// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Maxim MAX197 A/D Converter driver
   *
   * Copyright (c) 2012 Savoir-faire Linux Inc.
   *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>
   *

   * For further information, see the Documentation/hwmon/max197.rst file.

   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/mod_devicetable.h>

  #include <linux/init.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/mutex.h>
  #include <linux/device.h>
  #include <linux/sysfs.h>
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/platform_device.h>
  #include <linux/platform_data/max197.h>
  
  #define MAX199_LIMIT	4000		/* 4V */
  #define MAX197_LIMIT	10000		/* 10V */
  
  #define MAX197_NUM_CH	8		/* 8 Analog Input Channels */
  
  /* Control byte format */
  #define MAX197_BIP	(1 << 3)	/* Bipolarity */
  #define MAX197_RNG	(1 << 4)	/* Full range */
  
  #define MAX197_SCALE	12207		/* Scale coefficient for raw data */
  
  /* List of supported chips */
  enum max197_chips { max197, max199 };
  
  /**
   * struct max197_data - device instance specific data
   * @pdata:		Platform data.
   * @hwmon_dev:		The hwmon device.
   * @lock:		Read/Write mutex.
   * @limit:		Max range value (10V for MAX197, 4V for MAX199).
   * @scale:		Need to scale.
   * @ctrl_bytes:		Channels control byte.
   */
  struct max197_data {
  	struct max197_platform_data *pdata;
  	struct device *hwmon_dev;
  	struct mutex lock;
  	int limit;
  	bool scale;
  	u8 ctrl_bytes[MAX197_NUM_CH];
  };
  
  static inline void max197_set_unipolarity(struct max197_data *data, int channel)
  {
  	data->ctrl_bytes[channel] &= ~MAX197_BIP;
  }
  
  static inline void max197_set_bipolarity(struct max197_data *data, int channel)
  {
  	data->ctrl_bytes[channel] |= MAX197_BIP;
  }
  
  static inline void max197_set_half_range(struct max197_data *data, int channel)
  {
  	data->ctrl_bytes[channel] &= ~MAX197_RNG;
  }
  
  static inline void max197_set_full_range(struct max197_data *data, int channel)
  {
  	data->ctrl_bytes[channel] |= MAX197_RNG;
  }
  
  static inline bool max197_is_bipolar(struct max197_data *data, int channel)
  {
  	return data->ctrl_bytes[channel] & MAX197_BIP;
  }
  
  static inline bool max197_is_full_range(struct max197_data *data, int channel)
  {
  	return data->ctrl_bytes[channel] & MAX197_RNG;
  }
  
  /* Function called on read access on in{0,1,2,3,4,5,6,7}_{min,max} */
  static ssize_t max197_show_range(struct device *dev,
  				 struct device_attribute *devattr, char *buf)
  {
  	struct max197_data *data = dev_get_drvdata(dev);
  	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
  	int channel = attr->index;
  	bool is_min = attr->nr;
  	int range;
  
  	if (mutex_lock_interruptible(&data->lock))
  		return -ERESTARTSYS;
  
  	range = max197_is_full_range(data, channel) ?
  		data->limit : data->limit / 2;
  	if (is_min) {
  		if (max197_is_bipolar(data, channel))
  			range = -range;
  		else
  			range = 0;
  	}
  
  	mutex_unlock(&data->lock);
  
  	return sprintf(buf, "%d
  ", range);
  }
  
  /* Function called on write access on in{0,1,2,3,4,5,6,7}_{min,max} */
  static ssize_t max197_store_range(struct device *dev,
  				  struct device_attribute *devattr,
  				  const char *buf, size_t count)
  {
  	struct max197_data *data = dev_get_drvdata(dev);
  	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
  	int channel = attr->index;
  	bool is_min = attr->nr;
  	long value;
  	int half = data->limit / 2;
  	int full = data->limit;
  
  	if (kstrtol(buf, 10, &value))
  		return -EINVAL;
  
  	if (is_min) {
  		if (value <= -full)
  			value = -full;
  		else if (value < 0)
  			value = -half;
  		else
  			value = 0;
  	} else {
  		if (value >= full)
  			value = full;
  		else
  			value = half;
  	}
  
  	if (mutex_lock_interruptible(&data->lock))
  		return -ERESTARTSYS;
  
  	if (value == 0) {
  		/* We can deduce only the polarity */
  		max197_set_unipolarity(data, channel);
  	} else if (value == -half) {
  		max197_set_bipolarity(data, channel);
  		max197_set_half_range(data, channel);
  	} else if (value == -full) {
  		max197_set_bipolarity(data, channel);
  		max197_set_full_range(data, channel);
  	} else if (value == half) {
  		/* We can deduce only the range */
  		max197_set_half_range(data, channel);
  	} else if (value == full) {
  		/* We can deduce only the range */
  		max197_set_full_range(data, channel);
  	}
  
  	mutex_unlock(&data->lock);
  
  	return count;
  }
  
  /* Function called on read access on in{0,1,2,3,4,5,6,7}_input */
  static ssize_t max197_show_input(struct device *dev,
  				 struct device_attribute *devattr,
  				 char *buf)
  {
  	struct max197_data *data = dev_get_drvdata(dev);
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
  	int channel = attr->index;
  	s32 value;
  	int ret;
  
  	if (mutex_lock_interruptible(&data->lock))
  		return -ERESTARTSYS;
  
  	ret = data->pdata->convert(data->ctrl_bytes[channel]);
  	if (ret < 0) {
  		dev_err(dev, "conversion failed
  ");
  		goto unlock;
  	}
  	value = ret;
  
  	/*
  	 * Coefficient to apply on raw value.
  	 * See Table 1. Full Scale and Zero Scale in the MAX197 datasheet.
  	 */
  	if (data->scale) {
  		value *= MAX197_SCALE;
  		if (max197_is_full_range(data, channel))
  			value *= 2;
  		value /= 10000;
  	}
  
  	ret = sprintf(buf, "%d
  ", value);
  
  unlock:
  	mutex_unlock(&data->lock);
  	return ret;
  }

  static ssize_t name_show(struct device *dev, struct device_attribute *attr,
  			 char *buf)

  {
  	struct platform_device *pdev = to_platform_device(dev);
  	return sprintf(buf, "%s
  ", pdev->name);
  }
  
  #define MAX197_SENSOR_DEVICE_ATTR_CH(chan)				\
  	static SENSOR_DEVICE_ATTR(in##chan##_input, S_IRUGO,		\
  				  max197_show_input, NULL, chan);	\
  	static SENSOR_DEVICE_ATTR_2(in##chan##_min, S_IRUGO | S_IWUSR,	\
  				    max197_show_range,			\
  				    max197_store_range,			\
  				    true, chan);			\
  	static SENSOR_DEVICE_ATTR_2(in##chan##_max, S_IRUGO | S_IWUSR,	\
  				    max197_show_range,			\
  				    max197_store_range,			\
  				    false, chan)
  
  #define MAX197_SENSOR_DEV_ATTR_IN(chan)					\
  	&sensor_dev_attr_in##chan##_input.dev_attr.attr,		\
  	&sensor_dev_attr_in##chan##_max.dev_attr.attr,			\
  	&sensor_dev_attr_in##chan##_min.dev_attr.attr

  static DEVICE_ATTR_RO(name);

  
  MAX197_SENSOR_DEVICE_ATTR_CH(0);
  MAX197_SENSOR_DEVICE_ATTR_CH(1);
  MAX197_SENSOR_DEVICE_ATTR_CH(2);
  MAX197_SENSOR_DEVICE_ATTR_CH(3);
  MAX197_SENSOR_DEVICE_ATTR_CH(4);
  MAX197_SENSOR_DEVICE_ATTR_CH(5);
  MAX197_SENSOR_DEVICE_ATTR_CH(6);
  MAX197_SENSOR_DEVICE_ATTR_CH(7);
  
  static const struct attribute_group max197_sysfs_group = {
  	.attrs = (struct attribute *[]) {
  		&dev_attr_name.attr,
  		MAX197_SENSOR_DEV_ATTR_IN(0),
  		MAX197_SENSOR_DEV_ATTR_IN(1),
  		MAX197_SENSOR_DEV_ATTR_IN(2),
  		MAX197_SENSOR_DEV_ATTR_IN(3),
  		MAX197_SENSOR_DEV_ATTR_IN(4),
  		MAX197_SENSOR_DEV_ATTR_IN(5),
  		MAX197_SENSOR_DEV_ATTR_IN(6),
  		MAX197_SENSOR_DEV_ATTR_IN(7),
  		NULL
  	},
  };

  static int max197_probe(struct platform_device *pdev)

  {
  	int ch, ret;
  	struct max197_data *data;

  	struct max197_platform_data *pdata = dev_get_platdata(&pdev->dev);

  	enum max197_chips chip = platform_get_device_id(pdev)->driver_data;
  
  	if (pdata == NULL) {
  		dev_err(&pdev->dev, "no platform data supplied
  ");
  		return -EINVAL;
  	}
  
  	if (pdata->convert == NULL) {
  		dev_err(&pdev->dev, "no convert function supplied
  ");
  		return -EINVAL;
  	}
  
  	data = devm_kzalloc(&pdev->dev, sizeof(struct max197_data), GFP_KERNEL);

  	if (!data)

  		return -ENOMEM;

  
  	data->pdata = pdata;
  	mutex_init(&data->lock);
  
  	if (chip == max197) {
  		data->limit = MAX197_LIMIT;
  		data->scale = true;
  	} else {
  		data->limit = MAX199_LIMIT;
  		data->scale = false;
  	}
  
  	for (ch = 0; ch < MAX197_NUM_CH; ch++)
  		data->ctrl_bytes[ch] = (u8) ch;
  
  	platform_set_drvdata(pdev, data);
  
  	ret = sysfs_create_group(&pdev->dev.kobj, &max197_sysfs_group);
  	if (ret) {
  		dev_err(&pdev->dev, "sysfs create group failed
  ");
  		return ret;
  	}
  
  	data->hwmon_dev = hwmon_device_register(&pdev->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		ret = PTR_ERR(data->hwmon_dev);
  		dev_err(&pdev->dev, "hwmon device register failed
  ");
  		goto error;
  	}
  
  	return 0;
  
  error:
  	sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
  	return ret;
  }

  static int max197_remove(struct platform_device *pdev)

  {
  	struct max197_data *data = platform_get_drvdata(pdev);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
  
  	return 0;
  }

  static const struct platform_device_id max197_device_ids[] = {

  	{ "max197", max197 },
  	{ "max199", max199 },
  	{ }
  };
  MODULE_DEVICE_TABLE(platform, max197_device_ids);
  
  static struct platform_driver max197_driver = {
  	.driver = {
  		.name = "max197",

  	},
  	.probe = max197_probe,

  	.remove = max197_remove,

  	.id_table = max197_device_ids,
  };
  module_platform_driver(max197_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
  MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");