/* tmp421.c
   *
   * Copyright (C) 2009 Andre Prendel <andre.prendel@gmx.de>
   * Preliminary support by:
   * Melvin Rook, Raymond Ng
   *
   * 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.
   */
  
  /*
   * Driver for the Texas Instruments TMP421 SMBus temperature sensor IC.
   * Supported models: TMP421, TMP422, TMP423
   */
  
  #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>
  
  /* Addresses to scan */

  static const unsigned short normal_i2c[] = { 0x2a, 0x4c, 0x4d, 0x4e, 0x4f,
  					     I2C_CLIENT_END };

  enum chips { tmp421, tmp422, tmp423 };

  
  /* The TMP421 registers */
  #define TMP421_CONFIG_REG_1			0x09
  #define TMP421_CONVERSION_RATE_REG		0x0B
  #define TMP421_MANUFACTURER_ID_REG		0xFE
  #define TMP421_DEVICE_ID_REG			0xFF
  
  static const u8 TMP421_TEMP_MSB[4]		= { 0x00, 0x01, 0x02, 0x03 };
  static const u8 TMP421_TEMP_LSB[4]		= { 0x10, 0x11, 0x12, 0x13 };
  
  /* Flags */
  #define TMP421_CONFIG_SHUTDOWN			0x40
  #define TMP421_CONFIG_RANGE			0x04
  
  /* Manufacturer / Device ID's */
  #define TMP421_MANUFACTURER_ID			0x55
  #define TMP421_DEVICE_ID			0x21
  #define TMP422_DEVICE_ID			0x22
  #define TMP423_DEVICE_ID			0x23
  
  static const struct i2c_device_id tmp421_id[] = {

  	{ "tmp421", 2 },
  	{ "tmp422", 3 },
  	{ "tmp423", 4 },

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, tmp421_id);
  
  struct tmp421_data {
  	struct device *hwmon_dev;
  	struct mutex update_lock;
  	char valid;
  	unsigned long last_updated;

  	int channels;

  	u8 config;
  	s16 temp[4];
  };
  
  static int temp_from_s16(s16 reg)
  {

  	/* Mask out status bits */
  	int temp = reg & ~0xf;

  
  	return (temp * 1000 + 128) / 256;
  }
  
  static int temp_from_u16(u16 reg)
  {

  	/* Mask out status bits */
  	int temp = reg & ~0xf;

  
  	/* Add offset for extended temperature range. */
  	temp -= 64 * 256;
  
  	return (temp * 1000 + 128) / 256;
  }
  
  static struct tmp421_data *tmp421_update_device(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct tmp421_data *data = i2c_get_clientdata(client);
  	int i;
  
  	mutex_lock(&data->update_lock);
  
  	if (time_after(jiffies, data->last_updated + 2 * HZ) || !data->valid) {
  		data->config = i2c_smbus_read_byte_data(client,
  			TMP421_CONFIG_REG_1);

  		for (i = 0; i < data->channels; i++) {

  			data->temp[i] = i2c_smbus_read_byte_data(client,
  				TMP421_TEMP_MSB[i]) << 8;
  			data->temp[i] |= i2c_smbus_read_byte_data(client,
  				TMP421_TEMP_LSB[i]);
  		}
  		data->last_updated = jiffies;
  		data->valid = 1;
  	}
  
  	mutex_unlock(&data->update_lock);
  
  	return data;
  }
  
  static ssize_t show_temp_value(struct device *dev,
  			       struct device_attribute *devattr, char *buf)
  {
  	int index = to_sensor_dev_attr(devattr)->index;
  	struct tmp421_data *data = tmp421_update_device(dev);
  	int temp;
  
  	mutex_lock(&data->update_lock);
  	if (data->config & TMP421_CONFIG_RANGE)
  		temp = temp_from_u16(data->temp[index]);
  	else
  		temp = temp_from_s16(data->temp[index]);
  	mutex_unlock(&data->update_lock);
  
  	return sprintf(buf, "%d
  ", temp);
  }
  
  static ssize_t show_fault(struct device *dev,
  			  struct device_attribute *devattr, char *buf)
  {
  	int index = to_sensor_dev_attr(devattr)->index;
  	struct tmp421_data *data = tmp421_update_device(dev);
  
  	/*
  	 * The OPEN bit signals a fault. This is bit 0 of the temperature
  	 * register (low byte).
  	 */
  	if (data->temp[index] & 0x01)
  		return sprintf(buf, "1
  ");
  	else
  		return sprintf(buf, "0
  ");
  }

  static umode_t tmp421_is_visible(struct kobject *kobj, struct attribute *a,

  				int n)
  {
  	struct device *dev = container_of(kobj, struct device, kobj);
  	struct tmp421_data *data = dev_get_drvdata(dev);
  	struct device_attribute *devattr;
  	unsigned int index;
  
  	devattr = container_of(a, struct device_attribute, attr);
  	index = to_sensor_dev_attr(devattr)->index;

  	if (index < data->channels)

  		return a->mode;
  
  	return 0;
  }
  
  static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_value, NULL, 0);
  static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_value, NULL, 1);
  static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_fault, NULL, 1);
  static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, show_temp_value, NULL, 2);
  static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_fault, NULL, 2);
  static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, show_temp_value, NULL, 3);
  static SENSOR_DEVICE_ATTR(temp4_fault, S_IRUGO, show_fault, NULL, 3);
  
  static struct attribute *tmp421_attr[] = {
  	&sensor_dev_attr_temp1_input.dev_attr.attr,
  	&sensor_dev_attr_temp2_input.dev_attr.attr,
  	&sensor_dev_attr_temp2_fault.dev_attr.attr,
  	&sensor_dev_attr_temp3_input.dev_attr.attr,
  	&sensor_dev_attr_temp3_fault.dev_attr.attr,
  	&sensor_dev_attr_temp4_input.dev_attr.attr,
  	&sensor_dev_attr_temp4_fault.dev_attr.attr,
  	NULL
  };
  
  static const struct attribute_group tmp421_group = {
  	.attrs = tmp421_attr,
  	.is_visible = tmp421_is_visible,
  };
  
  static int tmp421_init_client(struct i2c_client *client)
  {
  	int config, config_orig;
  
  	/* Set the conversion rate to 2 Hz */
  	i2c_smbus_write_byte_data(client, TMP421_CONVERSION_RATE_REG, 0x05);
  
  	/* Start conversions (disable shutdown if necessary) */
  	config = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
  	if (config < 0) {
  		dev_err(&client->dev, "Could not read configuration"
  			 " register (%d)
  ", config);
  		return -ENODEV;
  	}
  
  	config_orig = config;
  	config &= ~TMP421_CONFIG_SHUTDOWN;
  
  	if (config != config_orig) {
  		dev_info(&client->dev, "Enable monitoring chip
  ");
  		i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_1, config);
  	}
  
  	return 0;
  }

  static int tmp421_detect(struct i2c_client *client,

  			 struct i2c_board_info *info)
  {

  	enum chips kind;

  	struct i2c_adapter *adapter = client->adapter;
  	const char *names[] = { "TMP421", "TMP422", "TMP423" };

  	u8 reg;

  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  		return -ENODEV;

  	reg = i2c_smbus_read_byte_data(client, TMP421_MANUFACTURER_ID_REG);
  	if (reg != TMP421_MANUFACTURER_ID)
  		return -ENODEV;
  
  	reg = i2c_smbus_read_byte_data(client, TMP421_DEVICE_ID_REG);
  	switch (reg) {
  	case TMP421_DEVICE_ID:
  		kind = tmp421;
  		break;
  	case TMP422_DEVICE_ID:
  		kind = tmp422;
  		break;
  	case TMP423_DEVICE_ID:
  		kind = tmp423;
  		break;
  	default:
  		return -ENODEV;

  	}

  	strlcpy(info->type, tmp421_id[kind].name, I2C_NAME_SIZE);

  	dev_info(&adapter->dev, "Detected TI %s chip at 0x%02x
  ",

  		 names[kind], client->addr);

  
  	return 0;
  }
  
  static int tmp421_probe(struct i2c_client *client,
  			const struct i2c_device_id *id)
  {
  	struct tmp421_data *data;
  	int err;
  
  	data = kzalloc(sizeof(struct tmp421_data), GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, data);
  	mutex_init(&data->update_lock);

  	data->channels = id->driver_data;

  
  	err = tmp421_init_client(client);
  	if (err)
  		goto exit_free;
  
  	err = sysfs_create_group(&client->dev.kobj, &tmp421_group);
  	if (err)
  		goto exit_free;
  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		data->hwmon_dev = NULL;
  		goto exit_remove;
  	}
  	return 0;
  
  exit_remove:
  	sysfs_remove_group(&client->dev.kobj, &tmp421_group);
  
  exit_free:

  	kfree(data);
  
  	return err;
  }
  
  static int tmp421_remove(struct i2c_client *client)
  {
  	struct tmp421_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&client->dev.kobj, &tmp421_group);

  	kfree(data);
  
  	return 0;
  }
  
  static struct i2c_driver tmp421_driver = {
  	.class = I2C_CLASS_HWMON,
  	.driver = {
  		.name	= "tmp421",
  	},
  	.probe = tmp421_probe,
  	.remove = tmp421_remove,
  	.id_table = tmp421_id,
  	.detect = tmp421_detect,

  	.address_list = normal_i2c,

  };
  
  static int __init tmp421_init(void)
  {
  	return i2c_add_driver(&tmp421_driver);
  }
  
  static void __exit tmp421_exit(void)
  {
  	i2c_del_driver(&tmp421_driver);
  }
  
  MODULE_AUTHOR("Andre Prendel <andre.prendel@gmx.de>");
  MODULE_DESCRIPTION("Texas Instruments TMP421/422/423 temperature sensor"
  		   " driver");
  MODULE_LICENSE("GPL");
  
  module_init(tmp421_init);
  module_exit(tmp421_exit);