Merge tag 'soc-ep93xx-dt-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc

[linux-block.git] / drivers / pwm / core.c

// 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/idr.h>
#include <linux/of.h>
#include <linux/pwm.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>

/* protects access to pwm_chips */
static DEFINE_MUTEX(pwm_lock);

static DEFINE_IDR(pwm_chips);

static void pwm_apply_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 = { 0 }, s2 = { 0 };
        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.
         */

        err = chip->ops->get_state(chip, pwm, &s1);
        trace_pwm_get(pwm, &s1, err);
        if (err)
                /* If that failed there isn't much to debug */
                return;

        /*
         * 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(pwmchip_parent(chip), ".apply ignored .polarity\n");

        if (state->enabled &&
            last->polarity == state->polarity &&
            last->period > s2.period &&
            last->period <= state->period)
                dev_warn(pwmchip_parent(chip),
                         ".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(pwmchip_parent(chip),
                         ".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(pwmchip_parent(chip),
                         ".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(pwmchip_parent(chip),
                         ".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(pwmchip_parent(chip),
                         "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);
        trace_pwm_apply(pwm, &s1, err);
        if (err) {
                *last = s1;
                dev_err(pwmchip_parent(chip), "failed to reapply current setting\n");
                return;
        }

        *last = (struct pwm_state){ 0 };
        err = chip->ops->get_state(chip, pwm, last);
        trace_pwm_get(pwm, last, err);
        if (err)
                return;

        /* 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(pwmchip_parent(chip),
                        ".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() - atomically apply a new state to a PWM device
 * @pwm: PWM device
 * @state: new state to apply
 */
static int __pwm_apply(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 &&
            state->usage_power == pwm->state.usage_power)
                return 0;

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

        pwm->state = *state;

        /*
         * only do this after pwm->state was applied as some
         * implementations of .get_state depend on this
         */
        pwm_apply_debug(pwm, state);

        return 0;
}

/**
 * pwm_apply_might_sleep() - atomically apply a new state to a PWM device
 * Cannot be used in atomic context.
 * @pwm: PWM device
 * @state: new state to apply
 */
int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
{
        int err;

        /*
         * Some lowlevel driver's implementations of .apply() make use of
         * mutexes, also with some drivers only returning when the new
         * configuration is active calling pwm_apply_might_sleep() from atomic context
         * is a bad idea. So make it explicit that calling this function might
         * sleep.
         */
        might_sleep();

        if (IS_ENABLED(CONFIG_PWM_DEBUG) && pwm->chip->atomic) {
                /*
                 * Catch any drivers that have been marked as atomic but
                 * that will sleep anyway.
                 */
                non_block_start();
                err = __pwm_apply(pwm, state);
                non_block_end();
        } else {
                err = __pwm_apply(pwm, state);
        }

        return err;
}
EXPORT_SYMBOL_GPL(pwm_apply_might_sleep);

/**
 * pwm_apply_atomic() - apply a new state to a PWM device from atomic context
 * Not all PWM devices support this function, check with pwm_might_sleep().
 * @pwm: PWM device
 * @state: new state to apply
 */
int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state)
{
        WARN_ONCE(!pwm->chip->atomic,
                  "sleeping PWM driver used in atomic context\n");

        return __pwm_apply(pwm, state);
}
EXPORT_SYMBOL_GPL(pwm_apply_atomic);

/**
 * 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_might_sleep(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_might_sleep(pwm, &state);
}
EXPORT_SYMBOL_GPL(pwm_adjust_config);

/**
 * 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);

static struct pwm_chip *pwmchip_find_by_name(const char *name)
{
        struct pwm_chip *chip;
        unsigned long id, tmp;

        if (!name)
                return NULL;

        mutex_lock(&pwm_lock);

        idr_for_each_entry_ul(&pwm_chips, chip, tmp, id) {
                const char *chip_name = dev_name(pwmchip_parent(chip));

                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;
        struct pwm_chip *chip = pwm->chip;
        const struct pwm_ops *ops = chip->ops;

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

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

        if (!get_device(&chip->dev)) {
                err = -ENODEV;
                goto err_get_device;
        }

        if (ops->request) {
                err = ops->request(chip, pwm);
                if (err) {
                        put_device(&chip->dev);
err_get_device:
                        module_put(chip->owner);
                        return err;
                }
        }

        if (ops->get_state) {
                /*
                 * Zero-initialize state because most drivers are unaware of
                 * .usage_power. The other members of state are supposed to be
                 * set by lowlevel drivers. We still initialize the whole
                 * structure for simplicity even though this might paper over
                 * faulty implementations of .get_state().
                 */
                struct pwm_state state = { 0, };

                err = ops->get_state(chip, pwm, &state);
                trace_pwm_get(pwm, &state, err);

                if (!err)
                        pwm->state = state;

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

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

        return 0;
}

/**
 * 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);


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

        /* period in the second cell and flags in the third cell are optional */
        if (args->args_count < 1)
                return ERR_PTR(-EINVAL);

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

        if (args->args_count > 1)
                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);

struct pwm_device *
of_pwm_single_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
{
        struct pwm_device *pwm;

        pwm = pwm_request_from_chip(chip, 0, NULL);
        if (IS_ERR(pwm))
                return pwm;

        if (args->args_count > 0)
                pwm->args.period = args->args[0];

        pwm->args.polarity = PWM_POLARITY_NORMAL;
        if (args->args_count > 1 && args->args[1] & PWM_POLARITY_INVERTED)
                pwm->args.polarity = PWM_POLARITY_INVERSED;

        return pwm;
}
EXPORT_SYMBOL_GPL(of_pwm_single_xlate);

struct pwm_export {
        struct device pwm_dev;
        struct pwm_device *pwm;
        struct mutex lock;
        struct pwm_state suspend;
};

static inline struct pwm_chip *pwmchip_from_dev(struct device *pwmchip_dev)
{
        return container_of(pwmchip_dev, struct pwm_chip, dev);
}

static inline struct pwm_export *pwmexport_from_dev(struct device *pwm_dev)
{
        return container_of(pwm_dev, struct pwm_export, pwm_dev);
}

static inline struct pwm_device *pwm_from_dev(struct device *pwm_dev)
{
        struct pwm_export *export = pwmexport_from_dev(pwm_dev);

        return export->pwm;
}

static ssize_t period_show(struct device *pwm_dev,
                           struct device_attribute *attr,
                           char *buf)
{
        const struct pwm_device *pwm = pwm_from_dev(pwm_dev);
        struct pwm_state state;

        pwm_get_state(pwm, &state);

        return sysfs_emit(buf, "%llu\n", state.period);
}

static ssize_t period_store(struct device *pwm_dev,
                            struct device_attribute *attr,
                            const char *buf, size_t size)
{
        struct pwm_export *export = pwmexport_from_dev(pwm_dev);
        struct pwm_device *pwm = export->pwm;
        struct pwm_state state;
        u64 val;
        int ret;

        ret = kstrtou64(buf, 0, &val);
        if (ret)
                return ret;

        mutex_lock(&export->lock);
        pwm_get_state(pwm, &state);
        state.period = val;
        ret = pwm_apply_might_sleep(pwm, &state);
        mutex_unlock(&export->lock);

        return ret ? : size;
}

static ssize_t duty_cycle_show(struct device *pwm_dev,
                               struct device_attribute *attr,
                               char *buf)
{
        const struct pwm_device *pwm = pwm_from_dev(pwm_dev);
        struct pwm_state state;

        pwm_get_state(pwm, &state);

        return sysfs_emit(buf, "%llu\n", state.duty_cycle);
}

static ssize_t duty_cycle_store(struct device *pwm_dev,
                                struct device_attribute *attr,
                                const char *buf, size_t size)
{
        struct pwm_export *export = pwmexport_from_dev(pwm_dev);
        struct pwm_device *pwm = export->pwm;
        struct pwm_state state;
        u64 val;
        int ret;

        ret = kstrtou64(buf, 0, &val);
        if (ret)
                return ret;

        mutex_lock(&export->lock);
        pwm_get_state(pwm, &state);
        state.duty_cycle = val;
        ret = pwm_apply_might_sleep(pwm, &state);
        mutex_unlock(&export->lock);

        return ret ? : size;
}

static ssize_t enable_show(struct device *pwm_dev,
                           struct device_attribute *attr,
                           char *buf)
{
        const struct pwm_device *pwm = pwm_from_dev(pwm_dev);
        struct pwm_state state;

        pwm_get_state(pwm, &state);

        return sysfs_emit(buf, "%d\n", state.enabled);
}

static ssize_t enable_store(struct device *pwm_dev,
                            struct device_attribute *attr,
                            const char *buf, size_t size)
{
        struct pwm_export *export = pwmexport_from_dev(pwm_dev);
        struct pwm_device *pwm = export->pwm;
        struct pwm_state state;
        int val, ret;

        ret = kstrtoint(buf, 0, &val);
        if (ret)
                return ret;

        mutex_lock(&export->lock);

        pwm_get_state(pwm, &state);

        switch (val) {
        case 0:
                state.enabled = false;
                break;
        case 1:
                state.enabled = true;
                break;
        default:
                ret = -EINVAL;
                goto unlock;
        }

        ret = pwm_apply_might_sleep(pwm, &state);

unlock:
        mutex_unlock(&export->lock);
        return ret ? : size;
}

static ssize_t polarity_show(struct device *pwm_dev,
                             struct device_attribute *attr,
                             char *buf)
{
        const struct pwm_device *pwm = pwm_from_dev(pwm_dev);
        const char *polarity = "unknown";
        struct pwm_state state;

        pwm_get_state(pwm, &state);

        switch (state.polarity) {
        case PWM_POLARITY_NORMAL:
                polarity = "normal";
                break;

        case PWM_POLARITY_INVERSED:
                polarity = "inversed";
                break;
        }

        return sysfs_emit(buf, "%s\n", polarity);
}

static ssize_t polarity_store(struct device *pwm_dev,
                              struct device_attribute *attr,
                              const char *buf, size_t size)
{
        struct pwm_export *export = pwmexport_from_dev(pwm_dev);
        struct pwm_device *pwm = export->pwm;
        enum pwm_polarity polarity;
        struct pwm_state state;
        int ret;

        if (sysfs_streq(buf, "normal"))
                polarity = PWM_POLARITY_NORMAL;
        else if (sysfs_streq(buf, "inversed"))
                polarity = PWM_POLARITY_INVERSED;
        else
                return -EINVAL;

        mutex_lock(&export->lock);
        pwm_get_state(pwm, &state);
        state.polarity = polarity;
        ret = pwm_apply_might_sleep(pwm, &state);
        mutex_unlock(&export->lock);

        return ret ? : size;
}

static ssize_t capture_show(struct device *pwm_dev,
                            struct device_attribute *attr,
                            char *buf)
{
        struct pwm_device *pwm = pwm_from_dev(pwm_dev);
        struct pwm_capture result;
        int ret;

        ret = pwm_capture(pwm, &result, jiffies_to_msecs(HZ));
        if (ret)
                return ret;

        return sysfs_emit(buf, "%u %u\n", result.period, result.duty_cycle);
}

static DEVICE_ATTR_RW(period);
static DEVICE_ATTR_RW(duty_cycle);
static DEVICE_ATTR_RW(enable);
static DEVICE_ATTR_RW(polarity);
static DEVICE_ATTR_RO(capture);

static struct attribute *pwm_attrs[] = {
        &dev_attr_period.attr,
        &dev_attr_duty_cycle.attr,
        &dev_attr_enable.attr,
        &dev_attr_polarity.attr,
        &dev_attr_capture.attr,
        NULL
};
ATTRIBUTE_GROUPS(pwm);

static void pwm_export_release(struct device *pwm_dev)
{
        struct pwm_export *export = pwmexport_from_dev(pwm_dev);

        kfree(export);
}

static int pwm_export_child(struct device *pwmchip_dev, struct pwm_device *pwm)
{
        struct pwm_export *export;
        char *pwm_prop[2];
        int ret;

        if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
                return -EBUSY;

        export = kzalloc(sizeof(*export), GFP_KERNEL);
        if (!export) {
                clear_bit(PWMF_EXPORTED, &pwm->flags);
                return -ENOMEM;
        }

        export->pwm = pwm;
        mutex_init(&export->lock);

        export->pwm_dev.release = pwm_export_release;
        export->pwm_dev.parent = pwmchip_dev;
        export->pwm_dev.devt = MKDEV(0, 0);
        export->pwm_dev.groups = pwm_groups;
        dev_set_name(&export->pwm_dev, "pwm%u", pwm->hwpwm);

        ret = device_register(&export->pwm_dev);
        if (ret) {
                clear_bit(PWMF_EXPORTED, &pwm->flags);
                put_device(&export->pwm_dev);
                export = NULL;
                return ret;
        }
        pwm_prop[0] = kasprintf(GFP_KERNEL, "EXPORT=pwm%u", pwm->hwpwm);
        pwm_prop[1] = NULL;
        kobject_uevent_env(&pwmchip_dev->kobj, KOBJ_CHANGE, pwm_prop);
        kfree(pwm_prop[0]);

        return 0;
}

static int pwm_unexport_match(struct device *pwm_dev, void *data)
{
        return pwm_from_dev(pwm_dev) == data;
}

static int pwm_unexport_child(struct device *pwmchip_dev, struct pwm_device *pwm)
{
        struct device *pwm_dev;
        char *pwm_prop[2];

        if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
                return -ENODEV;

        pwm_dev = device_find_child(pwmchip_dev, pwm, pwm_unexport_match);
        if (!pwm_dev)
                return -ENODEV;

        pwm_prop[0] = kasprintf(GFP_KERNEL, "UNEXPORT=pwm%u", pwm->hwpwm);
        pwm_prop[1] = NULL;
        kobject_uevent_env(&pwmchip_dev->kobj, KOBJ_CHANGE, pwm_prop);
        kfree(pwm_prop[0]);

        /* for device_find_child() */
        put_device(pwm_dev);
        device_unregister(pwm_dev);
        pwm_put(pwm);

        return 0;
}

static ssize_t export_store(struct device *pwmchip_dev,
                            struct device_attribute *attr,
                            const char *buf, size_t len)
{
        struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);
        struct pwm_device *pwm;
        unsigned int hwpwm;
        int ret;

        ret = kstrtouint(buf, 0, &hwpwm);
        if (ret < 0)
                return ret;

        if (hwpwm >= chip->npwm)
                return -ENODEV;

        pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
        if (IS_ERR(pwm))
                return PTR_ERR(pwm);

        ret = pwm_export_child(pwmchip_dev, pwm);
        if (ret < 0)
                pwm_put(pwm);

        return ret ? : len;
}
static DEVICE_ATTR_WO(export);

static ssize_t unexport_store(struct device *pwmchip_dev,
                              struct device_attribute *attr,
                              const char *buf, size_t len)
{
        struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);
        unsigned int hwpwm;
        int ret;

        ret = kstrtouint(buf, 0, &hwpwm);
        if (ret < 0)
                return ret;

        if (hwpwm >= chip->npwm)
                return -ENODEV;

        ret = pwm_unexport_child(pwmchip_dev, &chip->pwms[hwpwm]);

        return ret ? : len;
}
static DEVICE_ATTR_WO(unexport);

static ssize_t npwm_show(struct device *pwmchip_dev, struct device_attribute *attr,
                         char *buf)
{
        const struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);

        return sysfs_emit(buf, "%u\n", chip->npwm);
}
static DEVICE_ATTR_RO(npwm);

static struct attribute *pwm_chip_attrs[] = {
        &dev_attr_export.attr,
        &dev_attr_unexport.attr,
        &dev_attr_npwm.attr,
        NULL,
};
ATTRIBUTE_GROUPS(pwm_chip);

/* takes export->lock on success */
static struct pwm_export *pwm_class_get_state(struct device *pwmchip_dev,
                                              struct pwm_device *pwm,
                                              struct pwm_state *state)
{
        struct device *pwm_dev;
        struct pwm_export *export;

        if (!test_bit(PWMF_EXPORTED, &pwm->flags))
                return NULL;

        pwm_dev = device_find_child(pwmchip_dev, pwm, pwm_unexport_match);
        if (!pwm_dev)
                return NULL;

        export = pwmexport_from_dev(pwm_dev);
        put_device(pwm_dev);    /* for device_find_child() */

        mutex_lock(&export->lock);
        pwm_get_state(pwm, state);

        return export;
}

static int pwm_class_apply_state(struct pwm_export *export,
                                 struct pwm_device *pwm,
                                 struct pwm_state *state)
{
        int ret = pwm_apply_might_sleep(pwm, state);

        /* release lock taken in pwm_class_get_state */
        mutex_unlock(&export->lock);

        return ret;
}

static int pwm_class_resume_npwm(struct device *pwmchip_dev, unsigned int npwm)
{
        struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);
        unsigned int i;
        int ret = 0;

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

                export = pwm_class_get_state(pwmchip_dev, pwm, &state);
                if (!export)
                        continue;

                /* If pwmchip was not enabled before suspend, do nothing. */
                if (!export->suspend.enabled) {
                        /* release lock taken in pwm_class_get_state */
                        mutex_unlock(&export->lock);
                        continue;
                }

                state.enabled = export->suspend.enabled;
                ret = pwm_class_apply_state(export, pwm, &state);
                if (ret < 0)
                        break;
        }

        return ret;
}

static int pwm_class_suspend(struct device *pwmchip_dev)
{
        struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);
        unsigned int i;
        int ret = 0;

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

                export = pwm_class_get_state(pwmchip_dev, pwm, &state);
                if (!export)
                        continue;

                /*
                 * If pwmchip was not enabled before suspend, save
                 * state for resume time and do nothing else.
                 */
                export->suspend = state;
                if (!state.enabled) {
                        /* release lock taken in pwm_class_get_state */
                        mutex_unlock(&export->lock);
                        continue;
                }

                state.enabled = false;
                ret = pwm_class_apply_state(export, pwm, &state);
                if (ret < 0) {
                        /*
                         * roll back the PWM devices that were disabled by
                         * this suspend function.
                         */
                        pwm_class_resume_npwm(pwmchip_dev, i);
                        break;
                }
        }

        return ret;
}

static int pwm_class_resume(struct device *pwmchip_dev)
{
        struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);

        return pwm_class_resume_npwm(pwmchip_dev, chip->npwm);
}

static DEFINE_SIMPLE_DEV_PM_OPS(pwm_class_pm_ops, pwm_class_suspend, pwm_class_resume);

static struct class pwm_class = {
        .name = "pwm",
        .dev_groups = pwm_chip_groups,
        .pm = pm_sleep_ptr(&pwm_class_pm_ops),
};

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

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

                if (test_bit(PWMF_EXPORTED, &pwm->flags))
                        pwm_unexport_child(&chip->dev, pwm);
        }
}

#define PWMCHIP_ALIGN ARCH_DMA_MINALIGN

static void *pwmchip_priv(struct pwm_chip *chip)
{
        return (void *)chip + ALIGN(struct_size(chip, pwms, chip->npwm), PWMCHIP_ALIGN);
}

/* This is the counterpart to pwmchip_alloc() */
void pwmchip_put(struct pwm_chip *chip)
{
        put_device(&chip->dev);
}
EXPORT_SYMBOL_GPL(pwmchip_put);

static void pwmchip_release(struct device *pwmchip_dev)
{
        struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);

        kfree(chip);
}

struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv)
{
        struct pwm_chip *chip;
        struct device *pwmchip_dev;
        size_t alloc_size;
        unsigned int i;

        alloc_size = size_add(ALIGN(struct_size(chip, pwms, npwm), PWMCHIP_ALIGN),
                              sizeof_priv);

        chip = kzalloc(alloc_size, GFP_KERNEL);
        if (!chip)
                return ERR_PTR(-ENOMEM);

        chip->npwm = npwm;
        chip->uses_pwmchip_alloc = true;

        pwmchip_dev = &chip->dev;
        device_initialize(pwmchip_dev);
        pwmchip_dev->class = &pwm_class;
        pwmchip_dev->parent = parent;
        pwmchip_dev->release = pwmchip_release;

        pwmchip_set_drvdata(chip, pwmchip_priv(chip));

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

        return chip;
}
EXPORT_SYMBOL_GPL(pwmchip_alloc);

static void devm_pwmchip_put(void *data)
{
        struct pwm_chip *chip = data;

        pwmchip_put(chip);
}

struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv)
{
        struct pwm_chip *chip;
        int ret;

        chip = pwmchip_alloc(parent, npwm, sizeof_priv);
        if (IS_ERR(chip))
                return chip;

        ret = devm_add_action_or_reset(parent, devm_pwmchip_put, chip);
        if (ret)
                return ERR_PTR(ret);

        return chip;
}
EXPORT_SYMBOL_GPL(devm_pwmchip_alloc);

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

        if (!chip->of_xlate)
                chip->of_xlate = of_pwm_xlate_with_flags;

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

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

static bool pwm_ops_check(const struct pwm_chip *chip)
{
        const struct pwm_ops *ops = chip->ops;

        if (!ops->apply)
                return false;

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

        return true;
}

/**
 * __pwmchip_add() - register a new PWM chip
 * @chip: the PWM chip to add
 * @owner: reference to the module providing the chip.
 *
 * Register a new PWM chip. @owner is supposed to be THIS_MODULE, use the
 * pwmchip_add wrapper to do this right.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int __pwmchip_add(struct pwm_chip *chip, struct module *owner)
{
        int ret;

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

        /*
         * a struct pwm_chip must be allocated using (devm_)pwmchip_alloc,
         * otherwise the embedded struct device might disappear too early
         * resulting in memory corruption.
         * Catch drivers that were not converted appropriately.
         */
        if (!chip->uses_pwmchip_alloc)
                return -EINVAL;

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

        chip->owner = owner;

        mutex_lock(&pwm_lock);

        ret = idr_alloc(&pwm_chips, chip, 0, 0, GFP_KERNEL);
        if (ret < 0)
                goto err_idr_alloc;

        chip->id = ret;

        dev_set_name(&chip->dev, "pwmchip%u", chip->id);

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

        ret = device_add(&chip->dev);
        if (ret)
                goto err_device_add;

        mutex_unlock(&pwm_lock);

        return 0;

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

        idr_remove(&pwm_chips, chip->id);
err_idr_alloc:

        mutex_unlock(&pwm_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(__pwmchip_add);

/**
 * pwmchip_remove() - remove a PWM chip
 * @chip: the PWM chip to remove
 *
 * Removes a PWM chip.
 */
void pwmchip_remove(struct pwm_chip *chip)
{
        pwmchip_sysfs_unexport(chip);

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

        mutex_lock(&pwm_lock);

        idr_remove(&pwm_chips, chip->id);

        mutex_unlock(&pwm_lock);

        device_del(&chip->dev);
}
EXPORT_SYMBOL_GPL(pwmchip_remove);

static void devm_pwmchip_remove(void *data)
{
        struct pwm_chip *chip = data;

        pwmchip_remove(chip);
}

int __devm_pwmchip_add(struct device *dev, struct pwm_chip *chip, struct module *owner)
{
        int ret;

        ret = __pwmchip_add(chip, owner);
        if (ret)
                return ret;

        return devm_add_action_or_reset(dev, devm_pwmchip_remove, chip);
}
EXPORT_SYMBOL_GPL(__devm_pwmchip_add);

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(pwmchip_parent(pwm->chip),
                         "No consumer device specified to create a link to\n");
                return NULL;
        }

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

        return dl;
}

static struct pwm_chip *fwnode_to_pwmchip(struct fwnode_handle *fwnode)
{
        struct pwm_chip *chip;
        unsigned long id, tmp;

        mutex_lock(&pwm_lock);

        idr_for_each_entry_ul(&pwm_chips, chip, tmp, id)
                if (pwmchip_parent(chip) && device_match_fwnode(pwmchip_parent(chip), fwnode)) {
                        mutex_unlock(&pwm_lock);
                        return chip;
                }

        mutex_unlock(&pwm_lock);

        return ERR_PTR(-EPROBE_DEFER);
}

/**
 * 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.
 */
static 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 *chip;
        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);
        }

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

                pwm = ERR_CAST(chip);
                goto put;
        }

        pwm = chip->of_xlate(chip, &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_put(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;
}

/**
 * acpi_pwm_get() - request a PWM via parsing "pwms" property in ACPI
 * @fwnode: firmware node to get the "pwms" 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(const struct fwnode_handle *fwnode)
{
        struct pwm_device *pwm;
        struct fwnode_reference_args args;
        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);

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

        chip = fwnode_to_pwmchip(args.fwnode);
        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;

        return pwm;
}

static DEFINE_MUTEX(pwm_lookup_lock);
static LIST_HEAD(pwm_lookup_list);

/**
 * 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 struct fwnode_handle *fwnode = dev ? dev_fwnode(dev) : NULL;
        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_of_node(fwnode))
                return of_pwm_get(dev, to_of_node(fwnode), con_id);

        /* then lookup via ACPI */
        if (is_acpi_node(fwnode)) {
                pwm = acpi_pwm_get(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_put(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)
{
        struct pwm_chip *chip;

        if (!pwm)
                return;

        chip = pwm->chip;

        mutex_lock(&pwm_lock);

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

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

        pwm->label = NULL;

        put_device(&chip->dev);

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

static void devm_pwm_release(void *pwm)
{
        pwm_put(pwm);
}

/**
 * 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 *pwm;
        int ret;

        pwm = pwm_get(dev, con_id);
        if (IS_ERR(pwm))
                return pwm;

        ret = devm_add_action_or_reset(dev, devm_pwm_release, pwm);
        if (ret)
                return ERR_PTR(ret);

        return pwm;
}
EXPORT_SYMBOL_GPL(devm_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 *pwm = ERR_PTR(-ENODEV);
        int ret;

        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))
                return pwm;

        ret = devm_add_action_or_reset(dev, devm_pwm_release, pwm);
        if (ret)
                return ERR_PTR(ret);

        return pwm;
}
EXPORT_SYMBOL_GPL(devm_fwnode_pwm_get);

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");

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

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

static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
{
        unsigned long id = *pos;
        void *ret;

        mutex_lock(&pwm_lock);
        s->private = "";

        ret = idr_get_next_ul(&pwm_chips, &id);
        *pos = id;
        return ret;
}

static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        unsigned long id = *pos + 1;
        void *ret;

        s->private = "\n";

        ret = idr_get_next_ul(&pwm_chips, &id);
        *pos = id;
        return ret;
}

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 = v;

        seq_printf(s, "%s%d: %s/%s, %d PWM device%s\n",
                   (char *)s->private, chip->id,
                   pwmchip_parent(chip)->bus ? pwmchip_parent(chip)->bus->name : "no-bus",
                   dev_name(pwmchip_parent(chip)), 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_init(void)
{
        if (IS_ENABLED(CONFIG_DEBUG_FS))
                debugfs_create_file("pwm", 0444, NULL, NULL, &pwm_debugfs_fops);

        return class_register(&pwm_class);
}
subsys_initcall(pwm_init);