drivers/devfreq/exynos-bus.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Generic Exynos Bus frequency driver with DEVFREQ Framework
   4  *
   5  * Copyright (c) 2016 Samsung Electronics Co., Ltd.
   6  * Author : Chanwoo Choi <cw00.choi@samsung.com>
   7  *
   8  * This driver support Exynos Bus frequency feature by using
   9  * DEVFREQ framework and is based on drivers/devfreq/exynos/exynos4_bus.c.
  10  */
  11
  12 #include <linux/clk.h>
  13 #include <linux/devfreq.h>
  14 #include <linux/devfreq-event.h>
  15 #include <linux/device.h>
  16 #include <linux/export.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/pm_opp.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/regulator/consumer.h>
  22
  23 #define DEFAULT_SATURATION_RATIO        40
  24
  25 struct exynos_bus {
  26         struct device *dev;
  27
  28         struct devfreq *devfreq;
  29         struct devfreq_event_dev **edev;
  30         unsigned int edev_count;
  31         struct mutex lock;
  32
  33         unsigned long curr_freq;
  34
  35         struct opp_table *opp_table;
  36         struct clk *clk;
  37         unsigned int ratio;
  38 };
  39
  40 /*
  41  * Control the devfreq-event device to get the current state of bus
  42  */
  43 #define exynos_bus_ops_edev(ops)                                \
  44 static int exynos_bus_##ops(struct exynos_bus *bus)             \
  45 {                                                               \
  46         int i, ret;                                             \
  47                                                                 \
  48         for (i = 0; i < bus->edev_count; i++) {                 \
  49                 if (!bus->edev[i])                              \
  50                         continue;                               \
  51                 ret = devfreq_event_##ops(bus->edev[i]);        \
  52                 if (ret < 0)                                    \
  53                         return ret;                             \
  54         }                                                       \
  55                                                                 \
  56         return 0;                                               \
  57 }
  58 exynos_bus_ops_edev(enable_edev);
  59 exynos_bus_ops_edev(disable_edev);
  60 exynos_bus_ops_edev(set_event);
  61
  62 static int exynos_bus_get_event(struct exynos_bus *bus,
  63                                 struct devfreq_event_data *edata)
  64 {
  65         struct devfreq_event_data event_data;
  66         unsigned long load_count = 0, total_count = 0;
  67         int i, ret = 0;
  68
  69         for (i = 0; i < bus->edev_count; i++) {
  70                 if (!bus->edev[i])
  71                         continue;
  72
  73                 ret = devfreq_event_get_event(bus->edev[i], &event_data);
  74                 if (ret < 0)
  75                         return ret;
  76
  77                 if (i == 0 || event_data.load_count > load_count) {
  78                         load_count = event_data.load_count;
  79                         total_count = event_data.total_count;
  80                 }
  81         }
  82
  83         edata->load_count = load_count;
  84         edata->total_count = total_count;
  85
  86         return ret;
  87 }
  88
  89 /*
  90  * devfreq function for both simple-ondemand and passive governor
  91  */
  92 static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
  93 {
  94         struct exynos_bus *bus = dev_get_drvdata(dev);
  95         struct dev_pm_opp *new_opp;
  96         int ret = 0;
  97
  98         /* Get correct frequency for bus. */
  99         new_opp = devfreq_recommended_opp(dev, freq, flags);
 100         if (IS_ERR(new_opp)) {
 101                 dev_err(dev, "failed to get recommended opp instance\n");
 102                 return PTR_ERR(new_opp);
 103         }
 104
 105         dev_pm_opp_put(new_opp);
 106
 107         /* Change voltage and frequency according to new OPP level */
 108         mutex_lock(&bus->lock);
 109         ret = dev_pm_opp_set_rate(dev, *freq);
 110         if (!ret)
 111                 bus->curr_freq = *freq;
 112
 113         mutex_unlock(&bus->lock);
 114
 115         return ret;
 116 }
 117
 118 static int exynos_bus_get_dev_status(struct device *dev,
 119                                      struct devfreq_dev_status *stat)
 120 {
 121         struct exynos_bus *bus = dev_get_drvdata(dev);
 122         struct devfreq_event_data edata;
 123         int ret;
 124
 125         stat->current_frequency = bus->curr_freq;
 126
 127         ret = exynos_bus_get_event(bus, &edata);
 128         if (ret < 0) {
 129                 dev_err(dev, "failed to get event from devfreq-event devices\n");
 130                 stat->total_time = stat->busy_time = 0;
 131                 goto err;
 132         }
 133
 134         stat->busy_time = (edata.load_count * 100) / bus->ratio;
 135         stat->total_time = edata.total_count;
 136
 137         dev_dbg(dev, "Usage of devfreq-event : %lu/%lu\n", stat->busy_time,
 138                                                         stat->total_time);
 139
 140 err:
 141         ret = exynos_bus_set_event(bus);
 142         if (ret < 0) {
 143                 dev_err(dev, "failed to set event to devfreq-event devices\n");
 144                 return ret;
 145         }
 146
 147         return ret;
 148 }
 149
 150 static void exynos_bus_exit(struct device *dev)
 151 {
 152         struct exynos_bus *bus = dev_get_drvdata(dev);
 153         int ret;
 154
 155         ret = exynos_bus_disable_edev(bus);
 156         if (ret < 0)
 157                 dev_warn(dev, "failed to disable the devfreq-event devices\n");
 158
 159         dev_pm_opp_of_remove_table(dev);
 160         clk_disable_unprepare(bus->clk);
 161         if (bus->opp_table) {
 162                 dev_pm_opp_put_regulators(bus->opp_table);
 163                 bus->opp_table = NULL;
 164         }
 165 }
 166
 167 static void exynos_bus_passive_exit(struct device *dev)
 168 {
 169         struct exynos_bus *bus = dev_get_drvdata(dev);
 170
 171         dev_pm_opp_of_remove_table(dev);
 172         clk_disable_unprepare(bus->clk);
 173 }
 174
 175 static int exynos_bus_parent_parse_of(struct device_node *np,
 176                                         struct exynos_bus *bus)
 177 {
 178         struct device *dev = bus->dev;
 179         struct opp_table *opp_table;
 180         const char *vdd = "vdd";
 181         int i, ret, count, size;
 182
 183         opp_table = dev_pm_opp_set_regulators(dev, &vdd, 1);
 184         if (IS_ERR(opp_table)) {
 185                 ret = PTR_ERR(opp_table);
 186                 dev_err(dev, "failed to set regulators %d\n", ret);
 187                 return ret;
 188         }
 189
 190         bus->opp_table = opp_table;
 191
 192         /*
 193          * Get the devfreq-event devices to get the current utilization of
 194          * buses. This raw data will be used in devfreq ondemand governor.
 195          */
 196         count = devfreq_event_get_edev_count(dev);
 197         if (count < 0) {
 198                 dev_err(dev, "failed to get the count of devfreq-event dev\n");
 199                 ret = count;
 200                 goto err_regulator;
 201         }
 202         bus->edev_count = count;
 203
 204         size = sizeof(*bus->edev) * count;
 205         bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
 206         if (!bus->edev) {
 207                 ret = -ENOMEM;
 208                 goto err_regulator;
 209         }
 210
 211         for (i = 0; i < count; i++) {
 212                 bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
 213                 if (IS_ERR(bus->edev[i])) {
 214                         ret = -EPROBE_DEFER;
 215                         goto err_regulator;
 216                 }
 217         }
 218
 219         /*
 220          * Optionally, Get the saturation ratio according to Exynos SoC
 221          * When measuring the utilization of each AXI bus with devfreq-event
 222          * devices, the measured real cycle might be much lower than the
 223          * total cycle of bus during sampling rate. In result, the devfreq
 224          * simple-ondemand governor might not decide to change the current
 225          * frequency due to too utilization (= real cycle/total cycle).
 226          * So, this property is used to adjust the utilization when calculating
 227          * the busy_time in exynos_bus_get_dev_status().
 228          */
 229         if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
 230                 bus->ratio = DEFAULT_SATURATION_RATIO;
 231
 232         return 0;
 233
 234 err_regulator:
 235         dev_pm_opp_put_regulators(bus->opp_table);
 236         bus->opp_table = NULL;
 237
 238         return ret;
 239 }
 240
 241 static int exynos_bus_parse_of(struct device_node *np,
 242                               struct exynos_bus *bus)
 243 {
 244         struct device *dev = bus->dev;
 245         struct dev_pm_opp *opp;
 246         unsigned long rate;
 247         int ret;
 248
 249         /* Get the clock to provide each bus with source clock */
 250         bus->clk = devm_clk_get(dev, "bus");
 251         if (IS_ERR(bus->clk)) {
 252                 dev_err(dev, "failed to get bus clock\n");
 253                 return PTR_ERR(bus->clk);
 254         }
 255
 256         ret = clk_prepare_enable(bus->clk);
 257         if (ret < 0) {
 258                 dev_err(dev, "failed to get enable clock\n");
 259                 return ret;
 260         }
 261
 262         /* Get the freq and voltage from OPP table to scale the bus freq */
 263         ret = dev_pm_opp_of_add_table(dev);
 264         if (ret < 0) {
 265                 dev_err(dev, "failed to get OPP table\n");
 266                 goto err_clk;
 267         }
 268
 269         rate = clk_get_rate(bus->clk);
 270
 271         opp = devfreq_recommended_opp(dev, &rate, 0);
 272         if (IS_ERR(opp)) {
 273                 dev_err(dev, "failed to find dev_pm_opp\n");
 274                 ret = PTR_ERR(opp);
 275                 goto err_opp;
 276         }
 277         bus->curr_freq = dev_pm_opp_get_freq(opp);
 278         dev_pm_opp_put(opp);
 279
 280         return 0;
 281
 282 err_opp:
 283         dev_pm_opp_of_remove_table(dev);
 284 err_clk:
 285         clk_disable_unprepare(bus->clk);
 286
 287         return ret;
 288 }
 289
 290 static int exynos_bus_profile_init(struct exynos_bus *bus,
 291                                    struct devfreq_dev_profile *profile)
 292 {
 293         struct device *dev = bus->dev;
 294         struct devfreq_simple_ondemand_data *ondemand_data;
 295         int ret;
 296
 297         /* Initialize the struct profile and governor data for parent device */
 298         profile->polling_ms = 50;
 299         profile->target = exynos_bus_target;
 300         profile->get_dev_status = exynos_bus_get_dev_status;
 301         profile->exit = exynos_bus_exit;
 302
 303         ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
 304         if (!ondemand_data)
 305                 return -ENOMEM;
 306
 307         ondemand_data->upthreshold = 40;
 308         ondemand_data->downdifferential = 5;
 309
 310         /* Add devfreq device to monitor and handle the exynos bus */
 311         bus->devfreq = devm_devfreq_add_device(dev, profile,
 312                                                 DEVFREQ_GOV_SIMPLE_ONDEMAND,
 313                                                 ondemand_data);
 314         if (IS_ERR(bus->devfreq)) {
 315                 dev_err(dev, "failed to add devfreq device\n");
 316                 return PTR_ERR(bus->devfreq);
 317         }
 318
 319         /* Register opp_notifier to catch the change of OPP  */
 320         ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
 321         if (ret < 0) {
 322                 dev_err(dev, "failed to register opp notifier\n");
 323                 return ret;
 324         }
 325
 326         /*
 327          * Enable devfreq-event to get raw data which is used to determine
 328          * current bus load.
 329          */
 330         ret = exynos_bus_enable_edev(bus);
 331         if (ret < 0) {
 332                 dev_err(dev, "failed to enable devfreq-event devices\n");
 333                 return ret;
 334         }
 335
 336         ret = exynos_bus_set_event(bus);
 337         if (ret < 0) {
 338                 dev_err(dev, "failed to set event to devfreq-event devices\n");
 339                 goto err_edev;
 340         }
 341
 342         return 0;
 343
 344 err_edev:
 345         if (exynos_bus_disable_edev(bus))
 346                 dev_warn(dev, "failed to disable the devfreq-event devices\n");
 347
 348         return ret;
 349 }
 350
 351 static int exynos_bus_profile_init_passive(struct exynos_bus *bus,
 352                                            struct devfreq_dev_profile *profile)
 353 {
 354         struct device *dev = bus->dev;
 355         struct devfreq_passive_data *passive_data;
 356         struct devfreq *parent_devfreq;
 357
 358         /* Initialize the struct profile and governor data for passive device */
 359         profile->target = exynos_bus_target;
 360         profile->exit = exynos_bus_passive_exit;
 361
 362         /* Get the instance of parent devfreq device */
 363         parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
 364         if (IS_ERR(parent_devfreq))
 365                 return -EPROBE_DEFER;
 366
 367         passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
 368         if (!passive_data)
 369                 return -ENOMEM;
 370
 371         passive_data->parent = parent_devfreq;
 372
 373         /* Add devfreq device for exynos bus with passive governor */
 374         bus->devfreq = devm_devfreq_add_device(dev, profile, DEVFREQ_GOV_PASSIVE,
 375                                                 passive_data);
 376         if (IS_ERR(bus->devfreq)) {
 377                 dev_err(dev,
 378                         "failed to add devfreq dev with passive governor\n");
 379                 return PTR_ERR(bus->devfreq);
 380         }
 381
 382         return 0;
 383 }
 384
 385 static int exynos_bus_probe(struct platform_device *pdev)
 386 {
 387         struct device *dev = &pdev->dev;
 388         struct device_node *np = dev->of_node, *node;
 389         struct devfreq_dev_profile *profile;
 390         struct exynos_bus *bus;
 391         int ret, max_state;
 392         unsigned long min_freq, max_freq;
 393         bool passive = false;
 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         profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
 408         if (!profile)
 409                 return -ENOMEM;
 410
 411         node = of_parse_phandle(dev->of_node, "devfreq", 0);
 412         if (node) {
 413                 of_node_put(node);
 414                 passive = true;
 415         } else {
 416                 ret = exynos_bus_parent_parse_of(np, bus);
 417                 if (ret < 0)
 418                         return ret;
 419         }
 420
 421         /* Parse the device-tree to get the resource information */
 422         ret = exynos_bus_parse_of(np, bus);
 423         if (ret < 0)
 424                 goto err_reg;
 425
 426         if (passive)
 427                 ret = exynos_bus_profile_init_passive(bus, profile);
 428         else
 429                 ret = exynos_bus_profile_init(bus, profile);
 430
 431         if (ret < 0)
 432                 goto err;
 433
 434         max_state = bus->devfreq->profile->max_state;
 435         min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
 436         max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
 437         pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
 438                         dev_name(dev), min_freq, max_freq);
 439
 440         return 0;
 441
 442 err:
 443         dev_pm_opp_of_remove_table(dev);
 444         clk_disable_unprepare(bus->clk);
 445 err_reg:
 446         if (!passive) {
 447                 dev_pm_opp_put_regulators(bus->opp_table);
 448                 bus->opp_table = NULL;
 449         }
 450
 451         return ret;
 452 }
 453
 454 static void exynos_bus_shutdown(struct platform_device *pdev)
 455 {
 456         struct exynos_bus *bus = dev_get_drvdata(&pdev->dev);
 457
 458         devfreq_suspend_device(bus->devfreq);
 459 }
 460
 461 #ifdef CONFIG_PM_SLEEP
 462 static int exynos_bus_resume(struct device *dev)
 463 {
 464         struct exynos_bus *bus = dev_get_drvdata(dev);
 465         int ret;
 466
 467         ret = exynos_bus_enable_edev(bus);
 468         if (ret < 0) {
 469                 dev_err(dev, "failed to enable the devfreq-event devices\n");
 470                 return ret;
 471         }
 472
 473         return 0;
 474 }
 475
 476 static int exynos_bus_suspend(struct device *dev)
 477 {
 478         struct exynos_bus *bus = dev_get_drvdata(dev);
 479         int ret;
 480
 481         ret = exynos_bus_disable_edev(bus);
 482         if (ret < 0) {
 483                 dev_err(dev, "failed to disable the devfreq-event devices\n");
 484                 return ret;
 485         }
 486
 487         return 0;
 488 }
 489 #endif
 490
 491 static const struct dev_pm_ops exynos_bus_pm = {
 492         SET_SYSTEM_SLEEP_PM_OPS(exynos_bus_suspend, exynos_bus_resume)
 493 };
 494
 495 static const struct of_device_id exynos_bus_of_match[] = {
 496         { .compatible = "samsung,exynos-bus", },
 497         { /* sentinel */ },
 498 };
 499 MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
 500
 501 static struct platform_driver exynos_bus_platdrv = {
 502         .probe          = exynos_bus_probe,
 503         .shutdown       = exynos_bus_shutdown,
 504         .driver = {
 505                 .name   = "exynos-bus",
 506                 .pm     = &exynos_bus_pm,
 507                 .of_match_table = of_match_ptr(exynos_bus_of_match),
 508         },
 509 };
 510 module_platform_driver(exynos_bus_platdrv);
 511
 512 MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
 513 MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
 514 MODULE_LICENSE("GPL v2");