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