drivers/pwm/pwm-lpc18xx-sct.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
   4  *
   5  * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
   6  *
   7  * Notes
   8  * =====
   9  * NXP LPC18xx provides a State Configurable Timer (SCT) which can be configured
  10  * as a Pulse Width Modulator.
  11  *
  12  * SCT supports 16 outputs, 16 events and 16 registers. Each event will be
  13  * triggered when its related register matches the SCT counter value, and it
  14  * will set or clear a selected output.
  15  *
  16  * One of the events is preselected to generate the period, thus the maximum
  17  * number of simultaneous channels is limited to 15. Notice that period is
  18  * global to all the channels, thus PWM driver will refuse setting different
  19  * values to it, unless there's only one channel requested.
  20  */
  21
  22 #include <linux/clk.h>
  23 #include <linux/err.h>
  24 #include <linux/io.h>
  25 #include <linux/mod_devicetable.h>
  26 #include <linux/module.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/pwm.h>
  29
  30 /* LPC18xx SCT registers */
  31 #define LPC18XX_PWM_CONFIG              0x000
  32 #define LPC18XX_PWM_CONFIG_UNIFY        BIT(0)
  33 #define LPC18XX_PWM_CONFIG_NORELOAD     BIT(7)
  34
  35 #define LPC18XX_PWM_CTRL                0x004
  36 #define LPC18XX_PWM_CTRL_HALT           BIT(2)
  37 #define LPC18XX_PWM_BIDIR               BIT(4)
  38 #define LPC18XX_PWM_PRE_SHIFT           5
  39 #define LPC18XX_PWM_PRE_MASK            (0xff << LPC18XX_PWM_PRE_SHIFT)
  40 #define LPC18XX_PWM_PRE(x)              (x << LPC18XX_PWM_PRE_SHIFT)
  41
  42 #define LPC18XX_PWM_LIMIT               0x008
  43
  44 #define LPC18XX_PWM_RES_BASE            0x058
  45 #define LPC18XX_PWM_RES_SHIFT(_ch)      (_ch * 2)
  46 #define LPC18XX_PWM_RES(_ch, _action)   (_action << LPC18XX_PWM_RES_SHIFT(_ch))
  47 #define LPC18XX_PWM_RES_MASK(_ch)       (0x3 << LPC18XX_PWM_RES_SHIFT(_ch))
  48
  49 #define LPC18XX_PWM_MATCH_BASE          0x100
  50 #define LPC18XX_PWM_MATCH(_ch)          (LPC18XX_PWM_MATCH_BASE + _ch * 4)
  51
  52 #define LPC18XX_PWM_MATCHREL_BASE       0x200
  53 #define LPC18XX_PWM_MATCHREL(_ch)       (LPC18XX_PWM_MATCHREL_BASE + _ch * 4)
  54
  55 #define LPC18XX_PWM_EVSTATEMSK_BASE     0x300
  56 #define LPC18XX_PWM_EVSTATEMSK(_ch)     (LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
  57 #define LPC18XX_PWM_EVSTATEMSK_ALL      0xffffffff
  58
  59 #define LPC18XX_PWM_EVCTRL_BASE         0x304
  60 #define LPC18XX_PWM_EVCTRL(_ev)         (LPC18XX_PWM_EVCTRL_BASE + _ev * 8)
  61
  62 #define LPC18XX_PWM_EVCTRL_MATCH(_ch)   _ch
  63
  64 #define LPC18XX_PWM_EVCTRL_COMB_SHIFT   12
  65 #define LPC18XX_PWM_EVCTRL_COMB_MATCH   (0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)
  66
  67 #define LPC18XX_PWM_OUTPUTSET_BASE      0x500
  68 #define LPC18XX_PWM_OUTPUTSET(_ch)      (LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)
  69
  70 #define LPC18XX_PWM_OUTPUTCL_BASE       0x504
  71 #define LPC18XX_PWM_OUTPUTCL(_ch)       (LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)
  72
  73 /* LPC18xx SCT unified counter */
  74 #define LPC18XX_PWM_TIMER_MAX           0xffffffff
  75
  76 /* LPC18xx SCT events */
  77 #define LPC18XX_PWM_EVENT_PERIOD        0
  78 #define LPC18XX_PWM_EVENT_MAX           16
  79
  80 #define LPC18XX_NUM_PWMS                16
  81
  82 /* SCT conflict resolution */
  83 enum lpc18xx_pwm_res_action {
  84         LPC18XX_PWM_RES_NONE,
  85         LPC18XX_PWM_RES_SET,
  86         LPC18XX_PWM_RES_CLEAR,
  87         LPC18XX_PWM_RES_TOGGLE,
  88 };
  89
  90 struct lpc18xx_pwm_data {
  91         unsigned int duty_event;
  92 };
  93
  94 struct lpc18xx_pwm_chip {
  95         void __iomem *base;
  96         struct clk *pwm_clk;
  97         unsigned long clk_rate;
  98         unsigned int period_ns;
  99         unsigned int min_period_ns;
 100         u64 max_period_ns;
 101         unsigned int period_event;
 102         unsigned long event_map;
 103         struct mutex res_lock;
 104         struct mutex period_lock;
 105         struct lpc18xx_pwm_data channeldata[LPC18XX_NUM_PWMS];
 106 };
 107
 108 static inline struct lpc18xx_pwm_chip *
 109 to_lpc18xx_pwm_chip(struct pwm_chip *chip)
 110 {
 111         return pwmchip_get_drvdata(chip);
 112 }
 113
 114 static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 115                                       u32 reg, u32 val)
 116 {
 117         writel(val, lpc18xx_pwm->base + reg);
 118 }
 119
 120 static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 121                                     u32 reg)
 122 {
 123         return readl(lpc18xx_pwm->base + reg);
 124 }
 125
 126 static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 127                                          struct pwm_device *pwm,
 128                                          enum lpc18xx_pwm_res_action action)
 129 {
 130         u32 val;
 131
 132         mutex_lock(&lpc18xx_pwm->res_lock);
 133
 134         /*
 135          * Simultaneous set and clear may happen on an output, that is the case
 136          * when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
 137          * resolution action to be taken in such a case.
 138          */
 139         val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
 140         val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
 141         val |= LPC18XX_PWM_RES(pwm->hwpwm, action);
 142         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);
 143
 144         mutex_unlock(&lpc18xx_pwm->res_lock);
 145 }
 146
 147 static void lpc18xx_pwm_config_period(struct pwm_chip *chip, u64 period_ns)
 148 {
 149         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 150         u32 val;
 151
 152         /*
 153          * With clk_rate < NSEC_PER_SEC this cannot overflow.
 154          * With period_ns < max_period_ns this also fits into an u32.
 155          * As period_ns >= min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC, lpc18xx_pwm->clk_rate);
 156          * we have val >= 1.
 157          */
 158         val = mul_u64_u64_div_u64(period_ns, lpc18xx_pwm->clk_rate, NSEC_PER_SEC);
 159
 160         lpc18xx_pwm_writel(lpc18xx_pwm,
 161                            LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
 162                            val - 1);
 163
 164         lpc18xx_pwm_writel(lpc18xx_pwm,
 165                            LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
 166                            val - 1);
 167 }
 168
 169 static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
 170                                     struct pwm_device *pwm, u64 duty_ns)
 171 {
 172         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 173         struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
 174         u32 val;
 175
 176         /*
 177          * With clk_rate <= NSEC_PER_SEC this cannot overflow.
 178          * With duty_ns <= period_ns < max_period_ns this also fits into an u32.
 179          */
 180         val = mul_u64_u64_div_u64(duty_ns, lpc18xx_pwm->clk_rate, NSEC_PER_SEC);
 181
 182         lpc18xx_pwm_writel(lpc18xx_pwm,
 183                            LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
 184                            val);
 185
 186         lpc18xx_pwm_writel(lpc18xx_pwm,
 187                            LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
 188                            val);
 189 }
 190
 191 static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 192                               int duty_ns, int period_ns)
 193 {
 194         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 195         int requested_events;
 196
 197         if (period_ns < lpc18xx_pwm->min_period_ns ||
 198             period_ns > lpc18xx_pwm->max_period_ns) {
 199                 dev_err(pwmchip_parent(chip), "period %d not in range\n", period_ns);
 200                 return -ERANGE;
 201         }
 202
 203         mutex_lock(&lpc18xx_pwm->period_lock);
 204
 205         requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
 206                                          LPC18XX_PWM_EVENT_MAX);
 207
 208         /*
 209          * The PWM supports only a single period for all PWM channels.
 210          * Once the period is set, it can only be changed if no more than one
 211          * channel is requested at that moment.
 212          */
 213         if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
 214             lpc18xx_pwm->period_ns) {
 215                 dev_err(pwmchip_parent(chip), "conflicting period requested for PWM %u\n",
 216                         pwm->hwpwm);
 217                 mutex_unlock(&lpc18xx_pwm->period_lock);
 218                 return -EBUSY;
 219         }
 220
 221         if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) ||
 222             !lpc18xx_pwm->period_ns) {
 223                 lpc18xx_pwm->period_ns = period_ns;
 224                 lpc18xx_pwm_config_period(chip, period_ns);
 225         }
 226
 227         mutex_unlock(&lpc18xx_pwm->period_lock);
 228
 229         lpc18xx_pwm_config_duty(chip, pwm, duty_ns);
 230
 231         return 0;
 232 }
 233
 234 static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity)
 235 {
 236         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 237         struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
 238         enum lpc18xx_pwm_res_action res_action;
 239         unsigned int set_event, clear_event;
 240
 241         lpc18xx_pwm_writel(lpc18xx_pwm,
 242                            LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
 243                            LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) |
 244                            LPC18XX_PWM_EVCTRL_COMB_MATCH);
 245
 246         lpc18xx_pwm_writel(lpc18xx_pwm,
 247                            LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
 248                            LPC18XX_PWM_EVSTATEMSK_ALL);
 249
 250         if (polarity == PWM_POLARITY_NORMAL) {
 251                 set_event = lpc18xx_pwm->period_event;
 252                 clear_event = lpc18xx_data->duty_event;
 253                 res_action = LPC18XX_PWM_RES_SET;
 254         } else {
 255                 set_event = lpc18xx_data->duty_event;
 256                 clear_event = lpc18xx_pwm->period_event;
 257                 res_action = LPC18XX_PWM_RES_CLEAR;
 258         }
 259
 260         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
 261                            BIT(set_event));
 262         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
 263                            BIT(clear_event));
 264         lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);
 265
 266         return 0;
 267 }
 268
 269 static void lpc18xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 270 {
 271         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 272         struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
 273
 274         lpc18xx_pwm_writel(lpc18xx_pwm,
 275                            LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
 276         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
 277         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
 278 }
 279
 280 static int lpc18xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 281 {
 282         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 283         struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
 284         unsigned long event;
 285
 286         event = find_first_zero_bit(&lpc18xx_pwm->event_map,
 287                                     LPC18XX_PWM_EVENT_MAX);
 288
 289         if (event >= LPC18XX_PWM_EVENT_MAX) {
 290                 dev_err(pwmchip_parent(chip),
 291                         "maximum number of simultaneous channels reached\n");
 292                 return -EBUSY;
 293         }
 294
 295         set_bit(event, &lpc18xx_pwm->event_map);
 296         lpc18xx_data->duty_event = event;
 297
 298         return 0;
 299 }
 300
 301 static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 302 {
 303         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 304         struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
 305
 306         clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
 307 }
 308
 309 static int lpc18xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 310                              const struct pwm_state *state)
 311 {
 312         int err;
 313         bool enabled = pwm->state.enabled;
 314
 315         if (state->polarity != pwm->state.polarity && pwm->state.enabled) {
 316                 lpc18xx_pwm_disable(chip, pwm);
 317                 enabled = false;
 318         }
 319
 320         if (!state->enabled) {
 321                 if (enabled)
 322                         lpc18xx_pwm_disable(chip, pwm);
 323
 324                 return 0;
 325         }
 326
 327         err = lpc18xx_pwm_config(chip, pwm, state->duty_cycle, state->period);
 328         if (err)
 329                 return err;
 330
 331         if (!enabled)
 332                 err = lpc18xx_pwm_enable(chip, pwm, state->polarity);
 333
 334         return err;
 335 }
 336 static const struct pwm_ops lpc18xx_pwm_ops = {
 337         .apply = lpc18xx_pwm_apply,
 338         .request = lpc18xx_pwm_request,
 339         .free = lpc18xx_pwm_free,
 340 };
 341
 342 static const struct of_device_id lpc18xx_pwm_of_match[] = {
 343         { .compatible = "nxp,lpc1850-sct-pwm" },
 344         {}
 345 };
 346 MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);
 347
 348 static int lpc18xx_pwm_probe(struct platform_device *pdev)
 349 {
 350         struct pwm_chip *chip;
 351         struct lpc18xx_pwm_chip *lpc18xx_pwm;
 352         int ret;
 353         u64 val;
 354
 355         chip = devm_pwmchip_alloc(&pdev->dev, LPC18XX_NUM_PWMS, sizeof(*lpc18xx_pwm));
 356         if (IS_ERR(chip))
 357                 return PTR_ERR(chip);
 358         lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 359
 360         lpc18xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
 361         if (IS_ERR(lpc18xx_pwm->base))
 362                 return PTR_ERR(lpc18xx_pwm->base);
 363
 364         lpc18xx_pwm->pwm_clk = devm_clk_get_enabled(&pdev->dev, "pwm");
 365         if (IS_ERR(lpc18xx_pwm->pwm_clk))
 366                 return dev_err_probe(&pdev->dev, PTR_ERR(lpc18xx_pwm->pwm_clk),
 367                                      "failed to get pwm clock\n");
 368
 369         lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
 370         if (!lpc18xx_pwm->clk_rate)
 371                 return dev_err_probe(&pdev->dev,
 372                                      -EINVAL, "pwm clock has no frequency\n");
 373
 374         /*
 375          * If clkrate is too fast, the calculations in .apply() might overflow.
 376          */
 377         if (lpc18xx_pwm->clk_rate > NSEC_PER_SEC)
 378                 return dev_err_probe(&pdev->dev, -EINVAL, "pwm clock to fast\n");
 379
 380         mutex_init(&lpc18xx_pwm->res_lock);
 381         mutex_init(&lpc18xx_pwm->period_lock);
 382
 383         lpc18xx_pwm->max_period_ns =
 384                 mul_u64_u64_div_u64(NSEC_PER_SEC, LPC18XX_PWM_TIMER_MAX, lpc18xx_pwm->clk_rate);
 385
 386         lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
 387                                                   lpc18xx_pwm->clk_rate);
 388
 389         chip->ops = &lpc18xx_pwm_ops;
 390
 391         /* SCT counter must be in unify (32 bit) mode */
 392         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
 393                            LPC18XX_PWM_CONFIG_UNIFY);
 394
 395         /*
 396          * Everytime the timer counter reaches the period value, the related
 397          * event will be triggered and the counter reset to 0.
 398          */
 399         set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
 400         lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;
 401
 402         lpc18xx_pwm_writel(lpc18xx_pwm,
 403                            LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
 404                            LPC18XX_PWM_EVSTATEMSK_ALL);
 405
 406         val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) |
 407               LPC18XX_PWM_EVCTRL_COMB_MATCH;
 408         lpc18xx_pwm_writel(lpc18xx_pwm,
 409                            LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);
 410
 411         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
 412                            BIT(lpc18xx_pwm->period_event));
 413
 414         val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
 415         val &= ~LPC18XX_PWM_BIDIR;
 416         val &= ~LPC18XX_PWM_CTRL_HALT;
 417         val &= ~LPC18XX_PWM_PRE_MASK;
 418         val |= LPC18XX_PWM_PRE(0);
 419         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);
 420
 421         ret = pwmchip_add(chip);
 422         if (ret < 0)
 423                 return dev_err_probe(&pdev->dev, ret, "pwmchip_add failed\n");
 424
 425         platform_set_drvdata(pdev, chip);
 426
 427         return 0;
 428 }
 429
 430 static void lpc18xx_pwm_remove(struct platform_device *pdev)
 431 {
 432         struct pwm_chip *chip = platform_get_drvdata(pdev);
 433         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 434         u32 val;
 435
 436         pwmchip_remove(chip);
 437
 438         val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
 439         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
 440                            val | LPC18XX_PWM_CTRL_HALT);
 441 }
 442
 443 static struct platform_driver lpc18xx_pwm_driver = {
 444         .driver = {
 445                 .name = "lpc18xx-sct-pwm",
 446                 .of_match_table = lpc18xx_pwm_of_match,
 447         },
 448         .probe = lpc18xx_pwm_probe,
 449         .remove = lpc18xx_pwm_remove,
 450 };
 451 module_platform_driver(lpc18xx_pwm_driver);
 452
 453 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
 454 MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
 455 MODULE_LICENSE("GPL v2");