/*
   * An hwmon driver for the Analog Devices AD7414
   *
   * Copyright 2006 Stefan Roese <sr at denx.de>, DENX Software Engineering
   *
   * Copyright (c) 2008 PIKA Technologies
   *   Sean MacLennan <smaclennan@pikatech.com>
   *
   * Copyright (c) 2008 Spansion Inc.
   *   Frank Edelhaeuser <frank.edelhaeuser at spansion.com>
   *   (converted to "new style" I2C driver model, removed checkpatch.pl warnings)
   *
   * Based on ad7418.c
   * Copyright 2006 Tower Technologies, Alessandro Zummo <a.zummo at towertech.it>
   *
   * 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 of the License, or
   * (at your option) any later version.
   */
  
  #include <linux/module.h>
  #include <linux/jiffies.h>
  #include <linux/i2c.h>
  #include <linux/hwmon.h>
  #include <linux/hwmon-sysfs.h>
  #include <linux/err.h>
  #include <linux/mutex.h>
  #include <linux/sysfs.h>
  #include <linux/slab.h>
  
  
  /* AD7414 registers */
  #define AD7414_REG_TEMP		0x00
  #define AD7414_REG_CONF		0x01
  #define AD7414_REG_T_HIGH	0x02
  #define AD7414_REG_T_LOW	0x03
  
  static u8 AD7414_REG_LIMIT[] = { AD7414_REG_T_HIGH, AD7414_REG_T_LOW };
  
  struct ad7414_data {
  	struct device		*hwmon_dev;
  	struct mutex		lock;	/* atomic read data updates */
  	char			valid;	/* !=0 if following fields are valid */
  	unsigned long		next_update;	/* In jiffies */
  	s16			temp_input;	/* Register values */
  	s8			temps[ARRAY_SIZE(AD7414_REG_LIMIT)];
  };
  
  /* REG: (0.25C/bit, two's complement) << 6 */
  static inline int ad7414_temp_from_reg(s16 reg)
  {
  	/*
  	 * use integer division instead of equivalent right shift to
  	 * guarantee arithmetic shift and preserve the sign
  	 */
  	return ((int)reg / 64) * 250;
  }
  
  static inline int ad7414_read(struct i2c_client *client, u8 reg)
  {
  	if (reg == AD7414_REG_TEMP)
  		return i2c_smbus_read_word_swapped(client, reg);
  	else
  		return i2c_smbus_read_byte_data(client, reg);
  }
  
  static inline int ad7414_write(struct i2c_client *client, u8 reg, u8 value)
  {
  	return i2c_smbus_write_byte_data(client, reg, value);
  }
  
  static struct ad7414_data *ad7414_update_device(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct ad7414_data *data = i2c_get_clientdata(client);
  
  	mutex_lock(&data->lock);
  
  	if (time_after(jiffies, data->next_update) || !data->valid) {
  		int value, i;
  
  		dev_dbg(&client->dev, "starting ad7414 update
  ");
  
  		value = ad7414_read(client, AD7414_REG_TEMP);
  		if (value < 0)
  			dev_dbg(&client->dev, "AD7414_REG_TEMP err %d
  ",
  				value);
  		else
  			data->temp_input = value;
  
  		for (i = 0; i < ARRAY_SIZE(AD7414_REG_LIMIT); ++i) {
  			value = ad7414_read(client, AD7414_REG_LIMIT[i]);
  			if (value < 0)
  				dev_dbg(&client->dev, "AD7414 reg %d err %d
  ",
  					AD7414_REG_LIMIT[i], value);
  			else
  				data->temps[i] = value;
  		}
  
  		data->next_update = jiffies + HZ + HZ / 2;
  		data->valid = 1;
  	}
  
  	mutex_unlock(&data->lock);
  
  	return data;
  }
  
  static ssize_t show_temp_input(struct device *dev,
  			       struct device_attribute *attr, char *buf)
  {
  	struct ad7414_data *data = ad7414_update_device(dev);
  	return sprintf(buf, "%d
  ", ad7414_temp_from_reg(data->temp_input));
  }
  static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
  
  static ssize_t show_max_min(struct device *dev, struct device_attribute *attr,
  			  char *buf)
  {
  	int index = to_sensor_dev_attr(attr)->index;
  	struct ad7414_data *data = ad7414_update_device(dev);
  	return sprintf(buf, "%d
  ", data->temps[index] * 1000);
  }
  
  static ssize_t set_max_min(struct device *dev,
  			   struct device_attribute *attr,
  			   const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct ad7414_data *data = i2c_get_clientdata(client);
  	int index = to_sensor_dev_attr(attr)->index;
  	u8 reg = AD7414_REG_LIMIT[index];
  	long temp;
  	int ret = kstrtol(buf, 10, &temp);
  
  	if (ret < 0)
  		return ret;
  
  	temp = clamp_val(temp, -40000, 85000);
  	temp = (temp + (temp < 0 ? -500 : 500)) / 1000;
  
  	mutex_lock(&data->lock);
  	data->temps[index] = temp;
  	ad7414_write(client, reg, temp);
  	mutex_unlock(&data->lock);
  	return count;
  }
  
  static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
  			  show_max_min, set_max_min, 0);
  static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
  			  show_max_min, set_max_min, 1);
  
  static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
  			  char *buf)
  {
  	int bitnr = to_sensor_dev_attr(attr)->index;
  	struct ad7414_data *data = ad7414_update_device(dev);
  	int value = (data->temp_input >> bitnr) & 1;
  	return sprintf(buf, "%d
  ", value);
  }
  
  static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 3);
  static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 4);
  
  static struct attribute *ad7414_attributes[] = {
  	&sensor_dev_attr_temp1_input.dev_attr.attr,
  	&sensor_dev_attr_temp1_max.dev_attr.attr,
  	&sensor_dev_attr_temp1_min.dev_attr.attr,
  	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
  	NULL
  };
  
  static const struct attribute_group ad7414_group = {
  	.attrs = ad7414_attributes,
  };
  
  static int ad7414_probe(struct i2c_client *client,
  			const struct i2c_device_id *dev_id)
  {
  	struct ad7414_data *data;
  	int conf;
  	int err;
  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
  				     I2C_FUNC_SMBUS_READ_WORD_DATA))
  		return -EOPNOTSUPP;
  
  	data = devm_kzalloc(&client->dev, sizeof(struct ad7414_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, data);
  	mutex_init(&data->lock);
  
  	dev_info(&client->dev, "chip found
  ");
  
  	/* Make sure the chip is powered up. */
  	conf = i2c_smbus_read_byte_data(client, AD7414_REG_CONF);
  	if (conf < 0)
  		dev_warn(&client->dev,
  			 "ad7414_probe unable to read config register.
  ");
  	else {
  		conf &= ~(1 << 7);
  		i2c_smbus_write_byte_data(client, AD7414_REG_CONF, conf);
  	}
  
  	/* Register sysfs hooks */
  	err = sysfs_create_group(&client->dev.kobj, &ad7414_group);
  	if (err)
  		return err;
  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		goto exit_remove;
  	}
  
  	return 0;
  
  exit_remove:
  	sysfs_remove_group(&client->dev.kobj, &ad7414_group);
  	return err;
  }
  
  static int ad7414_remove(struct i2c_client *client)
  {
  	struct ad7414_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&client->dev.kobj, &ad7414_group);
  	return 0;
  }
  
  static const struct i2c_device_id ad7414_id[] = {
  	{ "ad7414", 0 },
  	{}
  };
  MODULE_DEVICE_TABLE(i2c, ad7414_id);
  
  static struct i2c_driver ad7414_driver = {
  	.driver = {
  		.name	= "ad7414",
  	},
  	.probe	= ad7414_probe,
  	.remove	= ad7414_remove,
  	.id_table = ad7414_id,
  };
  
  module_i2c_driver(ad7414_driver);
  
  MODULE_AUTHOR("Stefan Roese <sr at denx.de>, "
  	      "Frank Edelhaeuser <frank.edelhaeuser at spansion.com>");
  
  MODULE_DESCRIPTION("AD7414 driver");
  MODULE_LICENSE("GPL");