drivers/pwm/pwm-lpc18xx-sct.c

   1 /*
   2  * NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
   3  *
   4  * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License.
   9  *
  10  * Notes
  11  * =====
  12  * NXP LPC18xx provides a State Configurable Timer (SCT) which can be configured
  13  * as a Pulse Width Modulator.
  14  *
  15  * SCT supports 16 outputs, 16 events and 16 registers. Each event will be
  16  * triggered when its related register matches the SCT counter value, and it
  17  * will set or clear a selected output.
  18  *
  19  * One of the events is preselected to generate the period, thus the maximum
  20  * number of simultaneous channels is limited to 15. Notice that period is
  21  * global to all the channels, thus PWM driver will refuse setting different
  22  * values to it, unless there's only one channel requested.
  23  */
  24
  25 #include <linux/clk.h>
  26 #include <linux/err.h>
  27 #include <linux/io.h>
  28 #include <linux/module.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/pwm.h>
  31
  32 /* LPC18xx SCT registers */
  33 #define LPC18XX_PWM_CONFIG              0x000
  34 #define LPC18XX_PWM_CONFIG_UNIFY        BIT(0)
  35 #define LPC18XX_PWM_CONFIG_NORELOAD     BIT(7)
  36
  37 #define LPC18XX_PWM_CTRL                0x004
  38 #define LPC18XX_PWM_CTRL_HALT           BIT(2)
  39 #define LPC18XX_PWM_BIDIR               BIT(4)
  40 #define LPC18XX_PWM_PRE_SHIFT           5
  41 #define LPC18XX_PWM_PRE_MASK            (0xff << LPC18XX_PWM_PRE_SHIFT)
  42 #define LPC18XX_PWM_PRE(x)              (x << LPC18XX_PWM_PRE_SHIFT)
  43
  44 #define LPC18XX_PWM_LIMIT               0x008
  45
  46 #define LPC18XX_PWM_RES_BASE            0x058
  47 #define LPC18XX_PWM_RES_SHIFT(_ch)      (_ch * 2)
  48 #define LPC18XX_PWM_RES(_ch, _action)   (_action << LPC18XX_PWM_RES_SHIFT(_ch))
  49 #define LPC18XX_PWM_RES_MASK(_ch)       (0x3 << LPC18XX_PWM_RES_SHIFT(_ch))
  50
  51 #define LPC18XX_PWM_MATCH_BASE          0x100
  52 #define LPC18XX_PWM_MATCH(_ch)          (LPC18XX_PWM_MATCH_BASE + _ch * 4)
  53
  54 #define LPC18XX_PWM_MATCHREL_BASE       0x200
  55 #define LPC18XX_PWM_MATCHREL(_ch)       (LPC18XX_PWM_MATCHREL_BASE + _ch * 4)
  56
  57 #define LPC18XX_PWM_EVSTATEMSK_BASE     0x300
  58 #define LPC18XX_PWM_EVSTATEMSK(_ch)     (LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
  59 #define LPC18XX_PWM_EVSTATEMSK_ALL      0xffffffff
  60
  61 #define LPC18XX_PWM_EVCTRL_BASE         0x304
  62 #define LPC18XX_PWM_EVCTRL(_ev)         (LPC18XX_PWM_EVCTRL_BASE + _ev * 8)
  63
  64 #define LPC18XX_PWM_EVCTRL_MATCH(_ch)   _ch
  65
  66 #define LPC18XX_PWM_EVCTRL_COMB_SHIFT   12
  67 #define LPC18XX_PWM_EVCTRL_COMB_MATCH   (0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)
  68
  69 #define LPC18XX_PWM_OUTPUTSET_BASE      0x500
  70 #define LPC18XX_PWM_OUTPUTSET(_ch)      (LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)
  71
  72 #define LPC18XX_PWM_OUTPUTCL_BASE       0x504
  73 #define LPC18XX_PWM_OUTPUTCL(_ch)       (LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)
  74
  75 /* LPC18xx SCT unified counter */
  76 #define LPC18XX_PWM_TIMER_MAX           0xffffffff
  77
  78 /* LPC18xx SCT events */
  79 #define LPC18XX_PWM_EVENT_PERIOD        0
  80 #define LPC18XX_PWM_EVENT_MAX           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         struct device *dev;
  96         struct pwm_chip chip;
  97         void __iomem *base;
  98         struct clk *pwm_clk;
  99         unsigned long clk_rate;
 100         unsigned int period_ns;
 101         unsigned int min_period_ns;
 102         unsigned int max_period_ns;
 103         unsigned int period_event;
 104         unsigned long event_map;
 105         struct mutex res_lock;
 106         struct mutex period_lock;
 107 };
 108
 109 static inline struct lpc18xx_pwm_chip *
 110 to_lpc18xx_pwm_chip(struct pwm_chip *chip)
 111 {
 112         return container_of(chip, struct lpc18xx_pwm_chip, chip);
 113 }
 114
 115 static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 116                                       u32 reg, u32 val)
 117 {
 118         writel(val, lpc18xx_pwm->base + reg);
 119 }
 120
 121 static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 122                                     u32 reg)
 123 {
 124         return readl(lpc18xx_pwm->base + reg);
 125 }
 126
 127 static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
 128                                          struct pwm_device *pwm,
 129                                          enum lpc18xx_pwm_res_action action)
 130 {
 131         u32 val;
 132
 133         mutex_lock(&lpc18xx_pwm->res_lock);
 134
 135         /*
 136          * Simultaneous set and clear may happen on an output, that is the case
 137          * when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
 138          * resolution action to be taken in such a case.
 139          */
 140         val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
 141         val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
 142         val |= LPC18XX_PWM_RES(pwm->hwpwm, action);
 143         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);
 144
 145         mutex_unlock(&lpc18xx_pwm->res_lock);
 146 }
 147
 148 static void lpc18xx_pwm_config_period(struct pwm_chip *chip, int period_ns)
 149 {
 150         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 151         u64 val;
 152
 153         val = (u64)period_ns * lpc18xx_pwm->clk_rate;
 154         do_div(val, NSEC_PER_SEC);
 155
 156         lpc18xx_pwm_writel(lpc18xx_pwm,
 157                            LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
 158                            (u32)val - 1);
 159
 160         lpc18xx_pwm_writel(lpc18xx_pwm,
 161                            LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
 162                            (u32)val - 1);
 163 }
 164
 165 static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
 166                                     struct pwm_device *pwm, int duty_ns)
 167 {
 168         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 169         struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 170         u64 val;
 171
 172         val = (u64)duty_ns * lpc18xx_pwm->clk_rate;
 173         do_div(val, NSEC_PER_SEC);
 174
 175         lpc18xx_pwm_writel(lpc18xx_pwm,
 176                            LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
 177                            (u32)val);
 178
 179         lpc18xx_pwm_writel(lpc18xx_pwm,
 180                            LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
 181                            (u32)val);
 182 }
 183
 184 static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 185                               int duty_ns, int period_ns)
 186 {
 187         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 188         int requested_events, i;
 189
 190         if (period_ns < lpc18xx_pwm->min_period_ns ||
 191             period_ns > lpc18xx_pwm->max_period_ns) {
 192                 dev_err(chip->dev, "period %d not in range\n", period_ns);
 193                 return -ERANGE;
 194         }
 195
 196         mutex_lock(&lpc18xx_pwm->period_lock);
 197
 198         requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
 199                                          LPC18XX_PWM_EVENT_MAX);
 200
 201         /*
 202          * The PWM supports only a single period for all PWM channels.
 203          * Once the period is set, it can only be changed if no more than one
 204          * channel is requested at that moment.
 205          */
 206         if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
 207             lpc18xx_pwm->period_ns) {
 208                 dev_err(chip->dev, "conflicting period requested for PWM %u\n",
 209                         pwm->hwpwm);
 210                 mutex_unlock(&lpc18xx_pwm->period_lock);
 211                 return -EBUSY;
 212         }
 213
 214         if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) ||
 215             !lpc18xx_pwm->period_ns) {
 216                 lpc18xx_pwm->period_ns = period_ns;
 217                 for (i = 0; i < chip->npwm; i++)
 218                         pwm_set_period(&chip->pwms[i], period_ns);
 219                 lpc18xx_pwm_config_period(chip, period_ns);
 220         }
 221
 222         mutex_unlock(&lpc18xx_pwm->period_lock);
 223
 224         lpc18xx_pwm_config_duty(chip, pwm, duty_ns);
 225
 226         return 0;
 227 }
 228
 229 static int lpc18xx_pwm_set_polarity(struct pwm_chip *chip,
 230                                     struct pwm_device *pwm,
 231                                     enum pwm_polarity polarity)
 232 {
 233         return 0;
 234 }
 235
 236 static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 237 {
 238         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 239         struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 240         enum lpc18xx_pwm_res_action res_action;
 241         unsigned int set_event, clear_event;
 242
 243         lpc18xx_pwm_writel(lpc18xx_pwm,
 244                            LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
 245                            LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) |
 246                            LPC18XX_PWM_EVCTRL_COMB_MATCH);
 247
 248         lpc18xx_pwm_writel(lpc18xx_pwm,
 249                            LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
 250                            LPC18XX_PWM_EVSTATEMSK_ALL);
 251
 252         if (pwm_get_polarity(pwm) == PWM_POLARITY_NORMAL) {
 253                 set_event = lpc18xx_pwm->period_event;
 254                 clear_event = lpc18xx_data->duty_event;
 255                 res_action = LPC18XX_PWM_RES_SET;
 256         } else {
 257                 set_event = lpc18xx_data->duty_event;
 258                 clear_event = lpc18xx_pwm->period_event;
 259                 res_action = LPC18XX_PWM_RES_CLEAR;
 260         }
 261
 262         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
 263                            BIT(set_event));
 264         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
 265                            BIT(clear_event));
 266         lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);
 267
 268         return 0;
 269 }
 270
 271 static void lpc18xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 272 {
 273         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 274         struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 275
 276         lpc18xx_pwm_writel(lpc18xx_pwm,
 277                            LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
 278         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
 279         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
 280 }
 281
 282 static int lpc18xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 283 {
 284         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 285         struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 286         unsigned long event;
 287
 288         event = find_first_zero_bit(&lpc18xx_pwm->event_map,
 289                                     LPC18XX_PWM_EVENT_MAX);
 290
 291         if (event >= LPC18XX_PWM_EVENT_MAX) {
 292                 dev_err(lpc18xx_pwm->dev,
 293                         "maximum number of simultaneous channels reached\n");
 294                 return -EBUSY;
 295         };
 296
 297         set_bit(event, &lpc18xx_pwm->event_map);
 298         lpc18xx_data->duty_event = event;
 299
 300         return 0;
 301 }
 302
 303 static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 304 {
 305         struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
 306         struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
 307
 308         clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
 309 }
 310
 311 static const struct pwm_ops lpc18xx_pwm_ops = {
 312         .config = lpc18xx_pwm_config,
 313         .set_polarity = lpc18xx_pwm_set_polarity,
 314         .enable = lpc18xx_pwm_enable,
 315         .disable = lpc18xx_pwm_disable,
 316         .request = lpc18xx_pwm_request,
 317         .free = lpc18xx_pwm_free,
 318         .owner = THIS_MODULE,
 319 };
 320
 321 static const struct of_device_id lpc18xx_pwm_of_match[] = {
 322         { .compatible = "nxp,lpc1850-sct-pwm" },
 323         {}
 324 };
 325 MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);
 326
 327 static int lpc18xx_pwm_probe(struct platform_device *pdev)
 328 {
 329         struct lpc18xx_pwm_chip *lpc18xx_pwm;
 330         struct pwm_device *pwm;
 331         struct resource *res;
 332         int ret, i;
 333         u64 val;
 334
 335         lpc18xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*lpc18xx_pwm),
 336                                    GFP_KERNEL);
 337         if (!lpc18xx_pwm)
 338                 return -ENOMEM;
 339
 340         lpc18xx_pwm->dev = &pdev->dev;
 341
 342         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 343         lpc18xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
 344         if (IS_ERR(lpc18xx_pwm->base))
 345                 return PTR_ERR(lpc18xx_pwm->base);
 346
 347         lpc18xx_pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
 348         if (IS_ERR(lpc18xx_pwm->pwm_clk)) {
 349                 dev_err(&pdev->dev, "failed to get pwm clock\n");
 350                 return PTR_ERR(lpc18xx_pwm->pwm_clk);
 351         }
 352
 353         ret = clk_prepare_enable(lpc18xx_pwm->pwm_clk);
 354         if (ret < 0) {
 355                 dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
 356                 return ret;
 357         }
 358
 359         lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
 360         if (!lpc18xx_pwm->clk_rate) {
 361                 dev_err(&pdev->dev, "pwm clock has no frequency\n");
 362                 ret = -EINVAL;
 363                 goto disable_pwmclk;
 364         }
 365
 366         mutex_init(&lpc18xx_pwm->res_lock);
 367         mutex_init(&lpc18xx_pwm->period_lock);
 368
 369         val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
 370         do_div(val, lpc18xx_pwm->clk_rate);
 371         lpc18xx_pwm->max_period_ns = val;
 372
 373         lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
 374                                                   lpc18xx_pwm->clk_rate);
 375
 376         lpc18xx_pwm->chip.dev = &pdev->dev;
 377         lpc18xx_pwm->chip.ops = &lpc18xx_pwm_ops;
 378         lpc18xx_pwm->chip.base = -1;
 379         lpc18xx_pwm->chip.npwm = 16;
 380         lpc18xx_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 381         lpc18xx_pwm->chip.of_pwm_n_cells = 3;
 382
 383         /* SCT counter must be in unify (32 bit) mode */
 384         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
 385                            LPC18XX_PWM_CONFIG_UNIFY);
 386
 387         /*
 388          * Everytime the timer counter reaches the period value, the related
 389          * event will be triggered and the counter reset to 0.
 390          */
 391         set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
 392         lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;
 393
 394         lpc18xx_pwm_writel(lpc18xx_pwm,
 395                            LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
 396                            LPC18XX_PWM_EVSTATEMSK_ALL);
 397
 398         val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) |
 399               LPC18XX_PWM_EVCTRL_COMB_MATCH;
 400         lpc18xx_pwm_writel(lpc18xx_pwm,
 401                            LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);
 402
 403         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
 404                            BIT(lpc18xx_pwm->period_event));
 405
 406         ret = pwmchip_add(&lpc18xx_pwm->chip);
 407         if (ret < 0) {
 408                 dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
 409                 goto disable_pwmclk;
 410         }
 411
 412         for (i = 0; i < lpc18xx_pwm->chip.npwm; i++) {
 413                 struct lpc18xx_pwm_data *data;
 414
 415                 pwm = &lpc18xx_pwm->chip.pwms[i];
 416
 417                 data = devm_kzalloc(lpc18xx_pwm->dev, sizeof(*data),
 418                                     GFP_KERNEL);
 419                 if (!data) {
 420                         ret = -ENOMEM;
 421                         goto remove_pwmchip;
 422                 }
 423
 424                 pwm_set_chip_data(pwm, data);
 425         }
 426
 427         platform_set_drvdata(pdev, lpc18xx_pwm);
 428
 429         val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
 430         val &= ~LPC18XX_PWM_BIDIR;
 431         val &= ~LPC18XX_PWM_CTRL_HALT;
 432         val &= ~LPC18XX_PWM_PRE_MASK;
 433         val |= LPC18XX_PWM_PRE(0);
 434         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);
 435
 436         return 0;
 437
 438 remove_pwmchip:
 439         pwmchip_remove(&lpc18xx_pwm->chip);
 440 disable_pwmclk:
 441         clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
 442         return ret;
 443 }
 444
 445 static int lpc18xx_pwm_remove(struct platform_device *pdev)
 446 {
 447         struct lpc18xx_pwm_chip *lpc18xx_pwm = platform_get_drvdata(pdev);
 448         u32 val;
 449
 450         val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
 451         lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
 452                            val | LPC18XX_PWM_CTRL_HALT);
 453
 454         clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
 455
 456         return pwmchip_remove(&lpc18xx_pwm->chip);
 457 }
 458
 459 static struct platform_driver lpc18xx_pwm_driver = {
 460         .driver = {
 461                 .name = "lpc18xx-sct-pwm",
 462                 .of_match_table = lpc18xx_pwm_of_match,
 463         },
 464         .probe = lpc18xx_pwm_probe,
 465         .remove = lpc18xx_pwm_remove,
 466 };
 467 module_platform_driver(lpc18xx_pwm_driver);
 468
 469 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
 470 MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
 471 MODULE_LICENSE("GPL v2");