/*
   * Driver for +/-1 degree C, SMBus-Compatible Remote/Local Temperature Sensor
   * with Overtemperature Alarm
   *
   * Copyright (C) 2011 AppearTV AS
   *
   * Derived from:
   *
   *  Based on the max1619 driver.
   *  Copyright (C) 2003-2004 Oleksij Rempel <bug-track@fisher-privat.net>
   *                          Jean Delvare <jdelvare@suse.de>
   *
   * The MAX6642 is a sensor chip made by Maxim.
   * It reports up to two temperatures (its own plus up to
   * one external one). Complete datasheet can be
   * obtained from Maxim's website at:
   *   http://datasheets.maxim-ic.com/en/ds/MAX6642.pdf
   *
   * 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.
   *
   * 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; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/slab.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>
  
  static const unsigned short normal_i2c[] = {
  	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
  
  /*
   * The MAX6642 registers
   */
  
  #define MAX6642_REG_R_MAN_ID		0xFE
  #define MAX6642_REG_R_CONFIG		0x03
  #define MAX6642_REG_W_CONFIG		0x09
  #define MAX6642_REG_R_STATUS		0x02
  #define MAX6642_REG_R_LOCAL_TEMP	0x00
  #define MAX6642_REG_R_LOCAL_TEMPL	0x11
  #define MAX6642_REG_R_LOCAL_HIGH	0x05
  #define MAX6642_REG_W_LOCAL_HIGH	0x0B
  #define MAX6642_REG_R_REMOTE_TEMP	0x01
  #define MAX6642_REG_R_REMOTE_TEMPL	0x10
  #define MAX6642_REG_R_REMOTE_HIGH	0x07
  #define MAX6642_REG_W_REMOTE_HIGH	0x0D
  
  /*
   * Conversions
   */
  
  static int temp_from_reg10(int val)
  {
  	return val * 250;
  }
  
  static int temp_from_reg(int val)
  {
  	return val * 1000;
  }
  
  static int temp_to_reg(int val)
  {
  	return val / 1000;
  }
  
  /*
   * Client data (each client gets its own)
   */
  
  struct max6642_data {
  	struct i2c_client *client;
  	struct mutex update_lock;
  	bool valid; /* zero until following fields are valid */
  	unsigned long last_updated; /* in jiffies */
  
  	/* registers values */
  	u16 temp_input[2]; /* local/remote */
  	u16 temp_high[2]; /* local/remote */
  	u8 alarms;
  };
  
  /*
   * Real code
   */
  
  static void max6642_init_client(struct max6642_data *data,
  				struct i2c_client *client)
  {
  	u8 config;
  
  	/*
  	 * Start the conversions.
  	 */
  	config = i2c_smbus_read_byte_data(client, MAX6642_REG_R_CONFIG);
  	if (config & 0x40)
  		i2c_smbus_write_byte_data(client, MAX6642_REG_W_CONFIG,
  					  config & 0xBF); /* run */
  
  	data->temp_high[0] = i2c_smbus_read_byte_data(client,
  				MAX6642_REG_R_LOCAL_HIGH);
  	data->temp_high[1] = i2c_smbus_read_byte_data(client,
  				MAX6642_REG_R_REMOTE_HIGH);
  }
  
  /* Return 0 if detection is successful, -ENODEV otherwise */
  static int max6642_detect(struct i2c_client *client,
  			  struct i2c_board_info *info)
  {
  	struct i2c_adapter *adapter = client->adapter;
  	u8 reg_config, reg_status, man_id;
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  		return -ENODEV;
  
  	/* identification */
  	man_id = i2c_smbus_read_byte_data(client, MAX6642_REG_R_MAN_ID);
  	if (man_id != 0x4D)
  		return -ENODEV;
  
  	/* sanity check */
  	if (i2c_smbus_read_byte_data(client, 0x04) != 0x4D
  	    || i2c_smbus_read_byte_data(client, 0x06) != 0x4D
  	    || i2c_smbus_read_byte_data(client, 0xff) != 0x4D)
  		return -ENODEV;
  
  	/*
  	 * We read the config and status register, the 4 lower bits in the
  	 * config register should be zero and bit 5, 3, 1 and 0 should be
  	 * zero in the status register.
  	 */
  	reg_config = i2c_smbus_read_byte_data(client, MAX6642_REG_R_CONFIG);
  	if ((reg_config & 0x0f) != 0x00)
  		return -ENODEV;
  
  	/* in between, another round of sanity checks */
  	if (i2c_smbus_read_byte_data(client, 0x04) != reg_config
  	    || i2c_smbus_read_byte_data(client, 0x06) != reg_config
  	    || i2c_smbus_read_byte_data(client, 0xff) != reg_config)
  		return -ENODEV;
  
  	reg_status = i2c_smbus_read_byte_data(client, MAX6642_REG_R_STATUS);
  	if ((reg_status & 0x2b) != 0x00)
  		return -ENODEV;
  
  	strlcpy(info->type, "max6642", I2C_NAME_SIZE);
  
  	return 0;
  }
  
  static struct max6642_data *max6642_update_device(struct device *dev)
  {
  	struct max6642_data *data = dev_get_drvdata(dev);
  	struct i2c_client *client = data->client;
  	u16 val, tmp;
  
  	mutex_lock(&data->update_lock);
  
  	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
  		dev_dbg(dev, "Updating max6642 data.
  ");
  		val = i2c_smbus_read_byte_data(client,
  					MAX6642_REG_R_LOCAL_TEMPL);
  		tmp = (val >> 6) & 3;
  		val = i2c_smbus_read_byte_data(client,
  					MAX6642_REG_R_LOCAL_TEMP);
  		val = (val << 2) | tmp;
  		data->temp_input[0] = val;
  		val = i2c_smbus_read_byte_data(client,
  					MAX6642_REG_R_REMOTE_TEMPL);
  		tmp = (val >> 6) & 3;
  		val = i2c_smbus_read_byte_data(client,
  					MAX6642_REG_R_REMOTE_TEMP);
  		val = (val << 2) | tmp;
  		data->temp_input[1] = val;
  		data->alarms = i2c_smbus_read_byte_data(client,
  					MAX6642_REG_R_STATUS);
  
  		data->last_updated = jiffies;
  		data->valid = 1;
  	}
  
  	mutex_unlock(&data->update_lock);
  
  	return data;
  }
  
  /*
   * Sysfs stuff
   */
  
  static ssize_t show_temp_max10(struct device *dev,
  			       struct device_attribute *dev_attr, char *buf)
  {
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
  	struct max6642_data *data = max6642_update_device(dev);
  
  	return sprintf(buf, "%d
  ",
  		       temp_from_reg10(data->temp_input[attr->index]));
  }
  
  static ssize_t show_temp_max(struct device *dev, struct device_attribute *attr,
  			     char *buf)
  {
  	struct sensor_device_attribute_2 *attr2 = to_sensor_dev_attr_2(attr);
  	struct max6642_data *data = max6642_update_device(dev);
  
  	return sprintf(buf, "%d
  ", temp_from_reg(data->temp_high[attr2->nr]));
  }
  
  static ssize_t set_temp_max(struct device *dev, struct device_attribute *attr,
  			    const char *buf, size_t count)
  {
  	struct sensor_device_attribute_2 *attr2 = to_sensor_dev_attr_2(attr);
  	struct max6642_data *data = dev_get_drvdata(dev);
  	unsigned long val;
  	int err;
  
  	err = kstrtoul(buf, 10, &val);
  	if (err < 0)
  		return err;
  
  	mutex_lock(&data->update_lock);
  	data->temp_high[attr2->nr] = clamp_val(temp_to_reg(val), 0, 255);
  	i2c_smbus_write_byte_data(data->client, attr2->index,
  				  data->temp_high[attr2->nr]);
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
  			  char *buf)
  {
  	int bitnr = to_sensor_dev_attr(attr)->index;
  	struct max6642_data *data = max6642_update_device(dev);
  	return sprintf(buf, "%d
  ", (data->alarms >> bitnr) & 1);
  }
  
  static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_max10, NULL, 0);
  static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_max10, NULL, 1);
  static SENSOR_DEVICE_ATTR_2(temp1_max, S_IWUSR | S_IRUGO, show_temp_max,
  			    set_temp_max, 0, MAX6642_REG_W_LOCAL_HIGH);
  static SENSOR_DEVICE_ATTR_2(temp2_max, S_IWUSR | S_IRUGO, show_temp_max,
  			    set_temp_max, 1, MAX6642_REG_W_REMOTE_HIGH);
  static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_alarm, NULL, 2);
  static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 6);
  static SENSOR_DEVICE_ATTR(temp2_max_alarm, S_IRUGO, show_alarm, NULL, 4);
  
  static struct attribute *max6642_attrs[] = {
  	&sensor_dev_attr_temp1_input.dev_attr.attr,
  	&sensor_dev_attr_temp2_input.dev_attr.attr,
  	&sensor_dev_attr_temp1_max.dev_attr.attr,
  	&sensor_dev_attr_temp2_max.dev_attr.attr,
  
  	&sensor_dev_attr_temp2_fault.dev_attr.attr,
  	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
  	NULL
  };
  ATTRIBUTE_GROUPS(max6642);
  
  static int max6642_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	struct device *dev = &client->dev;
  	struct max6642_data *data;
  	struct device *hwmon_dev;
  
  	data = devm_kzalloc(dev, sizeof(struct max6642_data), GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	data->client = client;
  	mutex_init(&data->update_lock);
  
  	/* Initialize the MAX6642 chip */
  	max6642_init_client(data, client);
  
  	hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
  							   client->name, data,
  							   max6642_groups);
  	return PTR_ERR_OR_ZERO(hwmon_dev);
  }
  
  /*
   * Driver data (common to all clients)
   */
  
  static const struct i2c_device_id max6642_id[] = {
  	{ "max6642", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, max6642_id);
  
  static struct i2c_driver max6642_driver = {
  	.class		= I2C_CLASS_HWMON,
  	.driver = {
  		.name	= "max6642",
  	},
  	.probe		= max6642_probe,
  	.id_table	= max6642_id,
  	.detect		= max6642_detect,
  	.address_list	= normal_i2c,
  };
  
  module_i2c_driver(max6642_driver);
  
  MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
  MODULE_DESCRIPTION("MAX6642 sensor driver");
  MODULE_LICENSE("GPL");