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