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/of_device.h>
  41 #include <linux/platform_device.h>
  42 #include <linux/pwm.h>
  43 #include <linux/slab.h>
  44 #include <linux/spinlock.h>
  45
  46 #define REG_PWM_A               0x0
  47 #define REG_PWM_B               0x4
  48 #define PWM_LOW_MASK            GENMASK(15, 0)
  49 #define PWM_HIGH_MASK           GENMASK(31, 16)
  50
  51 #define REG_MISC_AB             0x8
  52 #define MISC_B_CLK_EN           BIT(23)
  53 #define MISC_A_CLK_EN           BIT(15)
  54 #define MISC_CLK_DIV_MASK       0x7f
  55 #define MISC_B_CLK_DIV_SHIFT    16
  56 #define MISC_A_CLK_DIV_SHIFT    8
  57 #define MISC_B_CLK_SEL_SHIFT    6
  58 #define MISC_A_CLK_SEL_SHIFT    4
  59 #define MISC_CLK_SEL_MASK       0x3
  60 #define MISC_B_EN               BIT(1)
  61 #define MISC_A_EN               BIT(0)
  62
  63 #define MESON_NUM_PWMS          2
  64
  65 static struct meson_pwm_channel_data {
  66         u8              reg_offset;
  67         u8              clk_sel_shift;
  68         u8              clk_div_shift;
  69         u32             clk_en_mask;
  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_mask    = MISC_A_CLK_EN,
  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_mask    = MISC_B_CLK_EN,
  84                 .pwm_en_mask    = MISC_B_EN,
  85         }
  86 };
  87
  88 struct meson_pwm_channel {
  89         unsigned int hi;
  90         unsigned int lo;
  91         u8 pre_div;
  92
  93         struct clk *clk_parent;
  94         struct clk_mux mux;
  95         struct clk *clk;
  96 };
  97
  98 struct meson_pwm_data {
  99         const char * const *parent_names;
 100         unsigned int num_parents;
 101 };
 102
 103 struct meson_pwm {
 104         struct pwm_chip chip;
 105         const struct meson_pwm_data *data;
 106         struct meson_pwm_channel channels[MESON_NUM_PWMS];
 107         void __iomem *base;
 108         /*
 109          * Protects register (write) access to the REG_MISC_AB register
 110          * that is shared between the two PWMs.
 111          */
 112         spinlock_t lock;
 113 };
 114
 115 static inline struct meson_pwm *to_meson_pwm(struct pwm_chip *chip)
 116 {
 117         return container_of(chip, struct meson_pwm, chip);
 118 }
 119
 120 static int meson_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 121 {
 122         struct meson_pwm *meson = to_meson_pwm(chip);
 123         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 124         struct device *dev = chip->dev;
 125         int err;
 126
 127         if (channel->clk_parent) {
 128                 err = clk_set_parent(channel->clk, channel->clk_parent);
 129                 if (err < 0) {
 130                         dev_err(dev, "failed to set parent %s for %s: %d\n",
 131                                 __clk_get_name(channel->clk_parent),
 132                                 __clk_get_name(channel->clk), err);
 133                         return err;
 134                 }
 135         }
 136
 137         err = clk_prepare_enable(channel->clk);
 138         if (err < 0) {
 139                 dev_err(dev, "failed to enable clock %s: %d\n",
 140                         __clk_get_name(channel->clk), err);
 141                 return err;
 142         }
 143
 144         return 0;
 145 }
 146
 147 static void meson_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 148 {
 149         struct meson_pwm *meson = to_meson_pwm(chip);
 150         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 151
 152         clk_disable_unprepare(channel->clk);
 153 }
 154
 155 static int meson_pwm_calc(struct meson_pwm *meson, struct pwm_device *pwm,
 156                           const struct pwm_state *state)
 157 {
 158         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 159         unsigned int duty, period, pre_div, cnt, duty_cnt;
 160         unsigned long fin_freq;
 161
 162         duty = state->duty_cycle;
 163         period = state->period;
 164
 165         if (state->polarity == PWM_POLARITY_INVERSED)
 166                 duty = period - duty;
 167
 168         fin_freq = clk_get_rate(channel->clk);
 169         if (fin_freq == 0) {
 170                 dev_err(meson->chip.dev, "invalid source clock frequency\n");
 171                 return -EINVAL;
 172         }
 173
 174         dev_dbg(meson->chip.dev, "fin_freq: %lu Hz\n", fin_freq);
 175
 176         pre_div = div64_u64(fin_freq * (u64)period, NSEC_PER_SEC * 0xffffLL);
 177         if (pre_div > MISC_CLK_DIV_MASK) {
 178                 dev_err(meson->chip.dev, "unable to get period pre_div\n");
 179                 return -EINVAL;
 180         }
 181
 182         cnt = div64_u64(fin_freq * (u64)period, NSEC_PER_SEC * (pre_div + 1));
 183         if (cnt > 0xffff) {
 184                 dev_err(meson->chip.dev, "unable to get period cnt\n");
 185                 return -EINVAL;
 186         }
 187
 188         dev_dbg(meson->chip.dev, "period=%u pre_div=%u cnt=%u\n", period,
 189                 pre_div, cnt);
 190
 191         if (duty == period) {
 192                 channel->pre_div = pre_div;
 193                 channel->hi = cnt;
 194                 channel->lo = 0;
 195         } else if (duty == 0) {
 196                 channel->pre_div = pre_div;
 197                 channel->hi = 0;
 198                 channel->lo = cnt;
 199         } else {
 200                 /* Then check is we can have the duty with the same pre_div */
 201                 duty_cnt = div64_u64(fin_freq * (u64)duty,
 202                                      NSEC_PER_SEC * (pre_div + 1));
 203                 if (duty_cnt > 0xffff) {
 204                         dev_err(meson->chip.dev, "unable to get duty cycle\n");
 205                         return -EINVAL;
 206                 }
 207
 208                 dev_dbg(meson->chip.dev, "duty=%u pre_div=%u duty_cnt=%u\n",
 209                         duty, pre_div, duty_cnt);
 210
 211                 channel->pre_div = pre_div;
 212                 channel->hi = duty_cnt;
 213                 channel->lo = cnt - duty_cnt;
 214         }
 215
 216         return 0;
 217 }
 218
 219 static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
 220 {
 221         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 222         struct meson_pwm_channel_data *channel_data;
 223         unsigned long flags;
 224         u32 value;
 225
 226         channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
 227
 228         spin_lock_irqsave(&meson->lock, flags);
 229
 230         value = readl(meson->base + REG_MISC_AB);
 231         value &= ~(MISC_CLK_DIV_MASK << channel_data->clk_div_shift);
 232         value |= channel->pre_div << channel_data->clk_div_shift;
 233         value |= channel_data->clk_en_mask;
 234         writel(value, meson->base + REG_MISC_AB);
 235
 236         value = FIELD_PREP(PWM_HIGH_MASK, channel->hi) |
 237                 FIELD_PREP(PWM_LOW_MASK, channel->lo);
 238         writel(value, meson->base + channel_data->reg_offset);
 239
 240         value = readl(meson->base + REG_MISC_AB);
 241         value |= channel_data->pwm_en_mask;
 242         writel(value, meson->base + REG_MISC_AB);
 243
 244         spin_unlock_irqrestore(&meson->lock, flags);
 245 }
 246
 247 static void meson_pwm_disable(struct meson_pwm *meson, struct pwm_device *pwm)
 248 {
 249         unsigned long flags;
 250         u32 value;
 251
 252         spin_lock_irqsave(&meson->lock, flags);
 253
 254         value = readl(meson->base + REG_MISC_AB);
 255         value &= ~meson_pwm_per_channel_data[pwm->hwpwm].pwm_en_mask;
 256         writel(value, meson->base + REG_MISC_AB);
 257
 258         spin_unlock_irqrestore(&meson->lock, flags);
 259 }
 260
 261 static int meson_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 262                            const struct pwm_state *state)
 263 {
 264         struct meson_pwm *meson = to_meson_pwm(chip);
 265         struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 266         int err = 0;
 267
 268         if (!state->enabled) {
 269                 if (state->polarity == PWM_POLARITY_INVERSED) {
 270                         /*
 271                          * This IP block revision doesn't have an "always high"
 272                          * setting which we can use for "inverted disabled".
 273                          * Instead we achieve this using the same settings
 274                          * that we use a pre_div of 0 (to get the shortest
 275                          * possible duration for one "count") and
 276                          * "period == duty_cycle". This results in a signal
 277                          * which is LOW for one "count", while being HIGH for
 278                          * the rest of the (so the signal is HIGH for slightly
 279                          * less than 100% of the period, but this is the best
 280                          * we can achieve).
 281                          */
 282                         channel->pre_div = 0;
 283                         channel->hi = ~0;
 284                         channel->lo = 0;
 285
 286                         meson_pwm_enable(meson, pwm);
 287                 } else {
 288                         meson_pwm_disable(meson, pwm);
 289                 }
 290         } else {
 291                 err = meson_pwm_calc(meson, pwm, state);
 292                 if (err < 0)
 293                         return err;
 294
 295                 meson_pwm_enable(meson, pwm);
 296         }
 297
 298         return 0;
 299 }
 300
 301 static unsigned int meson_pwm_cnt_to_ns(struct pwm_chip *chip,
 302                                         struct pwm_device *pwm, u32 cnt)
 303 {
 304         struct meson_pwm *meson = to_meson_pwm(chip);
 305         struct meson_pwm_channel *channel;
 306         unsigned long fin_freq;
 307         u32 fin_ns;
 308
 309         /* to_meson_pwm() can only be used after .get_state() is called */
 310         channel = &meson->channels[pwm->hwpwm];
 311
 312         fin_freq = clk_get_rate(channel->clk);
 313         if (fin_freq == 0)
 314                 return 0;
 315
 316         fin_ns = div_u64(NSEC_PER_SEC, fin_freq);
 317
 318         return cnt * fin_ns * (channel->pre_div + 1);
 319 }
 320
 321 static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 322                                struct pwm_state *state)
 323 {
 324         struct meson_pwm *meson = to_meson_pwm(chip);
 325         struct meson_pwm_channel_data *channel_data;
 326         struct meson_pwm_channel *channel;
 327         u32 value, tmp;
 328
 329         if (!state)
 330                 return 0;
 331
 332         channel = &meson->channels[pwm->hwpwm];
 333         channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
 334
 335         value = readl(meson->base + REG_MISC_AB);
 336
 337         tmp = channel_data->pwm_en_mask | channel_data->clk_en_mask;
 338         state->enabled = (value & tmp) == tmp;
 339
 340         tmp = value >> channel_data->clk_div_shift;
 341         channel->pre_div = FIELD_GET(MISC_CLK_DIV_MASK, tmp);
 342
 343         value = readl(meson->base + channel_data->reg_offset);
 344
 345         channel->lo = FIELD_GET(PWM_LOW_MASK, value);
 346         channel->hi = FIELD_GET(PWM_HIGH_MASK, value);
 347
 348         if (channel->lo == 0) {
 349                 state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
 350                 state->duty_cycle = state->period;
 351         } else if (channel->lo >= channel->hi) {
 352                 state->period = meson_pwm_cnt_to_ns(chip, pwm,
 353                                                     channel->lo + channel->hi);
 354                 state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm,
 355                                                         channel->hi);
 356         } else {
 357                 state->period = 0;
 358                 state->duty_cycle = 0;
 359         }
 360
 361         return 0;
 362 }
 363
 364 static const struct pwm_ops meson_pwm_ops = {
 365         .request = meson_pwm_request,
 366         .free = meson_pwm_free,
 367         .apply = meson_pwm_apply,
 368         .get_state = meson_pwm_get_state,
 369         .owner = THIS_MODULE,
 370 };
 371
 372 static const char * const pwm_meson8b_parent_names[] = {
 373         "xtal", "vid_pll", "fclk_div4", "fclk_div3"
 374 };
 375
 376 static const struct meson_pwm_data pwm_meson8b_data = {
 377         .parent_names = pwm_meson8b_parent_names,
 378         .num_parents = ARRAY_SIZE(pwm_meson8b_parent_names),
 379 };
 380
 381 static const char * const pwm_gxbb_parent_names[] = {
 382         "xtal", "hdmi_pll", "fclk_div4", "fclk_div3"
 383 };
 384
 385 static const struct meson_pwm_data pwm_gxbb_data = {
 386         .parent_names = pwm_gxbb_parent_names,
 387         .num_parents = ARRAY_SIZE(pwm_gxbb_parent_names),
 388 };
 389
 390 /*
 391  * Only the 2 first inputs of the GXBB AO PWMs are valid
 392  * The last 2 are grounded
 393  */
 394 static const char * const pwm_gxbb_ao_parent_names[] = {
 395         "xtal", "clk81"
 396 };
 397
 398 static const struct meson_pwm_data pwm_gxbb_ao_data = {
 399         .parent_names = pwm_gxbb_ao_parent_names,
 400         .num_parents = ARRAY_SIZE(pwm_gxbb_ao_parent_names),
 401 };
 402
 403 static const char * const pwm_axg_ee_parent_names[] = {
 404         "xtal", "fclk_div5", "fclk_div4", "fclk_div3"
 405 };
 406
 407 static const struct meson_pwm_data pwm_axg_ee_data = {
 408         .parent_names = pwm_axg_ee_parent_names,
 409         .num_parents = ARRAY_SIZE(pwm_axg_ee_parent_names),
 410 };
 411
 412 static const char * const pwm_axg_ao_parent_names[] = {
 413         "aoclk81", "xtal", "fclk_div4", "fclk_div5"
 414 };
 415
 416 static const struct meson_pwm_data pwm_axg_ao_data = {
 417         .parent_names = pwm_axg_ao_parent_names,
 418         .num_parents = ARRAY_SIZE(pwm_axg_ao_parent_names),
 419 };
 420
 421 static const char * const pwm_g12a_ao_ab_parent_names[] = {
 422         "xtal", "aoclk81", "fclk_div4", "fclk_div5"
 423 };
 424
 425 static const struct meson_pwm_data pwm_g12a_ao_ab_data = {
 426         .parent_names = pwm_g12a_ao_ab_parent_names,
 427         .num_parents = ARRAY_SIZE(pwm_g12a_ao_ab_parent_names),
 428 };
 429
 430 static const char * const pwm_g12a_ao_cd_parent_names[] = {
 431         "xtal", "aoclk81",
 432 };
 433
 434 static const struct meson_pwm_data pwm_g12a_ao_cd_data = {
 435         .parent_names = pwm_g12a_ao_cd_parent_names,
 436         .num_parents = ARRAY_SIZE(pwm_g12a_ao_cd_parent_names),
 437 };
 438
 439 static const char * const pwm_g12a_ee_parent_names[] = {
 440         "xtal", "hdmi_pll", "fclk_div4", "fclk_div3"
 441 };
 442
 443 static const struct meson_pwm_data pwm_g12a_ee_data = {
 444         .parent_names = pwm_g12a_ee_parent_names,
 445         .num_parents = ARRAY_SIZE(pwm_g12a_ee_parent_names),
 446 };
 447
 448 static const struct of_device_id meson_pwm_matches[] = {
 449         {
 450                 .compatible = "amlogic,meson8b-pwm",
 451                 .data = &pwm_meson8b_data
 452         },
 453         {
 454                 .compatible = "amlogic,meson-gxbb-pwm",
 455                 .data = &pwm_gxbb_data
 456         },
 457         {
 458                 .compatible = "amlogic,meson-gxbb-ao-pwm",
 459                 .data = &pwm_gxbb_ao_data
 460         },
 461         {
 462                 .compatible = "amlogic,meson-axg-ee-pwm",
 463                 .data = &pwm_axg_ee_data
 464         },
 465         {
 466                 .compatible = "amlogic,meson-axg-ao-pwm",
 467                 .data = &pwm_axg_ao_data
 468         },
 469         {
 470                 .compatible = "amlogic,meson-g12a-ee-pwm",
 471                 .data = &pwm_g12a_ee_data
 472         },
 473         {
 474                 .compatible = "amlogic,meson-g12a-ao-pwm-ab",
 475                 .data = &pwm_g12a_ao_ab_data
 476         },
 477         {
 478                 .compatible = "amlogic,meson-g12a-ao-pwm-cd",
 479                 .data = &pwm_g12a_ao_cd_data
 480         },
 481         {},
 482 };
 483 MODULE_DEVICE_TABLE(of, meson_pwm_matches);
 484
 485 static int meson_pwm_init_channels(struct meson_pwm *meson)
 486 {
 487         struct device *dev = meson->chip.dev;
 488         struct clk_init_data init;
 489         unsigned int i;
 490         char name[255];
 491         int err;
 492
 493         for (i = 0; i < meson->chip.npwm; i++) {
 494                 struct meson_pwm_channel *channel = &meson->channels[i];
 495
 496                 snprintf(name, sizeof(name), "%s#mux%u", dev_name(dev), i);
 497
 498                 init.name = name;
 499                 init.ops = &clk_mux_ops;
 500                 init.flags = 0;
 501                 init.parent_names = meson->data->parent_names;
 502                 init.num_parents = meson->data->num_parents;
 503
 504                 channel->mux.reg = meson->base + REG_MISC_AB;
 505                 channel->mux.shift =
 506                                 meson_pwm_per_channel_data[i].clk_sel_shift;
 507                 channel->mux.mask = MISC_CLK_SEL_MASK;
 508                 channel->mux.flags = 0;
 509                 channel->mux.lock = &meson->lock;
 510                 channel->mux.table = NULL;
 511                 channel->mux.hw.init = &init;
 512
 513                 channel->clk = devm_clk_register(dev, &channel->mux.hw);
 514                 if (IS_ERR(channel->clk)) {
 515                         err = PTR_ERR(channel->clk);
 516                         dev_err(dev, "failed to register %s: %d\n", name, err);
 517                         return err;
 518                 }
 519
 520                 snprintf(name, sizeof(name), "clkin%u", i);
 521
 522                 channel->clk_parent = devm_clk_get_optional(dev, name);
 523                 if (IS_ERR(channel->clk_parent))
 524                         return PTR_ERR(channel->clk_parent);
 525         }
 526
 527         return 0;
 528 }
 529
 530 static int meson_pwm_probe(struct platform_device *pdev)
 531 {
 532         struct meson_pwm *meson;
 533         int err;
 534
 535         meson = devm_kzalloc(&pdev->dev, sizeof(*meson), GFP_KERNEL);
 536         if (!meson)
 537                 return -ENOMEM;
 538
 539         meson->base = devm_platform_ioremap_resource(pdev, 0);
 540         if (IS_ERR(meson->base))
 541                 return PTR_ERR(meson->base);
 542
 543         spin_lock_init(&meson->lock);
 544         meson->chip.dev = &pdev->dev;
 545         meson->chip.ops = &meson_pwm_ops;
 546         meson->chip.npwm = MESON_NUM_PWMS;
 547
 548         meson->data = of_device_get_match_data(&pdev->dev);
 549
 550         err = meson_pwm_init_channels(meson);
 551         if (err < 0)
 552                 return err;
 553
 554         err = devm_pwmchip_add(&pdev->dev, &meson->chip);
 555         if (err < 0) {
 556                 dev_err(&pdev->dev, "failed to register PWM chip: %d\n", err);
 557                 return err;
 558         }
 559
 560         return 0;
 561 }
 562
 563 static struct platform_driver meson_pwm_driver = {
 564         .driver = {
 565                 .name = "meson-pwm",
 566                 .of_match_table = meson_pwm_matches,
 567         },
 568         .probe = meson_pwm_probe,
 569 };
 570 module_platform_driver(meson_pwm_driver);
 571
 572 MODULE_DESCRIPTION("Amlogic Meson PWM Generator driver");
 573 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
 574 MODULE_LICENSE("Dual BSD/GPL");