/*
   * A simple sysfs interface for the generic PWM framework
   *
   * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com>
   *
   * Based on previous work by Lars Poeschel <poeschel@lemonage.de>
   *
   * 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.
   */
  
  #include <linux/device.h>
  #include <linux/mutex.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/kdev_t.h>
  #include <linux/pwm.h>
  
  struct pwm_export {
  	struct device child;
  	struct pwm_device *pwm;
  };
  
  static struct pwm_export *child_to_pwm_export(struct device *child)
  {
  	return container_of(child, struct pwm_export, child);
  }
  
  static struct pwm_device *child_to_pwm_device(struct device *child)
  {
  	struct pwm_export *export = child_to_pwm_export(child);
  
  	return export->pwm;
  }
  
  static ssize_t pwm_period_show(struct device *child,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	const struct pwm_device *pwm = child_to_pwm_device(child);
  
  	return sprintf(buf, "%u
  ", pwm->period);
  }
  
  static ssize_t pwm_period_store(struct device *child,
  				struct device_attribute *attr,
  				const char *buf, size_t size)
  {
  	struct pwm_device *pwm = child_to_pwm_device(child);
  	unsigned int val;
  	int ret;
  
  	ret = kstrtouint(buf, 0, &val);
  	if (ret)
  		return ret;
  
  	ret = pwm_config(pwm, pwm->duty_cycle, val);
  
  	return ret ? : size;
  }
  
  static ssize_t pwm_duty_cycle_show(struct device *child,
  				   struct device_attribute *attr,
  				   char *buf)
  {
  	const struct pwm_device *pwm = child_to_pwm_device(child);
  
  	return sprintf(buf, "%u
  ", pwm->duty_cycle);
  }
  
  static ssize_t pwm_duty_cycle_store(struct device *child,
  				    struct device_attribute *attr,
  				    const char *buf, size_t size)
  {
  	struct pwm_device *pwm = child_to_pwm_device(child);
  	unsigned int val;
  	int ret;
  
  	ret = kstrtouint(buf, 0, &val);
  	if (ret)
  		return ret;
  
  	ret = pwm_config(pwm, val, pwm->period);
  
  	return ret ? : size;
  }
  
  static ssize_t pwm_enable_show(struct device *child,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	const struct pwm_device *pwm = child_to_pwm_device(child);
  	int enabled = test_bit(PWMF_ENABLED, &pwm->flags);
  
  	return sprintf(buf, "%d
  ", enabled);
  }
  
  static ssize_t pwm_enable_store(struct device *child,
  				struct device_attribute *attr,
  				const char *buf, size_t size)
  {
  	struct pwm_device *pwm = child_to_pwm_device(child);
  	int val, ret;
  
  	ret = kstrtoint(buf, 0, &val);
  	if (ret)
  		return ret;
  
  	switch (val) {
  	case 0:
  		pwm_disable(pwm);
  		break;
  	case 1:
  		ret = pwm_enable(pwm);
  		break;
  	default:
  		ret = -EINVAL;
  		break;
  	}
  
  	return ret ? : size;
  }
  
  static ssize_t pwm_polarity_show(struct device *child,
  				 struct device_attribute *attr,
  				 char *buf)
  {
  	const struct pwm_device *pwm = child_to_pwm_device(child);
  
  	return sprintf(buf, "%s
  ", pwm->polarity ? "inversed" : "normal");
  }
  
  static ssize_t pwm_polarity_store(struct device *child,
  				  struct device_attribute *attr,
  				  const char *buf, size_t size)
  {
  	struct pwm_device *pwm = child_to_pwm_device(child);
  	enum pwm_polarity polarity;
  	int ret;
  
  	if (sysfs_streq(buf, "normal"))
  		polarity = PWM_POLARITY_NORMAL;
  	else if (sysfs_streq(buf, "inversed"))
  		polarity = PWM_POLARITY_INVERSED;
  	else
  		return -EINVAL;
  
  	ret = pwm_set_polarity(pwm, polarity);
  
  	return ret ? : size;
  }
  
  static DEVICE_ATTR(period, 0644, pwm_period_show, pwm_period_store);
  static DEVICE_ATTR(duty_cycle, 0644, pwm_duty_cycle_show, pwm_duty_cycle_store);
  static DEVICE_ATTR(enable, 0644, pwm_enable_show, pwm_enable_store);
  static DEVICE_ATTR(polarity, 0644, pwm_polarity_show, pwm_polarity_store);
  
  static struct attribute *pwm_attrs[] = {
  	&dev_attr_period.attr,
  	&dev_attr_duty_cycle.attr,
  	&dev_attr_enable.attr,
  	&dev_attr_polarity.attr,
  	NULL
  };
  ATTRIBUTE_GROUPS(pwm);
  
  static void pwm_export_release(struct device *child)
  {
  	struct pwm_export *export = child_to_pwm_export(child);
  
  	kfree(export);
  }
  
  static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
  {
  	struct pwm_export *export;
  	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;
  
  	export->child.release = pwm_export_release;
  	export->child.parent = parent;
  	export->child.devt = MKDEV(0, 0);
  	export->child.groups = pwm_groups;
  	dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
  
  	ret = device_register(&export->child);
  	if (ret) {
  		clear_bit(PWMF_EXPORTED, &pwm->flags);
  		kfree(export);
  		return ret;
  	}
  
  	return 0;
  }
  
  static int pwm_unexport_match(struct device *child, void *data)
  {
  	return child_to_pwm_device(child) == data;
  }
  
  static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
  {
  	struct device *child;
  
  	if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
  		return -ENODEV;
  
  	child = device_find_child(parent, pwm, pwm_unexport_match);
  	if (!child)
  		return -ENODEV;
  
  	/* for device_find_child() */
  	put_device(child);
  	device_unregister(child);
  	pwm_put(pwm);
  
  	return 0;
  }
  
  static ssize_t pwm_export_store(struct device *parent,
  				struct device_attribute *attr,
  				const char *buf, size_t len)
  {
  	struct pwm_chip *chip = dev_get_drvdata(parent);
  	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(parent, pwm);
  	if (ret < 0)
  		pwm_put(pwm);
  
  	return ret ? : len;
  }
  static DEVICE_ATTR(export, 0200, NULL, pwm_export_store);
  
  static ssize_t pwm_unexport_store(struct device *parent,
  				  struct device_attribute *attr,
  				  const char *buf, size_t len)
  {
  	struct pwm_chip *chip = dev_get_drvdata(parent);
  	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(parent, &chip->pwms[hwpwm]);
  
  	return ret ? : len;
  }
  static DEVICE_ATTR(unexport, 0200, NULL, pwm_unexport_store);
  
  static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
  			 char *buf)
  {
  	const struct pwm_chip *chip = dev_get_drvdata(parent);
  
  	return sprintf(buf, "%u
  ", 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);
  
  static struct class pwm_class = {
  	.name		= "pwm",
  	.owner		= THIS_MODULE,
  	.dev_groups	= pwm_chip_groups,
  };
  
  static int pwmchip_sysfs_match(struct device *parent, const void *data)
  {
  	return dev_get_drvdata(parent) == data;
  }
  
  void pwmchip_sysfs_export(struct pwm_chip *chip)
  {
  	struct device *parent;
  
  	/*
  	 * If device_create() fails the pwm_chip is still usable by
  	 * the kernel its just not exported.
  	 */
  	parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
  			       "pwmchip%d", chip->base);
  	if (IS_ERR(parent)) {
  		dev_warn(chip->dev,
  			 "device_create failed for pwm_chip sysfs export
  ");
  	}
  }
  
  void pwmchip_sysfs_unexport(struct pwm_chip *chip)
  {
  	struct device *parent;
  
  	parent = class_find_device(&pwm_class, NULL, chip,
  				   pwmchip_sysfs_match);
  	if (parent) {
  		/* for class_find_device() */
  		put_device(parent);
  		device_unregister(parent);
  	}
  }
  
  static int __init pwm_sysfs_init(void)
  {
  	return class_register(&pwm_class);
  }
  subsys_initcall(pwm_sysfs_init);