LXR linux/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
  20#include <soc/tegra/pmc.h>
  21
  22struct tegra_regulator_coupler {
  23        struct regulator_coupler coupler;
  24        struct regulator_dev *core_rdev;
  25        struct regulator_dev *cpu_rdev;
  26        struct regulator_dev *rtc_rdev;
  27        struct notifier_block reboot_notifier;
  28        int core_min_uV, cpu_min_uV;
  29        bool sys_reboot_mode_req;
  30        bool sys_reboot_mode;
  31};
  32
  33static inline struct tegra_regulator_coupler *
  34to_tegra_coupler(struct regulator_coupler *coupler)
  35{
  36        return container_of(coupler, struct tegra_regulator_coupler, coupler);
  37}
  38
  39static int tegra20_core_limit(struct tegra_regulator_coupler *tegra,
  40                              struct regulator_dev *core_rdev)
  41{
  42        int core_min_uV = 0;
  43        int core_max_uV;
  44        int core_cur_uV;
  45        int err;
  46
  47        /*
  48         * Tegra20 SoC has critical DVFS-capable devices that are
  49         * permanently-active or active at a boot time, like EMC
  50         * (DRAM controller) or Display controller for example.
  51         *
  52         * The voltage of a CORE SoC power domain shall not be dropped below
  53         * a minimum level, which is determined by device's clock rate.
  54         * This means that we can't fully allow CORE voltage scaling until
  55         * the state of all DVFS-critical CORE devices is synced.
  56         */
  57        if (tegra_pmc_core_domain_state_synced() && !tegra->sys_reboot_mode) {
  58                pr_info_once("voltage state synced\n");
  59                return 0;
  60        }
  61
  62        if (tegra->core_min_uV > 0)
  63                return tegra->core_min_uV;
  64
  65        core_cur_uV = regulator_get_voltage_rdev(core_rdev);
  66        if (core_cur_uV < 0)
  67                return core_cur_uV;
  68
  69        core_max_uV = max(core_cur_uV, 1200000);
  70
  71        err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
  72        if (err)
  73                return err;
  74
  75        /*
  76         * Limit minimum CORE voltage to a value left from bootloader or,
  77         * if it's unreasonably low value, to the most common 1.2v or to
  78         * whatever maximum value defined via board's device-tree.
  79         */
  80        tegra->core_min_uV = core_max_uV;
  81
  82        pr_info("core voltage initialized to %duV\n", tegra->core_min_uV);
  83
  84        return tegra->core_min_uV;
  85}
  86
  87static int tegra20_core_rtc_max_spread(struct regulator_dev *core_rdev,
  88                                       struct regulator_dev *rtc_rdev)
  89{
  90        struct coupling_desc *c_desc = &core_rdev->coupling_desc;
  91        struct regulator_dev *rdev;
  92        int max_spread;
  93        unsigned int i;
  94
  95        for (i = 1; i < c_desc->n_coupled; i++) {
  96                max_spread = core_rdev->constraints->max_spread[i - 1];
  97                rdev = c_desc->coupled_rdevs[i];
  98
  99                if (rdev == rtc_rdev && max_spread)
 100                        return max_spread;
 101        }
 102
 103        pr_err_once("rtc-core max-spread is undefined in device-tree\n");
 104
 105        return 150000;
 106}
 107
 108static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra,
 109                                   struct regulator_dev *core_rdev,
 110                                   struct regulator_dev *rtc_rdev,
 111                                   int cpu_uV, int cpu_min_uV)
 112{
 113        int core_min_uV, core_max_uV = INT_MAX;
 114        int rtc_min_uV, rtc_max_uV = INT_MAX;
 115        int core_target_uV;
 116        int rtc_target_uV;
 117        int max_spread;
 118        int core_uV;
 119        int rtc_uV;
 120        int err;
 121
 122        /*
 123         * RTC and CORE voltages should be no more than 170mV from each other,
 124         * CPU should be below RTC and CORE by at least 120mV. This applies
 125         * to all Tegra20 SoC's.
 126         */
 127        max_spread = tegra20_core_rtc_max_spread(core_rdev, rtc_rdev);
 128
 129        /*
 130         * The core voltage scaling is currently not hooked up in drivers,
 131         * hence we will limit the minimum core voltage to a reasonable value.
 132         * This should be good enough for the time being.
 133         */
 134        core_min_uV = tegra20_core_limit(tegra, core_rdev);
 135        if (core_min_uV < 0)
 136                return core_min_uV;
 137
 138        err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
 139        if (err)
 140                return err;
 141
 142        err = regulator_check_consumers(core_rdev, &core_min_uV, &core_max_uV,
 143                                        PM_SUSPEND_ON);
 144        if (err)
 145                return err;
 146
 147        core_uV = regulator_get_voltage_rdev(core_rdev);
 148        if (core_uV < 0)
 149                return core_uV;
 150
 151        core_min_uV = max(cpu_min_uV + 125000, core_min_uV);
 152        if (core_min_uV > core_max_uV)
 153                return -EINVAL;
 154
 155        if (cpu_uV + 120000 > core_uV)
 156                pr_err("core-cpu voltage constraint violated: %d %d\n",
 157                       core_uV, cpu_uV + 120000);
 158
 159        rtc_uV = regulator_get_voltage_rdev(rtc_rdev);
 160        if (rtc_uV < 0)
 161                return rtc_uV;
 162
 163        if (cpu_uV + 120000 > rtc_uV)
 164                pr_err("rtc-cpu voltage constraint violated: %d %d\n",
 165                       rtc_uV, cpu_uV + 120000);
 166
 167        if (abs(core_uV - rtc_uV) > 170000)
 168                pr_err("core-rtc voltage constraint violated: %d %d\n",
 169                       core_uV, rtc_uV);
 170
 171        rtc_min_uV = max(cpu_min_uV + 125000, core_min_uV - max_spread);
 172
 173        err = regulator_check_voltage(rtc_rdev, &rtc_min_uV, &rtc_max_uV);
 174        if (err)
 175                return err;
 176
 177        while (core_uV != core_min_uV || rtc_uV != rtc_min_uV) {
 178                if (core_uV < core_min_uV) {
 179                        core_target_uV = min(core_uV + max_spread, core_min_uV);
 180                        core_target_uV = min(rtc_uV + max_spread, core_target_uV);
 181                } else {
 182                        core_target_uV = max(core_uV - max_spread, core_min_uV);
 183                        core_target_uV = max(rtc_uV - max_spread, core_target_uV);
 184                }
 185
 186                if (core_uV == core_target_uV)
 187                        goto update_rtc;
 188
 189                err = regulator_set_voltage_rdev(core_rdev,
 190                                                 core_target_uV,
 191                                                 core_max_uV,
 192                                                 PM_SUSPEND_ON);
 193                if (err)
 194                        return err;
 195
 196                core_uV = core_target_uV;
 197update_rtc:
 198                if (rtc_uV < rtc_min_uV) {
 199                        rtc_target_uV = min(rtc_uV + max_spread, rtc_min_uV);
 200                        rtc_target_uV = min(core_uV + max_spread, rtc_target_uV);
 201                } else {
 202                        rtc_target_uV = max(rtc_uV - max_spread, rtc_min_uV);
 203                        rtc_target_uV = max(core_uV - max_spread, rtc_target_uV);
 204                }
 205
 206                if (rtc_uV == rtc_target_uV)
 207                        continue;
 208
 209                err = regulator_set_voltage_rdev(rtc_rdev,
 210                                                 rtc_target_uV,
 211                                                 rtc_max_uV,
 212                                                 PM_SUSPEND_ON);
 213                if (err)
 214                        return err;
 215
 216                rtc_uV = rtc_target_uV;
 217        }
 218
 219        return 0;
 220}
 221
 222static int tegra20_core_voltage_update(struct tegra_regulator_coupler *tegra,
 223                                       struct regulator_dev *cpu_rdev,
 224                                       struct regulator_dev *core_rdev,
 225                                       struct regulator_dev *rtc_rdev)
 226{
 227        int cpu_uV;
 228
 229        cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
 230        if (cpu_uV < 0)
 231                return cpu_uV;
 232
 233        return tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
 234                                       cpu_uV, cpu_uV);
 235}
 236
 237static int tegra20_cpu_voltage_update(struct tegra_regulator_coupler *tegra,
 238                                      struct regulator_dev *cpu_rdev,
 239                                      struct regulator_dev *core_rdev,
 240                                      struct regulator_dev *rtc_rdev)
 241{
 242        int cpu_min_uV_consumers = 0;
 243        int cpu_max_uV = INT_MAX;
 244        int cpu_min_uV = 0;
 245        int cpu_uV;
 246        int err;
 247
 248        err = regulator_check_voltage(cpu_rdev, &cpu_min_uV, &cpu_max_uV);
 249        if (err)
 250                return err;
 251
 252        err = regulator_check_consumers(cpu_rdev, &cpu_min_uV, &cpu_max_uV,
 253                                        PM_SUSPEND_ON);
 254        if (err)
 255                return err;
 256
 257        err = regulator_check_consumers(cpu_rdev, &cpu_min_uV_consumers,
 258                                        &cpu_max_uV, PM_SUSPEND_ON);
 259        if (err)
 260                return err;
 261
 262        cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
 263        if (cpu_uV < 0)
 264                return cpu_uV;
 265
 266        /* store boot voltage level */
 267        if (!tegra->cpu_min_uV)
 268                tegra->cpu_min_uV = cpu_uV;
 269
 270        /*
 271         * CPU's regulator may not have any consumers, hence the voltage
 272         * must not be changed in that case because CPU simply won't
 273         * survive the voltage drop if it's running on a higher frequency.
 274         */
 275        if (!cpu_min_uV_consumers)
 276                cpu_min_uV = cpu_uV;
 277
 278        /* restore boot voltage level */
 279        if (tegra->sys_reboot_mode)
 280                cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV);
 281
 282        if (cpu_min_uV > cpu_uV) {
 283                err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
 284                                              cpu_uV, cpu_min_uV);
 285                if (err)
 286                        return err;
 287
 288                err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
 289                                                 cpu_max_uV, PM_SUSPEND_ON);
 290                if (err)
 291                        return err;
 292        } else if (cpu_min_uV < cpu_uV)  {
 293                err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
 294                                                 cpu_max_uV, PM_SUSPEND_ON);
 295                if (err)
 296                        return err;
 297
 298                err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
 299                                              cpu_uV, cpu_min_uV);
 300                if (err)
 301                        return err;
 302        }
 303
 304        return 0;
 305}
 306
 307static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler,
 308                                             struct regulator_dev *rdev,
 309                                             suspend_state_t state)
 310{
 311        struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
 312        struct regulator_dev *core_rdev = tegra->core_rdev;
 313        struct regulator_dev *cpu_rdev = tegra->cpu_rdev;
 314        struct regulator_dev *rtc_rdev = tegra->rtc_rdev;
 315
 316        if ((core_rdev != rdev && cpu_rdev != rdev && rtc_rdev != rdev) ||
 317            state != PM_SUSPEND_ON) {
 318                pr_err("regulators are not coupled properly\n");
 319                return -EINVAL;
 320        }
 321
 322        tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req);
 323
 324        if (rdev == cpu_rdev)
 325                return tegra20_cpu_voltage_update(tegra, cpu_rdev,
 326                                                  core_rdev, rtc_rdev);
 327
 328        if (rdev == core_rdev)
 329                return tegra20_core_voltage_update(tegra, cpu_rdev,
 330                                                   core_rdev, rtc_rdev);
 331
 332        pr_err("changing %s voltage not permitted\n", rdev_get_name(rtc_rdev));
 333
 334        return -EPERM;
 335}
 336
 337static int tegra20_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra,
 338                                            bool sys_reboot_mode)
 339{
 340        int err;
 341
 342        if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
 343                return 0;
 344
 345        WRITE_ONCE(tegra->sys_reboot_mode_req, true);
 346
 347        /*
 348         * Some devices use CPU soft-reboot method and in this case we
 349         * should ensure that voltages are sane for the reboot by restoring
 350         * the minimum boot levels.
 351         */
 352        err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
 353        if (err)
 354                return err;
 355
 356        err = regulator_sync_voltage_rdev(tegra->core_rdev);
 357        if (err)
 358                return err;
 359
 360        WRITE_ONCE(tegra->sys_reboot_mode_req, sys_reboot_mode);
 361
 362        return 0;
 363}
 364
 365static int tegra20_regulator_reboot(struct notifier_block *notifier,
 366                                    unsigned long event, void *cmd)
 367{
 368        struct tegra_regulator_coupler *tegra;
 369        int ret;
 370
 371        if (event != SYS_RESTART)
 372                return NOTIFY_DONE;
 373
 374        tegra = container_of(notifier, struct tegra_regulator_coupler,
 375                             reboot_notifier);
 376
 377        ret = tegra20_regulator_prepare_reboot(tegra, true);
 378
 379        return notifier_from_errno(ret);
 380}
 381
 382static int tegra20_regulator_attach(struct regulator_coupler *coupler,
 383                                    struct regulator_dev *rdev)
 384{
 385        struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
 386        struct device_node *np = rdev->dev.of_node;
 387
 388        if (of_property_read_bool(np, "nvidia,tegra-core-regulator") &&
 389            !tegra->core_rdev) {
 390                tegra->core_rdev = rdev;
 391                return 0;
 392        }
 393
 394        if (of_property_read_bool(np, "nvidia,tegra-rtc-regulator") &&
 395            !tegra->rtc_rdev) {
 396                tegra->rtc_rdev = rdev;
 397                return 0;
 398        }
 399
 400        if (of_property_read_bool(np, "nvidia,tegra-cpu-regulator") &&
 401            !tegra->cpu_rdev) {
 402                tegra->cpu_rdev = rdev;
 403                return 0;
 404        }
 405
 406        return -EINVAL;
 407}
 408
 409static int tegra20_regulator_detach(struct regulator_coupler *coupler,
 410                                    struct regulator_dev *rdev)
 411{
 412        struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
 413
 414        /*
 415         * We don't expect regulators to be decoupled during reboot,
 416         * this may race with the reboot handler and shouldn't ever
 417         * happen in practice.
 418         */
 419        if (WARN_ON_ONCE(system_state > SYSTEM_RUNNING))
 420                return -EPERM;
 421
 422        if (tegra->core_rdev == rdev) {
 423                tegra->core_rdev = NULL;
 424                return 0;
 425        }
 426
 427        if (tegra->rtc_rdev == rdev) {
 428                tegra->rtc_rdev = NULL;
 429                return 0;
 430        }
 431
 432        if (tegra->cpu_rdev == rdev) {
 433                tegra->cpu_rdev = NULL;
 434                return 0;
 435        }
 436
 437        return -EINVAL;
 438}
 439
 440static struct tegra_regulator_coupler tegra20_coupler = {
 441        .coupler = {
 442                .attach_regulator = tegra20_regulator_attach,
 443                .detach_regulator = tegra20_regulator_detach,
 444                .balance_voltage = tegra20_regulator_balance_voltage,
 445        },
 446        .reboot_notifier.notifier_call = tegra20_regulator_reboot,
 447};
 448
 449static int __init tegra_regulator_coupler_init(void)
 450{
 451        int err;
 452
 453        if (!of_machine_is_compatible("nvidia,tegra20"))
 454                return 0;
 455
 456        err = register_reboot_notifier(&tegra20_coupler.reboot_notifier);
 457        WARN_ON(err);
 458
 459        return regulator_coupler_register(&tegra20_coupler.coupler);
 460}
 461arch_initcall(tegra_regulator_coupler_init);
 462