOL_GPL(of_devfreq_cooling_register);
 449
 450/**
 451 * devfreq_cooling_register() - Register devfreq cooling device.
 452 * @df: Pointer to devfreq device.
 453 */
 454struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df)
 455{
 456        return of_devfreq_cooling_register(NULL, df);
 457}
 458EXPORT_SYMBOL_GPL(devfreq_cooling_register);
 459
 460/**
 461 * devfreq_cooling_em_register() - Register devfreq cooling device with
 462 *              power information and automatically register Energy Model (EM)
 463 * @df:         Pointer to devfreq device.
 464 * @dfc_power:  Pointer to devfreq_cooling_power.
 465 *
 466 * Register a devfreq cooling device and automatically register EM. The
 467 * available OPPs must be registered for the device.
 468 *
 469 * If @dfc_power is provided, the cooling device is registered with the
 470 * power extensions. It is using the simple Energy Model which requires
 471 * "dynamic-power-coefficient" a devicetree property. To not break drivers
 472 * which miss that DT property, the function won't bail out when the EM
 473 * registration failed. The cooling device will be registered if everything
 474 * else is OK.
 475 */
 476struct thermal_cooling_device *
 477devfreq_cooling_em_register(struct devfreq *df,
 478                            struct devfreq_cooling_power *dfc_power)
 479{
 480        struct thermal_cooling_device *cdev;
 481        struct device *dev;
 482        int ret;
 483
 484        if (IS_ERR_OR_NULL(df))
 485                return ERR_PTR(-EINVAL);
 486
 487        dev = df->dev.parent;
 488
 489        ret = dev_pm_opp_of_register_em(dev, NULL);
 490        if (ret)
 491                dev_dbg(dev, "Unable to register EM for devfreq cooling device (%d)\n",
 492                        ret);
 493
 494        cdev = of_devfreq_cooling_register_power(dev->of_node, df, dfc_power);
 495
 496        if (IS_ERR_OR_NULL(cdev))
 497                em_dev_unregister_perf_domain(dev);
 498
 499        return cdev;
 500}
 501EXPORT_SYMBOL_GPL(devfreq_cooling_em_register);
 502
 503/**
 504 * devfreq_cooling_unregister() - Unregister devfreq cooling device.
 505 * @cdev: Pointer to devfreq cooling device to unregister.
 506 *
 507 * Unregisters devfreq cooling device and related Energy Model if it was
 508 * present.
 509 */
 510void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
 511{
 512        struct devfreq_cooling_device *dfc;
 513        struct device *dev;
 514
 515        if (IS_ERR_OR_NULL(cdev))
 516                return;
 517
 518        dfc = cdev->devdata;
 519        dev = dfc->devfreq->dev.parent;
 520
 521        thermal_cooling_device_unregister(dfc->cdev);
 522        dev_pm_qos_remove_request(&dfc->req_max_freq);
 523
 524        em_dev_unregister_perf_domain(dev);
 525
 526        kfree(dfc->freq_table);
 527        kfree(dfc);
 528}
 529EXPORT_SYMBOL_GPL(devfreq_cooling_unregister);
 530