linux/drivers/pwm/core.c
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   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
  35static DEFINE_MUTEX(pwm_lookup_lock);
  36static LIST_HEAD(pwm_lookup_list);
  37static DEFINE_MUTEX(pwm_lock);
  38static LIST_HEAD(pwm_chips);
  39static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
  40static RADIX_TREE(pwm_tree, GFP_KERNEL);
  41
  42static struct pwm_device *pwm_to_device(unsigned int pwm)
  43{
  44        return radix_tree_lookup(&pwm_tree, pwm);
  45}
  46
  47static 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
  70static 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
  85static 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
 108static 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
 132static struct pwm_device *
 133of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
 134{
 135        struct pwm_device *pwm;
 136
 137        if (pc->of_pwm_n_cells < 2)
 138                return ERR_PTR(-EINVAL);
 139
 140        if (args->args[0] >= pc->npwm)
 141                return ERR_PTR(-EINVAL);
 142
 143        pwm = pwm_request_from_chip(pc, args->args[0], NULL);
 144        if (IS_ERR(pwm))
 145                return pwm;
 146
 147        pwm_set_period(pwm, args->args[1]);
 148
 149        return pwm;
 150}
 151
 152static void of_pwmchip_add(struct pwm_chip *chip)
 153{
 154        if (!chip->dev || !chip->dev->of_node)
 155                return;
 156
 157        if (!chip->of_xlate) {
 158                chip->of_xlate = of_pwm_simple_xlate;
 159                chip->of_pwm_n_cells = 2;
 160        }
 161
 162        of_node_get(chip->dev->of_node);
 163}
 164
 165static void of_pwmchip_remove(struct pwm_chip *chip)
 166{
 167        if (chip->dev && chip->dev->of_node)
 168                of_node_put(chip->dev->of_node);
 169}
 170
 171/**
 172 * pwm_set_chip_data() - set private chip data for a PWM
 173 * @pwm: PWM device
 174 * @data: pointer to chip-specific data
 175 */
 176int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 177{
 178        if (!pwm)
 179                return -EINVAL;
 180
 181        pwm->chip_data = data;
 182
 183        return 0;
 184}
 185
 186/**
 187 * pwm_get_chip_data() - get private chip data for a PWM
 188 * @pwm: PWM device
 189 */
 190void *pwm_get_chip_data(struct pwm_device *pwm)
 191{
 192        return pwm ? pwm->chip_data : NULL;
 193}
 194
 195/**
 196 * pwmchip_add() - register a new PWM chip
 197 * @chip: the PWM chip to add
 198 *
 199 * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
 200 * will be used.
 201 */
 202int pwmchip_add(struct pwm_chip *chip)
 203{
 204        struct pwm_device *pwm;
 205        unsigned int i;
 206        int ret;
 207
 208        if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
 209            !chip->ops->enable || !chip->ops->disable)
 210                return -EINVAL;
 211
 212        mutex_lock(&pwm_lock);
 213
 214        ret = alloc_pwms(chip->base, chip->npwm);
 215        if (ret < 0)
 216                goto out;
 217
 218        chip->pwms = kzalloc(chip->npwm * sizeof(*pwm), GFP_KERNEL);
 219        if (!chip->pwms) {
 220                ret = -ENOMEM;
 221                goto out;
 222        }
 223
 224        chip->base = ret;
 225
 226        for (i = 0; i < chip->npwm; i++) {
 227                pwm = &chip->pwms[i];
 228
 229                pwm->chip = chip;
 230                pwm->pwm = chip->base + i;
 231                pwm->hwpwm = i;
 232
 233                radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
 234        }
 235
 236        bitmap_set(allocated_pwms, chip->base, chip->npwm);
 237
 238        INIT_LIST_HEAD(&chip->list);
 239        list_add(&chip->list, &pwm_chips);
 240
 241        ret = 0;
 242
 243        if (IS_ENABLED(CONFIG_OF))
 244                of_pwmchip_add(chip);
 245
 246out:
 247        mutex_unlock(&pwm_lock);
 248        return ret;
 249}
 250EXPORT_SYMBOL_GPL(pwmchip_add);
 251
 252/**
 253 * pwmchip_remove() - remove a PWM chip
 254 * @chip: the PWM chip to remove
 255 *
 256 * Removes a PWM chip. This function may return busy if the PWM chip provides
 257 * a PWM device that is still requested.
 258 */
 259int pwmchip_remove(struct pwm_chip *chip)
 260{
 261        unsigned int i;
 262        int ret = 0;
 263
 264        mutex_lock(&pwm_lock);
 265
 266        for (i = 0; i < chip->npwm; i++) {
 267                struct pwm_device *pwm = &chip->pwms[i];
 268
 269                if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
 270                        ret = -EBUSY;
 271                        goto out;
 272                }
 273        }
 274
 275        list_del_init(&chip->list);
 276
 277        if (IS_ENABLED(CONFIG_OF))
 278                of_pwmchip_remove(chip);
 279
 280        free_pwms(chip);
 281
 282out:
 283        mutex_unlock(&pwm_lock);
 284        return ret;
 285}
 286EXPORT_SYMBOL_GPL(pwmchip_remove);
 287
 288/**
 289 * pwm_request() - request a PWM device
 290 * @pwm_id: global PWM device index
 291 * @label: PWM device label
 292 *
 293 * This function is deprecated, use pwm_get() instead.
 294 */
 295struct pwm_device *pwm_request(int pwm, const char *label)
 296{
 297        struct pwm_device *dev;
 298        int err;
 299
 300        if (pwm < 0 || pwm >= MAX_PWMS)
 301                return ERR_PTR(-EINVAL);
 302
 303        mutex_lock(&pwm_lock);
 304
 305        dev = pwm_to_device(pwm);
 306        if (!dev) {
 307                dev = ERR_PTR(-EPROBE_DEFER);
 308                goto out;
 309        }
 310
 311        err = pwm_device_request(dev, label);
 312        if (err < 0)
 313                dev = ERR_PTR(err);
 314
 315out:
 316        mutex_unlock(&pwm_lock);
 317
 318        return dev;
 319}
 320EXPORT_SYMBOL_GPL(pwm_request);
 321
 322/**
 323 * pwm_request_from_chip() - request a PWM device relative to a PWM chip
 324 * @chip: PWM chip
 325 * @index: per-chip index of the PWM to request
 326 * @label: a literal description string of this PWM
 327 *
 328 * Returns the PWM at the given index of the given PWM chip. A negative error
 329 * code is returned if the index is not valid for the specified PWM chip or
 330 * if the PWM device cannot be requested.
 331 */
 332struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 333                                         unsigned int index,
 334                                         const char *label)
 335{
 336        struct pwm_device *pwm;
 337        int err;
 338
 339        if (!chip || index >= chip->npwm)
 340                return ERR_PTR(-EINVAL);
 341
 342        mutex_lock(&pwm_lock);
 343        pwm = &chip->pwms[index];
 344
 345        err = pwm_device_request(pwm, label);
 346        if (err < 0)
 347                pwm = ERR_PTR(err);
 348
 349        mutex_unlock(&pwm_lock);
 350        return pwm;
 351}
 352EXPORT_SYMBOL_GPL(pwm_request_from_chip);
 353
 354/**
 355 * pwm_free() - free a PWM device
 356 * @pwm: PWM device
 357 *
 358 * This function is deprecated, use pwm_put() instead.
 359 */
 360void pwm_free(struct pwm_device *pwm)
 361{
 362        pwm_put(pwm);
 363}
 364EXPORT_SYMBOL_GPL(pwm_free);
 365
 366/**
 367 * pwm_config() - change a PWM device configuration
 368 * @pwm: PWM device
 369 * @duty_ns: "on" time (in nanoseconds)
 370 * @period_ns: duration (in nanoseconds) of one cycle
 371 */
 372int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 373{
 374        if (!pwm || period_ns == 0 || duty_ns > period_ns)
 375                return -EINVAL;
 376
 377        return pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
 378}
 379EXPORT_SYMBOL_GPL(pwm_config);
 380
 381/**
 382 * pwm_enable() - start a PWM output toggling
 383 * @pwm: PWM device
 384 */
 385int pwm_enable(struct pwm_device *pwm)
 386{
 387        if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
 388                return pwm->chip->ops->enable(pwm->chip, pwm);
 389
 390        return pwm ? 0 : -EINVAL;
 391}
 392EXPORT_SYMBOL_GPL(pwm_enable);
 393
 394/**
 395 * pwm_disable() - stop a PWM output toggling
 396 * @pwm: PWM device
 397 */
 398void pwm_disable(struct pwm_device *pwm)
 399{
 400        if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
 401                pwm->chip->ops->disable(pwm->chip, pwm);
 402}
 403EXPORT_SYMBOL_GPL(pwm_disable);
 404
 405static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
 406{
 407        struct pwm_chip *chip;
 408
 409        mutex_lock(&pwm_lock);
 410
 411        list_for_each_entry(chip, &pwm_chips, list)
 412                if (chip->dev && chip->dev->of_node == np) {
 413                        mutex_unlock(&pwm_lock);
 414                        return chip;
 415                }
 416
 417        mutex_unlock(&pwm_lock);
 418
 419        return ERR_PTR(-EPROBE_DEFER);
 420}
 421
 422/**
 423 * of_pwm_request() - request a PWM via the PWM framework
 424 * @np: device node to get the PWM from
 425 * @con_id: consumer name
 426 *
 427 * Returns the PWM device parsed from the phandle and index specified in the
 428 * "pwms" property of a device tree node or a negative error-code on failure.
 429 * Values parsed from the device tree are stored in the returned PWM device
 430 * object.
 431 *
 432 * If con_id is NULL, the first PWM device listed in the "pwms" property will
 433 * be requested. Otherwise the "pwm-names" property is used to do a reverse
 434 * lookup of the PWM index. This also means that the "pwm-names" property
 435 * becomes mandatory for devices that look up the PWM device via the con_id
 436 * parameter.
 437 */
 438static struct pwm_device *of_pwm_request(struct device_node *np,
 439                                         const char *con_id)
 440{
 441        struct pwm_device *pwm = NULL;
 442        struct of_phandle_args args;
 443        struct pwm_chip *pc;
 444        int index = 0;
 445        int err;
 446
 447        if (con_id) {
 448                index = of_property_match_string(np, "pwm-names", con_id);
 449                if (index < 0)
 450                        return ERR_PTR(index);
 451        }
 452
 453        err = of_parse_phandle_with_args(np, "pwms", "#pwm-cells", index,
 454                                         &args);
 455        if (err) {
 456                pr_debug("%s(): can't parse \"pwms\" property\n", __func__);
 457                return ERR_PTR(err);
 458        }
 459
 460        pc = of_node_to_pwmchip(args.np);
 461        if (IS_ERR(pc)) {
 462                pr_debug("%s(): PWM chip not found\n", __func__);
 463                pwm = ERR_CAST(pc);
 464                goto put;
 465        }
 466
 467        if (args.args_count != pc->of_pwm_n_cells) {
 468                pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name,
 469                         args.np->full_name);
 470                pwm = ERR_PTR(-EINVAL);
 471                goto put;
 472        }
 473
 474        pwm = pc->of_xlate(pc, &args);
 475        if (IS_ERR(pwm))
 476                goto put;
 477
 478        /*
 479         * If a consumer name was not given, try to look it up from the
 480         * "pwm-names" property if it exists. Otherwise use the name of
 481         * the user device node.
 482         */
 483        if (!con_id) {
 484                err = of_property_read_string_index(np, "pwm-names", index,
 485                                                    &con_id);
 486                if (err < 0)
 487                        con_id = np->name;
 488        }
 489
 490        pwm->label = con_id;
 491
 492put:
 493        of_node_put(args.np);
 494
 495        return pwm;
 496}
 497
 498/**
 499 * pwm_add_table() - register PWM device consumers
 500 * @table: array of consumers to register
 501 * @num: number of consumers in table
 502 */
 503void __init pwm_add_table(struct pwm_lookup *table, size_t num)
 504{
 505        mutex_lock(&pwm_lookup_lock);
 506
 507        while (num--) {
 508                list_add_tail(&table->list, &pwm_lookup_list);
 509                table++;
 510        }
 511
 512        mutex_unlock(&pwm_lookup_lock);
 513}
 514
 515/**
 516 * pwm_get() - look up and request a PWM device
 517 * @dev: device for PWM consumer
 518 * @con_id: consumer name
 519 *
 520 * Lookup is first attempted using DT. If the device was not instantiated from
 521 * a device tree, a PWM chip and a relative index is looked up via a table
 522 * supplied by board setup code (see pwm_add_table()).
 523 *
 524 * Once a PWM chip has been found the specified PWM device will be requested
 525 * and is ready to be used.
 526 */
 527struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 528{
 529        struct pwm_device *pwm = ERR_PTR(-EPROBE_DEFER);
 530        const char *dev_id = dev ? dev_name(dev) : NULL;
 531        struct pwm_chip *chip = NULL;
 532        unsigned int index = 0;
 533        unsigned int best = 0;
 534        struct pwm_lookup *p;
 535        unsigned int match;
 536
 537        /* look up via DT first */
 538        if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
 539                return of_pwm_request(dev->of_node, con_id);
 540
 541        /*
 542         * We look up the provider in the static table typically provided by
 543         * board setup code. We first try to lookup the consumer device by
 544         * name. If the consumer device was passed in as NULL or if no match
 545         * was found, we try to find the consumer by directly looking it up
 546         * by name.
 547         *
 548         * If a match is found, the provider PWM chip is looked up by name
 549         * and a PWM device is requested using the PWM device per-chip index.
 550         *
 551         * The lookup algorithm was shamelessly taken from the clock
 552         * framework:
 553         *
 554         * We do slightly fuzzy matching here:
 555         *  An entry with a NULL ID is assumed to be a wildcard.
 556         *  If an entry has a device ID, it must match
 557         *  If an entry has a connection ID, it must match
 558         * Then we take the most specific entry - with the following order
 559         * of precedence: dev+con > dev only > con only.
 560         */
 561        mutex_lock(&pwm_lookup_lock);
 562
 563        list_for_each_entry(p, &pwm_lookup_list, list) {
 564                match = 0;
 565
 566                if (p->dev_id) {
 567                        if (!dev_id || strcmp(p->dev_id, dev_id))
 568                                continue;
 569
 570                        match += 2;
 571                }
 572
 573                if (p->con_id) {
 574                        if (!con_id || strcmp(p->con_id, con_id))
 575                                continue;
 576
 577                        match += 1;
 578                }
 579
 580                if (match > best) {
 581                        chip = pwmchip_find_by_name(p->provider);
 582                        index = p->index;
 583
 584                        if (match != 3)
 585                                best = match;
 586                        else
 587                                break;
 588                }
 589        }
 590
 591        if (chip)
 592                pwm = pwm_request_from_chip(chip, index, con_id ?: dev_id);
 593
 594        mutex_unlock(&pwm_lookup_lock);
 595
 596        return pwm;
 597}
 598EXPORT_SYMBOL_GPL(pwm_get);
 599
 600/**
 601 * pwm_put() - release a PWM device
 602 * @pwm: PWM device
 603 */
 604void pwm_put(struct pwm_device *pwm)
 605{
 606        if (!pwm)
 607                return;
 608
 609        mutex_lock(&pwm_lock);
 610
 611        if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
 612                pr_warn("PWM device already freed\n");
 613                goto out;
 614        }
 615
 616        if (pwm->chip->ops->free)
 617                pwm->chip->ops->free(pwm->chip, pwm);
 618
 619        pwm->label = NULL;
 620
 621        module_put(pwm->chip->ops->owner);
 622out:
 623        mutex_unlock(&pwm_lock);
 624}
 625EXPORT_SYMBOL_GPL(pwm_put);
 626
 627#ifdef CONFIG_DEBUG_FS
 628static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 629{
 630        unsigned int i;
 631
 632        for (i = 0; i < chip->npwm; i++) {
 633                struct pwm_device *pwm = &chip->pwms[i];
 634
 635                seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
 636
 637                if (test_bit(PWMF_REQUESTED, &pwm->flags))
 638                        seq_printf(s, " requested");
 639
 640                if (test_bit(PWMF_ENABLED, &pwm->flags))
 641                        seq_printf(s, " enabled");
 642
 643                seq_printf(s, "\n");
 644        }
 645}
 646
 647static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
 648{
 649        mutex_lock(&pwm_lock);
 650        s->private = "";
 651
 652        return seq_list_start(&pwm_chips, *pos);
 653}
 654
 655static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
 656{
 657        s->private = "\n";
 658
 659        return seq_list_next(v, &pwm_chips, pos);
 660}
 661
 662static void pwm_seq_stop(struct seq_file *s, void *v)
 663{
 664        mutex_unlock(&pwm_lock);
 665}
 666
 667static int pwm_seq_show(struct seq_file *s, void *v)
 668{
 669        struct pwm_chip *chip = list_entry(v, struct pwm_chip, list);
 670
 671        seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private,
 672                   chip->dev->bus ? chip->dev->bus->name : "no-bus",
 673                   dev_name(chip->dev), chip->npwm,
 674                   (chip->npwm != 1) ? "s" : "");
 675
 676        if (chip->ops->dbg_show)
 677                chip->ops->dbg_show(chip, s);
 678        else
 679                pwm_dbg_show(chip, s);
 680
 681        return 0;
 682}
 683
 684static const struct seq_operations pwm_seq_ops = {
 685        .start = pwm_seq_start,
 686        .next = pwm_seq_next,
 687        .stop = pwm_seq_stop,
 688        .show = pwm_seq_show,
 689};
 690
 691static int pwm_seq_open(struct inode *inode, struct file *file)
 692{
 693        return seq_open(file, &pwm_seq_ops);
 694}
 695
 696static const struct file_operations pwm_debugfs_ops = {
 697        .owner = THIS_MODULE,
 698        .open = pwm_seq_open,
 699        .read = seq_read,
 700        .llseek = seq_lseek,
 701        .release = seq_release,
 702};
 703
 704static int __init pwm_debugfs_init(void)
 705{
 706        debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL,
 707                            &pwm_debugfs_ops);
 708
 709        return 0;
 710}
 711
 712subsys_initcall(pwm_debugfs_init);
 713#endif /* CONFIG_DEBUG_FS */
 714
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