/* Hwmon client for industrial I/O devices
   *
   * Copyright (c) 2011 Jonathan Cameron
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   */
  
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/platform_device.h>
  #include <linux/hwmon.h>

  #include <linux/of.h>

  #include <linux/hwmon-sysfs.h>

  #include <linux/iio/consumer.h>
  #include <linux/iio/types.h>

  
  /**
   * struct iio_hwmon_state - device instance state
   * @channels:		filled with array of channels from iio
   * @num_channels:	number of channels in channels (saves counting twice)
   * @hwmon_dev:		associated hwmon device
   * @attr_group:	the group of attributes
   * @attrs:		null terminated array of attribute pointers.
   */
  struct iio_hwmon_state {
  	struct iio_channel *channels;
  	int num_channels;
  	struct device *hwmon_dev;
  	struct attribute_group attr_group;

  	const struct attribute_group *groups[2];

  	struct attribute **attrs;
  };
  
  /*
   * Assumes that IIO and hwmon operate in the same base units.
   * This is supposed to be true, but needs verification for
   * new channel types.
   */
  static ssize_t iio_hwmon_read_val(struct device *dev,
  				  struct device_attribute *attr,
  				  char *buf)
  {

  	int result;
  	int ret;

  	struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  	struct iio_hwmon_state *state = dev_get_drvdata(dev);

  	ret = iio_read_channel_processed(&state->channels[sattr->index],
  					&result);

  	if (ret < 0)
  		return ret;

  	return sprintf(buf, "%d
  ", result);

  }

  static int iio_hwmon_probe(struct platform_device *pdev)

  {

  	struct device *dev = &pdev->dev;

  	struct iio_hwmon_state *st;
  	struct sensor_device_attribute *a;
  	int ret, i;

  	int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1;

  	enum iio_chan_type type;

  	struct iio_channel *channels;

  	const char *name = "iio_hwmon";

  	char *sname;

  
  	if (dev->of_node && dev->of_node->name)
  		name = dev->of_node->name;

  
  	channels = iio_channel_get_all(dev);

  	if (IS_ERR(channels)) {
  		if (PTR_ERR(channels) == -ENODEV)
  			return -EPROBE_DEFER;

  		return PTR_ERR(channels);

  	}

  	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);

  	if (st == NULL) {
  		ret = -ENOMEM;
  		goto error_release_channels;
  	}

  	st->channels = channels;

  
  	/* count how many attributes we have */
  	while (st->channels[st->num_channels].indio_dev)
  		st->num_channels++;

  	st->attrs = devm_kzalloc(dev,

  				 sizeof(*st->attrs) * (st->num_channels + 1),

  				 GFP_KERNEL);

  	if (st->attrs == NULL) {
  		ret = -ENOMEM;
  		goto error_release_channels;
  	}

  	for (i = 0; i < st->num_channels; i++) {

  		a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);

  		if (a == NULL) {
  			ret = -ENOMEM;

  			goto error_release_channels;

  		}
  
  		sysfs_attr_init(&a->dev_attr.attr);

  		ret = iio_get_channel_type(&st->channels[i], &type);

  		if (ret < 0)
  			goto error_release_channels;

  		switch (type) {
  		case IIO_VOLTAGE:

  			a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
  							       "in%d_input",
  							       in_i++);

  			break;
  		case IIO_TEMP:

  			a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
  							       "temp%d_input",
  							       temp_i++);

  			break;
  		case IIO_CURRENT:

  			a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
  							       "curr%d_input",
  							       curr_i++);

  			break;

  		case IIO_HUMIDITYRELATIVE:

  			a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
  							       "humidity%d_input",
  							       humidity_i++);

  			break;

  		default:
  			ret = -EINVAL;

  			goto error_release_channels;

  		}
  		if (a->dev_attr.attr.name == NULL) {

  			ret = -ENOMEM;

  			goto error_release_channels;

  		}
  		a->dev_attr.show = iio_hwmon_read_val;
  		a->dev_attr.attr.mode = S_IRUGO;
  		a->index = i;
  		st->attrs[i] = &a->dev_attr.attr;
  	}

  	st->attr_group.attrs = st->attrs;
  	st->groups[0] = &st->attr_group;

  
  	sname = devm_kstrdup(dev, name, GFP_KERNEL);
  	if (!sname) {
  		ret = -ENOMEM;
  		goto error_release_channels;
  	}
  
  	strreplace(sname, '-', '_');
  	st->hwmon_dev = hwmon_device_register_with_groups(dev, sname, st,

  							  st->groups);

  	if (IS_ERR(st->hwmon_dev)) {
  		ret = PTR_ERR(st->hwmon_dev);

  		goto error_release_channels;

  	}

  	platform_set_drvdata(pdev, st);

  	return 0;

  error_release_channels:

  	iio_channel_release_all(channels);

  	return ret;
  }

  static int iio_hwmon_remove(struct platform_device *pdev)

  {
  	struct iio_hwmon_state *st = platform_get_drvdata(pdev);
  
  	hwmon_device_unregister(st->hwmon_dev);

  	iio_channel_release_all(st->channels);

  
  	return 0;
  }

  static const struct of_device_id iio_hwmon_of_match[] = {

  	{ .compatible = "iio-hwmon", },
  	{ }
  };

  MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);

  static struct platform_driver __refdata iio_hwmon_driver = {
  	.driver = {
  		.name = "iio_hwmon",

  		.of_match_table = iio_hwmon_of_match,

  	},
  	.probe = iio_hwmon_probe,

  	.remove = iio_hwmon_remove,

  };

  module_platform_driver(iio_hwmon_driver);

  MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");

  MODULE_DESCRIPTION("IIO to hwmon driver");
  MODULE_LICENSE("GPL v2");