drivers/pwm/pwm-sti.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * PWM device driver for ST SoCs
   4  *
   5  * Copyright (C) 2013-2016 STMicroelectronics (R&D) Limited
   6  *
   7  * Author: Ajit Pal Singh <ajitpal.singh@st.com>
   8  *         Lee Jones <lee.jones@linaro.org>
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/math64.h>
  14 #include <linux/mfd/syscon.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/pwm.h>
  19 #include <linux/regmap.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22 #include <linux/time.h>
  23 #include <linux/wait.h>
  24
  25 #define PWM_OUT_VAL(x)  (0x00 + (4 * (x))) /* Device's Duty Cycle register */
  26 #define PWM_CPT_VAL(x)  (0x10 + (4 * (x))) /* Capture value */
  27 #define PWM_CPT_EDGE(x) (0x30 + (4 * (x))) /* Edge to capture on */
  28
  29 #define STI_PWM_CTRL            0x50    /* Control/Config register */
  30 #define STI_INT_EN              0x54    /* Interrupt Enable/Disable register */
  31 #define STI_INT_STA             0x58    /* Interrupt Status register */
  32 #define PWM_INT_ACK             0x5c
  33 #define PWM_PRESCALE_LOW_MASK   0x0f
  34 #define PWM_PRESCALE_HIGH_MASK  0xf0
  35 #define PWM_CPT_EDGE_MASK       0x03
  36 #define PWM_INT_ACK_MASK        0x1ff
  37
  38 #define STI_MAX_CPT_DEVS        4
  39 #define CPT_DC_MAX              0xff
  40
  41 /* Regfield IDs */
  42 enum {
  43         /* Bits in PWM_CTRL*/
  44         PWMCLK_PRESCALE_LOW,
  45         PWMCLK_PRESCALE_HIGH,
  46         CPTCLK_PRESCALE,
  47
  48         PWM_OUT_EN,
  49         PWM_CPT_EN,
  50
  51         PWM_CPT_INT_EN,
  52         PWM_CPT_INT_STAT,
  53
  54         /* Keep last */
  55         MAX_REGFIELDS
  56 };
  57
  58 /*
  59  * Each capture input can be programmed to detect rising-edge, falling-edge,
  60  * either edge or neither egde.
  61  */
  62 enum sti_cpt_edge {
  63         CPT_EDGE_DISABLED,
  64         CPT_EDGE_RISING,
  65         CPT_EDGE_FALLING,
  66         CPT_EDGE_BOTH,
  67 };
  68
  69 struct sti_cpt_ddata {
  70         u32 snapshot[3];
  71         unsigned int index;
  72         struct mutex lock;
  73         wait_queue_head_t wait;
  74 };
  75
  76 struct sti_pwm_compat_data {
  77         const struct reg_field *reg_fields;
  78         unsigned int pwm_num_devs;
  79         unsigned int cpt_num_devs;
  80         unsigned int max_pwm_cnt;
  81         unsigned int max_prescale;
  82         struct sti_cpt_ddata *ddata;
  83 };
  84
  85 struct sti_pwm_chip {
  86         struct device *dev;
  87         struct clk *pwm_clk;
  88         struct clk *cpt_clk;
  89         struct regmap *regmap;
  90         struct sti_pwm_compat_data *cdata;
  91         struct regmap_field *prescale_low;
  92         struct regmap_field *prescale_high;
  93         struct regmap_field *pwm_out_en;
  94         struct regmap_field *pwm_cpt_en;
  95         struct regmap_field *pwm_cpt_int_en;
  96         struct regmap_field *pwm_cpt_int_stat;
  97         struct pwm_device *cur;
  98         unsigned long configured;
  99         unsigned int en_count;
 100         struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
 101         void __iomem *mmio;
 102 };
 103
 104 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
 105         [PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWM_CTRL, 0, 3),
 106         [PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWM_CTRL, 11, 14),
 107         [CPTCLK_PRESCALE] = REG_FIELD(STI_PWM_CTRL, 4, 8),
 108         [PWM_OUT_EN] = REG_FIELD(STI_PWM_CTRL, 9, 9),
 109         [PWM_CPT_EN] = REG_FIELD(STI_PWM_CTRL, 10, 10),
 110         [PWM_CPT_INT_EN] = REG_FIELD(STI_INT_EN, 1, 4),
 111         [PWM_CPT_INT_STAT] = REG_FIELD(STI_INT_STA, 1, 4),
 112 };
 113
 114 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
 115 {
 116         return pwmchip_get_drvdata(chip);
 117 }
 118
 119 /*
 120  * Calculate the prescaler value corresponding to the period.
 121  */
 122 static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
 123                                 unsigned int *prescale)
 124 {
 125         struct sti_pwm_compat_data *cdata = pc->cdata;
 126         unsigned long clk_rate;
 127         unsigned long value;
 128         unsigned int ps;
 129
 130         clk_rate = clk_get_rate(pc->pwm_clk);
 131         if (!clk_rate) {
 132                 dev_err(pc->dev, "failed to get clock rate\n");
 133                 return -EINVAL;
 134         }
 135
 136         /*
 137          * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_cnt + 1)) - 1
 138          */
 139         value = NSEC_PER_SEC / clk_rate;
 140         value *= cdata->max_pwm_cnt + 1;
 141
 142         if (period % value)
 143                 return -EINVAL;
 144
 145         ps  = period / value - 1;
 146         if (ps > cdata->max_prescale)
 147                 return -EINVAL;
 148
 149         *prescale = ps;
 150
 151         return 0;
 152 }
 153
 154 /*
 155  * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles. The
 156  * only way to change the period (apart from changing the PWM input clock) is
 157  * to change the PWM clock prescaler.
 158  *
 159  * The prescaler is of 8 bits, so 256 prescaler values and hence 256 possible
 160  * period values are supported (for a particular clock rate). The requested
 161  * period will be applied only if it matches one of these 256 values.
 162  */
 163 static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 164                           int duty_ns, int period_ns)
 165 {
 166         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 167         struct sti_pwm_compat_data *cdata = pc->cdata;
 168         unsigned int ncfg, value, prescale = 0;
 169         struct pwm_device *cur = pc->cur;
 170         struct device *dev = pc->dev;
 171         bool period_same = false;
 172         int ret;
 173
 174         ncfg = hweight_long(pc->configured);
 175         if (ncfg)
 176                 period_same = (period_ns == pwm_get_period(cur));
 177
 178         /*
 179          * Allow configuration changes if one of the following conditions
 180          * satisfy.
 181          * 1. No devices have been configured.
 182          * 2. Only one device has been configured and the new request is for
 183          *    the same device.
 184          * 3. Only one device has been configured and the new request is for
 185          *    a new device and period of the new device is same as the current
 186          *    configured period.
 187          * 4. More than one devices are configured and period of the new
 188          *    requestis the same as the current period.
 189          */
 190         if (!ncfg ||
 191             ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
 192             ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
 193             ((ncfg > 1) && period_same)) {
 194                 /* Enable clock before writing to PWM registers. */
 195                 ret = clk_enable(pc->pwm_clk);
 196                 if (ret)
 197                         return ret;
 198
 199                 ret = clk_enable(pc->cpt_clk);
 200                 if (ret)
 201                         return ret;
 202
 203                 if (!period_same) {
 204                         ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
 205                         if (ret)
 206                                 goto clk_dis;
 207
 208                         value = prescale & PWM_PRESCALE_LOW_MASK;
 209
 210                         ret = regmap_field_write(pc->prescale_low, value);
 211                         if (ret)
 212                                 goto clk_dis;
 213
 214                         value = (prescale & PWM_PRESCALE_HIGH_MASK) >> 4;
 215
 216                         ret = regmap_field_write(pc->prescale_high, value);
 217                         if (ret)
 218                                 goto clk_dis;
 219                 }
 220
 221                 /*
 222                  * When PWMVal == 0, PWM pulse = 1 local clock cycle.
 223                  * When PWMVal == max_pwm_count,
 224                  * PWM pulse = (max_pwm_count + 1) local cycles,
 225                  * that is continuous pulse: signal never goes low.
 226                  */
 227                 value = cdata->max_pwm_cnt * duty_ns / period_ns;
 228
 229                 ret = regmap_write(pc->regmap, PWM_OUT_VAL(pwm->hwpwm), value);
 230                 if (ret)
 231                         goto clk_dis;
 232
 233                 ret = regmap_field_write(pc->pwm_cpt_int_en, 0);
 234
 235                 set_bit(pwm->hwpwm, &pc->configured);
 236                 pc->cur = pwm;
 237
 238                 dev_dbg(dev, "prescale:%u, period:%i, duty:%i, value:%u\n",
 239                         prescale, period_ns, duty_ns, value);
 240         } else {
 241                 return -EINVAL;
 242         }
 243
 244 clk_dis:
 245         clk_disable(pc->pwm_clk);
 246         clk_disable(pc->cpt_clk);
 247         return ret;
 248 }
 249
 250 static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 251 {
 252         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 253         struct device *dev = pc->dev;
 254         int ret = 0;
 255
 256         /*
 257          * Since we have a common enable for all PWM devices, do not enable if
 258          * already enabled.
 259          */
 260         mutex_lock(&pc->sti_pwm_lock);
 261
 262         if (!pc->en_count) {
 263                 ret = clk_enable(pc->pwm_clk);
 264                 if (ret)
 265                         goto out;
 266
 267                 ret = clk_enable(pc->cpt_clk);
 268                 if (ret)
 269                         goto out;
 270
 271                 ret = regmap_field_write(pc->pwm_out_en, 1);
 272                 if (ret) {
 273                         dev_err(dev, "failed to enable PWM device %u: %d\n",
 274                                 pwm->hwpwm, ret);
 275                         goto out;
 276                 }
 277         }
 278
 279         pc->en_count++;
 280
 281 out:
 282         mutex_unlock(&pc->sti_pwm_lock);
 283         return ret;
 284 }
 285
 286 static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 287 {
 288         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 289
 290         mutex_lock(&pc->sti_pwm_lock);
 291
 292         if (--pc->en_count) {
 293                 mutex_unlock(&pc->sti_pwm_lock);
 294                 return;
 295         }
 296
 297         regmap_field_write(pc->pwm_out_en, 0);
 298
 299         clk_disable(pc->pwm_clk);
 300         clk_disable(pc->cpt_clk);
 301
 302         mutex_unlock(&pc->sti_pwm_lock);
 303 }
 304
 305 static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 306 {
 307         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 308
 309         clear_bit(pwm->hwpwm, &pc->configured);
 310 }
 311
 312 static int sti_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm,
 313                            struct pwm_capture *result, unsigned long timeout)
 314 {
 315         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 316         struct sti_pwm_compat_data *cdata = pc->cdata;
 317         struct sti_cpt_ddata *ddata = &cdata->ddata[pwm->hwpwm];
 318         struct device *dev = pc->dev;
 319         unsigned int effective_ticks;
 320         unsigned long long high, low;
 321         int ret;
 322
 323         if (pwm->hwpwm >= cdata->cpt_num_devs) {
 324                 dev_err(dev, "device %u is not valid\n", pwm->hwpwm);
 325                 return -EINVAL;
 326         }
 327
 328         mutex_lock(&ddata->lock);
 329         ddata->index = 0;
 330
 331         /* Prepare capture measurement */
 332         regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_RISING);
 333         regmap_field_write(pc->pwm_cpt_int_en, BIT(pwm->hwpwm));
 334
 335         /* Enable capture */
 336         ret = regmap_field_write(pc->pwm_cpt_en, 1);
 337         if (ret) {
 338                 dev_err(dev, "failed to enable PWM capture %u: %d\n",
 339                         pwm->hwpwm, ret);
 340                 goto out;
 341         }
 342
 343         ret = wait_event_interruptible_timeout(ddata->wait, ddata->index > 1,
 344                                                msecs_to_jiffies(timeout));
 345
 346         regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_DISABLED);
 347
 348         if (ret == -ERESTARTSYS)
 349                 goto out;
 350
 351         switch (ddata->index) {
 352         case 0:
 353         case 1:
 354                 /*
 355                  * Getting here could mean:
 356                  *  - input signal is constant of less than 1 Hz
 357                  *  - there is no input signal at all
 358                  *
 359                  * In such case the frequency is rounded down to 0
 360                  */
 361                 result->period = 0;
 362                 result->duty_cycle = 0;
 363
 364                 break;
 365
 366         case 2:
 367                 /* We have everying we need */
 368                 high = ddata->snapshot[1] - ddata->snapshot[0];
 369                 low = ddata->snapshot[2] - ddata->snapshot[1];
 370
 371                 effective_ticks = clk_get_rate(pc->cpt_clk);
 372
 373                 result->period = (high + low) * NSEC_PER_SEC;
 374                 result->period /= effective_ticks;
 375
 376                 result->duty_cycle = high * NSEC_PER_SEC;
 377                 result->duty_cycle /= effective_ticks;
 378
 379                 break;
 380
 381         default:
 382                 dev_err(dev, "internal error\n");
 383                 break;
 384         }
 385
 386 out:
 387         /* Disable capture */
 388         regmap_field_write(pc->pwm_cpt_en, 0);
 389
 390         mutex_unlock(&ddata->lock);
 391         return ret;
 392 }
 393
 394 static int sti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 395                          const struct pwm_state *state)
 396 {
 397         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 398         struct sti_pwm_compat_data *cdata = pc->cdata;
 399         struct device *dev = pc->dev;
 400         int err;
 401
 402         if (pwm->hwpwm >= cdata->pwm_num_devs) {
 403                 dev_err(dev, "device %u is not valid for pwm mode\n",
 404                         pwm->hwpwm);
 405                 return -EINVAL;
 406         }
 407
 408         if (state->polarity != PWM_POLARITY_NORMAL)
 409                 return -EINVAL;
 410
 411         if (!state->enabled) {
 412                 if (pwm->state.enabled)
 413                         sti_pwm_disable(chip, pwm);
 414
 415                 return 0;
 416         }
 417
 418         err = sti_pwm_config(chip, pwm, state->duty_cycle, state->period);
 419         if (err)
 420                 return err;
 421
 422         if (!pwm->state.enabled)
 423                 err = sti_pwm_enable(chip, pwm);
 424
 425         return err;
 426 }
 427
 428 static const struct pwm_ops sti_pwm_ops = {
 429         .capture = sti_pwm_capture,
 430         .apply = sti_pwm_apply,
 431         .free = sti_pwm_free,
 432 };
 433
 434 static irqreturn_t sti_pwm_interrupt(int irq, void *data)
 435 {
 436         struct sti_pwm_chip *pc = data;
 437         struct device *dev = pc->dev;
 438         struct sti_cpt_ddata *ddata;
 439         int devicenum;
 440         unsigned int cpt_int_stat;
 441         unsigned int reg;
 442         int ret = IRQ_NONE;
 443
 444         ret = regmap_field_read(pc->pwm_cpt_int_stat, &cpt_int_stat);
 445         if (ret)
 446                 return ret;
 447
 448         while (cpt_int_stat) {
 449                 devicenum = ffs(cpt_int_stat) - 1;
 450
 451                 ddata = &pc->cdata->ddata[devicenum];
 452
 453                 /*
 454                  * Capture input:
 455                  *    _______                   _______
 456                  *   |       |                 |       |
 457                  * __|       |_________________|       |________
 458                  *   ^0      ^1                ^2
 459                  *
 460                  * Capture start by the first available rising edge. When a
 461                  * capture event occurs, capture value (CPT_VALx) is stored,
 462                  * index incremented, capture edge changed.
 463                  *
 464                  * After the capture, if the index > 1, we have collected the
 465                  * necessary data so we signal the thread waiting for it and
 466                  * disable the capture by setting capture edge to none
 467                  */
 468
 469                 regmap_read(pc->regmap,
 470                             PWM_CPT_VAL(devicenum),
 471                             &ddata->snapshot[ddata->index]);
 472
 473                 switch (ddata->index) {
 474                 case 0:
 475                 case 1:
 476                         regmap_read(pc->regmap, PWM_CPT_EDGE(devicenum), &reg);
 477                         reg ^= PWM_CPT_EDGE_MASK;
 478                         regmap_write(pc->regmap, PWM_CPT_EDGE(devicenum), reg);
 479
 480                         ddata->index++;
 481                         break;
 482
 483                 case 2:
 484                         regmap_write(pc->regmap,
 485                                      PWM_CPT_EDGE(devicenum),
 486                                      CPT_EDGE_DISABLED);
 487                         wake_up(&ddata->wait);
 488                         break;
 489
 490                 default:
 491                         dev_err(dev, "Internal error\n");
 492                 }
 493
 494                 cpt_int_stat &= ~BIT_MASK(devicenum);
 495
 496                 ret = IRQ_HANDLED;
 497         }
 498
 499         /* Just ACK everything */
 500         regmap_write(pc->regmap, PWM_INT_ACK, PWM_INT_ACK_MASK);
 501
 502         return ret;
 503 }
 504
 505 static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 506 {
 507         struct device *dev = pc->dev;
 508         const struct reg_field *reg_fields;
 509         struct sti_pwm_compat_data *cdata = pc->cdata;
 510
 511         reg_fields = cdata->reg_fields;
 512
 513         pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
 514                                         reg_fields[PWMCLK_PRESCALE_LOW]);
 515         if (IS_ERR(pc->prescale_low))
 516                 return PTR_ERR(pc->prescale_low);
 517
 518         pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
 519                                         reg_fields[PWMCLK_PRESCALE_HIGH]);
 520         if (IS_ERR(pc->prescale_high))
 521                 return PTR_ERR(pc->prescale_high);
 522
 523         pc->pwm_out_en = devm_regmap_field_alloc(dev, pc->regmap,
 524                                                  reg_fields[PWM_OUT_EN]);
 525         if (IS_ERR(pc->pwm_out_en))
 526                 return PTR_ERR(pc->pwm_out_en);
 527
 528         pc->pwm_cpt_en = devm_regmap_field_alloc(dev, pc->regmap,
 529                                                  reg_fields[PWM_CPT_EN]);
 530         if (IS_ERR(pc->pwm_cpt_en))
 531                 return PTR_ERR(pc->pwm_cpt_en);
 532
 533         pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
 534                                                 reg_fields[PWM_CPT_INT_EN]);
 535         if (IS_ERR(pc->pwm_cpt_int_en))
 536                 return PTR_ERR(pc->pwm_cpt_int_en);
 537
 538         pc->pwm_cpt_int_stat = devm_regmap_field_alloc(dev, pc->regmap,
 539                                                 reg_fields[PWM_CPT_INT_STAT]);
 540         if (PTR_ERR_OR_ZERO(pc->pwm_cpt_int_stat))
 541                 return PTR_ERR(pc->pwm_cpt_int_stat);
 542
 543         return 0;
 544 }
 545
 546 static const struct regmap_config sti_pwm_regmap_config = {
 547         .reg_bits = 32,
 548         .val_bits = 32,
 549         .reg_stride = 4,
 550 };
 551
 552 static int sti_pwm_probe(struct platform_device *pdev)
 553 {
 554         struct device *dev = &pdev->dev;
 555         struct device_node *np = dev->of_node;
 556         u32 num_devs;
 557         unsigned int pwm_num_devs = 0;
 558         unsigned int cpt_num_devs = 0;
 559         struct sti_pwm_compat_data *cdata;
 560         struct pwm_chip *chip;
 561         struct sti_pwm_chip *pc;
 562         unsigned int i;
 563         int irq, ret;
 564
 565         ret = of_property_read_u32(np, "st,pwm-num-chan", &num_devs);
 566         if (!ret)
 567                 pwm_num_devs = num_devs;
 568
 569         ret = of_property_read_u32(np, "st,capture-num-chan", &num_devs);
 570         if (!ret)
 571                 cpt_num_devs = num_devs;
 572
 573         if (!pwm_num_devs && !cpt_num_devs) {
 574                 dev_err(dev, "No channels configured\n");
 575                 return -EINVAL;
 576         }
 577
 578         chip = devm_pwmchip_alloc(dev, max(pwm_num_devs, cpt_num_devs), sizeof(*pc));
 579         if (IS_ERR(chip))
 580                 return PTR_ERR(chip);
 581         pc = to_sti_pwmchip(chip);
 582
 583         cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
 584         if (!cdata)
 585                 return -ENOMEM;
 586
 587         pc->mmio = devm_platform_ioremap_resource(pdev, 0);
 588         if (IS_ERR(pc->mmio))
 589                 return PTR_ERR(pc->mmio);
 590
 591         pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
 592                                            &sti_pwm_regmap_config);
 593         if (IS_ERR(pc->regmap))
 594                 return PTR_ERR(pc->regmap);
 595
 596         irq = platform_get_irq(pdev, 0);
 597         if (irq < 0)
 598                 return irq;
 599
 600         ret = devm_request_irq(&pdev->dev, irq, sti_pwm_interrupt, 0,
 601                                pdev->name, pc);
 602         if (ret < 0) {
 603                 dev_err(&pdev->dev, "Failed to request IRQ\n");
 604                 return ret;
 605         }
 606
 607         /*
 608          * Setup PWM data with default values: some values could be replaced
 609          * with specific ones provided from Device Tree.
 610          */
 611         cdata->reg_fields = sti_pwm_regfields;
 612         cdata->max_prescale = 0xff;
 613         cdata->max_pwm_cnt = 255;
 614         cdata->pwm_num_devs = pwm_num_devs;
 615         cdata->cpt_num_devs = cpt_num_devs;
 616
 617         pc->cdata = cdata;
 618         pc->dev = dev;
 619         pc->en_count = 0;
 620         mutex_init(&pc->sti_pwm_lock);
 621
 622         ret = sti_pwm_probe_dt(pc);
 623         if (ret)
 624                 return ret;
 625
 626         if (cdata->pwm_num_devs) {
 627                 pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
 628                 if (IS_ERR(pc->pwm_clk)) {
 629                         dev_err(dev, "failed to get PWM clock\n");
 630                         return PTR_ERR(pc->pwm_clk);
 631                 }
 632
 633                 ret = clk_prepare(pc->pwm_clk);
 634                 if (ret) {
 635                         dev_err(dev, "failed to prepare clock\n");
 636                         return ret;
 637                 }
 638         }
 639
 640         if (cdata->cpt_num_devs) {
 641                 pc->cpt_clk = of_clk_get_by_name(dev->of_node, "capture");
 642                 if (IS_ERR(pc->cpt_clk)) {
 643                         dev_err(dev, "failed to get PWM capture clock\n");
 644                         return PTR_ERR(pc->cpt_clk);
 645                 }
 646
 647                 ret = clk_prepare(pc->cpt_clk);
 648                 if (ret) {
 649                         dev_err(dev, "failed to prepare clock\n");
 650                         return ret;
 651                 }
 652
 653                 cdata->ddata = devm_kzalloc(dev, cdata->cpt_num_devs * sizeof(*cdata->ddata), GFP_KERNEL);
 654                 if (!cdata->ddata)
 655                         return -ENOMEM;
 656         }
 657
 658         chip->ops = &sti_pwm_ops;
 659
 660         for (i = 0; i < cdata->cpt_num_devs; i++) {
 661                 struct sti_cpt_ddata *ddata = &cdata->ddata[i];
 662
 663                 init_waitqueue_head(&ddata->wait);
 664                 mutex_init(&ddata->lock);
 665         }
 666
 667         ret = pwmchip_add(chip);
 668         if (ret < 0) {
 669                 clk_unprepare(pc->pwm_clk);
 670                 clk_unprepare(pc->cpt_clk);
 671                 return ret;
 672         }
 673
 674         platform_set_drvdata(pdev, chip);
 675
 676         return 0;
 677 }
 678
 679 static void sti_pwm_remove(struct platform_device *pdev)
 680 {
 681         struct pwm_chip *chip = platform_get_drvdata(pdev);
 682         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 683
 684         pwmchip_remove(chip);
 685
 686         clk_unprepare(pc->pwm_clk);
 687         clk_unprepare(pc->cpt_clk);
 688 }
 689
 690 static const struct of_device_id sti_pwm_of_match[] = {
 691         { .compatible = "st,sti-pwm", },
 692         { /* sentinel */ }
 693 };
 694 MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
 695
 696 static struct platform_driver sti_pwm_driver = {
 697         .driver = {
 698                 .name = "sti-pwm",
 699                 .of_match_table = sti_pwm_of_match,
 700         },
 701         .probe = sti_pwm_probe,
 702         .remove_new = sti_pwm_remove,
 703 };
 704 module_platform_driver(sti_pwm_driver);
 705
 706 MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
 707 MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
 708 MODULE_LICENSE("GPL");