drivers/pwm/pwm-meson.c

   1 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
   2 /*
   3  * PWM controller driver for Amlogic Meson SoCs.
   4  *
   5  * This PWM is only a set of Gates, Dividers and Counters:
   6  * PWM output is achieved by calculating a clock that permits calculating
   7  * two periods (low and high). The counter then has to be set to switch after
   8  * N cycles for the first half period.
   9  * The hardware has no "polarity" setting. This driver reverses the period
  10  * cycles (the low length is inverted with the high length) for
  11  * PWM_POLARITY_INVERSED. This means that .get_state cannot read the polarity
  12  * from the hardware.
  13  * Setting the duty cycle will disable and re-enable the PWM output.
  14  * Disabling the PWM stops the output immediately (without waiting for the
  15  * current period to complete first).
  16  *
  17  * The public S912 (GXM) datasheet contains some documentation for this PWM
  18  * controller starting on page 543:
  19  * https://dl.khadas.com/Hardware/VIM2/Datasheet/S912_Datasheet_V0.220170314publicversion-Wesion.pdf
  20  * An updated version of this IP block is found in S922X (G12B) SoCs. The
  21  * datasheet contains the description for this IP block revision starting at
  22  * page 1084:
  23  * https://dn.odroid.com/S922X/ODROID-N2/Datasheet/S922X_Public_Datasheet_V0.2.pdf
  24  *
  25  * Copyright (c) 2016 BayLibre, SAS.
  26  * Author: Neil Armstrong <narmstrong@baylibre.com>
  27  * Copyright (C) 2014 Amlogic, Inc.
  28  */
  29
  30 #include <linux/bitfield.h>
  31 #include <linux/bits.h>
  32 #include <linux/clk.h>
  33 #include <linux/clk-provider.h>
  34 #include <linux/err.h>
  35 #include <linux/io.h>
  36 #include <linux/kernel.h>
  37 #include <linux/math64.h>
  38 #include <linux/module.h>
  39 #include <linux/of.h>
  40 #include <linux/platform_device.h>
  41 #include <linux/pwm.h>
  42 #include <linux/slab.h>
  43 #include <linux/spinlock.h>
  44
  45 #define REG_PWM_A               0x0
  46 #define REG_PWM_B               0x4
  47 #define PWM_LOW_MASK            GENMASK(15, 0)
  48 #define PWM_HIGH_MASK           GENMASK(31, 16)
  49
  50 #define REG_MISC_AB             0x8
  51 #define MISC_B_CLK_EN_SHIFT     23
  52 #define MISC_A_CLK_EN_SHIFT     15
  53 #define MISC_CLK_DIV_WIDTH      7
  54 #define MISC_B_CLK_DIV_SHIFT    16
  55 #define MISC_A_CLK_DIV_SHIFT    8
  56 #define MISC_B_CLK_SEL_SHIFT    6
  57 #define MISC_A_CLK_SEL_SHIFT    4
  58 #define MISC_CLK_SEL_MASK       0x3
  59 #define MISC_B_EN               BIT(1)
  60 #define MISC_A_EN               BIT(0)
  61
  62 #define MESON_NUM_PWMS          2
  63 #define MESON_MAX_MUX_PARENTS   4
  64
  65 static struct meson_pwm_channel_data {
  66         u8              reg_offset;
  67         u8              clk_sel_shift;
  68         u8              clk_div_shift;
  69         u8              clk_en_shift;
  70         u32             pwm_en_mask;
  71 } meson_pwm_per_channel_data[MESON_NUM_PWMS] = {
  72         {
  73                 .reg_offset     = REG_PWM_A,
  74                 .clk_sel_shift  = MISC_A_CLK_SEL_SHIFT,
  75                 .clk_div_shift  = MISC_A_CLK_DIV_SHIFT,
  76                 .clk_en_shift   = MISC_A_CLK_EN_SHIFT,
  77                 .pwm_en_mask    = MISC_A_EN,
  78         },
  79         {
  80                 .reg_offset     = REG_PWM_B,
  81                 .clk_sel_shift  = MISC_B_CLK_SEL_SHIFT,
  82                 .clk_div_shift  = MISC_B_CLK_DIV_SHIFT,
  83                 .clk_en_shift   = MISC_B_CLK_EN_SHIFT,
  84                 .pwm_en_mask    = MISC_B_EN,
  85         }
  86 };
  87
  88 struct meson_pwm_channel {
  89         unsigned long rate;
  90         unsigned int hi;
  91         unsigned int lo;
  92
  93         struct clk_mux mux;
  94         struct clk_divider div;
  95         struct clk_gate gate;
  96         struct clk *clk;
  97 };
  98
  99 struct meson_pwm_data {
 100         const char * const *parent_names;
 101         unsigned int num_parents;
 102 };
 103
 104 struct meson_pwm {
 105         struct pwm_chip chip;
 106         const struct meson_pwm_data *data;
 107         struct meson_pwm_channel channels[MESON_NUM_PWMS];
 108         void __iomem *base;
 109         /*
 110          * Protects register (write) access to the REG_MISC_AB register
 111          * that is shared between the two PWMs.
 112          */
 113         spinlock_t lock;
 114 };
 115
 116 static inline struct meson_pwm *to_meson_pwm(struct pwm_chip *chip)
 117 {
 118         return container_of(chip, struct meson_pwm, chip);
 119 }
 120
 121 static int meson_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 122 {
 123         struct meson_pwm *meson = to_meson_pwm(chip);
 124         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 125         struct device *dev = chip->dev;
 126         int err;
 127
 128         err = clk_prepare_enable(channel->clk);
 129         if (err < 0) {
 130                 dev_err(dev, "failed to enable clock %s: %d\n",
 131                         __clk_get_name(channel->clk), err);
 132                 return err;
 133         }
 134
 135         return 0;
 136 }
 137
 138 static void meson_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 139 {
 140         struct meson_pwm *meson = to_meson_pwm(chip);
 141         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 142
 143         clk_disable_unprepare(channel->clk);
 144 }
 145
 146 static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
 147                           const struct pwm_state *state)
 148 {
 149         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 150         unsigned int cnt, duty_cnt;
 151         unsigned long fin_freq;
 152         u64 duty, period, freq;
 153
 154         duty = state->duty_cycle;
 155         period = state->period;
 156
 157         /*
 158          * Note this is wrong. The result is an output wave that isn't really
 159          * inverted and so is wrongly identified by .get_state as normal.
 160          * Fixing this needs some care however as some machines might rely on
 161          * this.
 162          */
 163         if (state->polarity == PWM_POLARITY_INVERSED)
 164                 duty = period - duty;
 165
 166         freq = div64_u64(NSEC_PER_SEC * 0xffffULL, period);
 167         if (freq > ULONG_MAX)
 168                 freq = ULONG_MAX;
 169
 170         fin_freq = clk_round_rate(channel->clk, freq);
 171         if (fin_freq == 0) {
 172                 dev_err(meson->chip.dev, "invalid source clock frequency\n");
 173                 return -EINVAL;
 174         }
 175
 176         dev_dbg(meson->chip.dev, "fin_freq: %lu Hz\n", fin_freq);
 177
 178         cnt = div_u64(fin_freq * period, NSEC_PER_SEC);
 179         if (cnt > 0xffff) {
 180                 dev_err(meson->chip.dev, "unable to get period cnt\n");
 181                 return -EINVAL;
 182         }
 183
 184         dev_dbg(meson->chip.dev, "period=%llu cnt=%u\n", period, cnt);
 185
 186         if (duty == period) {
 187                 channel->hi = cnt;
 188                 channel->lo = 0;
 189         } else if (duty == 0) {
 190                 channel->hi = 0;
 191                 channel->lo = cnt;
 192         } else {
 193                 duty_cnt = div_u64(fin_freq * duty, NSEC_PER_SEC);
 194
 195                 dev_dbg(meson->chip.dev, "duty=%llu duty_cnt=%u\n", duty, duty_cnt);
 196
 197                 channel->hi = duty_cnt;
 198                 channel->lo = cnt - duty_cnt;
 199         }
 200
 201         channel->rate = fin_freq;
 202
 203         return 0;
 204 }
 205
 206 static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
 207 {
 208         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 209         struct meson_pwm_channel_data *channel_data;
 210         unsigned long flags;
 211         u32 value;
 212         int err;
 213
 214         channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
 215
 216         err = clk_set_rate(channel->clk, channel->rate);
 217         if (err)
 218                 dev_err(meson->chip.dev, "setting clock rate failed\n");
 219
 220         spin_lock_irqsave(&meson->lock, flags);
 221
 222         value = FIELD_PREP(PWM_HIGH_MASK, channel->hi) |
 223                 FIELD_PREP(PWM_LOW_MASK, channel->lo);
 224         writel(value, meson->base + channel_data->reg_offset);
 225
 226         value = readl(meson->base + REG_MISC_AB);
 227         value |= channel_data->pwm_en_mask;
 228         writel(value, meson->base + REG_MISC_AB);
 229
 230         spin_unlock_irqrestore(&meson->lock, flags);
 231 }
 232
 233 static void meson_pwm_disable(struct meson_pwm *meson, struct pwm_device *pwm)
 234 {
 235         unsigned long flags;
 236         u32 value;
 237
 238         spin_lock_irqsave(&meson->lock, flags);
 239
 240         value = readl(meson->base + REG_MISC_AB);
 241         value &= ~meson_pwm_per_channel_data[pwm->hwpwm].pwm_en_mask;
 242         writel(value, meson->base + REG_MISC_AB);
 243
 244         spin_unlock_irqrestore(&meson->lock, flags);
 245 }
 246
 247 static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 248                            const struct pwm_state *state)
 249 {
 250         struct meson_pwm *meson = to_meson_pwm(chip);
 251         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 252         int err = 0;
 253
 254         if (!state->enabled) {
 255                 if (state->polarity == PWM_POLARITY_INVERSED) {
 256                         /*
 257                          * This IP block revision doesn't have an "always high"
 258                          * setting which we can use for "inverted disabled".
 259                          * Instead we achieve this by setting mux parent with
 260                          * highest rate and minimum divider value, resulting
 261                          * in the shortest possible duration for one "count"
 262                          * and "period == duty_cycle". This results in a signal
 263                          * which is LOW for one "count", while being HIGH for
 264                          * the rest of the (so the signal is HIGH for slightly
 265                          * less than 100% of the period, but this is the best
 266                          * we can achieve).
 267                          */
 268                         channel->rate = ULONG_MAX;
 269                         channel->hi = ~0;
 270                         channel->lo = 0;
 271
 272                         meson_pwm_enable(meson, pwm);
 273                 } else {
 274                         meson_pwm_disable(meson, pwm);
 275                 }
 276         } else {
 277                 err = meson_pwm_calc(meson, pwm, state);
 278                 if (err < 0)
 279                         return err;
 280
 281                 meson_pwm_enable(meson, pwm);
 282         }
 283
 284         return 0;
 285 }
 286
 287 static u64 meson_pwm_cnt_to_ns(struct pwm_chip *chip, struct pwm_device *pwm,
 288                                u32 cnt)
 289 {
 290         struct meson_pwm *meson = to_meson_pwm(chip);
 291         struct meson_pwm_channel *channel;
 292         unsigned long fin_freq;
 293
 294         /* to_meson_pwm() can only be used after .get_state() is called */
 295         channel = &meson->channels[pwm->hwpwm];
 296
 297         fin_freq = clk_get_rate(channel->clk);
 298         if (fin_freq == 0)
 299                 return 0;
 300
 301         return div64_ul(NSEC_PER_SEC * (u64)cnt, fin_freq);
 302 }
 303
 304 static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 305                                struct pwm_state *state)
 306 {
 307         struct meson_pwm *meson = to_meson_pwm(chip);
 308         struct meson_pwm_channel_data *channel_data;
 309         struct meson_pwm_channel *channel;
 310         u32 value;
 311
 312         if (!state)
 313                 return 0;
 314
 315         channel = &meson->channels[pwm->hwpwm];
 316         channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
 317
 318         value = readl(meson->base + REG_MISC_AB);
 319         state->enabled = value & channel_data->pwm_en_mask;
 320
 321         value = readl(meson->base + channel_data->reg_offset);
 322         channel->lo = FIELD_GET(PWM_LOW_MASK, value);
 323         channel->hi = FIELD_GET(PWM_HIGH_MASK, value);
 324
 325         state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->lo + channel->hi);
 326         state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
 327
 328         state->polarity = PWM_POLARITY_NORMAL;
 329
 330         return 0;
 331 }
 332
 333 static const struct pwm_ops meson_pwm_ops = {
 334         .request = meson_pwm_request,
 335         .free = meson_pwm_free,
 336         .apply = meson_pwm_apply,
 337         .get_state = meson_pwm_get_state,
 338 };
 339
 340 static const char * const pwm_meson8b_parent_names[] = {
 341         "xtal", NULL, "fclk_div4", "fclk_div3"
 342 };
 343
 344 static const struct meson_pwm_data pwm_meson8b_data = {
 345         .parent_names = pwm_meson8b_parent_names,
 346         .num_parents = ARRAY_SIZE(pwm_meson8b_parent_names),
 347 };
 348
 349 /*
 350  * Only the 2 first inputs of the GXBB AO PWMs are valid
 351  * The last 2 are grounded
 352  */
 353 static const char * const pwm_gxbb_ao_parent_names[] = {
 354         "xtal", "clk81"
 355 };
 356
 357 static const struct meson_pwm_data pwm_gxbb_ao_data = {
 358         .parent_names = pwm_gxbb_ao_parent_names,
 359         .num_parents = ARRAY_SIZE(pwm_gxbb_ao_parent_names),
 360 };
 361
 362 static const char * const pwm_axg_ee_parent_names[] = {
 363         "xtal", "fclk_div5", "fclk_div4", "fclk_div3"
 364 };
 365
 366 static const struct meson_pwm_data pwm_axg_ee_data = {
 367         .parent_names = pwm_axg_ee_parent_names,
 368         .num_parents = ARRAY_SIZE(pwm_axg_ee_parent_names),
 369 };
 370
 371 static const char * const pwm_axg_ao_parent_names[] = {
 372         "xtal", "axg_ao_clk81", "fclk_div4", "fclk_div5"
 373 };
 374
 375 static const struct meson_pwm_data pwm_axg_ao_data = {
 376         .parent_names = pwm_axg_ao_parent_names,
 377         .num_parents = ARRAY_SIZE(pwm_axg_ao_parent_names),
 378 };
 379
 380 static const char * const pwm_g12a_ao_ab_parent_names[] = {
 381         "xtal", "g12a_ao_clk81", "fclk_div4", "fclk_div5"
 382 };
 383
 384 static const struct meson_pwm_data pwm_g12a_ao_ab_data = {
 385         .parent_names = pwm_g12a_ao_ab_parent_names,
 386         .num_parents = ARRAY_SIZE(pwm_g12a_ao_ab_parent_names),
 387 };
 388
 389 static const char * const pwm_g12a_ao_cd_parent_names[] = {
 390         "xtal", "g12a_ao_clk81",
 391 };
 392
 393 static const struct meson_pwm_data pwm_g12a_ao_cd_data = {
 394         .parent_names = pwm_g12a_ao_cd_parent_names,
 395         .num_parents = ARRAY_SIZE(pwm_g12a_ao_cd_parent_names),
 396 };
 397
 398 static const struct of_device_id meson_pwm_matches[] = {
 399         {
 400                 .compatible = "amlogic,meson8b-pwm",
 401                 .data = &pwm_meson8b_data
 402         },
 403         {
 404                 .compatible = "amlogic,meson-gxbb-pwm",
 405                 .data = &pwm_meson8b_data
 406         },
 407         {
 408                 .compatible = "amlogic,meson-gxbb-ao-pwm",
 409                 .data = &pwm_gxbb_ao_data
 410         },
 411         {
 412                 .compatible = "amlogic,meson-axg-ee-pwm",
 413                 .data = &pwm_axg_ee_data
 414         },
 415         {
 416                 .compatible = "amlogic,meson-axg-ao-pwm",
 417                 .data = &pwm_axg_ao_data
 418         },
 419         {
 420                 .compatible = "amlogic,meson-g12a-ee-pwm",
 421                 .data = &pwm_meson8b_data
 422         },
 423         {
 424                 .compatible = "amlogic,meson-g12a-ao-pwm-ab",
 425                 .data = &pwm_g12a_ao_ab_data
 426         },
 427         {
 428                 .compatible = "amlogic,meson-g12a-ao-pwm-cd",
 429                 .data = &pwm_g12a_ao_cd_data
 430         },
 431         {},
 432 };
 433 MODULE_DEVICE_TABLE(of, meson_pwm_matches);
 434
 435 static int meson_pwm_init_channels(struct meson_pwm *meson)
 436 {
 437         struct clk_parent_data mux_parent_data[MESON_MAX_MUX_PARENTS] = {};
 438         struct device *dev = meson->chip.dev;
 439         unsigned int i;
 440         char name[255];
 441         int err;
 442
 443         for (i = 0; i < meson->data->num_parents; i++) {
 444                 mux_parent_data[i].index = -1;
 445                 mux_parent_data[i].name = meson->data->parent_names[i];
 446         }
 447
 448         for (i = 0; i < meson->chip.npwm; i++) {
 449                 struct meson_pwm_channel *channel = &meson->channels[i];
 450                 struct clk_parent_data div_parent = {}, gate_parent = {};
 451                 struct clk_init_data init = {};
 452
 453                 snprintf(name, sizeof(name), "%s#mux%u", dev_name(dev), i);
 454
 455                 init.name = name;
 456                 init.ops = &clk_mux_ops;
 457                 init.flags = 0;
 458                 init.parent_data = mux_parent_data;
 459                 init.num_parents = meson->data->num_parents;
 460
 461                 channel->mux.reg = meson->base + REG_MISC_AB;
 462                 channel->mux.shift =
 463                                 meson_pwm_per_channel_data[i].clk_sel_shift;
 464                 channel->mux.mask = MISC_CLK_SEL_MASK;
 465                 channel->mux.flags = 0;
 466                 channel->mux.lock = &meson->lock;
 467                 channel->mux.table = NULL;
 468                 channel->mux.hw.init = &init;
 469
 470                 err = devm_clk_hw_register(dev, &channel->mux.hw);
 471                 if (err)
 472                         return dev_err_probe(dev, err,
 473                                              "failed to register %s\n", name);
 474
 475                 snprintf(name, sizeof(name), "%s#div%u", dev_name(dev), i);
 476
 477                 init.name = name;
 478                 init.ops = &clk_divider_ops;
 479                 init.flags = CLK_SET_RATE_PARENT;
 480                 div_parent.index = -1;
 481                 div_parent.hw = &channel->mux.hw;
 482                 init.parent_data = &div_parent;
 483                 init.num_parents = 1;
 484
 485                 channel->div.reg = meson->base + REG_MISC_AB;
 486                 channel->div.shift = meson_pwm_per_channel_data[i].clk_div_shift;
 487                 channel->div.width = MISC_CLK_DIV_WIDTH;
 488                 channel->div.hw.init = &init;
 489                 channel->div.flags = 0;
 490                 channel->div.lock = &meson->lock;
 491
 492                 err = devm_clk_hw_register(dev, &channel->div.hw);
 493                 if (err)
 494                         return dev_err_probe(dev, err,
 495                                              "failed to register %s\n", name);
 496
 497                 snprintf(name, sizeof(name), "%s#gate%u", dev_name(dev), i);
 498
 499                 init.name = name;
 500                 init.ops = &clk_gate_ops;
 501                 init.flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED;
 502                 gate_parent.index = -1;
 503                 gate_parent.hw = &channel->div.hw;
 504                 init.parent_data = &gate_parent;
 505                 init.num_parents = 1;
 506
 507                 channel->gate.reg = meson->base + REG_MISC_AB;
 508                 channel->gate.bit_idx = meson_pwm_per_channel_data[i].clk_en_shift;
 509                 channel->gate.hw.init = &init;
 510                 channel->gate.flags = 0;
 511                 channel->gate.lock = &meson->lock;
 512
 513                 err = devm_clk_hw_register(dev, &channel->gate.hw);
 514                 if (err)
 515                         return dev_err_probe(dev, err, "failed to register %s\n", name);
 516
 517                 channel->clk = devm_clk_hw_get_clk(dev, &channel->gate.hw, NULL);
 518                 if (IS_ERR(channel->clk))
 519                         return dev_err_probe(dev, PTR_ERR(channel->clk),
 520                                              "failed to register %s\n", name);
 521         }
 522
 523         return 0;
 524 }
 525
 526 static int meson_pwm_probe(struct platform_device *pdev)
 527 {
 528         struct meson_pwm *meson;
 529         int err;
 530
 531         meson = devm_kzalloc(&pdev->dev, sizeof(*meson), GFP_KERNEL);
 532         if (!meson)
 533                 return -ENOMEM;
 534
 535         meson->base = devm_platform_ioremap_resource(pdev, 0);
 536         if (IS_ERR(meson->base))
 537                 return PTR_ERR(meson->base);
 538
 539         spin_lock_init(&meson->lock);
 540         meson->chip.dev = &pdev->dev;
 541         meson->chip.ops = &meson_pwm_ops;
 542         meson->chip.npwm = MESON_NUM_PWMS;
 543
 544         meson->data = of_device_get_match_data(&pdev->dev);
 545
 546         err = meson_pwm_init_channels(meson);
 547         if (err < 0)
 548                 return err;
 549
 550         err = devm_pwmchip_add(&pdev->dev, &meson->chip);
 551         if (err < 0)
 552                 return dev_err_probe(&pdev->dev, err,
 553                                      "failed to register PWM chip\n");
 554
 555         return 0;
 556 }
 557
 558 static struct platform_driver meson_pwm_driver = {
 559         .driver = {
 560                 .name = "meson-pwm",
 561                 .of_match_table = meson_pwm_matches,
 562         },
 563         .probe = meson_pwm_probe,
 564 };
 565 module_platform_driver(meson_pwm_driver);
 566
 567 MODULE_DESCRIPTION("Amlogic Meson PWM Generator driver");
 568 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
 569 MODULE_LICENSE("Dual BSD/GPL");