// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Generic pwmlib implementation
 *
 * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
 * Copyright (C) 2011-2012 Avionic Design GmbH
 */

#include <linux/acpi.h>
#include <linux/module.h>
#include <linux/pwm.h>
#include <linux/radix-tree.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>

#include <dt-bindings/pwm/pwm.h>

#define CREATE_TRACE_POINTS
#include <trace/events/pwm.h>

#define MAX_PWMS 1024

static DEFINE_MUTEX(pwm_lookup_lock);
static LIST_HEAD(pwm_lookup_list);
static DEFINE_MUTEX(pwm_lock);
static LIST_HEAD(pwm_chips);
static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
static RADIX_TREE(pwm_tree, GFP_KERNEL);

static struct pwm_device *pwm_to_device(unsigned int pwm)
{
        return radix_tree_lookup(&pwm_tree, pwm);
}

static int alloc_pwms(unsigned int count)
{
        unsigned int start;

        start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, 0,
                                           count, 0);

        if (start + count > MAX_PWMS)
                return -ENOSPC;

        return start;
}

static void free_pwms(struct pwm_chip *chip)
{
        unsigned int i;

        for (i = 0; i < chip->npwm; i++) {
                struct pwm_device *pwm = &chip->pwms[i];

                radix_tree_delete(&pwm_tree, pwm->pwm);
        }

        bitmap_clear(allocated_pwms, chip->base, chip->npwm);

        kfree(chip->pwms);
        chip->pwms = NULL;
}

static struct pwm_chip *pwmchip_find_by_name(const char *name)
{
        struct pwm_chip *chip;

        if (!name)
                return NULL;

        mutex_lock(&pwm_lock);

        list_for_each_entry(chip, &pwm_chips, list) {
                const char *chip_name = dev_name(chip->dev);

                if (chip_name && strcmp(chip_name, name) == 0) {
                        mutex_unlock(&pwm_lock);
                        return chip;
                }
        }

        mutex_unlock(&pwm_lock);

        return NULL;
}

static int pwm_device_request(struct pwm_device *pwm, const char *label)
{
        int err;

        if (test_bit(PWMF_REQUESTED, &pwm->flags))
                return -EBUSY;

        if (!try_module_get(pwm->chip->ops->owner))
                return -ENODEV;

        if (pwm->chip->ops->request) {
                err = pwm->chip->ops->request(pwm->chip, pwm);
                if (err) {
                        module_put(pwm->chip->ops->owner);
                        return err;
                }
        }

        if (pwm->chip->ops->get_state) {
                pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
                trace_pwm_get(pwm, &pwm->state);

                if (IS_ENABLED(CONFIG_PWM_DEBUG))
                        pwm->last = pwm->state;
        }

        set_bit(PWMF_REQUESTED, &pwm->flags);
        pwm->label = label;

        return 0;
}

struct pwm_device *
of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
{
        struct pwm_device *pwm;

        /* check, whether the driver supports a third cell for flags */
        if (pc->of_pwm_n_cells < 3)
                return ERR_PTR(-EINVAL);

        /* flags in the third cell are optional */
        if (args->args_count < 2)
                return ERR_PTR(-EINVAL);

        if (args->args[0] >= pc->npwm)
                return ERR_PTR(-EINVAL);

        pwm = pwm_request_from_chip(pc, args->args[0], NULL);
        if (IS_ERR(pwm))
                return pwm;

        pwm->args.period = args->args[1];
        pwm->args.polarity = PWM_POLARITY_NORMAL;

        if (args->args_count > 2 && args->args[2] & PWM_POLARITY_INVERTED)
                pwm->args.polarity = PWM_POLARITY_INVERSED;

        return pwm;
}
EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags);

static struct pwm_device *
of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
{
        struct pwm_device *pwm;

        /* sanity check driver support */
        if (pc->of_pwm_n_cells < 2)
                return ERR_PTR(-EINVAL);

        /* all cells are required */
        if (args->args_count != pc->of_pwm_n_cells)
                return ERR_PTR(-EINVAL);

        if (args->args[0] >= pc->npwm)
                return ERR_PTR(-EINVAL);

        pwm = pwm_request_from_chip(pc, args->args[0], NULL);
        if (IS_ERR(pwm))
                return pwm;

        pwm->args.period = args->args[1];

        return pwm;
}

static void of_pwmchip_add(struct pwm_chip *chip)
{
        if (!chip->dev || !chip->dev->of_node)
                return;

        if (!chip->of_xlate) {
                chip->of_xlate = of_pwm_simple_xlate;
                chip->of_pwm_n_cells = 2;
        }

        of_node_get(chip->dev->of_node);
}

static void of_pwmchip_remove(struct pwm_chip *chip)
{
        if (chip->dev)
                of_node_put(chip->dev->of_node);
}

/**
 * pwm_set_chip_data() - set private chip data for a PWM
 * @pwm: PWM device
 * @data: pointer to chip-specific data
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int pwm_set_chip_data(struct pwm_device *pwm, void *data)
{
        if (!pwm)
                return -EINVAL;

        pwm->chip_data = data;

        return 0;
}
EXPORT_SYMBOL_GPL(pwm_set_chip_data);

/**
 * pwm_get_chip_data() - get private chip data for a PWM
 * @pwm: PWM device
 *
 * Returns: A pointer to the chip-private data for the PWM device.
 */
void *pwm_get_chip_data(struct pwm_device *pwm)
{
        return pwm ? pwm->chip_data : NULL;
}
EXPORT_SYMBOL_GPL(pwm_get_chip_data);

static bool pwm_ops_check(const struct pwm_chip *chip)
{

        const struct pwm_ops *ops = chip->ops;

        /* driver supports legacy, non-atomic operation */
        if (ops->config && ops->enable && ops->disable) {
                if (IS_ENABLED(CONFIG_PWM_DEBUG))
                        dev_warn(chip->dev,
                                 "Driver needs updating to atomic API\n");

                return true;
        }

        if (!ops->apply)
                return false;

        if (IS_ENABLED(CONFIG_PWM_DEBUG) && !ops->get_state)
                dev_warn(chip->dev,
                         "Please implement the .get_state() callback\n");

        return true;
}

/**
 * pwmchip_add() - register a new PWM chip
 * @chip: the PWM chip to add
 *
 * Register a new PWM chip.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int pwmchip_add(struct pwm_chip *chip)
{
        struct pwm_device *pwm;
        unsigned int i;
        int ret;

        if (!chip || !chip->dev || !chip->ops || !chip->npwm)
                return -EINVAL;

        if (!pwm_ops_check(chip))
                return -EINVAL;

        mutex_lock(&pwm_lock);

        ret = alloc_pwms(chip->npwm);
        if (ret < 0)
                goto out;

        chip->base = ret;

        chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
        if (!chip->pwms) {
                ret = -ENOMEM;
                goto out;
        }

        for (i = 0; i < chip->npwm; i++) {
                pwm = &chip->pwms[i];

                pwm->chip = chip;
                pwm->pwm = chip->base + i;
                pwm->hwpwm = i;

                radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
        }

        bitmap_set(allocated_pwms, chip->base, chip->npwm);

        INIT_LIST_HEAD(&chip->list);
        list_add(&chip->list, &pwm_chips);

        ret = 0;

        if (IS_ENABLED(CONFIG_OF))
                of_pwmchip_add(chip);

out:
        mutex_unlock(&pwm_lock);

        if (!ret)
                pwmchip_sysfs_export(chip);

        return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_add);

/**
 * pwmchip_remove() - remove a PWM chip
 * @chip: the PWM chip to remove
 *
 * Removes a PWM chip. This function may return busy if the PWM chip provides
 * a PWM device that is still requested.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int pwmchip_remove(struct pwm_chip *chip)
{
        unsigned int i;
        int ret = 0;

        pwmchip_sysfs_unexport(chip);

        mutex_lock(&pwm_lock);

        for (i = 0; i < chip->npwm; i++) {
                struct pwm_device *pwm = &chip->pwms[i];

                if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
                        ret = -EBUSY;
                        goto out;
                }
        }

        list_del_init(&chip->list);

        if (IS_ENABLED(CONFIG_OF))
                of_pwmchip_remove(chip);

        free_pwms(chip);

out:
        mutex_unlock(&pwm_lock);
        return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_remove);

/**
 * pwm_request() - request a PWM device
 * @pwm: global PWM device index
 * @label: PWM device label
 *
 * This function is deprecated, use pwm_get() instead.
 *
 * Returns: A pointer to a PWM device or an ERR_PTR()-encoded error code on
 * failure.
 */
struct pwm_device *pwm_request(int pwm, const char *label)
{
        struct pwm_device *dev;
        int err;

        if (pwm < 0 || pwm >= MAX_PWMS)
                return ERR_PTR(-EINVAL);

        mutex_lock(&pwm_lock);

        dev = pwm_to_device(pwm);
        if (!dev) {
                dev = ERR_PTR(-EPROBE_DEFER);
                goto out;
        }

        err = pwm_device_request(dev, label);
        if (err < 0)
                dev = ERR_PTR(err);

out:
        mutex_unlock(&pwm_lock);

        return dev;
}
EXPORT_SYMBOL_GPL(pwm_request);

/**
 * pwm_request_from_chip() - request a PWM device relative to a PWM chip
 * @chip: PWM chip
 * @index: per-chip index of the PWM to request
 * @label: a literal description string of this PWM
 *
 * Returns: A pointer to the PWM device at the given index of the given PWM
 * chip. A negative error code is returned if the index is not valid for the
 * specified PWM chip or if the PWM device cannot be requested.
 */
struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
                                         unsigned int index,
                                         const char *label)
{
        struct pwm_device *pwm;
        int err;

        if (!chip || index >= chip->npwm)
                return ERR_PTR(-EINVAL);

        mutex_lock(&pwm_lock);
        pwm = &chip->pwms[index];

        err = pwm_device_request(pwm, label);
        if (err < 0)
                pwm = ERR_PTR(err);

        mutex_unlock(&pwm_lock);
        return pwm;
}
EXPORT_SYMBOL_GPL(pwm_request_from_chip);

/**
 * pwm_free() - free a PWM device
 * @pwm: PWM device
 *
 * This function is deprecated, use pwm_put() instead.
 */
void pwm_free(struct pwm_device *pwm)
{
        pwm_put(pwm);
}
EXPORT_SYMBOL_GPL(pwm_free);

static void pwm_apply_state_debug(struct pwm_device *pwm,
                                  const struct pwm_state *state)
{
        struct pwm_state *last = &pwm->last;
        struct pwm_chip *chip = pwm->chip;
        struct pwm_state s1, s2;
        int err;

        if (!IS_ENABLED(CONFIG_PWM_DEBUG))
                return;

        /* No reasonable diagnosis possible without .get_state() */
        if (!chip->ops->get_state)
                return;

        /*
         * *state was just applied. Read out the hardware state and do some
         * checks.
         */

        chip->ops->get_state(chip, pwm, &s1);
        trace_pwm_get(pwm, &s1);

        /*
         * The lowlevel driver either ignored .polarity (which is a bug) or as
         * best effort inverted .polarity and fixed .duty_cycle respectively.
         * Undo this inversion and fixup for further tests.
         */
        if (s1.enabled && s1.polarity != state->polarity) {
                s2.polarity = state->polarity;
                s2.duty_cycle = s1.period - s1.duty_cycle;
                s2.period = s1.period;
                s2.enabled = s1.enabled;
        } else {
                s2 = s1;
        }

        if (s2.polarity != state->polarity &&
            state->duty_cycle < state->period)
                dev_warn(chip->dev, ".apply ignored .polarity\n");

        if (state->enabled &&
            last->polarity == state->polarity &&
            last->period > s2.period &&
            last->period <= state->period)
                dev_warn(chip->dev,
                         ".apply didn't pick the best available period (requested: %llu, applied: %llu, possible: %llu)\n",
                         state->period, s2.period, last->period);

        if (state->enabled && state->period < s2.period)
                dev_warn(chip->dev,
                         ".apply is supposed to round down period (requested: %llu, applied: %llu)\n",
                         state->period, s2.period);

        if (state->enabled &&
            last->polarity == state->polarity &&
            last->period == s2.period &&
            last->duty_cycle > s2.duty_cycle &&
            last->duty_cycle <= state->duty_cycle)
                dev_warn(chip->dev,
                         ".apply didn't pick the best available duty cycle (requested: %llu/%llu, applied: %llu/%llu, possible: %llu/%llu)\n",
                         state->duty_cycle, state->period,
                         s2.duty_cycle, s2.period,
                         last->duty_cycle, last->period);

        if (state->enabled && state->duty_cycle < s2.duty_cycle)
                dev_warn(chip->dev,
                         ".apply is supposed to round down duty_cycle (requested: %llu/%llu, applied: %llu/%llu)\n",
                         state->duty_cycle, state->period,
                         s2.duty_cycle, s2.period);

        if (!state->enabled && s2.enabled && s2.duty_cycle > 0)
                dev_warn(chip->dev,
                         "requested disabled, but yielded enabled with duty > 0\n");

        /* reapply the state that the driver reported being configured. */
        err = chip->ops->apply(chip, pwm, &s1);
        if (err) {
                *last = s1;
                dev_err(chip->dev, "failed to reapply current setting\n");
                return;
        }

        trace_pwm_apply(pwm, &s1);

        chip->ops->get_state(chip, pwm, last);
        trace_pwm_get(pwm, last);

        /* reapplication of the current state should give an exact match */
        if (s1.enabled != last->enabled ||
            s1.polarity != last->polarity ||
            (s1.enabled && s1.period != last->period) ||
            (s1.enabled && s1.duty_cycle != last->duty_cycle)) {
                dev_err(chip->dev,
                        ".apply is not idempotent (ena=%d pol=%d %llu/%llu) -> (ena=%d pol=%d %llu/%llu)\n",
                        s1.enabled, s1.polarity, s1.duty_cycle, s1.period,
                        last->enabled, last->polarity, last->duty_cycle,
                        last->period);
        }
}

/**
 * pwm_apply_state() - atomically apply a new state to a PWM device
 * @pwm: PWM device
 * @state: new state to apply
 */
int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
{
        struct pwm_chip *chip;
        int err;

        if (!pwm || !state || !state->period ||
            state->duty_cycle > state->period)
                return -EINVAL;

        chip = pwm->chip;

        if (state->period == pwm->state.period &&
            state->duty_cycle == pwm->state.duty_cycle &&
            state->polarity == pwm->state.polarity &&
            state->enabled == pwm->state.enabled)
                return 0;

        if (chip->ops->apply) {
                err = chip->ops->apply(chip, pwm, state);
                if (err)
                        return err;

                trace_pwm_apply(pwm, state);

                pwm->state = *state;

                /*
                 * only do this after pwm->state was applied as some
                 * implementations of .get_state depend on this
                 */
                pwm_apply_state_debug(pwm, state);
        } else {
                /*
                 * FIXME: restore the initial state in case of error.
                 */
                if (state->polarity != pwm->state.polarity) {
                        if (!chip->ops->set_polarity)
                                return -EINVAL;

                        /*
                         * Changing the polarity of a running PWM is
                         * only allowed when the PWM driver implements
                         * ->apply().
                         */
                        if (pwm->state.enabled) {
                                chip->ops->disable(chip, pwm);
                                pwm->state.enabled = false;
                        }

                        err = chip->ops->set_polarity(chip, pwm,
                                                      state->polarity);
                        if (err)
                                return err;

                        pwm->state.polarity = state->polarity;
                }

                if (state->period != pwm->state.period ||
                    state->duty_cycle != pwm->state.duty_cycle) {
                        err = chip->ops->config(pwm->chip, pwm,
                                                state->duty_cycle,
                                                state->period);
                        if (err)
                                return err;

                        pwm->state.duty_cycle = state->duty_cycle;
                        pwm->state.period = state->period;
                }

                if (state->enabled != pwm->state.enabled) {
                        if (state->enabled) {
                                err = chip->ops->enable(chip, pwm);
                                if (err)
                                        return err;
                        } else {
                                chip->ops->disable(chip, pwm);
                        }

                        pwm->state.enabled = state->enabled;
                }
        }

        return 0;
}
EXPORT_SYMBOL_GPL(pwm_apply_state);

/**
 * pwm_capture() - capture and report a PWM signal
 * @pwm: PWM device
 * @result: structure to fill with capture result
 * @timeout: time to wait, in milliseconds, before giving up on capture
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
                unsigned long timeout)
{
        int err;

        if (!pwm || !pwm->chip->ops)
                return -EINVAL;

        if (!pwm->chip->ops->capture)
                return -ENOSYS;

        mutex_lock(&pwm_lock);
        err = pwm->chip->ops->capture(pwm->chip, pwm, result, timeout);
        mutex_unlock(&pwm_lock);

        return err;
}
EXPORT_SYMBOL_GPL(pwm_capture);

/**
 * pwm_adjust_config() - adjust the current PWM config to the PWM arguments
 * @pwm: PWM device
 *
 * This function will adjust the PWM config to the PWM arguments provided
 * by the DT or PWM lookup table. This is particularly useful to adapt
 * the bootloader config to the Linux one.
 */
int pwm_adjust_config(struct pwm_device *pwm)
{
        struct pwm_state state;
        struct pwm_args pargs;

        pwm_get_args(pwm, &pargs);
        pwm_get_state(pwm, &state);

        /*
         * If the current period is zero it means that either the PWM driver
         * does not support initial state retrieval or the PWM has not yet
         * been configured.
         *
         * In either case, we setup the new period and polarity, and assign a
         * duty cycle of 0.
         */
        if (!state.period) {
                state.duty_cycle = 0;
                state.period = pargs.period;
                state.polarity = pargs.polarity;

                return pwm_apply_state(pwm, &state);
        }

        /*
         * Adjust the PWM duty cycle/period based on the period value provided
         * in PWM args.
         */
        if (pargs.period != state.period) {
                u64 dutycycle = (u64)state.duty_cycle * pargs.period;

                do_div(dutycycle, state.period);
                state.duty_cycle = dutycycle;
                state.period = pargs.period;
        }

        /*
         * If the polarity changed, we should also change the duty cycle.
         */
        if (pargs.polarity != state.polarity) {
                state.polarity = pargs.polarity;
                state.duty_cycle = state.period - state.duty_cycle;
        }

        return pwm_apply_state(pwm, &state);
}
EXPORT_SYMBOL_GPL(pwm_adjust_config);

static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
{
        struct pwm_chip *chip;

        mutex_lock(&pwm_lock);

        list_for_each_entry(chip, &pwm_chips, list)
                if (chip->dev && chip->dev->of_node == np) {
                        mutex_unlock(&pwm_lock);
                        return chip;
                }

        mutex_unlock(&pwm_lock);

        return ERR_PTR(-EPROBE_DEFER);
}

static struct device_link *pwm_device_link_add(struct device *dev,
                                               struct pwm_device *pwm)
{
        struct device_link *dl;

        if (!dev) {
                /*
                 * No device for the PWM consumer has been provided. It may
                 * impact the PM sequence ordering: the PWM supplier may get
                 * suspended before the consumer.
                 */
                dev_warn(pwm->chip->dev,
                         "No consumer device specified to create a link to\n");
                return NULL;
        }

        dl = device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
        if (!dl) {
                dev_err(dev, "failed to create device link to %s\n",
                        dev_name(pwm->chip->dev));
                return ERR_PTR(-EINVAL);
        }

        return dl;
}

/**
 * of_pwm_get() - request a PWM via the PWM framework
 * @dev: device for PWM consumer
 * @np: device node to get the PWM from
 * @con_id: consumer name
 *
 * Returns the PWM device parsed from the phandle and index specified in the
 * "pwms" property of a device tree node or a negative error-code on failure.
 * Values parsed from the device tree are stored in the returned PWM device
 * object.
 *
 * If con_id is NULL, the first PWM device listed in the "pwms" property will
 * be requested. Otherwise the "pwm-names" property is used to do a reverse
 * lookup of the PWM index. This also means that the "pwm-names" property
 * becomes mandatory for devices that look up the PWM device via the con_id
 * parameter.
 *
 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
 * error code on failure.
 */
struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,
                              const char *con_id)
{
        struct pwm_device *pwm = NULL;
        struct of_phandle_args args;
        struct device_link *dl;
        struct pwm_chip *pc;
        int index = 0;
        int err;

        if (con_id) {
                index = of_property_match_string(np, "pwm-names", con_id);
                if (index < 0)
                        return ERR_PTR(index);
        }

        err = of_parse_phandle_with_args(np, "pwms", "#pwm-cells", index,
                                         &args);
        if (err) {
                pr_err("%s(): can't parse \"pwms\" property\n", __func__);
                return ERR_PTR(err);
        }

        pc = of_node_to_pwmchip(args.np);
        if (IS_ERR(pc)) {
                if (PTR_ERR(pc) != -EPROBE_DEFER)
                        pr_err("%s(): PWM chip not found\n", __func__);

                pwm = ERR_CAST(pc);
                goto put;
        }

        pwm = pc->of_xlate(pc, &args);
        if (IS_ERR(pwm))
                goto put;

        dl = pwm_device_link_add(dev, pwm);
        if (IS_ERR(dl)) {
                /* of_xlate ended up calling pwm_request_from_chip() */
                pwm_free(pwm);
                pwm = ERR_CAST(dl);
                goto put;
        }

        /*
         * If a consumer name was not given, try to look it up from the
         * "pwm-names" property if it exists. Otherwise use the name of
         * the user device node.
         */
        if (!con_id) {
                err = of_property_read_string_index(np, "pwm-names", index,
                                                    &con_id);
                if (err < 0)
                        con_id = np->name;
        }

        pwm->label = con_id;

put:
        of_node_put(args.np);

        return pwm;
}
EXPORT_SYMBOL_GPL(of_pwm_get);

#if IS_ENABLED(CONFIG_ACPI)
static struct pwm_chip *device_to_pwmchip(struct device *dev)
{
        struct pwm_chip *chip;

        mutex_lock(&pwm_lock);

        list_for_each_entry(chip, &pwm_chips, list) {
                struct acpi_device *adev = ACPI_COMPANION(chip->dev);

                if ((chip->dev == dev) || (adev && &adev->dev == dev)) {
                        mutex_unlock(&pwm_lock);
                        return chip;
                }
        }

        mutex_unlock(&pwm_lock);

        return ERR_PTR(-EPROBE_DEFER);
}
#endif

/**
 * acpi_pwm_get() - request a PWM via parsing "pwms" property in ACPI
 * @fwnode: firmware node to get the "pwm" property from
 *
 * Returns the PWM device parsed from the fwnode and index specified in the
 * "pwms" property or a negative error-code on failure.
 * Values parsed from the device tree are stored in the returned PWM device
 * object.
 *
 * This is analogous to of_pwm_get() except con_id is not yet supported.
 * ACPI entries must look like
 * Package () {"pwms", Package ()
 *     { <PWM device reference>, <PWM index>, <PWM period> [, <PWM flags>]}}
 *
 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
 * error code on failure.
 */
static struct pwm_device *acpi_pwm_get(struct fwnode_handle *fwnode)
{
        struct pwm_device *pwm = ERR_PTR(-ENODEV);
#if IS_ENABLED(CONFIG_ACPI)
        struct fwnode_reference_args args;
        struct acpi_device *acpi;
        struct pwm_chip *chip;
        int ret;

        memset(&args, 0, sizeof(args));

        ret = __acpi_node_get_property_reference(fwnode, "pwms", 0, 3, &args);
        if (ret < 0)
                return ERR_PTR(ret);

        acpi = to_acpi_device_node(args.fwnode);
        if (!acpi)
                return ERR_PTR(-EINVAL);

        if (args.nargs < 2)
                return ERR_PTR(-EPROTO);

        chip = device_to_pwmchip(&acpi->dev);
        if (IS_ERR(chip))
                return ERR_CAST(chip);

        pwm = pwm_request_from_chip(chip, args.args[0], NULL);
        if (IS_ERR(pwm))
                return pwm;

        pwm->args.period = args.args[1];
        pwm->args.polarity = PWM_POLARITY_NORMAL;

        if (args.nargs > 2 && args.args[2] & PWM_POLARITY_INVERTED)
                pwm->args.polarity = PWM_POLARITY_INVERSED;
#endif

        return pwm;
}

/**
 * pwm_add_table() - register PWM device consumers
 * @table: array of consumers to register
 * @num: number of consumers in table
 */
void pwm_add_table(struct pwm_lookup *table, size_t num)
{
        mutex_lock(&pwm_lookup_lock);

        while (num--) {
                list_add_tail(&table->list, &pwm_lookup_list);
                table++;
        }

        mutex_unlock(&pwm_lookup_lock);
}

/**
 * pwm_remove_table() - unregister PWM device consumers
 * @table: array of consumers to unregister
 * @num: number of consumers in table
 */
void pwm_remove_table(struct pwm_lookup *table, size_t num)
{
        mutex_lock(&pwm_lookup_lock);

        while (num--) {
                list_del(&table->list);
                table++;
        }

        mutex_unlock(&pwm_lookup_lock);
}

/**
 * pwm_get() - look up and request a PWM device
 * @dev: device for PWM consumer
 * @con_id: consumer name
 *
 * Lookup is first attempted using DT. If the device was not instantiated from
 * a device tree, a PWM chip and a relative index is looked up via a table
 * supplied by board setup code (see pwm_add_table()).
 *
 * Once a PWM chip has been found the specified PWM device will be requested
 * and is ready to be used.
 *
 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
 * error code on failure.
 */
struct pwm_device *pwm_get(struct device *dev, const char *con_id)
{
        const char *dev_id = dev ? dev_name(dev) : NULL;
        struct pwm_device *pwm;
        struct pwm_chip *chip;
        struct device_link *dl;
        unsigned int best = 0;
        struct pwm_lookup *p, *chosen = NULL;
        unsigned int match;
        int err;

        /* look up via DT first */
        if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
                return of_pwm_get(dev, dev->of_node, con_id);

        /* then lookup via ACPI */
        if (dev && is_acpi_node(dev->fwnode)) {
                pwm = acpi_pwm_get(dev->fwnode);
                if (!IS_ERR(pwm) || PTR_ERR(pwm) != -ENOENT)
                        return pwm;
        }

        /*
         * We look up the provider in the static table typically provided by
         * board setup code. We first try to lookup the consumer device by
         * name. If the consumer device was passed in as NULL or if no match
         * was found, we try to find the consumer by directly looking it up
         * by name.
         *
         * If a match is found, the provider PWM chip is looked up by name
         * and a PWM device is requested using the PWM device per-chip index.
         *
         * The lookup algorithm was shamelessly taken from the clock

         * framework:
         *
         * We do slightly fuzzy matching here:
         *  An entry with a NULL ID is assumed to be a wildcard.
         *  If an entry has a device ID, it must match
         *  If an entry has a connection ID, it must match
         * Then we take the most specific entry - with the following order
         * of precedence: dev+con > dev only > con only.
         */
        mutex_lock(&pwm_lookup_lock);

        list_for_each_entry(p, &pwm_lookup_list, list) {
                match = 0;

                if (p->dev_id) {
                        if (!dev_id || strcmp(p->dev_id, dev_id))
                                continue;

                        match += 2;
                }

                if (p->con_id) {
                        if (!con_id || strcmp(p->con_id, con_id))
                                continue;

                        match += 1;
                }

                if (match > best) {
                        chosen = p;

                        if (match != 3)
                                best = match;
                        else
                                break;
                }
        }

        mutex_unlock(&pwm_lookup_lock);

        if (!chosen)
                return ERR_PTR(-ENODEV);

        chip = pwmchip_find_by_name(chosen->provider);

        /*
         * If the lookup entry specifies a module, load the module and retry
         * the PWM chip lookup. This can be used to work around driver load
         * ordering issues if driver's can't be made to properly support the
         * deferred probe mechanism.
         */
        if (!chip && chosen->module) {
                err = request_module(chosen->module);
                if (err == 0)
                        chip = pwmchip_find_by_name(chosen->provider);
        }

        if (!chip)
                return ERR_PTR(-EPROBE_DEFER);

        pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id);
        if (IS_ERR(pwm))
                return pwm;

        dl = pwm_device_link_add(dev, pwm);
        if (IS_ERR(dl)) {
                pwm_free(pwm);
                return ERR_CAST(dl);
        }

        pwm->args.period = chosen->period;
        pwm->args.polarity = chosen->polarity;

        return pwm;
}
EXPORT_SYMBOL_GPL(pwm_get);

/**
 * pwm_put() - release a PWM device
 * @pwm: PWM device
 */
void pwm_put(struct pwm_device *pwm)
{
        if (!pwm)
                return;

        mutex_lock(&pwm_lock);

        if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
                pr_warn("PWM device already freed\n");
                goto out;
        }

        if (pwm->chip->ops->free)
                pwm->chip->ops->free(pwm->chip, pwm);

        pwm_set_chip_data(pwm, NULL);
        pwm->label = NULL;

        module_put(pwm->chip->ops->owner);
out:
        mutex_unlock(&pwm_lock);
}
EXPORT_SYMBOL_GPL(pwm_put);

static void devm_pwm_release(struct device *dev, void *res)
{
        pwm_put(*(struct pwm_device **)res);
}

/**
 * devm_pwm_get() - resource managed pwm_get()
 * @dev: device for PWM consumer
 * @con_id: consumer name
 *
 * This function performs like pwm_get() but the acquired PWM device will
 * automatically be released on driver detach.
 *
 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
 * error code on failure.
 */
struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id)
{
        struct pwm_device **ptr, *pwm;

        ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                return ERR_PTR(-ENOMEM);

        pwm = pwm_get(dev, con_id);
        if (!IS_ERR(pwm)) {
                *ptr = pwm;
                devres_add(dev, ptr);
        } else {
                devres_free(ptr);
        }

        return pwm;
}
EXPORT_SYMBOL_GPL(devm_pwm_get);

/**
 * devm_of_pwm_get() - resource managed of_pwm_get()
 * @dev: device for PWM consumer
 * @np: device node to get the PWM from
 * @con_id: consumer name
 *
 * This function performs like of_pwm_get() but the acquired PWM device will
 * automatically be released on driver detach.
 *
 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
 * error code on failure.
 */
struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
                                   const char *con_id)
{
        struct pwm_device **ptr, *pwm;

        ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                return ERR_PTR(-ENOMEM);

        pwm = of_pwm_get(dev, np, con_id);
        if (!IS_ERR(pwm)) {
                *ptr = pwm;
                devres_add(dev, ptr);
        } else {
                devres_free(ptr);
        }

        return pwm;
}
EXPORT_SYMBOL_GPL(devm_of_pwm_get);

/**
 * devm_fwnode_pwm_get() - request a resource managed PWM from firmware node
 * @dev: device for PWM consumer
 * @fwnode: firmware node to get the PWM from
 * @con_id: consumer name
 *
 * Returns the PWM device parsed from the firmware node. See of_pwm_get() and
 * acpi_pwm_get() for a detailed description.
 *
 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
 * error code on failure.
 */
struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
                                       struct fwnode_handle *fwnode,
                                       const char *con_id)
{
        struct pwm_device **ptr, *pwm = ERR_PTR(-ENODEV);

        ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                return ERR_PTR(-ENOMEM);

        if (is_of_node(fwnode))
                pwm = of_pwm_get(dev, to_of_node(fwnode), con_id);
        else if (is_acpi_node(fwnode))
                pwm = acpi_pwm_get(fwnode);

        if (!IS_ERR(pwm)) {
                *ptr = pwm;
                devres_add(dev, ptr);
        } else {
                devres_free(ptr);
        }

        return pwm;
}
EXPORT_SYMBOL_GPL(devm_fwnode_pwm_get);

static int devm_pwm_match(struct device *dev, void *res, void *data)
{
        struct pwm_device **p = res;

        if (WARN_ON(!p || !*p))
                return 0;

        return *p == data;
}

/**
 * devm_pwm_put() - resource managed pwm_put()
 * @dev: device for PWM consumer
 * @pwm: PWM device
 *
 * Release a PWM previously allocated using devm_pwm_get(). Calling this
 * function is usually not needed because devm-allocated resources are
 * automatically released on driver detach.
 */
void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
{
        WARN_ON(devres_release(dev, devm_pwm_release, devm_pwm_match, pwm));
}
EXPORT_SYMBOL_GPL(devm_pwm_put);

#ifdef CONFIG_DEBUG_FS
static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
{
        unsigned int i;

        for (i = 0; i < chip->npwm; i++) {
                struct pwm_device *pwm = &chip->pwms[i];
                struct pwm_state state;

                pwm_get_state(pwm, &state);

                seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);

                if (test_bit(PWMF_REQUESTED, &pwm->flags))
                        seq_puts(s, " requested");

                if (state.enabled)
                        seq_puts(s, " enabled");

                seq_printf(s, " period: %llu ns", state.period);
                seq_printf(s, " duty: %llu ns", state.duty_cycle);
                seq_printf(s, " polarity: %s",
                           state.polarity ? "inverse" : "normal");

                seq_puts(s, "\n");
        }
}

static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
{
        mutex_lock(&pwm_lock);
        s->private = "";

        return seq_list_start(&pwm_chips, *pos);
}

static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        s->private = "\n";

        return seq_list_next(v, &pwm_chips, pos);
}

static void pwm_seq_stop(struct seq_file *s, void *v)
{
        mutex_unlock(&pwm_lock);
}

static int pwm_seq_show(struct seq_file *s, void *v)
{
        struct pwm_chip *chip = list_entry(v, struct pwm_chip, list);

        seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private,
                   chip->dev->bus ? chip->dev->bus->name : "no-bus",
                   dev_name(chip->dev), chip->npwm,
                   (chip->npwm != 1) ? "s" : "");

        pwm_dbg_show(chip, s);

        return 0;
}

static const struct seq_operations pwm_debugfs_sops = {
        .start = pwm_seq_start,
        .next = pwm_seq_next,
        .stop = pwm_seq_stop,
        .show = pwm_seq_show,
};

DEFINE_SEQ_ATTRIBUTE(pwm_debugfs);

static int __init pwm_debugfs_init(void)
{
        debugfs_create_file("pwm", S_IFREG | 0444, NULL, NULL,
                            &pwm_debugfs_fops);

        return 0;
}
subsys_initcall(pwm_debugfs_init);
#endif /* CONFIG_DEBUG_FS */