drivers/soc/tegra/regulators-tegra20.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Voltage regulators coupler for NVIDIA Tegra20
   4  * Copyright (C) 2019 GRATE-DRIVER project
   5  *
   6  * Voltage constraints borrowed from downstream kernel sources
   7  * Copyright (C) 2010-2011 NVIDIA Corporation
   8  */
   9
  10 #define pr_fmt(fmt)     "tegra voltage-coupler: " fmt
  11
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/of.h>
  15 #include <linux/reboot.h>
  16 #include <linux/regulator/coupler.h>
  17 #include <linux/regulator/driver.h>
  18 #include <linux/regulator/machine.h>
  19 #include <linux/suspend.h>
  20
  21 #include <soc/tegra/fuse.h>
  22 #include <soc/tegra/pmc.h>
  23
  24 struct tegra_regulator_coupler {
  25         struct regulator_coupler coupler;
  26         struct regulator_dev *core_rdev;
  27         struct regulator_dev *cpu_rdev;
  28         struct regulator_dev *rtc_rdev;
  29         struct notifier_block reboot_notifier;
  30         struct notifier_block suspend_notifier;
  31         int core_min_uV, cpu_min_uV;
  32         bool sys_reboot_mode_req;
  33         bool sys_reboot_mode;
  34         bool sys_suspend_mode_req;
  35         bool sys_suspend_mode;
  36 };
  37
  38 static inline struct tegra_regulator_coupler *
  39 to_tegra_coupler(struct regulator_coupler *coupler)
  40 {
  41         return container_of(coupler, struct tegra_regulator_coupler, coupler);
  42 }
  43
  44 static int tegra20_core_limit(struct tegra_regulator_coupler *tegra,
  45                               struct regulator_dev *core_rdev)
  46 {
  47         int core_min_uV = 0;
  48         int core_max_uV;
  49         int core_cur_uV;
  50         int err;
  51
  52         /*
  53          * Tegra20 SoC has critical DVFS-capable devices that are
  54          * permanently-active or active at a boot time, like EMC
  55          * (DRAM controller) or Display controller for example.
  56          *
  57          * The voltage of a CORE SoC power domain shall not be dropped below
  58          * a minimum level, which is determined by device's clock rate.
  59          * This means that we can't fully allow CORE voltage scaling until
  60          * the state of all DVFS-critical CORE devices is synced.
  61          */
  62         if (tegra_pmc_core_domain_state_synced() && !tegra->sys_reboot_mode) {
  63                 pr_info_once("voltage state synced\n");
  64                 return 0;
  65         }
  66
  67         if (tegra->core_min_uV > 0)
  68                 return tegra->core_min_uV;
  69
  70         core_cur_uV = regulator_get_voltage_rdev(core_rdev);
  71         if (core_cur_uV < 0)
  72                 return core_cur_uV;
  73
  74         core_max_uV = max(core_cur_uV, 1200000);
  75
  76         err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
  77         if (err)
  78                 return err;
  79
  80         /*
  81          * Limit minimum CORE voltage to a value left from bootloader or,
  82          * if it's unreasonably low value, to the most common 1.2v or to
  83          * whatever maximum value defined via board's device-tree.
  84          */
  85         tegra->core_min_uV = core_max_uV;
  86
  87         pr_info("core voltage initialized to %duV\n", tegra->core_min_uV);
  88
  89         return tegra->core_min_uV;
  90 }
  91
  92 static int tegra20_core_rtc_max_spread(struct regulator_dev *core_rdev,
  93                                        struct regulator_dev *rtc_rdev)
  94 {
  95         struct coupling_desc *c_desc = &core_rdev->coupling_desc;
  96         struct regulator_dev *rdev;
  97         int max_spread;
  98         unsigned int i;
  99
 100         for (i = 1; i < c_desc->n_coupled; i++) {
 101                 max_spread = core_rdev->constraints->max_spread[i - 1];
 102                 rdev = c_desc->coupled_rdevs[i];
 103
 104                 if (rdev == rtc_rdev && max_spread)
 105                         return max_spread;
 106         }
 107
 108         pr_err_once("rtc-core max-spread is undefined in device-tree\n");
 109
 110         return 150000;
 111 }
 112
 113 static int tegra20_cpu_nominal_uV(void)
 114 {
 115         switch (tegra_sku_info.soc_speedo_id) {
 116         case 0:
 117                 return 1100000;
 118         case 1:
 119                 return 1025000;
 120         default:
 121                 return 1125000;
 122         }
 123 }
 124
 125 static int tegra20_core_nominal_uV(void)
 126 {
 127         switch (tegra_sku_info.soc_speedo_id) {
 128         default:
 129                 return 1225000;
 130         case 2:
 131                 return 1300000;
 132         }
 133 }
 134
 135 static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra,
 136                                    struct regulator_dev *core_rdev,
 137                                    struct regulator_dev *rtc_rdev,
 138                                    int cpu_uV, int cpu_min_uV)
 139 {
 140         int core_min_uV, core_max_uV = INT_MAX;
 141         int rtc_min_uV, rtc_max_uV = INT_MAX;
 142         int core_target_uV;
 143         int rtc_target_uV;
 144         int max_spread;
 145         int core_uV;
 146         int rtc_uV;
 147         int err;
 148
 149         /*
 150          * RTC and CORE voltages should be no more than 170mV from each other,
 151          * CPU should be below RTC and CORE by at least 120mV. This applies
 152          * to all Tegra20 SoC's.
 153          */
 154         max_spread = tegra20_core_rtc_max_spread(core_rdev, rtc_rdev);
 155
 156         /*
 157          * The core voltage scaling is currently not hooked up in drivers,
 158          * hence we will limit the minimum core voltage to a reasonable value.
 159          * This should be good enough for the time being.
 160          */
 161         core_min_uV = tegra20_core_limit(tegra, core_rdev);
 162         if (core_min_uV < 0)
 163                 return core_min_uV;
 164
 165         err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
 166         if (err)
 167                 return err;
 168
 169         err = regulator_check_consumers(core_rdev, &core_min_uV, &core_max_uV,
 170                                         PM_SUSPEND_ON);
 171         if (err)
 172                 return err;
 173
 174         /* prepare voltage level for suspend */
 175         if (tegra->sys_suspend_mode)
 176                 core_min_uV = clamp(tegra20_core_nominal_uV(),
 177                                     core_min_uV, core_max_uV);
 178
 179         core_uV = regulator_get_voltage_rdev(core_rdev);
 180         if (core_uV < 0)
 181                 return core_uV;
 182
 183         core_min_uV = max(cpu_min_uV + 125000, core_min_uV);
 184         if (core_min_uV > core_max_uV)
 185                 return -EINVAL;
 186
 187         if (cpu_uV + 120000 > core_uV)
 188                 pr_err("core-cpu voltage constraint violated: %d %d\n",
 189                        core_uV, cpu_uV + 120000);
 190
 191         rtc_uV = regulator_get_voltage_rdev(rtc_rdev);
 192         if (rtc_uV < 0)
 193                 return rtc_uV;
 194
 195         if (cpu_uV + 120000 > rtc_uV)
 196                 pr_err("rtc-cpu voltage constraint violated: %d %d\n",
 197                        rtc_uV, cpu_uV + 120000);
 198
 199         if (abs(core_uV - rtc_uV) > 170000)
 200                 pr_err("core-rtc voltage constraint violated: %d %d\n",
 201                        core_uV, rtc_uV);
 202
 203         rtc_min_uV = max(cpu_min_uV + 125000, core_min_uV - max_spread);
 204
 205         err = regulator_check_voltage(rtc_rdev, &rtc_min_uV, &rtc_max_uV);
 206         if (err)
 207                 return err;
 208
 209         while (core_uV != core_min_uV || rtc_uV != rtc_min_uV) {
 210                 if (core_uV < core_min_uV) {
 211                         core_target_uV = min(core_uV + max_spread, core_min_uV);
 212                         core_target_uV = min(rtc_uV + max_spread, core_target_uV);
 213                 } else {
 214                         core_target_uV = max(core_uV - max_spread, core_min_uV);
 215                         core_target_uV = max(rtc_uV - max_spread, core_target_uV);
 216                 }
 217
 218                 if (core_uV == core_target_uV)
 219                         goto update_rtc;
 220
 221                 err = regulator_set_voltage_rdev(core_rdev,
 222                                                  core_target_uV,
 223                                                  core_max_uV,
 224                                                  PM_SUSPEND_ON);
 225                 if (err)
 226                         return err;
 227
 228                 core_uV = core_target_uV;
 229 update_rtc:
 230                 if (rtc_uV < rtc_min_uV) {
 231                         rtc_target_uV = min(rtc_uV + max_spread, rtc_min_uV);
 232                         rtc_target_uV = min(core_uV + max_spread, rtc_target_uV);
 233                 } else {
 234                         rtc_target_uV = max(rtc_uV - max_spread, rtc_min_uV);
 235                         rtc_target_uV = max(core_uV - max_spread, rtc_target_uV);
 236                 }
 237
 238                 if (rtc_uV == rtc_target_uV)
 239                         continue;
 240
 241                 err = regulator_set_voltage_rdev(rtc_rdev,
 242                                                  rtc_target_uV,
 243                                                  rtc_max_uV,
 244                                                  PM_SUSPEND_ON);
 245                 if (err)
 246                         return err;
 247
 248                 rtc_uV = rtc_target_uV;
 249         }
 250
 251         return 0;
 252 }
 253
 254 static int tegra20_core_voltage_update(struct tegra_regulator_coupler *tegra,
 255                                        struct regulator_dev *cpu_rdev,
 256                                        struct regulator_dev *core_rdev,
 257                                        struct regulator_dev *rtc_rdev)
 258 {
 259         int cpu_uV;
 260
 261         cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
 262         if (cpu_uV < 0)
 263                 return cpu_uV;
 264
 265         return tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
 266                                        cpu_uV, cpu_uV);
 267 }
 268
 269 static int tegra20_cpu_voltage_update(struct tegra_regulator_coupler *tegra,
 270                                       struct regulator_dev *cpu_rdev,
 271                                       struct regulator_dev *core_rdev,
 272                                       struct regulator_dev *rtc_rdev)
 273 {
 274         int cpu_min_uV_consumers = 0;
 275         int cpu_max_uV = INT_MAX;
 276         int cpu_min_uV = 0;
 277         int cpu_uV;
 278         int err;
 279
 280         err = regulator_check_voltage(cpu_rdev, &cpu_min_uV, &cpu_max_uV);
 281         if (err)
 282                 return err;
 283
 284         err = regulator_check_consumers(cpu_rdev, &cpu_min_uV, &cpu_max_uV,
 285                                         PM_SUSPEND_ON);
 286         if (err)
 287                 return err;
 288
 289         err = regulator_check_consumers(cpu_rdev, &cpu_min_uV_consumers,
 290                                         &cpu_max_uV, PM_SUSPEND_ON);
 291         if (err)
 292                 return err;
 293
 294         cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
 295         if (cpu_uV < 0)
 296                 return cpu_uV;
 297
 298         /* store boot voltage level */
 299         if (!tegra->cpu_min_uV)
 300                 tegra->cpu_min_uV = cpu_uV;
 301
 302         /*
 303          * CPU's regulator may not have any consumers, hence the voltage
 304          * must not be changed in that case because CPU simply won't
 305          * survive the voltage drop if it's running on a higher frequency.
 306          */
 307         if (!cpu_min_uV_consumers)
 308                 cpu_min_uV = cpu_uV;
 309
 310         /* restore boot voltage level */
 311         if (tegra->sys_reboot_mode)
 312                 cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV);
 313
 314         /* prepare voltage level for suspend */
 315         if (tegra->sys_suspend_mode)
 316                 cpu_min_uV = clamp(tegra20_cpu_nominal_uV(),
 317                                    cpu_min_uV, cpu_max_uV);
 318
 319         if (cpu_min_uV > cpu_uV) {
 320                 err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
 321                                               cpu_uV, cpu_min_uV);
 322                 if (err)
 323                         return err;
 324
 325                 err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
 326                                                  cpu_max_uV, PM_SUSPEND_ON);
 327                 if (err)
 328                         return err;
 329         } else if (cpu_min_uV < cpu_uV)  {
 330                 err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
 331                                                  cpu_max_uV, PM_SUSPEND_ON);
 332                 if (err)
 333                         return err;
 334
 335                 err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
 336                                               cpu_uV, cpu_min_uV);
 337                 if (err)
 338                         return err;
 339         }
 340
 341         return 0;
 342 }
 343
 344 static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler,
 345                                              struct regulator_dev *rdev,
 346                                              suspend_state_t state)
 347 {
 348         struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
 349         struct regulator_dev *core_rdev = tegra->core_rdev;
 350         struct regulator_dev *cpu_rdev = tegra->cpu_rdev;
 351         struct regulator_dev *rtc_rdev = tegra->rtc_rdev;
 352
 353         if ((core_rdev != rdev && cpu_rdev != rdev && rtc_rdev != rdev) ||
 354             state != PM_SUSPEND_ON) {
 355                 pr_err("regulators are not coupled properly\n");
 356                 return -EINVAL;
 357         }
 358
 359         tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req);
 360         tegra->sys_suspend_mode = READ_ONCE(tegra->sys_suspend_mode_req);
 361
 362         if (rdev == cpu_rdev)
 363                 return tegra20_cpu_voltage_update(tegra, cpu_rdev,
 364                                                   core_rdev, rtc_rdev);
 365
 366         if (rdev == core_rdev)
 367                 return tegra20_core_voltage_update(tegra, cpu_rdev,
 368                                                    core_rdev, rtc_rdev);
 369
 370         pr_err("changing %s voltage not permitted\n", rdev_get_name(rtc_rdev));
 371
 372         return -EPERM;
 373 }
 374
 375 static int tegra20_regulator_prepare_suspend(struct tegra_regulator_coupler *tegra,
 376                                              bool sys_suspend_mode)
 377 {
 378         int err;
 379
 380         if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
 381                 return 0;
 382
 383         /*
 384          * All power domains are enabled early during resume from suspend
 385          * by GENPD core.  Domains like VENC may require a higher voltage
 386          * when enabled during resume from suspend.  This also prepares
 387          * hardware for resuming from LP0.
 388          */
 389
 390         WRITE_ONCE(tegra->sys_suspend_mode_req, sys_suspend_mode);
 391
 392         err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
 393         if (err)
 394                 return err;
 395
 396         err = regulator_sync_voltage_rdev(tegra->core_rdev);
 397         if (err)
 398                 return err;
 399
 400         return 0;
 401 }
 402
 403 static int tegra20_regulator_suspend(struct notifier_block *notifier,
 404                                      unsigned long mode, void *arg)
 405 {
 406         struct tegra_regulator_coupler *tegra;
 407         int ret = 0;
 408
 409         tegra = container_of(notifier, struct tegra_regulator_coupler,
 410                              suspend_notifier);
 411
 412         switch (mode) {
 413         case PM_HIBERNATION_PREPARE:
 414         case PM_RESTORE_PREPARE:
 415         case PM_SUSPEND_PREPARE:
 416                 ret = tegra20_regulator_prepare_suspend(tegra, true);
 417                 break;
 418
 419         case PM_POST_HIBERNATION:
 420         case PM_POST_RESTORE:
 421         case PM_POST_SUSPEND:
 422                 ret = tegra20_regulator_prepare_suspend(tegra, false);
 423                 break;
 424         }
 425
 426         if (ret)
 427                 pr_err("failed to prepare regulators: %d\n", ret);
 428
 429         return notifier_from_errno(ret);
 430 }
 431
 432 static int tegra20_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra,
 433                                             bool sys_reboot_mode)
 434 {
 435         int err;
 436
 437         if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
 438                 return 0;
 439
 440         WRITE_ONCE(tegra->sys_reboot_mode_req, true);
 441
 442         /*
 443          * Some devices use CPU soft-reboot method and in this case we
 444          * should ensure that voltages are sane for the reboot by restoring
 445          * the minimum boot levels.
 446          */
 447         err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
 448         if (err)
 449                 return err;
 450
 451         err = regulator_sync_voltage_rdev(tegra->core_rdev);
 452         if (err)
 453                 return err;
 454
 455         WRITE_ONCE(tegra->sys_reboot_mode_req, sys_reboot_mode);
 456
 457         return 0;
 458 }
 459
 460 static int tegra20_regulator_reboot(struct notifier_block *notifier,
 461                                     unsigned long event, void *cmd)
 462 {
 463         struct tegra_regulator_coupler *tegra;
 464         int ret;
 465
 466         if (event != SYS_RESTART)
 467                 return NOTIFY_DONE;
 468
 469         tegra = container_of(notifier, struct tegra_regulator_coupler,
 470                              reboot_notifier);
 471
 472         ret = tegra20_regulator_prepare_reboot(tegra, true);
 473
 474         return notifier_from_errno(ret);
 475 }
 476
 477 static int tegra20_regulator_attach(struct regulator_coupler *coupler,
 478                                     struct regulator_dev *rdev)
 479 {
 480         struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
 481         struct device_node *np = rdev->dev.of_node;
 482
 483         if (of_property_read_bool(np, "nvidia,tegra-core-regulator") &&
 484             !tegra->core_rdev) {
 485                 tegra->core_rdev = rdev;
 486                 return 0;
 487         }
 488
 489         if (of_property_read_bool(np, "nvidia,tegra-rtc-regulator") &&
 490             !tegra->rtc_rdev) {
 491                 tegra->rtc_rdev = rdev;
 492                 return 0;
 493         }
 494
 495         if (of_property_read_bool(np, "nvidia,tegra-cpu-regulator") &&
 496             !tegra->cpu_rdev) {
 497                 tegra->cpu_rdev = rdev;
 498                 return 0;
 499         }
 500
 501         return -EINVAL;
 502 }
 503
 504 static int tegra20_regulator_detach(struct regulator_coupler *coupler,
 505                                     struct regulator_dev *rdev)
 506 {
 507         struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
 508
 509         /*
 510          * We don't expect regulators to be decoupled during reboot,
 511          * this may race with the reboot handler and shouldn't ever
 512          * happen in practice.
 513          */
 514         if (WARN_ON_ONCE(system_state > SYSTEM_RUNNING))
 515                 return -EPERM;
 516
 517         if (tegra->core_rdev == rdev) {
 518                 tegra->core_rdev = NULL;
 519                 return 0;
 520         }
 521
 522         if (tegra->rtc_rdev == rdev) {
 523                 tegra->rtc_rdev = NULL;
 524                 return 0;
 525         }
 526
 527         if (tegra->cpu_rdev == rdev) {
 528                 tegra->cpu_rdev = NULL;
 529                 return 0;
 530         }
 531
 532         return -EINVAL;
 533 }
 534
 535 static struct tegra_regulator_coupler tegra20_coupler = {
 536         .coupler = {
 537                 .attach_regulator = tegra20_regulator_attach,
 538                 .detach_regulator = tegra20_regulator_detach,
 539                 .balance_voltage = tegra20_regulator_balance_voltage,
 540         },
 541         .reboot_notifier.notifier_call = tegra20_regulator_reboot,
 542         .suspend_notifier.notifier_call = tegra20_regulator_suspend,
 543 };
 544
 545 static int __init tegra_regulator_coupler_init(void)
 546 {
 547         int err;
 548
 549         if (!of_machine_is_compatible("nvidia,tegra20"))
 550                 return 0;
 551
 552         err = register_reboot_notifier(&tegra20_coupler.reboot_notifier);
 553         WARN_ON(err);
 554
 555         err = register_pm_notifier(&tegra20_coupler.suspend_notifier);
 556         WARN_ON(err);
 557
 558         return regulator_coupler_register(&tegra20_coupler.coupler);
 559 }
 560 arch_initcall(tegra_regulator_coupler_init);