path: root/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/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->owner))
		return -ENODEV;

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