drivers/regulator/vctrl-regulator.c

   1 /*
   2  * Driver for voltage controller regulators
   3  *
   4  * Copyright (C) 2017 Google, Inc.
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <linux/delay.h>
  17 #include <linux/err.h>
  18 #include <linux/init.h>
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21 #include <linux/of_device.h>
  22 #include <linux/regulator/driver.h>
  23 #include <linux/regulator/of_regulator.h>
  24 #include <linux/sort.h>
  25
  26 struct vctrl_voltage_range {
  27         int min_uV;
  28         int max_uV;
  29 };
  30
  31 struct vctrl_voltage_ranges {
  32         struct vctrl_voltage_range ctrl;
  33         struct vctrl_voltage_range out;
  34 };
  35
  36 struct vctrl_voltage_table {
  37         int ctrl;
  38         int out;
  39         int ovp_min_sel;
  40 };
  41
  42 struct vctrl_data {
  43         struct regulator_dev *rdev;
  44         struct regulator_desc desc;
  45         struct regulator *ctrl_reg;
  46         bool enabled;
  47         unsigned int min_slew_down_rate;
  48         unsigned int ovp_threshold;
  49         struct vctrl_voltage_ranges vrange;
  50         struct vctrl_voltage_table *vtable;
  51         unsigned int sel;
  52 };
  53
  54 static int vctrl_calc_ctrl_voltage(struct vctrl_data *vctrl, int out_uV)
  55 {
  56         struct vctrl_voltage_range *ctrl = &vctrl->vrange.ctrl;
  57         struct vctrl_voltage_range *out = &vctrl->vrange.out;
  58
  59         return ctrl->min_uV +
  60                 DIV_ROUND_CLOSEST_ULL((s64)(out_uV - out->min_uV) *
  61                                       (ctrl->max_uV - ctrl->min_uV),
  62                                       out->max_uV - out->min_uV);
  63 }
  64
  65 static int vctrl_calc_output_voltage(struct vctrl_data *vctrl, int ctrl_uV)
  66 {
  67         struct vctrl_voltage_range *ctrl = &vctrl->vrange.ctrl;
  68         struct vctrl_voltage_range *out = &vctrl->vrange.out;
  69
  70         if (ctrl_uV < 0) {
  71                 pr_err("vctrl: failed to get control voltage\n");
  72                 return ctrl_uV;
  73         }
  74
  75         if (ctrl_uV < ctrl->min_uV)
  76                 return out->min_uV;
  77
  78         if (ctrl_uV > ctrl->max_uV)
  79                 return out->max_uV;
  80
  81         return out->min_uV +
  82                 DIV_ROUND_CLOSEST_ULL((s64)(ctrl_uV - ctrl->min_uV) *
  83                                       (out->max_uV - out->min_uV),
  84                                       ctrl->max_uV - ctrl->min_uV);
  85 }
  86
  87 static int vctrl_get_voltage(struct regulator_dev *rdev)
  88 {
  89         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
  90         int ctrl_uV = regulator_get_voltage(vctrl->ctrl_reg);
  91
  92         return vctrl_calc_output_voltage(vctrl, ctrl_uV);
  93 }
  94
  95 static int vctrl_set_voltage(struct regulator_dev *rdev,
  96                              int req_min_uV, int req_max_uV,
  97                              unsigned int *selector)
  98 {
  99         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
 100         struct regulator *ctrl_reg = vctrl->ctrl_reg;
 101         int orig_ctrl_uV = regulator_get_voltage(ctrl_reg);
 102         int uV = vctrl_calc_output_voltage(vctrl, orig_ctrl_uV);
 103         int ret;
 104
 105         if (req_min_uV >= uV || !vctrl->ovp_threshold)
 106                 /* voltage rising or no OVP */
 107                 return regulator_set_voltage(
 108                         ctrl_reg,
 109                         vctrl_calc_ctrl_voltage(vctrl, req_min_uV),
 110                         vctrl_calc_ctrl_voltage(vctrl, req_max_uV));
 111
 112         while (uV > req_min_uV) {
 113                 int max_drop_uV = (uV * vctrl->ovp_threshold) / 100;
 114                 int next_uV;
 115                 int next_ctrl_uV;
 116                 int delay;
 117
 118                 /* Make sure no infinite loop even in crazy cases */
 119                 if (max_drop_uV == 0)
 120                         max_drop_uV = 1;
 121
 122                 next_uV = max_t(int, req_min_uV, uV - max_drop_uV);
 123                 next_ctrl_uV = vctrl_calc_ctrl_voltage(vctrl, next_uV);
 124
 125                 ret = regulator_set_voltage(ctrl_reg,
 126                                             next_ctrl_uV,
 127                                             next_ctrl_uV);
 128                 if (ret)
 129                         goto err;
 130
 131                 delay = DIV_ROUND_UP(uV - next_uV, vctrl->min_slew_down_rate);
 132                 usleep_range(delay, delay + DIV_ROUND_UP(delay, 10));
 133
 134                 uV = next_uV;
 135         }
 136
 137         return 0;
 138
 139 err:
 140         /* Try to go back to original voltage */
 141         regulator_set_voltage(ctrl_reg, orig_ctrl_uV, orig_ctrl_uV);
 142
 143         return ret;
 144 }
 145
 146 static int vctrl_get_voltage_sel(struct regulator_dev *rdev)
 147 {
 148         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
 149
 150         return vctrl->sel;
 151 }
 152
 153 static int vctrl_set_voltage_sel(struct regulator_dev *rdev,
 154                                  unsigned int selector)
 155 {
 156         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
 157         struct regulator *ctrl_reg = vctrl->ctrl_reg;
 158         unsigned int orig_sel = vctrl->sel;
 159         int ret;
 160
 161         if (selector >= rdev->desc->n_voltages)
 162                 return -EINVAL;
 163
 164         if (selector >= vctrl->sel || !vctrl->ovp_threshold) {
 165                 /* voltage rising or no OVP */
 166                 ret = regulator_set_voltage(ctrl_reg,
 167                                             vctrl->vtable[selector].ctrl,
 168                                             vctrl->vtable[selector].ctrl);
 169                 if (!ret)
 170                         vctrl->sel = selector;
 171
 172                 return ret;
 173         }
 174
 175         while (vctrl->sel != selector) {
 176                 unsigned int next_sel;
 177                 int delay;
 178
 179                 if (selector >= vctrl->vtable[vctrl->sel].ovp_min_sel)
 180                         next_sel = selector;
 181                 else
 182                         next_sel = vctrl->vtable[vctrl->sel].ovp_min_sel;
 183
 184                 ret = regulator_set_voltage(ctrl_reg,
 185                                             vctrl->vtable[next_sel].ctrl,
 186                                             vctrl->vtable[next_sel].ctrl);
 187                 if (ret) {
 188                         dev_err(&rdev->dev,
 189                                 "failed to set control voltage to %duV\n",
 190                                 vctrl->vtable[next_sel].ctrl);
 191                         goto err;
 192                 }
 193                 vctrl->sel = next_sel;
 194
 195                 delay = DIV_ROUND_UP(vctrl->vtable[vctrl->sel].out -
 196                                      vctrl->vtable[next_sel].out,
 197                                      vctrl->min_slew_down_rate);
 198                 usleep_range(delay, delay + DIV_ROUND_UP(delay, 10));
 199         }
 200
 201         return 0;
 202
 203 err:
 204         if (vctrl->sel != orig_sel) {
 205                 /* Try to go back to original voltage */
 206                 if (!regulator_set_voltage(ctrl_reg,
 207                                            vctrl->vtable[orig_sel].ctrl,
 208                                            vctrl->vtable[orig_sel].ctrl))
 209                         vctrl->sel = orig_sel;
 210                 else
 211                         dev_warn(&rdev->dev,
 212                                  "failed to restore original voltage\n");
 213         }
 214
 215         return ret;
 216 }
 217
 218 static int vctrl_list_voltage(struct regulator_dev *rdev,
 219                               unsigned int selector)
 220 {
 221         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
 222
 223         if (selector >= rdev->desc->n_voltages)
 224                 return -EINVAL;
 225
 226         return vctrl->vtable[selector].out;
 227 }
 228
 229 static int vctrl_parse_dt(struct platform_device *pdev,
 230                           struct vctrl_data *vctrl)
 231 {
 232         int ret;
 233         struct device_node *np = pdev->dev.of_node;
 234         u32 pval;
 235         u32 vrange_ctrl[2];
 236
 237         vctrl->ctrl_reg = devm_regulator_get(&pdev->dev, "ctrl");
 238         if (IS_ERR(vctrl->ctrl_reg))
 239                 return PTR_ERR(vctrl->ctrl_reg);
 240
 241         ret = of_property_read_u32(np, "ovp-threshold-percent", &pval);
 242         if (!ret) {
 243                 vctrl->ovp_threshold = pval;
 244                 if (vctrl->ovp_threshold > 100) {
 245                         dev_err(&pdev->dev,
 246                                 "ovp-threshold-percent (%u) > 100\n",
 247                                 vctrl->ovp_threshold);
 248                         return -EINVAL;
 249                 }
 250         }
 251
 252         ret = of_property_read_u32(np, "min-slew-down-rate", &pval);
 253         if (!ret) {
 254                 vctrl->min_slew_down_rate = pval;
 255
 256                 /* We use the value as int and as divider; sanity check */
 257                 if (vctrl->min_slew_down_rate == 0) {
 258                         dev_err(&pdev->dev,
 259                                 "min-slew-down-rate must not be 0\n");
 260                         return -EINVAL;
 261                 } else if (vctrl->min_slew_down_rate > INT_MAX) {
 262                         dev_err(&pdev->dev, "min-slew-down-rate (%u) too big\n",
 263                                 vctrl->min_slew_down_rate);
 264                         return -EINVAL;
 265                 }
 266         }
 267
 268         if (vctrl->ovp_threshold && !vctrl->min_slew_down_rate) {
 269                 dev_err(&pdev->dev,
 270                         "ovp-threshold-percent requires min-slew-down-rate\n");
 271                 return -EINVAL;
 272         }
 273
 274         ret = of_property_read_u32(np, "regulator-min-microvolt", &pval);
 275         if (ret) {
 276                 dev_err(&pdev->dev,
 277                         "failed to read regulator-min-microvolt: %d\n", ret);
 278                 return ret;
 279         }
 280         vctrl->vrange.out.min_uV = pval;
 281
 282         ret = of_property_read_u32(np, "regulator-max-microvolt", &pval);
 283         if (ret) {
 284                 dev_err(&pdev->dev,
 285                         "failed to read regulator-max-microvolt: %d\n", ret);
 286                 return ret;
 287         }
 288         vctrl->vrange.out.max_uV = pval;
 289
 290         ret = of_property_read_u32_array(np, "ctrl-voltage-range", vrange_ctrl,
 291                                          2);
 292         if (ret) {
 293                 dev_err(&pdev->dev, "failed to read ctrl-voltage-range: %d\n",
 294                         ret);
 295                 return ret;
 296         }
 297
 298         if (vrange_ctrl[0] >= vrange_ctrl[1]) {
 299                 dev_err(&pdev->dev, "ctrl-voltage-range is invalid: %d-%d\n",
 300                         vrange_ctrl[0], vrange_ctrl[1]);
 301                 return -EINVAL;
 302         }
 303
 304         vctrl->vrange.ctrl.min_uV = vrange_ctrl[0];
 305         vctrl->vrange.ctrl.max_uV = vrange_ctrl[1];
 306
 307         return 0;
 308 }
 309
 310 static int vctrl_cmp_ctrl_uV(const void *a, const void *b)
 311 {
 312         const struct vctrl_voltage_table *at = a;
 313         const struct vctrl_voltage_table *bt = b;
 314
 315         return at->ctrl - bt->ctrl;
 316 }
 317
 318 static int vctrl_init_vtable(struct platform_device *pdev)
 319 {
 320         struct vctrl_data *vctrl = platform_get_drvdata(pdev);
 321         struct regulator_desc *rdesc = &vctrl->desc;
 322         struct regulator *ctrl_reg = vctrl->ctrl_reg;
 323         struct vctrl_voltage_range *vrange_ctrl = &vctrl->vrange.ctrl;
 324         int n_voltages;
 325         int ctrl_uV;
 326         int i, idx_vt;
 327
 328         n_voltages = regulator_count_voltages(ctrl_reg);
 329
 330         rdesc->n_voltages = n_voltages;
 331
 332         /* determine number of steps within the range of the vctrl regulator */
 333         for (i = 0; i < n_voltages; i++) {
 334                 ctrl_uV = regulator_list_voltage(ctrl_reg, i);
 335
 336                 if (ctrl_uV < vrange_ctrl->min_uV ||
 337                     ctrl_uV > vrange_ctrl->max_uV) {
 338                         rdesc->n_voltages--;
 339                         continue;
 340                 }
 341         }
 342
 343         if (rdesc->n_voltages == 0) {
 344                 dev_err(&pdev->dev, "invalid configuration\n");
 345                 return -EINVAL;
 346         }
 347
 348         vctrl->vtable = devm_kcalloc(&pdev->dev, rdesc->n_voltages,
 349                                      sizeof(struct vctrl_voltage_table),
 350                                      GFP_KERNEL);
 351         if (!vctrl->vtable)
 352                 return -ENOMEM;
 353
 354         /* create mapping control <=> output voltage */
 355         for (i = 0, idx_vt = 0; i < n_voltages; i++) {
 356                 ctrl_uV = regulator_list_voltage(ctrl_reg, i);
 357
 358                 if (ctrl_uV < vrange_ctrl->min_uV ||
 359                     ctrl_uV > vrange_ctrl->max_uV)
 360                         continue;
 361
 362                 vctrl->vtable[idx_vt].ctrl = ctrl_uV;
 363                 vctrl->vtable[idx_vt].out =
 364                         vctrl_calc_output_voltage(vctrl, ctrl_uV);
 365                 idx_vt++;
 366         }
 367
 368         /* we rely on the table to be ordered by ascending voltage */
 369         sort(vctrl->vtable, rdesc->n_voltages,
 370              sizeof(struct vctrl_voltage_table), vctrl_cmp_ctrl_uV,
 371              NULL);
 372
 373         /* pre-calculate OVP-safe downward transitions */
 374         for (i = rdesc->n_voltages - 1; i > 0; i--) {
 375                 int j;
 376                 int ovp_min_uV = (vctrl->vtable[i].out *
 377                                   (100 - vctrl->ovp_threshold)) / 100;
 378
 379                 for (j = 0; j < i; j++) {
 380                         if (vctrl->vtable[j].out >= ovp_min_uV) {
 381                                 vctrl->vtable[i].ovp_min_sel = j;
 382                                 break;
 383                         }
 384                 }
 385
 386                 if (j == i) {
 387                         dev_warn(&pdev->dev, "switching down from %duV may cause OVP shutdown\n",
 388                                 vctrl->vtable[i].out);
 389                         /* use next lowest voltage */
 390                         vctrl->vtable[i].ovp_min_sel = i - 1;
 391                 }
 392         }
 393
 394         return 0;
 395 }
 396
 397 static int vctrl_enable(struct regulator_dev *rdev)
 398 {
 399         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
 400         int ret = regulator_enable(vctrl->ctrl_reg);
 401
 402         if (!ret)
 403                 vctrl->enabled = true;
 404
 405         return ret;
 406 }
 407
 408 static int vctrl_disable(struct regulator_dev *rdev)
 409 {
 410         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
 411         int ret = regulator_disable(vctrl->ctrl_reg);
 412
 413         if (!ret)
 414                 vctrl->enabled = false;
 415
 416         return ret;
 417 }
 418
 419 static int vctrl_is_enabled(struct regulator_dev *rdev)
 420 {
 421         struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
 422
 423         return vctrl->enabled;
 424 }
 425
 426 static const struct regulator_ops vctrl_ops_cont = {
 427         .enable           = vctrl_enable,
 428         .disable          = vctrl_disable,
 429         .is_enabled       = vctrl_is_enabled,
 430         .get_voltage      = vctrl_get_voltage,
 431         .set_voltage      = vctrl_set_voltage,
 432 };
 433
 434 static const struct regulator_ops vctrl_ops_non_cont = {
 435         .enable           = vctrl_enable,
 436         .disable          = vctrl_disable,
 437         .is_enabled       = vctrl_is_enabled,
 438         .set_voltage_sel = vctrl_set_voltage_sel,
 439         .get_voltage_sel = vctrl_get_voltage_sel,
 440         .list_voltage    = vctrl_list_voltage,
 441         .map_voltage     = regulator_map_voltage_iterate,
 442 };
 443
 444 static int vctrl_probe(struct platform_device *pdev)
 445 {
 446         struct device_node *np = pdev->dev.of_node;
 447         struct vctrl_data *vctrl;
 448         const struct regulator_init_data *init_data;
 449         struct regulator_desc *rdesc;
 450         struct regulator_config cfg = { };
 451         struct vctrl_voltage_range *vrange_ctrl;
 452         int ctrl_uV;
 453         int ret;
 454
 455         vctrl = devm_kzalloc(&pdev->dev, sizeof(struct vctrl_data),
 456                              GFP_KERNEL);
 457         if (!vctrl)
 458                 return -ENOMEM;
 459
 460         platform_set_drvdata(pdev, vctrl);
 461
 462         ret = vctrl_parse_dt(pdev, vctrl);
 463         if (ret)
 464                 return ret;
 465
 466         vrange_ctrl = &vctrl->vrange.ctrl;
 467
 468         rdesc = &vctrl->desc;
 469         rdesc->name = "vctrl";
 470         rdesc->type = REGULATOR_VOLTAGE;
 471         rdesc->owner = THIS_MODULE;
 472
 473         if ((regulator_get_linear_step(vctrl->ctrl_reg) == 1) ||
 474             (regulator_count_voltages(vctrl->ctrl_reg) == -EINVAL)) {
 475                 rdesc->continuous_voltage_range = true;
 476                 rdesc->ops = &vctrl_ops_cont;
 477         } else {
 478                 rdesc->ops = &vctrl_ops_non_cont;
 479         }
 480
 481         init_data = of_get_regulator_init_data(&pdev->dev, np, rdesc);
 482         if (!init_data)
 483                 return -ENOMEM;
 484
 485         cfg.of_node = np;
 486         cfg.dev = &pdev->dev;
 487         cfg.driver_data = vctrl;
 488         cfg.init_data = init_data;
 489
 490         if (!rdesc->continuous_voltage_range) {
 491                 ret = vctrl_init_vtable(pdev);
 492                 if (ret)
 493                         return ret;
 494
 495                 ctrl_uV = regulator_get_voltage(vctrl->ctrl_reg);
 496                 if (ctrl_uV < 0) {
 497                         dev_err(&pdev->dev, "failed to get control voltage\n");
 498                         return ctrl_uV;
 499                 }
 500
 501                 /* determine current voltage selector from control voltage */
 502                 if (ctrl_uV < vrange_ctrl->min_uV) {
 503                         vctrl->sel = 0;
 504                 } else if (ctrl_uV > vrange_ctrl->max_uV) {
 505                         vctrl->sel = rdesc->n_voltages - 1;
 506                 } else {
 507                         int i;
 508
 509                         for (i = 0; i < rdesc->n_voltages; i++) {
 510                                 if (ctrl_uV == vctrl->vtable[i].ctrl) {
 511                                         vctrl->sel = i;
 512                                         break;
 513                                 }
 514                         }
 515                 }
 516         }
 517
 518         vctrl->rdev = devm_regulator_register(&pdev->dev, rdesc, &cfg);
 519         if (IS_ERR(vctrl->rdev)) {
 520                 ret = PTR_ERR(vctrl->rdev);
 521                 dev_err(&pdev->dev, "failed to register regulator: %d\n", ret);
 522                 return ret;
 523         }
 524
 525         return 0;
 526 }
 527
 528 static const struct of_device_id vctrl_of_match[] = {
 529         { .compatible = "vctrl-regulator", },
 530         {},
 531 };
 532 MODULE_DEVICE_TABLE(of, vctrl_of_match);
 533
 534 static struct platform_driver vctrl_driver = {
 535         .probe          = vctrl_probe,
 536         .driver         = {
 537                 .name           = "vctrl-regulator",
 538                 .of_match_table = of_match_ptr(vctrl_of_match),
 539         },
 540 };
 541
 542 module_platform_driver(vctrl_driver);
 543
 544 MODULE_DESCRIPTION("Voltage Controlled Regulator Driver");
 545 MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
 546 MODULE_LICENSE("GPL v2");