soc/tegra/regulators-tegra20.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * Voltage regulators coupler for NVIDIA Tegra20
0004  * Copyright (C) 2019 GRATE-DRIVER project
0005  *
0006  * Voltage constraints borrowed from downstream kernel sources
0007  * Copyright (C) 2010-2011 NVIDIA Corporation
0008  */
0009
0010 #define pr_fmt(fmt) "tegra voltage-coupler: " fmt
0011
0012 #include <linux/init.h>
0013 #include <linux/kernel.h>
0014 #include <linux/of.h>
0015 #include <linux/reboot.h>
0016 #include <linux/regulator/coupler.h>
0017 #include <linux/regulator/driver.h>
0018 #include <linux/regulator/machine.h>
0019 #include <linux/suspend.h>
0020
0021 #include <soc/tegra/fuse.h>
0022 #include <soc/tegra/pmc.h>
0023
0024 struct tegra_regulator_coupler {
0025     struct regulator_coupler coupler;
0026     struct regulator_dev *core_rdev;
0027     struct regulator_dev *cpu_rdev;
0028     struct regulator_dev *rtc_rdev;
0029     struct notifier_block reboot_notifier;
0030     struct notifier_block suspend_notifier;
0031     int core_min_uV, cpu_min_uV;
0032     bool sys_reboot_mode_req;
0033     bool sys_reboot_mode;
0034     bool sys_suspend_mode_req;
0035     bool sys_suspend_mode;
0036 };
0037
0038 static inline struct tegra_regulator_coupler *
0039 to_tegra_coupler(struct regulator_coupler *coupler)
0040 {
0041     return container_of(coupler, struct tegra_regulator_coupler, coupler);
0042 }
0043
0044 static int tegra20_core_limit(struct tegra_regulator_coupler *tegra,
0045                   struct regulator_dev *core_rdev)
0046 {
0047     int core_min_uV = 0;
0048     int core_max_uV;
0049     int core_cur_uV;
0050     int err;
0051
0052     /*
0053      * Tegra20 SoC has critical DVFS-capable devices that are
0054      * permanently-active or active at a boot time, like EMC
0055      * (DRAM controller) or Display controller for example.
0056      *
0057      * The voltage of a CORE SoC power domain shall not be dropped below
0058      * a minimum level, which is determined by device's clock rate.
0059      * This means that we can't fully allow CORE voltage scaling until
0060      * the state of all DVFS-critical CORE devices is synced.
0061      */
0062     if (tegra_pmc_core_domain_state_synced() && !tegra->sys_reboot_mode) {
0063         pr_info_once("voltage state synced\n");
0064         return 0;
0065     }
0066
0067     if (tegra->core_min_uV > 0)
0068         return tegra->core_min_uV;
0069
0070     core_cur_uV = regulator_get_voltage_rdev(core_rdev);
0071     if (core_cur_uV < 0)
0072         return core_cur_uV;
0073
0074     core_max_uV = max(core_cur_uV, 1200000);
0075
0076     err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
0077     if (err)
0078         return err;
0079
0080     /*
0081      * Limit minimum CORE voltage to a value left from bootloader or,
0082      * if it's unreasonably low value, to the most common 1.2v or to
0083      * whatever maximum value defined via board's device-tree.
0084      */
0085     tegra->core_min_uV = core_max_uV;
0086
0087     pr_info("core voltage initialized to %duV\n", tegra->core_min_uV);
0088
0089     return tegra->core_min_uV;
0090 }
0091
0092 static int tegra20_core_rtc_max_spread(struct regulator_dev *core_rdev,
0093                        struct regulator_dev *rtc_rdev)
0094 {
0095     struct coupling_desc *c_desc = &core_rdev->coupling_desc;
0096     struct regulator_dev *rdev;
0097     int max_spread;
0098     unsigned int i;
0099
0100     for (i = 1; i < c_desc->n_coupled; i++) {
0101         max_spread = core_rdev->constraints->max_spread[i - 1];
0102         rdev = c_desc->coupled_rdevs[i];
0103
0104         if (rdev == rtc_rdev && max_spread)
0105             return max_spread;
0106     }
0107
0108     pr_err_once("rtc-core max-spread is undefined in device-tree\n");
0109
0110     return 150000;
0111 }
0112
0113 static int tegra20_cpu_nominal_uV(void)
0114 {
0115     switch (tegra_sku_info.soc_speedo_id) {
0116     case 0:
0117         return 1100000;
0118     case 1:
0119         return 1025000;
0120     default:
0121         return 1125000;
0122     }
0123 }
0124
0125 static int tegra20_core_nominal_uV(void)
0126 {
0127     switch (tegra_sku_info.soc_speedo_id) {
0128     default:
0129         return 1225000;
0130     case 2:
0131         return 1300000;
0132     }
0133 }
0134
0135 static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra,
0136                    struct regulator_dev *core_rdev,
0137                    struct regulator_dev *rtc_rdev,
0138                    int cpu_uV, int cpu_min_uV)
0139 {
0140     int core_min_uV, core_max_uV = INT_MAX;
0141     int rtc_min_uV, rtc_max_uV = INT_MAX;
0142     int core_target_uV;
0143     int rtc_target_uV;
0144     int max_spread;
0145     int core_uV;
0146     int rtc_uV;
0147     int err;
0148
0149     /*
0150      * RTC and CORE voltages should be no more than 170mV from each other,
0151      * CPU should be below RTC and CORE by at least 120mV. This applies
0152      * to all Tegra20 SoC's.
0153      */
0154     max_spread = tegra20_core_rtc_max_spread(core_rdev, rtc_rdev);
0155
0156     /*
0157      * The core voltage scaling is currently not hooked up in drivers,
0158      * hence we will limit the minimum core voltage to a reasonable value.
0159      * This should be good enough for the time being.
0160      */
0161     core_min_uV = tegra20_core_limit(tegra, core_rdev);
0162     if (core_min_uV < 0)
0163         return core_min_uV;
0164
0165     err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
0166     if (err)
0167         return err;
0168
0169     err = regulator_check_consumers(core_rdev, &core_min_uV, &core_max_uV,
0170                     PM_SUSPEND_ON);
0171     if (err)
0172         return err;
0173
0174     /* prepare voltage level for suspend */
0175     if (tegra->sys_suspend_mode)
0176         core_min_uV = clamp(tegra20_core_nominal_uV(),
0177                     core_min_uV, core_max_uV);
0178
0179     core_uV = regulator_get_voltage_rdev(core_rdev);
0180     if (core_uV < 0)
0181         return core_uV;
0182
0183     core_min_uV = max(cpu_min_uV + 125000, core_min_uV);
0184     if (core_min_uV > core_max_uV)
0185         return -EINVAL;
0186
0187     if (cpu_uV + 120000 > core_uV)
0188         pr_err("core-cpu voltage constraint violated: %d %d\n",
0189                core_uV, cpu_uV + 120000);
0190
0191     rtc_uV = regulator_get_voltage_rdev(rtc_rdev);
0192     if (rtc_uV < 0)
0193         return rtc_uV;
0194
0195     if (cpu_uV + 120000 > rtc_uV)
0196         pr_err("rtc-cpu voltage constraint violated: %d %d\n",
0197                rtc_uV, cpu_uV + 120000);
0198
0199     if (abs(core_uV - rtc_uV) > 170000)
0200         pr_err("core-rtc voltage constraint violated: %d %d\n",
0201                core_uV, rtc_uV);
0202
0203     rtc_min_uV = max(cpu_min_uV + 125000, core_min_uV - max_spread);
0204
0205     err = regulator_check_voltage(rtc_rdev, &rtc_min_uV, &rtc_max_uV);
0206     if (err)
0207         return err;
0208
0209     while (core_uV != core_min_uV || rtc_uV != rtc_min_uV) {
0210         if (core_uV < core_min_uV) {
0211             core_target_uV = min(core_uV + max_spread, core_min_uV);
0212             core_target_uV = min(rtc_uV + max_spread, core_target_uV);
0213         } else {
0214             core_target_uV = max(core_uV - max_spread, core_min_uV);
0215             core_target_uV = max(rtc_uV - max_spread, core_target_uV);
0216         }
0217
0218         if (core_uV == core_target_uV)
0219             goto update_rtc;
0220
0221         err = regulator_set_voltage_rdev(core_rdev,
0222                          core_target_uV,
0223                          core_max_uV,
0224                          PM_SUSPEND_ON);
0225         if (err)
0226             return err;
0227
0228         core_uV = core_target_uV;
0229 update_rtc:
0230         if (rtc_uV < rtc_min_uV) {
0231             rtc_target_uV = min(rtc_uV + max_spread, rtc_min_uV);
0232             rtc_target_uV = min(core_uV + max_spread, rtc_target_uV);
0233         } else {
0234             rtc_target_uV = max(rtc_uV - max_spread, rtc_min_uV);
0235             rtc_target_uV = max(core_uV - max_spread, rtc_target_uV);
0236         }
0237
0238         if (rtc_uV == rtc_target_uV)
0239             continue;
0240
0241         err = regulator_set_voltage_rdev(rtc_rdev,
0242                          rtc_target_uV,
0243                          rtc_max_uV,
0244                          PM_SUSPEND_ON);
0245         if (err)
0246             return err;
0247
0248         rtc_uV = rtc_target_uV;
0249     }
0250
0251     return 0;
0252 }
0253
0254 static int tegra20_core_voltage_update(struct tegra_regulator_coupler *tegra,
0255                        struct regulator_dev *cpu_rdev,
0256                        struct regulator_dev *core_rdev,
0257                        struct regulator_dev *rtc_rdev)
0258 {
0259     int cpu_uV;
0260
0261     cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
0262     if (cpu_uV < 0)
0263         return cpu_uV;
0264
0265     return tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
0266                        cpu_uV, cpu_uV);
0267 }
0268
0269 static int tegra20_cpu_voltage_update(struct tegra_regulator_coupler *tegra,
0270                       struct regulator_dev *cpu_rdev,
0271                       struct regulator_dev *core_rdev,
0272                       struct regulator_dev *rtc_rdev)
0273 {
0274     int cpu_min_uV_consumers = 0;
0275     int cpu_max_uV = INT_MAX;
0276     int cpu_min_uV = 0;
0277     int cpu_uV;
0278     int err;
0279
0280     err = regulator_check_voltage(cpu_rdev, &cpu_min_uV, &cpu_max_uV);
0281     if (err)
0282         return err;
0283
0284     err = regulator_check_consumers(cpu_rdev, &cpu_min_uV, &cpu_max_uV,
0285                     PM_SUSPEND_ON);
0286     if (err)
0287         return err;
0288
0289     err = regulator_check_consumers(cpu_rdev, &cpu_min_uV_consumers,
0290                     &cpu_max_uV, PM_SUSPEND_ON);
0291     if (err)
0292         return err;
0293
0294     cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
0295     if (cpu_uV < 0)
0296         return cpu_uV;
0297
0298     /* store boot voltage level */
0299     if (!tegra->cpu_min_uV)
0300         tegra->cpu_min_uV = cpu_uV;
0301
0302     /*
0303      * CPU's regulator may not have any consumers, hence the voltage
0304      * must not be changed in that case because CPU simply won't
0305      * survive the voltage drop if it's running on a higher frequency.
0306      */
0307     if (!cpu_min_uV_consumers)
0308         cpu_min_uV = cpu_uV;
0309
0310     /* restore boot voltage level */
0311     if (tegra->sys_reboot_mode)
0312         cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV);
0313
0314     /* prepare voltage level for suspend */
0315     if (tegra->sys_suspend_mode)
0316         cpu_min_uV = clamp(tegra20_cpu_nominal_uV(),
0317                    cpu_min_uV, cpu_max_uV);
0318
0319     if (cpu_min_uV > cpu_uV) {
0320         err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
0321                           cpu_uV, cpu_min_uV);
0322         if (err)
0323             return err;
0324
0325         err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
0326                          cpu_max_uV, PM_SUSPEND_ON);
0327         if (err)
0328             return err;
0329     } else if (cpu_min_uV < cpu_uV)  {
0330         err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
0331                          cpu_max_uV, PM_SUSPEND_ON);
0332         if (err)
0333             return err;
0334
0335         err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
0336                           cpu_uV, cpu_min_uV);
0337         if (err)
0338             return err;
0339     }
0340
0341     return 0;
0342 }
0343
0344 static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler,
0345                          struct regulator_dev *rdev,
0346                          suspend_state_t state)
0347 {
0348     struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
0349     struct regulator_dev *core_rdev = tegra->core_rdev;
0350     struct regulator_dev *cpu_rdev = tegra->cpu_rdev;
0351     struct regulator_dev *rtc_rdev = tegra->rtc_rdev;
0352
0353     if ((core_rdev != rdev && cpu_rdev != rdev && rtc_rdev != rdev) ||
0354         state != PM_SUSPEND_ON) {
0355         pr_err("regulators are not coupled properly\n");
0356         return -EINVAL;
0357     }
0358
0359     tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req);
0360     tegra->sys_suspend_mode = READ_ONCE(tegra->sys_suspend_mode_req);
0361
0362     if (rdev == cpu_rdev)
0363         return tegra20_cpu_voltage_update(tegra, cpu_rdev,
0364                           core_rdev, rtc_rdev);
0365
0366     if (rdev == core_rdev)
0367         return tegra20_core_voltage_update(tegra, cpu_rdev,
0368                            core_rdev, rtc_rdev);
0369
0370     pr_err("changing %s voltage not permitted\n", rdev_get_name(rtc_rdev));
0371
0372     return -EPERM;
0373 }
0374
0375 static int tegra20_regulator_prepare_suspend(struct tegra_regulator_coupler *tegra,
0376                          bool sys_suspend_mode)
0377 {
0378     int err;
0379
0380     if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
0381         return 0;
0382
0383     /*
0384      * All power domains are enabled early during resume from suspend
0385      * by GENPD core.  Domains like VENC may require a higher voltage
0386      * when enabled during resume from suspend.  This also prepares
0387      * hardware for resuming from LP0.
0388      */
0389
0390     WRITE_ONCE(tegra->sys_suspend_mode_req, sys_suspend_mode);
0391
0392     err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
0393     if (err)
0394         return err;
0395
0396     err = regulator_sync_voltage_rdev(tegra->core_rdev);
0397     if (err)
0398         return err;
0399
0400     return 0;
0401 }
0402
0403 static int tegra20_regulator_suspend(struct notifier_block *notifier,
0404                      unsigned long mode, void *arg)
0405 {
0406     struct tegra_regulator_coupler *tegra;
0407     int ret = 0;
0408
0409     tegra = container_of(notifier, struct tegra_regulator_coupler,
0410                  suspend_notifier);
0411
0412     switch (mode) {
0413     case PM_HIBERNATION_PREPARE:
0414     case PM_RESTORE_PREPARE:
0415     case PM_SUSPEND_PREPARE:
0416         ret = tegra20_regulator_prepare_suspend(tegra, true);
0417         break;
0418
0419     case PM_POST_HIBERNATION:
0420     case PM_POST_RESTORE:
0421     case PM_POST_SUSPEND:
0422         ret = tegra20_regulator_prepare_suspend(tegra, false);
0423         break;
0424     }
0425
0426     if (ret)
0427         pr_err("failed to prepare regulators: %d\n", ret);
0428
0429     return notifier_from_errno(ret);
0430 }
0431
0432 static int tegra20_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra,
0433                         bool sys_reboot_mode)
0434 {
0435     int err;
0436
0437     if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
0438         return 0;
0439
0440     WRITE_ONCE(tegra->sys_reboot_mode_req, true);
0441
0442     /*
0443      * Some devices use CPU soft-reboot method and in this case we
0444      * should ensure that voltages are sane for the reboot by restoring
0445      * the minimum boot levels.
0446      */
0447     err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
0448     if (err)
0449         return err;
0450
0451     err = regulator_sync_voltage_rdev(tegra->core_rdev);
0452     if (err)
0453         return err;
0454
0455     WRITE_ONCE(tegra->sys_reboot_mode_req, sys_reboot_mode);
0456
0457     return 0;
0458 }
0459
0460 static int tegra20_regulator_reboot(struct notifier_block *notifier,
0461                     unsigned long event, void *cmd)
0462 {
0463     struct tegra_regulator_coupler *tegra;
0464     int ret;
0465
0466     if (event != SYS_RESTART)
0467         return NOTIFY_DONE;
0468
0469     tegra = container_of(notifier, struct tegra_regulator_coupler,
0470                  reboot_notifier);
0471
0472     ret = tegra20_regulator_prepare_reboot(tegra, true);
0473
0474     return notifier_from_errno(ret);
0475 }
0476
0477 static int tegra20_regulator_attach(struct regulator_coupler *coupler,
0478                     struct regulator_dev *rdev)
0479 {
0480     struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
0481     struct device_node *np = rdev->dev.of_node;
0482
0483     if (of_property_read_bool(np, "nvidia,tegra-core-regulator") &&
0484         !tegra->core_rdev) {
0485         tegra->core_rdev = rdev;
0486         return 0;
0487     }
0488
0489     if (of_property_read_bool(np, "nvidia,tegra-rtc-regulator") &&
0490         !tegra->rtc_rdev) {
0491         tegra->rtc_rdev = rdev;
0492         return 0;
0493     }
0494
0495     if (of_property_read_bool(np, "nvidia,tegra-cpu-regulator") &&
0496         !tegra->cpu_rdev) {
0497         tegra->cpu_rdev = rdev;
0498         return 0;
0499     }
0500
0501     return -EINVAL;
0502 }
0503
0504 static int tegra20_regulator_detach(struct regulator_coupler *coupler,
0505                     struct regulator_dev *rdev)
0506 {
0507     struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
0508
0509     /*
0510      * We don't expect regulators to be decoupled during reboot,
0511      * this may race with the reboot handler and shouldn't ever
0512      * happen in practice.
0513      */
0514     if (WARN_ON_ONCE(system_state > SYSTEM_RUNNING))
0515         return -EPERM;
0516
0517     if (tegra->core_rdev == rdev) {
0518         tegra->core_rdev = NULL;
0519         return 0;
0520     }
0521
0522     if (tegra->rtc_rdev == rdev) {
0523         tegra->rtc_rdev = NULL;
0524         return 0;
0525     }
0526
0527     if (tegra->cpu_rdev == rdev) {
0528         tegra->cpu_rdev = NULL;
0529         return 0;
0530     }
0531
0532     return -EINVAL;
0533 }
0534
0535 static struct tegra_regulator_coupler tegra20_coupler = {
0536     .coupler = {
0537         .attach_regulator = tegra20_regulator_attach,
0538         .detach_regulator = tegra20_regulator_detach,
0539         .balance_voltage = tegra20_regulator_balance_voltage,
0540     },
0541     .reboot_notifier.notifier_call = tegra20_regulator_reboot,
0542     .suspend_notifier.notifier_call = tegra20_regulator_suspend,
0543 };
0544
0545 static int __init tegra_regulator_coupler_init(void)
0546 {
0547     int err;
0548
0549     if (!of_machine_is_compatible("nvidia,tegra20"))
0550         return 0;
0551
0552     err = register_reboot_notifier(&tegra20_coupler.reboot_notifier);
0553     WARN_ON(err);
0554
0555     err = register_pm_notifier(&tegra20_coupler.suspend_notifier);
0556     WARN_ON(err);
0557
0558     return regulator_coupler_register(&tegra20_coupler.coupler);
0559 }
0560 arch_initcall(tegra_regulator_coupler_init);