drivers/pwm/core.c

   1 /*
   2  * Generic pwmlib implementation
   3  *
   4  * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
   5  * Copyright (C) 2011-2012 Avionic Design GmbH
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2, or (at your option)
  10  *  any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with this program; see the file COPYING.  If not, write to
  19  *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/pwm.h>
  24 #include <linux/radix-tree.h>
  25 #include <linux/list.h>
  26 #include <linux/mutex.h>
  27 #include <linux/err.h>
  28 #include <linux/slab.h>
  29 #include <linux/device.h>
  30 #include <linux/debugfs.h>
  31 #include <linux/seq_file.h>
  32
  33 #define MAX_PWMS 1024
  34
  35 static DEFINE_MUTEX(pwm_lookup_lock);
  36 static LIST_HEAD(pwm_lookup_list);
  37 static DEFINE_MUTEX(pwm_lock);
  38 static LIST_HEAD(pwm_chips);
  39 static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
  40 static RADIX_TREE(pwm_tree, GFP_KERNEL);
  41
  42 static struct pwm_device *pwm_to_device(unsigned int pwm)
  43 {
  44         return radix_tree_lookup(&pwm_tree, pwm);
  45 }
  46
  47 static int alloc_pwms(int pwm, unsigned int count)
  48 {
  49         unsigned int from = 0;
  50         unsigned int start;
  51
  52         if (pwm >= MAX_PWMS)
  53                 return -EINVAL;
  54
  55         if (pwm >= 0)
  56                 from = pwm;
  57
  58         start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from,
  59                                            count, 0);
  60
  61         if (pwm >= 0 && start != pwm)
  62                 return -EEXIST;
  63
  64         if (start + count > MAX_PWMS)
  65                 return -ENOSPC;
  66
  67         return start;
  68 }
  69
  70 static void free_pwms(struct pwm_chip *chip)
  71 {
  72         unsigned int i;
  73
  74         for (i = 0; i < chip->npwm; i++) {
  75                 struct pwm_device *pwm = &chip->pwms[i];
  76                 radix_tree_delete(&pwm_tree, pwm->pwm);
  77         }
  78
  79         bitmap_clear(allocated_pwms, chip->base, chip->npwm);
  80
  81         kfree(chip->pwms);
  82         chip->pwms = NULL;
  83 }
  84
  85 static struct pwm_chip *pwmchip_find_by_name(const char *name)
  86 {
  87         struct pwm_chip *chip;
  88
  89         if (!name)
  90                 return NULL;
  91
  92         mutex_lock(&pwm_lock);
  93
  94         list_for_each_entry(chip, &pwm_chips, list) {
  95                 const char *chip_name = dev_name(chip->dev);
  96
  97                 if (chip_name && strcmp(chip_name, name) == 0) {
  98                         mutex_unlock(&pwm_lock);
  99                         return chip;
 100                 }
 101         }
 102
 103         mutex_unlock(&pwm_lock);
 104
 105         return NULL;
 106 }
 107
 108 static int pwm_device_request(struct pwm_device *pwm, const char *label)
 109 {
 110         int err;
 111
 112         if (test_bit(PWMF_REQUESTED, &pwm->flags))
 113                 return -EBUSY;
 114
 115         if (!try_module_get(pwm->chip->ops->owner))
 116                 return -ENODEV;
 117
 118         if (pwm->chip->ops->request) {
 119                 err = pwm->chip->ops->request(pwm->chip, pwm);
 120                 if (err) {
 121                         module_put(pwm->chip->ops->owner);
 122                         return err;
 123                 }
 124         }
 125
 126         set_bit(PWMF_REQUESTED, &pwm->flags);
 127         pwm->label = label;
 128
 129         return 0;
 130 }
 131
 132 /**
 133  * pwm_set_chip_data() - set private chip data for a PWM
 134  * @pwm: PWM device
 135  * @data: pointer to chip-specific data
 136  */
 137 int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 138 {
 139         if (!pwm)
 140                 return -EINVAL;
 141
 142         pwm->chip_data = data;
 143
 144         return 0;
 145 }
 146
 147 /**
 148  * pwm_get_chip_data() - get private chip data for a PWM
 149  * @pwm: PWM device
 150  */
 151 void *pwm_get_chip_data(struct pwm_device *pwm)
 152 {
 153         return pwm ? pwm->chip_data : NULL;
 154 }
 155
 156 /**
 157  * pwmchip_add() - register a new PWM chip
 158  * @chip: the PWM chip to add
 159  *
 160  * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
 161  * will be used.
 162  */
 163 int pwmchip_add(struct pwm_chip *chip)
 164 {
 165         struct pwm_device *pwm;
 166         unsigned int i;
 167         int ret;
 168
 169         if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
 170             !chip->ops->enable || !chip->ops->disable)
 171                 return -EINVAL;
 172
 173         mutex_lock(&pwm_lock);
 174
 175         ret = alloc_pwms(chip->base, chip->npwm);
 176         if (ret < 0)
 177                 goto out;
 178
 179         chip->pwms = kzalloc(chip->npwm * sizeof(*pwm), GFP_KERNEL);
 180         if (!chip->pwms) {
 181                 ret = -ENOMEM;
 182                 goto out;
 183         }
 184
 185         chip->base = ret;
 186
 187         for (i = 0; i < chip->npwm; i++) {
 188                 pwm = &chip->pwms[i];
 189
 190                 pwm->chip = chip;
 191                 pwm->pwm = chip->base + i;
 192                 pwm->hwpwm = i;
 193
 194                 radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
 195         }
 196
 197         bitmap_set(allocated_pwms, chip->base, chip->npwm);
 198
 199         INIT_LIST_HEAD(&chip->list);
 200         list_add(&chip->list, &pwm_chips);
 201
 202         ret = 0;
 203
 204 out:
 205         mutex_unlock(&pwm_lock);
 206         return ret;
 207 }
 208 EXPORT_SYMBOL_GPL(pwmchip_add);
 209
 210 /**
 211  * pwmchip_remove() - remove a PWM chip
 212  * @chip: the PWM chip to remove
 213  *
 214  * Removes a PWM chip. This function may return busy if the PWM chip provides
 215  * a PWM device that is still requested.
 216  */
 217 int pwmchip_remove(struct pwm_chip *chip)
 218 {
 219         unsigned int i;
 220         int ret = 0;
 221
 222         mutex_lock(&pwm_lock);
 223
 224         for (i = 0; i < chip->npwm; i++) {
 225                 struct pwm_device *pwm = &chip->pwms[i];
 226
 227                 if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
 228                         ret = -EBUSY;
 229                         goto out;
 230                 }
 231         }
 232
 233         list_del_init(&chip->list);
 234         free_pwms(chip);
 235
 236 out:
 237         mutex_unlock(&pwm_lock);
 238         return ret;
 239 }
 240 EXPORT_SYMBOL_GPL(pwmchip_remove);
 241
 242 /**
 243  * pwm_request() - request a PWM device
 244  * @pwm_id: global PWM device index
 245  * @label: PWM device label
 246  *
 247  * This function is deprecated, use pwm_get() instead.
 248  */
 249 struct pwm_device *pwm_request(int pwm, const char *label)
 250 {
 251         struct pwm_device *dev;
 252         int err;
 253
 254         if (pwm < 0 || pwm >= MAX_PWMS)
 255                 return ERR_PTR(-EINVAL);
 256
 257         mutex_lock(&pwm_lock);
 258
 259         dev = pwm_to_device(pwm);
 260         if (!dev) {
 261                 dev = ERR_PTR(-EPROBE_DEFER);
 262                 goto out;
 263         }
 264
 265         err = pwm_device_request(dev, label);
 266         if (err < 0)
 267                 dev = ERR_PTR(err);
 268
 269 out:
 270         mutex_unlock(&pwm_lock);
 271
 272         return dev;
 273 }
 274 EXPORT_SYMBOL_GPL(pwm_request);
 275
 276 /**
 277  * pwm_request_from_chip() - request a PWM device relative to a PWM chip
 278  * @chip: PWM chip
 279  * @index: per-chip index of the PWM to request
 280  * @label: a literal description string of this PWM
 281  *
 282  * Returns the PWM at the given index of the given PWM chip. A negative error
 283  * code is returned if the index is not valid for the specified PWM chip or
 284  * if the PWM device cannot be requested.
 285  */
 286 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 287                                          unsigned int index,
 288                                          const char *label)
 289 {
 290         struct pwm_device *pwm;
 291         int err;
 292
 293         if (!chip || index >= chip->npwm)
 294                 return ERR_PTR(-EINVAL);
 295
 296         mutex_lock(&pwm_lock);
 297         pwm = &chip->pwms[index];
 298
 299         err = pwm_device_request(pwm, label);
 300         if (err < 0)
 301                 pwm = ERR_PTR(err);
 302
 303         mutex_unlock(&pwm_lock);
 304         return pwm;
 305 }
 306 EXPORT_SYMBOL_GPL(pwm_request_from_chip);
 307
 308 /**
 309  * pwm_free() - free a PWM device
 310  * @pwm: PWM device
 311  *
 312  * This function is deprecated, use pwm_put() instead.
 313  */
 314 void pwm_free(struct pwm_device *pwm)
 315 {
 316         pwm_put(pwm);
 317 }
 318 EXPORT_SYMBOL_GPL(pwm_free);
 319
 320 /**
 321  * pwm_config() - change a PWM device configuration
 322  * @pwm: PWM device
 323  * @duty_ns: "on" time (in nanoseconds)
 324  * @period_ns: duration (in nanoseconds) of one cycle
 325  */
 326 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 327 {
 328         if (!pwm || period_ns == 0 || duty_ns > period_ns)
 329                 return -EINVAL;
 330
 331         return pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
 332 }
 333 EXPORT_SYMBOL_GPL(pwm_config);
 334
 335 /**
 336  * pwm_enable() - start a PWM output toggling
 337  * @pwm: PWM device
 338  */
 339 int pwm_enable(struct pwm_device *pwm)
 340 {
 341         if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
 342                 return pwm->chip->ops->enable(pwm->chip, pwm);
 343
 344         return pwm ? 0 : -EINVAL;
 345 }
 346 EXPORT_SYMBOL_GPL(pwm_enable);
 347
 348 /**
 349  * pwm_disable() - stop a PWM output toggling
 350  * @pwm: PWM device
 351  */
 352 void pwm_disable(struct pwm_device *pwm)
 353 {
 354         if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
 355                 pwm->chip->ops->disable(pwm->chip, pwm);
 356 }
 357 EXPORT_SYMBOL_GPL(pwm_disable);
 358
 359 /**
 360  * pwm_add_table() - register PWM device consumers
 361  * @table: array of consumers to register
 362  * @num: number of consumers in table
 363  */
 364 void __init pwm_add_table(struct pwm_lookup *table, size_t num)
 365 {
 366         mutex_lock(&pwm_lookup_lock);
 367
 368         while (num--) {
 369                 list_add_tail(&table->list, &pwm_lookup_list);
 370                 table++;
 371         }
 372
 373         mutex_unlock(&pwm_lookup_lock);
 374 }
 375
 376 /**
 377  * pwm_get() - look up and request a PWM device
 378  * @dev: device for PWM consumer
 379  * @con_id: consumer name
 380  *
 381  * Look up a PWM chip and a relative index via a table supplied by board setup
 382  * code (see pwm_add_table()).
 383  *
 384  * Once a PWM chip has been found the specified PWM device will be requested
 385  * and is ready to be used.
 386  */
 387 struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 388 {
 389         struct pwm_device *pwm = ERR_PTR(-EPROBE_DEFER);
 390         const char *dev_id = dev ? dev_name(dev): NULL;
 391         struct pwm_chip *chip = NULL;
 392         unsigned int best = 0;
 393         struct pwm_lookup *p;
 394         unsigned int index;
 395         unsigned int match;
 396
 397         /*
 398          * We look up the provider in the static table typically provided by
 399          * board setup code. We first try to lookup the consumer device by
 400          * name. If the consumer device was passed in as NULL or if no match
 401          * was found, we try to find the consumer by directly looking it up
 402          * by name.
 403          *
 404          * If a match is found, the provider PWM chip is looked up by name
 405          * and a PWM device is requested using the PWM device per-chip index.
 406          *
 407          * The lookup algorithm was shamelessly taken from the clock
 408          * framework:
 409          *
 410          * We do slightly fuzzy matching here:
 411          *  An entry with a NULL ID is assumed to be a wildcard.
 412          *  If an entry has a device ID, it must match
 413          *  If an entry has a connection ID, it must match
 414          * Then we take the most specific entry - with the following order
 415          * of precedence: dev+con > dev only > con only.
 416          */
 417         mutex_lock(&pwm_lookup_lock);
 418
 419         list_for_each_entry(p, &pwm_lookup_list, list) {
 420                 match = 0;
 421
 422                 if (p->dev_id) {
 423                         if (!dev_id || strcmp(p->dev_id, dev_id))
 424                                 continue;
 425
 426                         match += 2;
 427                 }
 428
 429                 if (p->con_id) {
 430                         if (!con_id || strcmp(p->con_id, con_id))
 431                                 continue;
 432
 433                         match += 1;
 434                 }
 435
 436                 if (match > best) {
 437                         chip = pwmchip_find_by_name(p->provider);
 438                         index = p->index;
 439
 440                         if (match != 3)
 441                                 best = match;
 442                         else
 443                                 break;
 444                 }
 445         }
 446
 447         if (chip)
 448                 pwm = pwm_request_from_chip(chip, index, con_id ?: dev_id);
 449
 450         mutex_unlock(&pwm_lookup_lock);
 451
 452         return pwm;
 453 }
 454 EXPORT_SYMBOL_GPL(pwm_get);
 455
 456 /**
 457  * pwm_put() - release a PWM device
 458  * @pwm: PWM device
 459  */
 460 void pwm_put(struct pwm_device *pwm)
 461 {
 462         if (!pwm)
 463                 return;
 464
 465         mutex_lock(&pwm_lock);
 466
 467         if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
 468                 pr_warning("PWM device already freed\n");
 469                 goto out;
 470         }
 471
 472         if (pwm->chip->ops->free)
 473                 pwm->chip->ops->free(pwm->chip, pwm);
 474
 475         pwm->label = NULL;
 476
 477         module_put(pwm->chip->ops->owner);
 478 out:
 479         mutex_unlock(&pwm_lock);
 480 }
 481 EXPORT_SYMBOL_GPL(pwm_put);
 482
 483 #ifdef CONFIG_DEBUG_FS
 484 static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 485 {
 486         unsigned int i;
 487
 488         for (i = 0; i < chip->npwm; i++) {
 489                 struct pwm_device *pwm = &chip->pwms[i];
 490
 491                 seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
 492
 493                 if (test_bit(PWMF_REQUESTED, &pwm->flags))
 494                         seq_printf(s, " requested");
 495
 496                 if (test_bit(PWMF_ENABLED, &pwm->flags))
 497                         seq_printf(s, " enabled");
 498
 499                 seq_printf(s, "\n");
 500         }
 501 }
 502
 503 static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
 504 {
 505         mutex_lock(&pwm_lock);
 506         s->private = "";
 507
 508         return seq_list_start(&pwm_chips, *pos);
 509 }
 510
 511 static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
 512 {
 513         s->private = "\n";
 514
 515         return seq_list_next(v, &pwm_chips, pos);
 516 }
 517
 518 static void pwm_seq_stop(struct seq_file *s, void *v)
 519 {
 520         mutex_unlock(&pwm_lock);
 521 }
 522
 523 static int pwm_seq_show(struct seq_file *s, void *v)
 524 {
 525         struct pwm_chip *chip = list_entry(v, struct pwm_chip, list);
 526
 527         seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private,
 528                    chip->dev->bus ? chip->dev->bus->name : "no-bus",
 529                    dev_name(chip->dev), chip->npwm,
 530                    (chip->npwm != 1) ? "s" : "");
 531
 532         if (chip->ops->dbg_show)
 533                 chip->ops->dbg_show(chip, s);
 534         else
 535                 pwm_dbg_show(chip, s);
 536
 537         return 0;
 538 }
 539
 540 static const struct seq_operations pwm_seq_ops = {
 541         .start = pwm_seq_start,
 542         .next = pwm_seq_next,
 543         .stop = pwm_seq_stop,
 544         .show = pwm_seq_show,
 545 };
 546
 547 static int pwm_seq_open(struct inode *inode, struct file *file)
 548 {
 549         return seq_open(file, &pwm_seq_ops);
 550 }
 551
 552 static const struct file_operations pwm_debugfs_ops = {
 553         .owner = THIS_MODULE,
 554         .open = pwm_seq_open,
 555         .read = seq_read,
 556         .llseek = seq_lseek,
 557         .release = seq_release,
 558 };
 559
 560 static int __init pwm_debugfs_init(void)
 561 {
 562         debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL,
 563                             &pwm_debugfs_ops);
 564
 565         return 0;
 566 }
 567
 568 subsys_initcall(pwm_debugfs_init);
 569 #endif /* CONFIG_DEBUG_FS */