drivers/devfreq/exynos-bus.c

   1 /*
   2  * Generic Exynos Bus frequency driver with DEVFREQ Framework
   3  *
   4  * Copyright (c) 2016 Samsung Electronics Co., Ltd.
   5  * Author : Chanwoo Choi <cw00.choi@samsung.com>
   6  *
   7  * This driver support Exynos Bus frequency feature by using
   8  * DEVFREQ framework and is based on drivers/devfreq/exynos/exynos4_bus.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 #include <linux/clk.h>
  16 #include <linux/devfreq.h>
  17 #include <linux/devfreq-event.h>
  18 #include <linux/device.h>
  19 #include <linux/export.h>
  20 #include <linux/module.h>
  21 #include <linux/of_device.h>
  22 #include <linux/pm_opp.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/regulator/consumer.h>
  25 #include <linux/slab.h>
  26
  27 #define DEFAULT_SATURATION_RATIO        40
  28 #define DEFAULT_VOLTAGE_TOLERANCE       2
  29
  30 struct exynos_bus {
  31         struct device *dev;
  32
  33         struct devfreq *devfreq;
  34         struct devfreq_event_dev **edev;
  35         unsigned int edev_count;
  36         struct mutex lock;
  37
  38         struct dev_pm_opp *curr_opp;
  39
  40         struct regulator *regulator;
  41         struct clk *clk;
  42         unsigned int voltage_tolerance;
  43         unsigned int ratio;
  44 };
  45
  46 /*
  47  * Control the devfreq-event device to get the current state of bus
  48  */
  49 #define exynos_bus_ops_edev(ops)                                \
  50 static int exynos_bus_##ops(struct exynos_bus *bus)             \
  51 {                                                               \
  52         int i, ret;                                             \
  53                                                                 \
  54         for (i = 0; i < bus->edev_count; i++) {                 \
  55                 if (!bus->edev[i])                              \
  56                         continue;                               \
  57                 ret = devfreq_event_##ops(bus->edev[i]);        \
  58                 if (ret < 0)                                    \
  59                         return ret;                             \
  60         }                                                       \
  61                                                                 \
  62         return 0;                                               \
  63 }
  64 exynos_bus_ops_edev(enable_edev);
  65 exynos_bus_ops_edev(disable_edev);
  66 exynos_bus_ops_edev(set_event);
  67
  68 static int exynos_bus_get_event(struct exynos_bus *bus,
  69                                 struct devfreq_event_data *edata)
  70 {
  71         struct devfreq_event_data event_data;
  72         unsigned long load_count = 0, total_count = 0;
  73         int i, ret = 0;
  74
  75         for (i = 0; i < bus->edev_count; i++) {
  76                 if (!bus->edev[i])
  77                         continue;
  78
  79                 ret = devfreq_event_get_event(bus->edev[i], &event_data);
  80                 if (ret < 0)
  81                         return ret;
  82
  83                 if (i == 0 || event_data.load_count > load_count) {
  84                         load_count = event_data.load_count;
  85                         total_count = event_data.total_count;
  86                 }
  87         }
  88
  89         edata->load_count = load_count;
  90         edata->total_count = total_count;
  91
  92         return ret;
  93 }
  94
  95 /*
  96  * Must necessary function for devfreq simple-ondemand governor
  97  */
  98 static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
  99 {
 100         struct exynos_bus *bus = dev_get_drvdata(dev);
 101         struct dev_pm_opp *new_opp;
 102         unsigned long old_freq, new_freq, old_volt, new_volt, tol;
 103         int ret = 0;
 104
 105         /* Get new opp-bus instance according to new bus clock */
 106         rcu_read_lock();
 107         new_opp = devfreq_recommended_opp(dev, freq, flags);
 108         if (IS_ERR(new_opp)) {
 109                 dev_err(dev, "failed to get recommended opp instance\n");
 110                 rcu_read_unlock();
 111                 return PTR_ERR(new_opp);
 112         }
 113
 114         new_freq = dev_pm_opp_get_freq(new_opp);
 115         new_volt = dev_pm_opp_get_voltage(new_opp);
 116         old_freq = dev_pm_opp_get_freq(bus->curr_opp);
 117         old_volt = dev_pm_opp_get_voltage(bus->curr_opp);
 118         rcu_read_unlock();
 119
 120         if (old_freq == new_freq)
 121                 return 0;
 122         tol = new_volt * bus->voltage_tolerance / 100;
 123
 124         /* Change voltage and frequency according to new OPP level */
 125         mutex_lock(&bus->lock);
 126
 127         if (old_freq < new_freq) {
 128                 ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
 129                 if (ret < 0) {
 130                         dev_err(bus->dev, "failed to set voltage\n");
 131                         goto out;
 132                 }
 133         }
 134
 135         ret = clk_set_rate(bus->clk, new_freq);
 136         if (ret < 0) {
 137                 dev_err(dev, "failed to change clock of bus\n");
 138                 clk_set_rate(bus->clk, old_freq);
 139                 goto out;
 140         }
 141
 142         if (old_freq > new_freq) {
 143                 ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
 144                 if (ret < 0) {
 145                         dev_err(bus->dev, "failed to set voltage\n");
 146                         goto out;
 147                 }
 148         }
 149         bus->curr_opp = new_opp;
 150
 151         dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\n",
 152                         old_freq/1000, new_freq/1000);
 153 out:
 154         mutex_unlock(&bus->lock);
 155
 156         return ret;
 157 }
 158
 159 static int exynos_bus_get_dev_status(struct device *dev,
 160                                      struct devfreq_dev_status *stat)
 161 {
 162         struct exynos_bus *bus = dev_get_drvdata(dev);
 163         struct devfreq_event_data edata;
 164         int ret;
 165
 166         rcu_read_lock();
 167         stat->current_frequency = dev_pm_opp_get_freq(bus->curr_opp);
 168         rcu_read_unlock();
 169
 170         ret = exynos_bus_get_event(bus, &edata);
 171         if (ret < 0) {
 172                 stat->total_time = stat->busy_time = 0;
 173                 goto err;
 174         }
 175
 176         stat->busy_time = (edata.load_count * 100) / bus->ratio;
 177         stat->total_time = edata.total_count;
 178
 179         dev_dbg(dev, "Usage of devfreq-event : %lu/%lu\n", stat->busy_time,
 180                                                         stat->total_time);
 181
 182 err:
 183         ret = exynos_bus_set_event(bus);
 184         if (ret < 0) {
 185                 dev_err(dev, "failed to set event to devfreq-event devices\n");
 186                 return ret;
 187         }
 188
 189         return ret;
 190 }
 191
 192 static void exynos_bus_exit(struct device *dev)
 193 {
 194         struct exynos_bus *bus = dev_get_drvdata(dev);
 195         int ret;
 196
 197         ret = exynos_bus_disable_edev(bus);
 198         if (ret < 0)
 199                 dev_warn(dev, "failed to disable the devfreq-event devices\n");
 200
 201         if (bus->regulator)
 202                 regulator_disable(bus->regulator);
 203
 204         dev_pm_opp_of_remove_table(dev);
 205         clk_disable_unprepare(bus->clk);
 206 }
 207
 208 /*
 209  * Must necessary function for devfreq passive governor
 210  */
 211 static int exynos_bus_passive_target(struct device *dev, unsigned long *freq,
 212                                         u32 flags)
 213 {
 214         struct exynos_bus *bus = dev_get_drvdata(dev);
 215         struct dev_pm_opp *new_opp;
 216         unsigned long old_freq, new_freq;
 217         int ret = 0;
 218
 219         /* Get new opp-bus instance according to new bus clock */
 220         rcu_read_lock();
 221         new_opp = devfreq_recommended_opp(dev, freq, flags);
 222         if (IS_ERR(new_opp)) {
 223                 dev_err(dev, "failed to get recommended opp instance\n");
 224                 rcu_read_unlock();
 225                 return PTR_ERR(new_opp);
 226         }
 227
 228         new_freq = dev_pm_opp_get_freq(new_opp);
 229         old_freq = dev_pm_opp_get_freq(bus->curr_opp);
 230         rcu_read_unlock();
 231
 232         if (old_freq == new_freq)
 233                 return 0;
 234
 235         /* Change the frequency according to new OPP level */
 236         mutex_lock(&bus->lock);
 237
 238         ret = clk_set_rate(bus->clk, new_freq);
 239         if (ret < 0) {
 240                 dev_err(dev, "failed to set the clock of bus\n");
 241                 goto out;
 242         }
 243
 244         *freq = new_freq;
 245         bus->curr_opp = new_opp;
 246
 247         dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\n",
 248                         old_freq/1000, new_freq/1000);
 249 out:
 250         mutex_unlock(&bus->lock);
 251
 252         return ret;
 253 }
 254
 255 static void exynos_bus_passive_exit(struct device *dev)
 256 {
 257         struct exynos_bus *bus = dev_get_drvdata(dev);
 258
 259         dev_pm_opp_of_remove_table(dev);
 260         clk_disable_unprepare(bus->clk);
 261 }
 262
 263 static int exynos_bus_parent_parse_of(struct device_node *np,
 264                                         struct exynos_bus *bus)
 265 {
 266         struct device *dev = bus->dev;
 267         int i, ret, count, size;
 268
 269         /* Get the regulator to provide each bus with the power */
 270         bus->regulator = devm_regulator_get(dev, "vdd");
 271         if (IS_ERR(bus->regulator)) {
 272                 dev_err(dev, "failed to get VDD regulator\n");
 273                 return PTR_ERR(bus->regulator);
 274         }
 275
 276         ret = regulator_enable(bus->regulator);
 277         if (ret < 0) {
 278                 dev_err(dev, "failed to enable VDD regulator\n");
 279                 return ret;
 280         }
 281
 282         /*
 283          * Get the devfreq-event devices to get the current utilization of
 284          * buses. This raw data will be used in devfreq ondemand governor.
 285          */
 286         count = devfreq_event_get_edev_count(dev);
 287         if (count < 0) {
 288                 dev_err(dev, "failed to get the count of devfreq-event dev\n");
 289                 ret = count;
 290                 goto err_regulator;
 291         }
 292         bus->edev_count = count;
 293
 294         size = sizeof(*bus->edev) * count;
 295         bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
 296         if (!bus->edev) {
 297                 ret = -ENOMEM;
 298                 goto err_regulator;
 299         }
 300
 301         for (i = 0; i < count; i++) {
 302                 bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
 303                 if (IS_ERR(bus->edev[i])) {
 304                         ret = -EPROBE_DEFER;
 305                         goto err_regulator;
 306                 }
 307         }
 308
 309         /*
 310          * Optionally, Get the saturation ratio according to Exynos SoC
 311          * When measuring the utilization of each AXI bus with devfreq-event
 312          * devices, the measured real cycle might be much lower than the
 313          * total cycle of bus during sampling rate. In result, the devfreq
 314          * simple-ondemand governor might not decide to change the current
 315          * frequency due to too utilization (= real cycle/total cycle).
 316          * So, this property is used to adjust the utilization when calculating
 317          * the busy_time in exynos_bus_get_dev_status().
 318          */
 319         if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
 320                 bus->ratio = DEFAULT_SATURATION_RATIO;
 321
 322         if (of_property_read_u32(np, "exynos,voltage-tolerance",
 323                                         &bus->voltage_tolerance))
 324                 bus->voltage_tolerance = DEFAULT_VOLTAGE_TOLERANCE;
 325
 326         return 0;
 327
 328 err_regulator:
 329         regulator_disable(bus->regulator);
 330
 331         return ret;
 332 }
 333
 334 static int exynos_bus_parse_of(struct device_node *np,
 335                               struct exynos_bus *bus)
 336 {
 337         struct device *dev = bus->dev;
 338         unsigned long rate;
 339         int ret;
 340
 341         /* Get the clock to provide each bus with source clock */
 342         bus->clk = devm_clk_get(dev, "bus");
 343         if (IS_ERR(bus->clk)) {
 344                 dev_err(dev, "failed to get bus clock\n");
 345                 return PTR_ERR(bus->clk);
 346         }
 347
 348         ret = clk_prepare_enable(bus->clk);
 349         if (ret < 0) {
 350                 dev_err(dev, "failed to get enable clock\n");
 351                 return ret;
 352         }
 353
 354         /* Get the freq and voltage from OPP table to scale the bus freq */
 355         rcu_read_lock();
 356         ret = dev_pm_opp_of_add_table(dev);
 357         if (ret < 0) {
 358                 dev_err(dev, "failed to get OPP table\n");
 359                 rcu_read_unlock();
 360                 goto err_clk;
 361         }
 362
 363         rate = clk_get_rate(bus->clk);
 364         bus->curr_opp = devfreq_recommended_opp(dev, &rate, 0);
 365         if (IS_ERR(bus->curr_opp)) {
 366                 dev_err(dev, "failed to find dev_pm_opp\n");
 367                 rcu_read_unlock();
 368                 ret = PTR_ERR(bus->curr_opp);
 369                 goto err_opp;
 370         }
 371         rcu_read_unlock();
 372
 373         return 0;
 374
 375 err_opp:
 376         dev_pm_opp_of_remove_table(dev);
 377 err_clk:
 378         clk_disable_unprepare(bus->clk);
 379
 380         return ret;
 381 }
 382
 383 static int exynos_bus_probe(struct platform_device *pdev)
 384 {
 385         struct device *dev = &pdev->dev;
 386         struct device_node *np = dev->of_node, *node;
 387         struct devfreq_dev_profile *profile;
 388         struct devfreq_simple_ondemand_data *ondemand_data;
 389         struct devfreq_passive_data *passive_data;
 390         struct devfreq *parent_devfreq;
 391         struct exynos_bus *bus;
 392         int ret, max_state;
 393         unsigned long min_freq, max_freq;
 394
 395         if (!np) {
 396                 dev_err(dev, "failed to find devicetree node\n");
 397                 return -EINVAL;
 398         }
 399
 400         bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
 401         if (!bus)
 402                 return -ENOMEM;
 403         mutex_init(&bus->lock);
 404         bus->dev = &pdev->dev;
 405         platform_set_drvdata(pdev, bus);
 406
 407         /* Parse the device-tree to get the resource information */
 408         ret = exynos_bus_parse_of(np, bus);
 409         if (ret < 0)
 410                 return ret;
 411
 412         profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
 413         if (!profile) {
 414                 ret = -ENOMEM;
 415                 goto err;
 416         }
 417
 418         node = of_parse_phandle(dev->of_node, "devfreq", 0);
 419         if (node) {
 420                 of_node_put(node);
 421                 goto passive;
 422         } else {
 423                 ret = exynos_bus_parent_parse_of(np, bus);
 424         }
 425
 426         if (ret < 0)
 427                 goto err;
 428
 429         /* Initialize the struct profile and governor data for parent device */
 430         profile->polling_ms = 50;
 431         profile->target = exynos_bus_target;
 432         profile->get_dev_status = exynos_bus_get_dev_status;
 433         profile->exit = exynos_bus_exit;
 434
 435         ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
 436         if (!ondemand_data) {
 437                 ret = -ENOMEM;
 438                 goto err;
 439         }
 440         ondemand_data->upthreshold = 40;
 441         ondemand_data->downdifferential = 5;
 442
 443         /* Add devfreq device to monitor and handle the exynos bus */
 444         bus->devfreq = devm_devfreq_add_device(dev, profile, "simple_ondemand",
 445                                                 ondemand_data);
 446         if (IS_ERR(bus->devfreq)) {
 447                 dev_err(dev, "failed to add devfreq device\n");
 448                 ret = PTR_ERR(bus->devfreq);
 449                 goto err;
 450         }
 451
 452         /* Register opp_notifier to catch the change of OPP  */
 453         ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
 454         if (ret < 0) {
 455                 dev_err(dev, "failed to register opp notifier\n");
 456                 goto err;
 457         }
 458
 459         /*
 460          * Enable devfreq-event to get raw data which is used to determine
 461          * current bus load.
 462          */
 463         ret = exynos_bus_enable_edev(bus);
 464         if (ret < 0) {
 465                 dev_err(dev, "failed to enable devfreq-event devices\n");
 466                 goto err;
 467         }
 468
 469         ret = exynos_bus_set_event(bus);
 470         if (ret < 0) {
 471                 dev_err(dev, "failed to set event to devfreq-event devices\n");
 472                 goto err;
 473         }
 474
 475         goto out;
 476 passive:
 477         /* Initialize the struct profile and governor data for passive device */
 478         profile->target = exynos_bus_passive_target;
 479         profile->exit = exynos_bus_passive_exit;
 480
 481         /* Get the instance of parent devfreq device */
 482         parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
 483         if (IS_ERR(parent_devfreq)) {
 484                 ret = -EPROBE_DEFER;
 485                 goto err;
 486         }
 487
 488         passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
 489         if (!passive_data) {
 490                 ret = -ENOMEM;
 491                 goto err;
 492         }
 493         passive_data->parent = parent_devfreq;
 494
 495         /* Add devfreq device for exynos bus with passive governor */
 496         bus->devfreq = devm_devfreq_add_device(dev, profile, "passive",
 497                                                 passive_data);
 498         if (IS_ERR(bus->devfreq)) {
 499                 dev_err(dev,
 500                         "failed to add devfreq dev with passive governor\n");
 501                 ret = -EPROBE_DEFER;
 502                 goto err;
 503         }
 504
 505 out:
 506         max_state = bus->devfreq->profile->max_state;
 507         min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
 508         max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
 509         pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
 510                         dev_name(dev), min_freq, max_freq);
 511
 512         return 0;
 513
 514 err:
 515         dev_pm_opp_of_remove_table(dev);
 516         clk_disable_unprepare(bus->clk);
 517
 518         return ret;
 519 }
 520
 521 #ifdef CONFIG_PM_SLEEP
 522 static int exynos_bus_resume(struct device *dev)
 523 {
 524         struct exynos_bus *bus = dev_get_drvdata(dev);
 525         int ret;
 526
 527         ret = exynos_bus_enable_edev(bus);
 528         if (ret < 0) {
 529                 dev_err(dev, "failed to enable the devfreq-event devices\n");
 530                 return ret;
 531         }
 532
 533         return 0;
 534 }
 535
 536 static int exynos_bus_suspend(struct device *dev)
 537 {
 538         struct exynos_bus *bus = dev_get_drvdata(dev);
 539         int ret;
 540
 541         ret = exynos_bus_disable_edev(bus);
 542         if (ret < 0) {
 543                 dev_err(dev, "failed to disable the devfreq-event devices\n");
 544                 return ret;
 545         }
 546
 547         return 0;
 548 }
 549 #endif
 550
 551 static const struct dev_pm_ops exynos_bus_pm = {
 552         SET_SYSTEM_SLEEP_PM_OPS(exynos_bus_suspend, exynos_bus_resume)
 553 };
 554
 555 static const struct of_device_id exynos_bus_of_match[] = {
 556         { .compatible = "samsung,exynos-bus", },
 557         { /* sentinel */ },
 558 };
 559 MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
 560
 561 static struct platform_driver exynos_bus_platdrv = {
 562         .probe          = exynos_bus_probe,
 563         .driver = {
 564                 .name   = "exynos-bus",
 565                 .pm     = &exynos_bus_pm,
 566                 .of_match_table = of_match_ptr(exynos_bus_of_match),
 567         },
 568 };
 569 module_platform_driver(exynos_bus_platdrv);
 570
 571 MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
 572 MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
 573 MODULE_LICENSE("GPL v2");