drivers/regulator/of_regulator.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * OF helpers for regulator framework
   4  *
   5  * Copyright (C) 2011 Texas Instruments, Inc.
   6  * Rajendra Nayak <rnayak@ti.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/slab.h>
  11 #include <linux/of.h>
  12 #include <linux/regulator/machine.h>
  13 #include <linux/regulator/driver.h>
  14 #include <linux/regulator/of_regulator.h>
  15
  16 #include "internal.h"
  17
  18 static const char *const regulator_states[PM_SUSPEND_MAX + 1] = {
  19         [PM_SUSPEND_STANDBY]    = "regulator-state-standby",
  20         [PM_SUSPEND_MEM]        = "regulator-state-mem",
  21         [PM_SUSPEND_MAX]        = "regulator-state-disk",
  22 };
  23
  24 static void fill_limit(int *limit, int val)
  25 {
  26         if (val)
  27                 if (val == 1)
  28                         *limit = REGULATOR_NOTIF_LIMIT_ENABLE;
  29                 else
  30                         *limit = val;
  31         else
  32                 *limit = REGULATOR_NOTIF_LIMIT_DISABLE;
  33 }
  34
  35 static void of_get_regulator_prot_limits(struct device_node *np,
  36                                 struct regulation_constraints *constraints)
  37 {
  38         u32 pval;
  39         int i;
  40         static const char *const props[] = {
  41                 "regulator-oc-%s-microamp",
  42                 "regulator-ov-%s-microvolt",
  43                 "regulator-temp-%s-kelvin",
  44                 "regulator-uv-%s-microvolt",
  45         };
  46         struct notification_limit *limits[] = {
  47                 &constraints->over_curr_limits,
  48                 &constraints->over_voltage_limits,
  49                 &constraints->temp_limits,
  50                 &constraints->under_voltage_limits,
  51         };
  52         bool set[4] = {0};
  53
  54         /* Protection limits: */
  55         for (i = 0; i < ARRAY_SIZE(props); i++) {
  56                 char prop[255];
  57                 bool found;
  58                 int j;
  59                 static const char *const lvl[] = {
  60                         "protection", "error", "warn"
  61                 };
  62                 int *l[] = {
  63                         &limits[i]->prot, &limits[i]->err, &limits[i]->warn,
  64                 };
  65
  66                 for (j = 0; j < ARRAY_SIZE(lvl); j++) {
  67                         snprintf(prop, 255, props[i], lvl[j]);
  68                         found = !of_property_read_u32(np, prop, &pval);
  69                         if (found)
  70                                 fill_limit(l[j], pval);
  71                         set[i] |= found;
  72                 }
  73         }
  74         constraints->over_current_detection = set[0];
  75         constraints->over_voltage_detection = set[1];
  76         constraints->over_temp_detection = set[2];
  77         constraints->under_voltage_detection = set[3];
  78 }
  79
  80 static int of_get_regulation_constraints(struct device *dev,
  81                                         struct device_node *np,
  82                                         struct regulator_init_data **init_data,
  83                                         const struct regulator_desc *desc)
  84 {
  85         struct regulation_constraints *constraints = &(*init_data)->constraints;
  86         struct regulator_state *suspend_state;
  87         struct device_node *suspend_np;
  88         unsigned int mode;
  89         int ret, i, len;
  90         int n_phandles;
  91         u32 pval;
  92
  93         n_phandles = of_count_phandle_with_args(np, "regulator-coupled-with",
  94                                                 NULL);
  95         n_phandles = max(n_phandles, 0);
  96
  97         constraints->name = of_get_property(np, "regulator-name", NULL);
  98
  99         if (!of_property_read_u32(np, "regulator-min-microvolt", &pval))
 100                 constraints->min_uV = pval;
 101
 102         if (!of_property_read_u32(np, "regulator-max-microvolt", &pval))
 103                 constraints->max_uV = pval;
 104
 105         /* Voltage change possible? */
 106         if (constraints->min_uV != constraints->max_uV)
 107                 constraints->valid_ops_mask |= REGULATOR_CHANGE_VOLTAGE;
 108
 109         /* Do we have a voltage range, if so try to apply it? */
 110         if (constraints->min_uV && constraints->max_uV)
 111                 constraints->apply_uV = true;
 112
 113         if (!of_property_read_u32(np, "regulator-microvolt-offset", &pval))
 114                 constraints->uV_offset = pval;
 115         if (!of_property_read_u32(np, "regulator-min-microamp", &pval))
 116                 constraints->min_uA = pval;
 117         if (!of_property_read_u32(np, "regulator-max-microamp", &pval))
 118                 constraints->max_uA = pval;
 119
 120         if (!of_property_read_u32(np, "regulator-input-current-limit-microamp",
 121                                   &pval))
 122                 constraints->ilim_uA = pval;
 123
 124         /* Current change possible? */
 125         if (constraints->min_uA != constraints->max_uA)
 126                 constraints->valid_ops_mask |= REGULATOR_CHANGE_CURRENT;
 127
 128         constraints->boot_on = of_property_read_bool(np, "regulator-boot-on");
 129         constraints->always_on = of_property_read_bool(np, "regulator-always-on");
 130         if (!constraints->always_on) /* status change should be possible. */
 131                 constraints->valid_ops_mask |= REGULATOR_CHANGE_STATUS;
 132
 133         constraints->pull_down = of_property_read_bool(np, "regulator-pull-down");
 134
 135         if (of_property_read_bool(np, "regulator-allow-bypass"))
 136                 constraints->valid_ops_mask |= REGULATOR_CHANGE_BYPASS;
 137
 138         if (of_property_read_bool(np, "regulator-allow-set-load"))
 139                 constraints->valid_ops_mask |= REGULATOR_CHANGE_DRMS;
 140
 141         ret = of_property_read_u32(np, "regulator-ramp-delay", &pval);
 142         if (!ret) {
 143                 if (pval)
 144                         constraints->ramp_delay = pval;
 145                 else
 146                         constraints->ramp_disable = true;
 147         }
 148
 149         ret = of_property_read_u32(np, "regulator-settling-time-us", &pval);
 150         if (!ret)
 151                 constraints->settling_time = pval;
 152
 153         ret = of_property_read_u32(np, "regulator-settling-time-up-us", &pval);
 154         if (!ret)
 155                 constraints->settling_time_up = pval;
 156         if (constraints->settling_time_up && constraints->settling_time) {
 157                 pr_warn("%pOFn: ambiguous configuration for settling time, ignoring 'regulator-settling-time-up-us'\n",
 158                         np);
 159                 constraints->settling_time_up = 0;
 160         }
 161
 162         ret = of_property_read_u32(np, "regulator-settling-time-down-us",
 163                                    &pval);
 164         if (!ret)
 165                 constraints->settling_time_down = pval;
 166         if (constraints->settling_time_down && constraints->settling_time) {
 167                 pr_warn("%pOFn: ambiguous configuration for settling time, ignoring 'regulator-settling-time-down-us'\n",
 168                         np);
 169                 constraints->settling_time_down = 0;
 170         }
 171
 172         ret = of_property_read_u32(np, "regulator-enable-ramp-delay", &pval);
 173         if (!ret)
 174                 constraints->enable_time = pval;
 175
 176         constraints->soft_start = of_property_read_bool(np,
 177                                         "regulator-soft-start");
 178         ret = of_property_read_u32(np, "regulator-active-discharge", &pval);
 179         if (!ret) {
 180                 constraints->active_discharge =
 181                                 (pval) ? REGULATOR_ACTIVE_DISCHARGE_ENABLE :
 182                                         REGULATOR_ACTIVE_DISCHARGE_DISABLE;
 183         }
 184
 185         if (!of_property_read_u32(np, "regulator-initial-mode", &pval)) {
 186                 if (desc && desc->of_map_mode) {
 187                         mode = desc->of_map_mode(pval);
 188                         if (mode == REGULATOR_MODE_INVALID)
 189                                 pr_err("%pOFn: invalid mode %u\n", np, pval);
 190                         else
 191                                 constraints->initial_mode = mode;
 192                 } else {
 193                         pr_warn("%pOFn: mapping for mode %d not defined\n",
 194                                 np, pval);
 195                 }
 196         }
 197
 198         len = of_property_count_elems_of_size(np, "regulator-allowed-modes",
 199                                                 sizeof(u32));
 200         if (len > 0) {
 201                 if (desc && desc->of_map_mode) {
 202                         for (i = 0; i < len; i++) {
 203                                 ret = of_property_read_u32_index(np,
 204                                         "regulator-allowed-modes", i, &pval);
 205                                 if (ret) {
 206                                         pr_err("%pOFn: couldn't read allowed modes index %d, ret=%d\n",
 207                                                 np, i, ret);
 208                                         break;
 209                                 }
 210                                 mode = desc->of_map_mode(pval);
 211                                 if (mode == REGULATOR_MODE_INVALID)
 212                                         pr_err("%pOFn: invalid regulator-allowed-modes element %u\n",
 213                                                 np, pval);
 214                                 else
 215                                         constraints->valid_modes_mask |= mode;
 216                         }
 217                         if (constraints->valid_modes_mask)
 218                                 constraints->valid_ops_mask
 219                                         |= REGULATOR_CHANGE_MODE;
 220                 } else {
 221                         pr_warn("%pOFn: mode mapping not defined\n", np);
 222                 }
 223         }
 224
 225         if (!of_property_read_u32(np, "regulator-system-load", &pval))
 226                 constraints->system_load = pval;
 227
 228         if (n_phandles) {
 229                 constraints->max_spread = devm_kzalloc(dev,
 230                                 sizeof(*constraints->max_spread) * n_phandles,
 231                                 GFP_KERNEL);
 232
 233                 if (!constraints->max_spread)
 234                         return -ENOMEM;
 235
 236                 of_property_read_u32_array(np, "regulator-coupled-max-spread",
 237                                            constraints->max_spread, n_phandles);
 238         }
 239
 240         if (!of_property_read_u32(np, "regulator-max-step-microvolt",
 241                                   &pval))
 242                 constraints->max_uV_step = pval;
 243
 244         constraints->over_current_protection = of_property_read_bool(np,
 245                                         "regulator-over-current-protection");
 246
 247         of_get_regulator_prot_limits(np, constraints);
 248
 249         for (i = 0; i < ARRAY_SIZE(regulator_states); i++) {
 250                 switch (i) {
 251                 case PM_SUSPEND_MEM:
 252                         suspend_state = &constraints->state_mem;
 253                         break;
 254                 case PM_SUSPEND_MAX:
 255                         suspend_state = &constraints->state_disk;
 256                         break;
 257                 case PM_SUSPEND_STANDBY:
 258                         suspend_state = &constraints->state_standby;
 259                         break;
 260                 case PM_SUSPEND_ON:
 261                 case PM_SUSPEND_TO_IDLE:
 262                 default:
 263                         continue;
 264                 }
 265
 266                 suspend_np = of_get_child_by_name(np, regulator_states[i]);
 267                 if (!suspend_np)
 268                         continue;
 269                 if (!suspend_state) {
 270                         of_node_put(suspend_np);
 271                         continue;
 272                 }
 273
 274                 if (!of_property_read_u32(suspend_np, "regulator-mode",
 275                                           &pval)) {
 276                         if (desc && desc->of_map_mode) {
 277                                 mode = desc->of_map_mode(pval);
 278                                 if (mode == REGULATOR_MODE_INVALID)
 279                                         pr_err("%pOFn: invalid mode %u\n",
 280                                                np, pval);
 281                                 else
 282                                         suspend_state->mode = mode;
 283                         } else {
 284                                 pr_warn("%pOFn: mapping for mode %d not defined\n",
 285                                         np, pval);
 286                         }
 287                 }
 288
 289                 if (of_property_read_bool(suspend_np,
 290                                         "regulator-on-in-suspend"))
 291                         suspend_state->enabled = ENABLE_IN_SUSPEND;
 292                 else if (of_property_read_bool(suspend_np,
 293                                         "regulator-off-in-suspend"))
 294                         suspend_state->enabled = DISABLE_IN_SUSPEND;
 295
 296                 if (!of_property_read_u32(suspend_np,
 297                                 "regulator-suspend-min-microvolt", &pval))
 298                         suspend_state->min_uV = pval;
 299
 300                 if (!of_property_read_u32(suspend_np,
 301                                 "regulator-suspend-max-microvolt", &pval))
 302                         suspend_state->max_uV = pval;
 303
 304                 if (!of_property_read_u32(suspend_np,
 305                                         "regulator-suspend-microvolt", &pval))
 306                         suspend_state->uV = pval;
 307                 else /* otherwise use min_uV as default suspend voltage */
 308                         suspend_state->uV = suspend_state->min_uV;
 309
 310                 if (of_property_read_bool(suspend_np,
 311                                         "regulator-changeable-in-suspend"))
 312                         suspend_state->changeable = true;
 313
 314                 if (i == PM_SUSPEND_MEM)
 315                         constraints->initial_state = PM_SUSPEND_MEM;
 316
 317                 of_node_put(suspend_np);
 318                 suspend_state = NULL;
 319                 suspend_np = NULL;
 320         }
 321
 322         return 0;
 323 }
 324
 325 /**
 326  * of_get_regulator_init_data - extract regulator_init_data structure info
 327  * @dev: device requesting for regulator_init_data
 328  * @node: regulator device node
 329  * @desc: regulator description
 330  *
 331  * Populates regulator_init_data structure by extracting data from device
 332  * tree node, returns a pointer to the populated structure or NULL if memory
 333  * alloc fails.
 334  */
 335 struct regulator_init_data *of_get_regulator_init_data(struct device *dev,
 336                                           struct device_node *node,
 337                                           const struct regulator_desc *desc)
 338 {
 339         struct regulator_init_data *init_data;
 340
 341         if (!node)
 342                 return NULL;
 343
 344         init_data = devm_kzalloc(dev, sizeof(*init_data), GFP_KERNEL);
 345         if (!init_data)
 346                 return NULL; /* Out of memory? */
 347
 348         if (of_get_regulation_constraints(dev, node, &init_data, desc))
 349                 return NULL;
 350
 351         return init_data;
 352 }
 353 EXPORT_SYMBOL_GPL(of_get_regulator_init_data);
 354
 355 struct devm_of_regulator_matches {
 356         struct of_regulator_match *matches;
 357         unsigned int num_matches;
 358 };
 359
 360 static void devm_of_regulator_put_matches(struct device *dev, void *res)
 361 {
 362         struct devm_of_regulator_matches *devm_matches = res;
 363         int i;
 364
 365         for (i = 0; i < devm_matches->num_matches; i++)
 366                 of_node_put(devm_matches->matches[i].of_node);
 367 }
 368
 369 /**
 370  * of_regulator_match - extract multiple regulator init data from device tree.
 371  * @dev: device requesting the data
 372  * @node: parent device node of the regulators
 373  * @matches: match table for the regulators
 374  * @num_matches: number of entries in match table
 375  *
 376  * This function uses a match table specified by the regulator driver to
 377  * parse regulator init data from the device tree. @node is expected to
 378  * contain a set of child nodes, each providing the init data for one
 379  * regulator. The data parsed from a child node will be matched to a regulator
 380  * based on either the deprecated property regulator-compatible if present,
 381  * or otherwise the child node's name. Note that the match table is modified
 382  * in place and an additional of_node reference is taken for each matched
 383  * regulator.
 384  *
 385  * Returns the number of matches found or a negative error code on failure.
 386  */
 387 int of_regulator_match(struct device *dev, struct device_node *node,
 388                        struct of_regulator_match *matches,
 389                        unsigned int num_matches)
 390 {
 391         unsigned int count = 0;
 392         unsigned int i;
 393         const char *name;
 394         struct device_node *child;
 395         struct devm_of_regulator_matches *devm_matches;
 396
 397         if (!dev || !node)
 398                 return -EINVAL;
 399
 400         devm_matches = devres_alloc(devm_of_regulator_put_matches,
 401                                     sizeof(struct devm_of_regulator_matches),
 402                                     GFP_KERNEL);
 403         if (!devm_matches)
 404                 return -ENOMEM;
 405
 406         devm_matches->matches = matches;
 407         devm_matches->num_matches = num_matches;
 408
 409         devres_add(dev, devm_matches);
 410
 411         for (i = 0; i < num_matches; i++) {
 412                 struct of_regulator_match *match = &matches[i];
 413                 match->init_data = NULL;
 414                 match->of_node = NULL;
 415         }
 416
 417         for_each_child_of_node(node, child) {
 418                 name = of_get_property(child,
 419                                         "regulator-compatible", NULL);
 420                 if (!name)
 421                         name = child->name;
 422                 for (i = 0; i < num_matches; i++) {
 423                         struct of_regulator_match *match = &matches[i];
 424                         if (match->of_node)
 425                                 continue;
 426
 427                         if (strcmp(match->name, name))
 428                                 continue;
 429
 430                         match->init_data =
 431                                 of_get_regulator_init_data(dev, child,
 432                                                            match->desc);
 433                         if (!match->init_data) {
 434                                 dev_err(dev,
 435                                         "failed to parse DT for regulator %pOFn\n",
 436                                         child);
 437                                 of_node_put(child);
 438                                 return -EINVAL;
 439                         }
 440                         match->of_node = of_node_get(child);
 441                         count++;
 442                         break;
 443                 }
 444         }
 445
 446         return count;
 447 }
 448 EXPORT_SYMBOL_GPL(of_regulator_match);
 449
 450 static struct
 451 device_node *regulator_of_get_init_node(struct device *dev,
 452                                         const struct regulator_desc *desc)
 453 {
 454         struct device_node *search, *child;
 455         const char *name;
 456
 457         if (!dev->of_node || !desc->of_match)
 458                 return NULL;
 459
 460         if (desc->regulators_node) {
 461                 search = of_get_child_by_name(dev->of_node,
 462                                               desc->regulators_node);
 463         } else {
 464                 search = of_node_get(dev->of_node);
 465
 466                 if (!strcmp(desc->of_match, search->name))
 467                         return search;
 468         }
 469
 470         if (!search) {
 471                 dev_dbg(dev, "Failed to find regulator container node '%s'\n",
 472                         desc->regulators_node);
 473                 return NULL;
 474         }
 475
 476         for_each_available_child_of_node(search, child) {
 477                 name = of_get_property(child, "regulator-compatible", NULL);
 478                 if (!name) {
 479                         if (!desc->of_match_full_name)
 480                                 name = child->name;
 481                         else
 482                                 name = child->full_name;
 483                 }
 484
 485                 if (!strcmp(desc->of_match, name)) {
 486                         of_node_put(search);
 487                         /*
 488                          * 'of_node_get(child)' is already performed by the
 489                          * for_each loop.
 490                          */
 491                         return child;
 492                 }
 493         }
 494
 495         of_node_put(search);
 496
 497         return NULL;
 498 }
 499
 500 struct regulator_init_data *regulator_of_get_init_data(struct device *dev,
 501                                             const struct regulator_desc *desc,
 502                                             struct regulator_config *config,
 503                                             struct device_node **node)
 504 {
 505         struct device_node *child;
 506         struct regulator_init_data *init_data = NULL;
 507
 508         child = regulator_of_get_init_node(dev, desc);
 509         if (!child)
 510                 return NULL;
 511
 512         init_data = of_get_regulator_init_data(dev, child, desc);
 513         if (!init_data) {
 514                 dev_err(dev, "failed to parse DT for regulator %pOFn\n", child);
 515                 goto error;
 516         }
 517
 518         if (desc->of_parse_cb) {
 519                 int ret;
 520
 521                 ret = desc->of_parse_cb(child, desc, config);
 522                 if (ret) {
 523                         if (ret == -EPROBE_DEFER) {
 524                                 of_node_put(child);
 525                                 return ERR_PTR(-EPROBE_DEFER);
 526                         }
 527                         dev_err(dev,
 528                                 "driver callback failed to parse DT for regulator %pOFn\n",
 529                                 child);
 530                         goto error;
 531                 }
 532         }
 533
 534         *node = child;
 535
 536         return init_data;
 537
 538 error:
 539         of_node_put(child);
 540
 541         return NULL;
 542 }
 543
 544 struct regulator_dev *of_find_regulator_by_node(struct device_node *np)
 545 {
 546         struct device *dev;
 547
 548         dev = class_find_device_by_of_node(&regulator_class, np);
 549
 550         return dev ? dev_to_rdev(dev) : NULL;
 551 }
 552
 553 /*
 554  * Returns number of regulators coupled with rdev.
 555  */
 556 int of_get_n_coupled(struct regulator_dev *rdev)
 557 {
 558         struct device_node *node = rdev->dev.of_node;
 559         int n_phandles;
 560
 561         n_phandles = of_count_phandle_with_args(node,
 562                                                 "regulator-coupled-with",
 563                                                 NULL);
 564
 565         return (n_phandles > 0) ? n_phandles : 0;
 566 }
 567
 568 /* Looks for "to_find" device_node in src's "regulator-coupled-with" property */
 569 static bool of_coupling_find_node(struct device_node *src,
 570                                   struct device_node *to_find,
 571                                   int *index)
 572 {
 573         int n_phandles, i;
 574         bool found = false;
 575
 576         n_phandles = of_count_phandle_with_args(src,
 577                                                 "regulator-coupled-with",
 578                                                 NULL);
 579
 580         for (i = 0; i < n_phandles; i++) {
 581                 struct device_node *tmp = of_parse_phandle(src,
 582                                            "regulator-coupled-with", i);
 583
 584                 if (!tmp)
 585                         break;
 586
 587                 /* found */
 588                 if (tmp == to_find)
 589                         found = true;
 590
 591                 of_node_put(tmp);
 592
 593                 if (found) {
 594                         *index = i;
 595                         break;
 596                 }
 597         }
 598
 599         return found;
 600 }
 601
 602 /**
 603  * of_check_coupling_data - Parse rdev's coupling properties and check data
 604  *                          consistency
 605  * @rdev: pointer to regulator_dev whose data is checked
 606  *
 607  * Function checks if all the following conditions are met:
 608  * - rdev's max_spread is greater than 0
 609  * - all coupled regulators have the same max_spread
 610  * - all coupled regulators have the same number of regulator_dev phandles
 611  * - all regulators are linked to each other
 612  *
 613  * Returns true if all conditions are met.
 614  */
 615 bool of_check_coupling_data(struct regulator_dev *rdev)
 616 {
 617         struct device_node *node = rdev->dev.of_node;
 618         int n_phandles = of_get_n_coupled(rdev);
 619         struct device_node *c_node;
 620         int index;
 621         int i;
 622         bool ret = true;
 623
 624         /* iterate over rdev's phandles */
 625         for (i = 0; i < n_phandles; i++) {
 626                 int max_spread = rdev->constraints->max_spread[i];
 627                 int c_max_spread, c_n_phandles;
 628
 629                 if (max_spread <= 0) {
 630                         dev_err(&rdev->dev, "max_spread value invalid\n");
 631                         return false;
 632                 }
 633
 634                 c_node = of_parse_phandle(node,
 635                                           "regulator-coupled-with", i);
 636
 637                 if (!c_node)
 638                         ret = false;
 639
 640                 c_n_phandles = of_count_phandle_with_args(c_node,
 641                                                           "regulator-coupled-with",
 642                                                           NULL);
 643
 644                 if (c_n_phandles != n_phandles) {
 645                         dev_err(&rdev->dev, "number of coupled reg phandles mismatch\n");
 646                         ret = false;
 647                         goto clean;
 648                 }
 649
 650                 if (!of_coupling_find_node(c_node, node, &index)) {
 651                         dev_err(&rdev->dev, "missing 2-way linking for coupled regulators\n");
 652                         ret = false;
 653                         goto clean;
 654                 }
 655
 656                 if (of_property_read_u32_index(c_node, "regulator-coupled-max-spread",
 657                                                index, &c_max_spread)) {
 658                         ret = false;
 659                         goto clean;
 660                 }
 661
 662                 if (c_max_spread != max_spread) {
 663                         dev_err(&rdev->dev,
 664                                 "coupled regulators max_spread mismatch\n");
 665                         ret = false;
 666                         goto clean;
 667                 }
 668
 669 clean:
 670                 of_node_put(c_node);
 671                 if (!ret)
 672                         break;
 673         }
 674
 675         return ret;
 676 }
 677
 678 /**
 679  * of_parse_coupled regulator - Get regulator_dev pointer from rdev's property
 680  * @rdev: Pointer to regulator_dev, whose DTS is used as a source to parse
 681  *        "regulator-coupled-with" property
 682  * @index: Index in phandles array
 683  *
 684  * Returns the regulator_dev pointer parsed from DTS. If it has not been yet
 685  * registered, returns NULL
 686  */
 687 struct regulator_dev *of_parse_coupled_regulator(struct regulator_dev *rdev,
 688                                                  int index)
 689 {
 690         struct device_node *node = rdev->dev.of_node;
 691         struct device_node *c_node;
 692         struct regulator_dev *c_rdev;
 693
 694         c_node = of_parse_phandle(node, "regulator-coupled-with", index);
 695         if (!c_node)
 696                 return NULL;
 697
 698         c_rdev = of_find_regulator_by_node(c_node);
 699
 700         of_node_put(c_node);
 701
 702         return c_rdev;
 703 }