initial Olimex linux tree from Daniel, originally Feb 3, 2016

1 files changed, 895 insertions, 0 deletions

diff --git a/linux/drivers/pwm/core.c b/linux/drivers/pwm/core.c
new file mode 100644
index 00000000..ba34c7d8
--- /dev/null
+++ b/linux/drivers/pwm/core.c
@@ -0,0 +1,895 @@
+/*
+ * Generic pwmlib implementation
+ *
+ * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
+ * Copyright (C) 2011-2012 Avionic Design GmbH
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; see the file COPYING.  If not, write to
+ *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#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 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(int pwm, unsigned int count)
+{
+	unsigned int from = 0;
+	unsigned int start;
+
+	if (pwm >= MAX_PWMS)
+		return -EINVAL;
+
+	if (pwm >= 0)
+		from = pwm;
+
+	start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from,
+					   count, 0);
+
+	if (pwm >= 0 && start != pwm)
+		return -EEXIST;
+
+	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;
+		}
+	}
+
+	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;
+
+	if (pc->of_pwm_n_cells < 3)
+		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_set_period(pwm, args->args[1]);
+
+	if (args->args[2] & PWM_POLARITY_INVERTED)
+		pwm_set_polarity(pwm, PWM_POLARITY_INVERSED);
+	else
+		pwm_set_polarity(pwm, PWM_POLARITY_NORMAL);
+
+	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;
+
+	if (pc->of_pwm_n_cells < 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_set_period(pwm, 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
+ */
+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
+ */
+void *pwm_get_chip_data(struct pwm_device *pwm)
+{
+	return pwm ? pwm->chip_data : NULL;
+}
+EXPORT_SYMBOL_GPL(pwm_get_chip_data);
+
+/**
+ * pwmchip_add() - register a new PWM chip
+ * @chip: the PWM chip to add
+ *
+ * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
+ * will be used.
+ */
+int pwmchip_add(struct pwm_chip *chip)
+{
+	struct pwm_device *pwm;
+	unsigned int i;
+	int ret;
+
+	if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
+	    !chip->ops->enable || !chip->ops->disable || !chip->npwm)
+		return -EINVAL;
+
+	mutex_lock(&pwm_lock);
+
+	ret = alloc_pwms(chip->base, chip->npwm);
+	if (ret < 0)
+		goto out;
+
+	chip->pwms = kzalloc(chip->npwm * sizeof(*pwm), GFP_KERNEL);
+	if (!chip->pwms) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	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;
+
+		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);
+
+	pwmchip_sysfs_export(chip);
+
+out:
+	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. This function may return busy if the PWM chip provides
+ * a PWM device that is still requested.
+ */
+int pwmchip_remove(struct pwm_chip *chip)
+{
+	unsigned int i;
+	int ret = 0;
+
+	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);
+
+	pwmchip_sysfs_unexport(chip);
+
+out:
+	mutex_unlock(&pwm_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwmchip_remove);
+
+/**
+ * pwm_request() - request a PWM device
+ * @pwm_id: global PWM device index
+ * @label: PWM device label
+ *
+ * This function is deprecated, use pwm_get() instead.
+ */
+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 the PWM 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);
+
+/**
+ * pwm_config() - change a PWM device configuration
+ * @pwm: PWM device
+ * @duty_ns: "on" time (in nanoseconds)
+ * @period_ns: duration (in nanoseconds) of one cycle
+ */
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+	int err;
+
+	if (!pwm || duty_ns < 0 || period_ns <= 0 || duty_ns > period_ns)
+		return -EINVAL;
+
+	err = pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
+	if (err)
+		return err;
+
+	pwm->duty_cycle = duty_ns;
+	pwm->period = period_ns;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pwm_config);
+
+/**
+ * pwm_set_polarity() - configure the polarity of a PWM signal
+ * @pwm: PWM device
+ * @polarity: new polarity of the PWM signal
+ *
+ * Note that the polarity cannot be configured while the PWM device is enabled
+ */
+int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
+{
+	int err;
+
+	if (!pwm || !pwm->chip->ops)
+		return -EINVAL;
+
+	if (!pwm->chip->ops->set_polarity)
+		return -ENOSYS;
+
+	if (test_bit(PWMF_ENABLED, &pwm->flags))
+		return -EBUSY;
+
+	err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);
+	if (err)
+		return err;
+
+	pwm->polarity = polarity;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pwm_set_polarity);
+
+/**
+ * pwm_enable() - start a PWM output toggling
+ * @pwm: PWM device
+ */
+int pwm_enable(struct pwm_device *pwm)
+{
+	if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
+		return pwm->chip->ops->enable(pwm->chip, pwm);
+
+	return pwm ? 0 : -EINVAL;
+}
+EXPORT_SYMBOL_GPL(pwm_enable);
+
+/**
+ * pwm_disable() - stop a PWM output toggling
+ * @pwm: PWM device
+ */
+void pwm_disable(struct pwm_device *pwm)
+{
+	if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
+		pwm->chip->ops->disable(pwm->chip, pwm);
+}
+EXPORT_SYMBOL_GPL(pwm_disable);
+
+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);
+}
+
+/**
+ * of_pwm_get() - request a PWM via the PWM framework
+ * @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.
+ */
+struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
+{
+	struct pwm_device *pwm = NULL;
+	struct of_phandle_args args;
+	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_debug("%s(): can't parse \"pwms\" property\n", __func__);
+		return ERR_PTR(err);
+	}
+
+	pc = of_node_to_pwmchip(args.np);
+	if (IS_ERR(pc)) {
+		pr_debug("%s(): PWM chip not found\n", __func__);
+		pwm = ERR_CAST(pc);
+		goto put;
+	}
+
+	if (args.args_count != pc->of_pwm_n_cells) {
+		pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name,
+			 args.np->full_name);
+		pwm = ERR_PTR(-EINVAL);
+		goto put;
+	}
+
+	pwm = pc->of_xlate(pc, &args);
+	if (IS_ERR(pwm))
+		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);
+
+/**
+ * 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_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.
+ */
+struct pwm_device *pwm_get(struct device *dev, const char *con_id)
+{
+	struct pwm_device *pwm = ERR_PTR(-EPROBE_DEFER);
+	const char *dev_id = dev ? dev_name(dev) : NULL;
+	struct pwm_chip *chip = NULL;
+	unsigned int best = 0;
+	struct pwm_lookup *p, *chosen = NULL;
+	unsigned int match;
+
+	/* look up via DT first */
+	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
+		return of_pwm_get(dev->of_node, con_id);
+
+	/*
+	 * 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;
+		}
+	}
+
+	if (!chosen)
+		goto out;
+
+	chip = pwmchip_find_by_name(chosen->provider);
+	if (!chip)
+		goto out;
+
+	pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id);
+	if (IS_ERR(pwm))
+		goto out;
+
+	pwm_set_period(pwm, chosen->period);
+	pwm_set_polarity(pwm, chosen->polarity);
+
+out:
+	mutex_unlock(&pwm_lookup_lock);
+	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->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.
+ */
+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.
+ */
+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(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);
+
+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);
+
+/**
+  * pwm_can_sleep() - report whether PWM access will sleep
+  * @pwm: PWM device
+  *
+  * It returns true if accessing the PWM can sleep, false otherwise.
+  */
+bool pwm_can_sleep(struct pwm_device *pwm)
+{
+	return pwm->chip->can_sleep;
+}
+EXPORT_SYMBOL_GPL(pwm_can_sleep);
+
+#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];
+
+		seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
+
+		if (test_bit(PWMF_REQUESTED, &pwm->flags))
+			seq_puts(s, " requested");
+
+		if (test_bit(PWMF_ENABLED, &pwm->flags))
+			seq_puts(s, " enabled");
+
+		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" : "");
+
+	if (chip->ops->dbg_show)
+		chip->ops->dbg_show(chip, s);
+	else
+		pwm_dbg_show(chip, s);
+
+	return 0;
+}
+
+static const struct seq_operations pwm_seq_ops = {
+	.start = pwm_seq_start,
+	.next = pwm_seq_next,
+	.stop = pwm_seq_stop,
+	.show = pwm_seq_show,
+};
+
+static int pwm_seq_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &pwm_seq_ops);
+}
+
+static const struct file_operations pwm_debugfs_ops = {
+	.owner = THIS_MODULE,
+	.open = pwm_seq_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+
+static int __init pwm_debugfs_init(void)
+{
+	debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL,
+			    &pwm_debugfs_ops);
+
+	return 0;
+}
+
+subsys_initcall(pwm_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */