path: root/drivers/pwm/core.c

/*
 * 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