/*
   * w83l785ts.c - Part of lm_sensors, Linux kernel modules for hardware
   *               monitoring

   * Copyright (C) 2003-2009  Jean Delvare <khali@linux-fr.org>

   *
   * Inspired from the lm83 driver. The W83L785TS-S is a sensor chip made
   * by Winbond. It reports a single external temperature with a 1 deg
   * resolution and a 3 deg accuracy. Datasheet can be obtained from
   * Winbond's website at:
   *   http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83L785TS-S.pdf
   *
   * Ported to Linux 2.6 by Wolfgang Ziegler <nuppla@gmx.at> and Jean Delvare
   * <khali@linux-fr.org>.
   *
   * Thanks to James Bolt <james@evilpenguin.com> for benchmarking the read
   * error handling mechanism.
   *
   * 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/delay.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>

  
  /* How many retries on register read error */
  #define MAX_RETRIES	5
  
  /*
   * Address to scan
   * Address is fully defined internally and cannot be changed.
   */

  static const unsigned short normal_i2c[] = { 0x2e, I2C_CLIENT_END };

  
  /*

   * The W83L785TS-S registers
   * Manufacturer ID is 0x5CA3 for Winbond.
   */
  
  #define W83L785TS_REG_MAN_ID1		0x4D
  #define W83L785TS_REG_MAN_ID2		0x4C
  #define W83L785TS_REG_CHIP_ID		0x4E
  #define W83L785TS_REG_CONFIG		0x40
  #define W83L785TS_REG_TYPE		0x52
  #define W83L785TS_REG_TEMP		0x27
  #define W83L785TS_REG_TEMP_OVER		0x53 /* not sure about this one */
  
  /*
   * Conversions
   * The W83L785TS-S uses signed 8-bit values.
   */

  #define TEMP_FROM_REG(val)	((val) * 1000)

  
  /*
   * Functions declaration
   */

  static int w83l785ts_probe(struct i2c_client *client,
  			   const struct i2c_device_id *id);

  static int w83l785ts_detect(struct i2c_client *client,

  			    struct i2c_board_info *info);
  static int w83l785ts_remove(struct i2c_client *client);

  static u8 w83l785ts_read_value(struct i2c_client *client, u8 reg, u8 defval);
  static struct w83l785ts_data *w83l785ts_update_device(struct device *dev);
  
  /*
   * Driver data (common to all clients)
   */
   

  static const struct i2c_device_id w83l785ts_id[] = {

  	{ "w83l785ts", 0 },

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, w83l785ts_id);

  static struct i2c_driver w83l785ts_driver = {

  	.class		= I2C_CLASS_HWMON,

  	.driver = {

  		.name	= "w83l785ts",
  	},

  	.probe		= w83l785ts_probe,
  	.remove		= w83l785ts_remove,
  	.id_table	= w83l785ts_id,
  	.detect		= w83l785ts_detect,

  	.address_list	= normal_i2c,

  };
  
  /*
   * Client data (each client gets its own)
   */
  
  struct w83l785ts_data {

  	struct device *hwmon_dev;

  	struct mutex update_lock;

  	char valid; /* zero until following fields are valid */
  	unsigned long last_updated; /* in jiffies */
  
  	/* registers values */

  	s8 temp[2]; /* 0: input

  		       1: critical limit */

  };
  
  /*
   * Sysfs stuff
   */

  static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
  	char *buf)

  {

  	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

  	struct w83l785ts_data *data = w83l785ts_update_device(dev);

  	return sprintf(buf, "%d
  ", TEMP_FROM_REG(data->temp[attr->index]));

  }

  static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
  static SENSOR_DEVICE_ATTR(temp1_max, S_IRUGO, show_temp, NULL, 1);

  
  /*
   * Real code
   */

  /* Return 0 if detection is successful, -ENODEV otherwise */

  static int w83l785ts_detect(struct i2c_client *client,

  			    struct i2c_board_info *info)

  {

  	struct i2c_adapter *adapter = client->adapter;
  	u16 man_id;
  	u8 chip_id;

  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))

  		return -ENODEV;

  	/* detection */
  	if ((w83l785ts_read_value(client, W83L785TS_REG_CONFIG, 0) & 0x80)
  	 || (w83l785ts_read_value(client, W83L785TS_REG_TYPE, 0) & 0xFC)) {
  		dev_dbg(&adapter->dev,
  			"W83L785TS-S detection failed at 0x%02x
  ",
  			client->addr);
  		return -ENODEV;

  	}

  	/* Identification */
  	man_id = (w83l785ts_read_value(client, W83L785TS_REG_MAN_ID1, 0) << 8)
  	       + w83l785ts_read_value(client, W83L785TS_REG_MAN_ID2, 0);
  	chip_id = w83l785ts_read_value(client, W83L785TS_REG_CHIP_ID, 0);
  
  	if (man_id != 0x5CA3		/* Winbond */
  	 || chip_id != 0x70) {		/* W83L785TS-S */
  		dev_dbg(&adapter->dev,
  			"Unsupported chip (man_id=0x%04X, chip_id=0x%02X)
  ",
  			man_id, chip_id);
  		return -ENODEV;

  	}

  	strlcpy(info->type, "w83l785ts", I2C_NAME_SIZE);
  
  	return 0;
  }
  
  static int w83l785ts_probe(struct i2c_client *new_client,
  			   const struct i2c_device_id *id)
  {
  	struct w83l785ts_data *data;
  	int err = 0;
  
  	data = kzalloc(sizeof(struct w83l785ts_data), GFP_KERNEL);
  	if (!data) {
  		err = -ENOMEM;
  		goto exit;
  	}
  
  	i2c_set_clientdata(new_client, data);

  	data->valid = 0;

  	mutex_init(&data->update_lock);

  
  	/* Default values in case the first read fails (unlikely). */

  	data->temp[1] = data->temp[0] = 0;

  	/*
  	 * Initialize the W83L785TS chip
  	 * Nothing yet, assume it is already started.
  	 */

  	err = device_create_file(&new_client->dev,
  				 &sensor_dev_attr_temp1_input.dev_attr);
  	if (err)
  		goto exit_remove;
  
  	err = device_create_file(&new_client->dev,
  				 &sensor_dev_attr_temp1_max.dev_attr);
  	if (err)
  		goto exit_remove;

  	/* Register sysfs hooks */

  	data->hwmon_dev = hwmon_device_register(&new_client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);

  		goto exit_remove;

  	}

  	return 0;

  exit_remove:
  	device_remove_file(&new_client->dev,
  			   &sensor_dev_attr_temp1_input.dev_attr);
  	device_remove_file(&new_client->dev,
  			   &sensor_dev_attr_temp1_max.dev_attr);

  	kfree(data);
  exit:
  	return err;
  }

  static int w83l785ts_remove(struct i2c_client *client)

  {

  	struct w83l785ts_data *data = i2c_get_clientdata(client);

  	hwmon_device_unregister(data->hwmon_dev);

  	device_remove_file(&client->dev,
  			   &sensor_dev_attr_temp1_input.dev_attr);
  	device_remove_file(&client->dev,
  			   &sensor_dev_attr_temp1_max.dev_attr);

  	kfree(data);

  	return 0;
  }
  
  static u8 w83l785ts_read_value(struct i2c_client *client, u8 reg, u8 defval)
  {
  	int value, i;

  	struct device *dev;
  	const char *prefix;
  
  	/* We might be called during detection, at which point the client
  	   isn't yet fully initialized, so we can't use dev_dbg on it */
  	if (i2c_get_clientdata(client)) {
  		dev = &client->dev;
  		prefix = "";
  	} else {
  		dev = &client->adapter->dev;
  		prefix = "w83l785ts: ";
  	}

  
  	/* Frequent read errors have been reported on Asus boards, so we
  	 * retry on read errors. If it still fails (unlikely), return the
  	 * default value requested by the caller. */
  	for (i = 1; i <= MAX_RETRIES; i++) {
  		value = i2c_smbus_read_byte_data(client, reg);
  		if (value >= 0) {

  			dev_dbg(dev, "%sRead 0x%02x from register 0x%02x.
  ",
  				prefix, value, reg);

  			return value;
  		}

  		dev_dbg(dev, "%sRead failed, will retry in %d.
  ", prefix, i);

  		msleep(i);
  	}

  	dev_err(dev, "%sCouldn't read value from register 0x%02x.
  ", prefix,

  		reg);

  	return defval;
  }
  
  static struct w83l785ts_data *w83l785ts_update_device(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct w83l785ts_data *data = i2c_get_clientdata(client);

  	mutex_lock(&data->update_lock);

  
  	if (!data->valid || time_after(jiffies, data->last_updated + HZ * 2)) {
  		dev_dbg(&client->dev, "Updating w83l785ts data.
  ");

  		data->temp[0] = w83l785ts_read_value(client,
  				W83L785TS_REG_TEMP, data->temp[0]);
  		data->temp[1] = w83l785ts_read_value(client,
  				W83L785TS_REG_TEMP_OVER, data->temp[1]);

  
  		data->last_updated = jiffies;
  		data->valid = 1;
  	}

  	mutex_unlock(&data->update_lock);

  
  	return data;
  }
  
  static int __init sensors_w83l785ts_init(void)
  {
  	return i2c_add_driver(&w83l785ts_driver);
  }
  
  static void __exit sensors_w83l785ts_exit(void)
  {
  	i2c_del_driver(&w83l785ts_driver);
  }
  
  MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
  MODULE_DESCRIPTION("W83L785TS-S driver");
  MODULE_LICENSE("GPL");
  
  module_init(sensors_w83l785ts_init);
  module_exit(sensors_w83l785ts_exit);