Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1136 insertions, 0 deletions

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
new file mode 100644
index 000000000..0c8c63239
--- /dev/null
+++ b/drivers/pwm/core.c
@@ -0,0 +1,1136 @@
+// 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/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>
+
+#define MAX_PWMS 1024
+
+static DEFINE_MUTEX(pwm_lookup_lock);
+static LIST_HEAD(pwm_lookup_list);
+
+/* protects access to pwm_chips and allocated_pwms */
+static DEFINE_MUTEX(pwm_lock);
+
+static LIST_HEAD(pwm_chips);
+static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
+
+/* Called with pwm_lock held */
+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;
+
+	bitmap_set(allocated_pwms, start, count);
+
+	return start;
+}
+
+/* Called with pwm_lock held */
+static void free_pwms(struct pwm_chip *chip)
+{
+	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) {
+		/*
+		 * 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 = pwm->chip->ops->get_state(pwm->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;
+}
+
+struct pwm_device *
+of_pwm_xlate_with_flags(struct pwm_chip *chip, const struct of_phandle_args *args)
+{
+	struct pwm_device *pwm;
+
+	if (chip->of_pwm_n_cells < 2)
+		return ERR_PTR(-EINVAL);
+
+	/* flags in the third cell are optional */
+	if (args->args_count < 2)
+		return ERR_PTR(-EINVAL);
+
+	if (args->args[0] >= chip->npwm)
+		return ERR_PTR(-EINVAL);
+
+	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 (chip->of_pwm_n_cells >= 3) {
+		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;
+
+	if (chip->of_pwm_n_cells < 1)
+		return ERR_PTR(-EINVAL);
+
+	/* validate that one cell is specified, optionally with flags */
+	if (args->args_count != 1 && args->args_count != 2)
+		return ERR_PTR(-EINVAL);
+
+	pwm = pwm_request_from_chip(chip, 0, NULL);
+	if (IS_ERR(pwm))
+		return pwm;
+
+	pwm->args.period = args->args[0];
+	pwm->args.polarity = PWM_POLARITY_NORMAL;
+
+	if (args->args_count == 2 && args->args[1] & PWM_POLARITY_INVERTED)
+		pwm->args.polarity = PWM_POLARITY_INVERSED;
+
+	return pwm;
+}
+EXPORT_SYMBOL_GPL(of_pwm_single_xlate);
+
+static void of_pwmchip_add(struct pwm_chip *chip)
+{
+	if (!chip->dev || !chip->dev->of_node)
+		return;
+
+	if (!chip->of_xlate) {
+		u32 pwm_cells;
+
+		if (of_property_read_u32(chip->dev->of_node, "#pwm-cells",
+					 &pwm_cells))
+			pwm_cells = 2;
+
+		chip->of_xlate = of_pwm_xlate_with_flags;
+		chip->of_pwm_n_cells = pwm_cells;
+	}
+
+	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;
+
+	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;
+
+	chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
+	if (!chip->pwms)
+		return -ENOMEM;
+
+	mutex_lock(&pwm_lock);
+
+	ret = alloc_pwms(chip->npwm);
+	if (ret < 0) {
+		mutex_unlock(&pwm_lock);
+		kfree(chip->pwms);
+		return ret;
+	}
+
+	chip->base = ret;
+
+	for (i = 0; i < chip->npwm; i++) {
+		pwm = &chip->pwms[i];
+
+		pwm->chip = chip;
+		pwm->pwm = chip->base + i;
+		pwm->hwpwm = i;
+	}
+
+	list_add(&chip->list, &pwm_chips);
+
+	mutex_unlock(&pwm_lock);
+
+	if (IS_ENABLED(CONFIG_OF))
+		of_pwmchip_add(chip);
+
+	pwmchip_sysfs_export(chip);
+
+	return 0;
+}
+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);
+
+	list_del_init(&chip->list);
+
+	free_pwms(chip);
+
+	mutex_unlock(&pwm_lock);
+}
+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)
+{
+	int ret;
+
+	ret = pwmchip_add(chip);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, devm_pwmchip_remove, chip);
+}
+EXPORT_SYMBOL_GPL(devm_pwmchip_add);
+
+/**
+ * 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);
+
+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 = { 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(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);
+	trace_pwm_apply(pwm, &s1, err);
+	if (err) {
+		*last = s1;
+		dev_err(chip->dev, "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(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;
+
+	/*
+	 * 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_state() from atomic context
+	 * is a bad idea. So make it explicit that calling this function might
+	 * sleep.
+	 */
+	might_sleep();
+
+	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_state_debug(pwm, state);
+
+	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 *fwnode_to_pwmchip(struct fwnode_handle *fwnode)
+{
+	struct pwm_chip *chip;
+
+	mutex_lock(&pwm_lock);
+
+	list_for_each_entry(chip, &pwm_chips, list)
+		if (chip->dev && device_match_fwnode(chip->dev, fwnode)) {
+			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.
+ */
+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;
+}
+
+/**
+ * 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)
+{
+	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(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);
+
+#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");
+
+		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)
+{
+	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", 0444, NULL, NULL, &pwm_debugfs_fops);
+
+	return 0;
+}
+subsys_initcall(pwm_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */