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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Voltage regulators coupler for NVIDIA Tegra204 * Copyright (C) 2019 GRATE-DRIVER project5 *6 * Voltage constraints borrowed from downstream kernel sources7 * Copyright (C) 2010-2011 NVIDIA Corporation8 */9 10#define pr_fmt(fmt) "tegra voltage-coupler: " fmt11 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 24struct 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 38static inline struct tegra_regulator_coupler *39to_tegra_coupler(struct regulator_coupler *coupler)40{41 return container_of(coupler, struct tegra_regulator_coupler, coupler);42}43 44static 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 are54 * permanently-active or active at a boot time, like EMC55 * (DRAM controller) or Display controller for example.56 *57 * The voltage of a CORE SoC power domain shall not be dropped below58 * a minimum level, which is determined by device's clock rate.59 * This means that we can't fully allow CORE voltage scaling until60 * 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 to83 * 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 92static 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 113static 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 125static 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 135static 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 applies152 * 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;229update_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 254static 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 269static 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 voltage304 * must not be changed in that case because CPU simply won't305 * 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 344static 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 375static 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 suspend385 * by GENPD core. Domains like VENC may require a higher voltage386 * when enabled during resume from suspend. This also prepares387 * 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 403static 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 432static 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 we444 * should ensure that voltages are sane for the reboot by restoring445 * 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 460static 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 477static 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 504static 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 ever512 * 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 535static 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 545static 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}560arch_initcall(tegra_regulator_coupler_init);561