/*
   * lm77.c - Part of lm_sensors, Linux kernel modules for hardware
   *	    monitoring
   *
   * Copyright (c) 2004  Andras BALI <drewie@freemail.hu>
   *
   * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>.  The LM77
   * is a temperature sensor and thermal window comparator with 0.5 deg
   * resolution made by National Semiconductor.  Complete datasheet can be
   * obtained at their site:
   *	http://www.national.com/pf/LM/LM77.html
   *
   * 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>
  
  /* Addresses to scan */
  static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
  						I2C_CLIENT_END };
  
  /* The LM77 registers */
  #define LM77_REG_TEMP		0x00
  #define LM77_REG_CONF		0x01
  #define LM77_REG_TEMP_HYST	0x02
  #define LM77_REG_TEMP_CRIT	0x03
  #define LM77_REG_TEMP_MIN	0x04
  #define LM77_REG_TEMP_MAX	0x05
  
  /* Each client has this additional data */
  struct lm77_data {
  	struct device		*hwmon_dev;
  	struct mutex		update_lock;
  	char			valid;
  	unsigned long		last_updated;	/* In jiffies */
  	int			temp_input;	/* Temperatures */
  	int			temp_crit;
  	int			temp_min;
  	int			temp_max;
  	int			temp_hyst;
  	u8			alarms;
  };
  
  static int lm77_probe(struct i2c_client *client,
  		      const struct i2c_device_id *id);
  static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info);
  static void lm77_init_client(struct i2c_client *client);
  static int lm77_remove(struct i2c_client *client);
  static u16 lm77_read_value(struct i2c_client *client, u8 reg);
  static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value);
  
  static struct lm77_data *lm77_update_device(struct device *dev);
  
  
  static const struct i2c_device_id lm77_id[] = {
  	{ "lm77", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, lm77_id);
  
  /* This is the driver that will be inserted */
  static struct i2c_driver lm77_driver = {
  	.class		= I2C_CLASS_HWMON,
  	.driver = {
  		.name	= "lm77",
  	},
  	.probe		= lm77_probe,
  	.remove		= lm77_remove,
  	.id_table	= lm77_id,
  	.detect		= lm77_detect,
  	.address_list	= normal_i2c,
  };
  
  /* straight from the datasheet */
  #define LM77_TEMP_MIN (-55000)
  #define LM77_TEMP_MAX 125000
  
  /*
   * In the temperature registers, the low 3 bits are not part of the
   * temperature values; they are the status bits.
   */
  static inline s16 LM77_TEMP_TO_REG(int temp)
  {
  	int ntemp = clamp_val(temp, LM77_TEMP_MIN, LM77_TEMP_MAX);
  	return (ntemp / 500) * 8;
  }
  
  static inline int LM77_TEMP_FROM_REG(s16 reg)
  {
  	return (reg / 8) * 500;
  }
  
  /* sysfs stuff */
  
  /* read routines for temperature limits */
  #define show(value)	\
  static ssize_t show_##value(struct device *dev,			\
  			    struct device_attribute *attr,	\
  			    char *buf)				\
  {								\
  	struct lm77_data *data = lm77_update_device(dev);	\
  	return sprintf(buf, "%d
  ", data->value);		\
  }
  
  show(temp_input);
  show(temp_crit);
  show(temp_min);
  show(temp_max);
  
  /* read routines for hysteresis values */
  static ssize_t show_temp_crit_hyst(struct device *dev,
  				   struct device_attribute *attr, char *buf)
  {
  	struct lm77_data *data = lm77_update_device(dev);
  	return sprintf(buf, "%d
  ", data->temp_crit - data->temp_hyst);
  }
  static ssize_t show_temp_min_hyst(struct device *dev,
  				  struct device_attribute *attr, char *buf)
  {
  	struct lm77_data *data = lm77_update_device(dev);
  	return sprintf(buf, "%d
  ", data->temp_min + data->temp_hyst);
  }
  static ssize_t show_temp_max_hyst(struct device *dev,
  				  struct device_attribute *attr, char *buf)
  {
  	struct lm77_data *data = lm77_update_device(dev);
  	return sprintf(buf, "%d
  ", data->temp_max - data->temp_hyst);
  }
  
  /* write routines */
  #define set(value, reg)	\
  static ssize_t set_##value(struct device *dev, struct device_attribute *attr, \
  			   const char *buf, size_t count)		\
  {									\
  	struct i2c_client *client = to_i2c_client(dev);			\
  	struct lm77_data *data = i2c_get_clientdata(client);		\
  	long val;							\
  	int err = kstrtol(buf, 10, &val);				\
  	if (err)							\
  		return err;						\
  									\
  	mutex_lock(&data->update_lock);					\
  	data->value = val;						\
  	lm77_write_value(client, reg, LM77_TEMP_TO_REG(data->value));	\
  	mutex_unlock(&data->update_lock);				\
  	return count;							\
  }
  
  set(temp_min, LM77_REG_TEMP_MIN);
  set(temp_max, LM77_REG_TEMP_MAX);
  
  /*
   * hysteresis is stored as a relative value on the chip, so it has to be
   * converted first
   */
  static ssize_t set_temp_crit_hyst(struct device *dev,
  				  struct device_attribute *attr,
  				  const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct lm77_data *data = i2c_get_clientdata(client);
  	unsigned long val;
  	int err;
  
  	err = kstrtoul(buf, 10, &val);
  	if (err)
  		return err;
  
  	mutex_lock(&data->update_lock);
  	data->temp_hyst = data->temp_crit - val;
  	lm77_write_value(client, LM77_REG_TEMP_HYST,
  			 LM77_TEMP_TO_REG(data->temp_hyst));
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  /* preserve hysteresis when setting T_crit */
  static ssize_t set_temp_crit(struct device *dev, struct device_attribute *attr,
  			     const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct lm77_data *data = i2c_get_clientdata(client);
  	int oldcrithyst;
  	unsigned long val;
  	int err;
  
  	err = kstrtoul(buf, 10, &val);
  	if (err)
  		return err;
  
  	mutex_lock(&data->update_lock);
  	oldcrithyst = data->temp_crit - data->temp_hyst;
  	data->temp_crit = val;
  	data->temp_hyst = data->temp_crit - oldcrithyst;
  	lm77_write_value(client, LM77_REG_TEMP_CRIT,
  			 LM77_TEMP_TO_REG(data->temp_crit));
  	lm77_write_value(client, LM77_REG_TEMP_HYST,
  			 LM77_TEMP_TO_REG(data->temp_hyst));
  	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 lm77_data *data = lm77_update_device(dev);
  	return sprintf(buf, "%u
  ", (data->alarms >> bitnr) & 1);
  }
  
  static DEVICE_ATTR(temp1_input, S_IRUGO,
  		   show_temp_input, NULL);
  static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO,
  		   show_temp_crit, set_temp_crit);
  static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
  		   show_temp_min, set_temp_min);
  static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
  		   show_temp_max, set_temp_max);
  
  static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO,
  		   show_temp_crit_hyst, set_temp_crit_hyst);
  static DEVICE_ATTR(temp1_min_hyst, S_IRUGO,
  		   show_temp_min_hyst, NULL);
  static DEVICE_ATTR(temp1_max_hyst, S_IRUGO,
  		   show_temp_max_hyst, NULL);
  
  static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
  static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
  static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
  
  static struct attribute *lm77_attributes[] = {
  	&dev_attr_temp1_input.attr,
  	&dev_attr_temp1_crit.attr,
  	&dev_attr_temp1_min.attr,
  	&dev_attr_temp1_max.attr,
  	&dev_attr_temp1_crit_hyst.attr,
  	&dev_attr_temp1_min_hyst.attr,
  	&dev_attr_temp1_max_hyst.attr,
  	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
  	NULL
  };
  
  static const struct attribute_group lm77_group = {
  	.attrs = lm77_attributes,
  };
  
  /* Return 0 if detection is successful, -ENODEV otherwise */
  static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
  {
  	struct i2c_adapter *adapter = client->adapter;
  	int i, cur, conf, hyst, crit, min, max;
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
  				     I2C_FUNC_SMBUS_WORD_DATA))
  		return -ENODEV;
  
  	/*
  	 * Here comes the remaining detection.  Since the LM77 has no
  	 * register dedicated to identification, we have to rely on the
  	 * following tricks:
  	 *
  	 * 1. the high 4 bits represent the sign and thus they should
  	 *    always be the same
  	 * 2. the high 3 bits are unused in the configuration register
  	 * 3. addresses 0x06 and 0x07 return the last read value
  	 * 4. registers cycling over 8-address boundaries
  	 *
  	 * Word-sized registers are high-byte first.
  	 */
  
  	/* addresses cycling */
  	cur = i2c_smbus_read_word_data(client, 0);
  	conf = i2c_smbus_read_byte_data(client, 1);
  	hyst = i2c_smbus_read_word_data(client, 2);
  	crit = i2c_smbus_read_word_data(client, 3);
  	min = i2c_smbus_read_word_data(client, 4);
  	max = i2c_smbus_read_word_data(client, 5);
  	for (i = 8; i <= 0xff; i += 8) {
  		if (i2c_smbus_read_byte_data(client, i + 1) != conf
  		 || i2c_smbus_read_word_data(client, i + 2) != hyst
  		 || i2c_smbus_read_word_data(client, i + 3) != crit
  		 || i2c_smbus_read_word_data(client, i + 4) != min
  		 || i2c_smbus_read_word_data(client, i + 5) != max)
  			return -ENODEV;
  	}
  
  	/* sign bits */
  	if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
  	 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
  	 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
  	 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
  	 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
  		return -ENODEV;
  
  	/* unused bits */
  	if (conf & 0xe0)
  		return -ENODEV;
  
  	/* 0x06 and 0x07 return the last read value */
  	cur = i2c_smbus_read_word_data(client, 0);
  	if (i2c_smbus_read_word_data(client, 6) != cur
  	 || i2c_smbus_read_word_data(client, 7) != cur)
  		return -ENODEV;
  	hyst = i2c_smbus_read_word_data(client, 2);
  	if (i2c_smbus_read_word_data(client, 6) != hyst
  	 || i2c_smbus_read_word_data(client, 7) != hyst)
  		return -ENODEV;
  	min = i2c_smbus_read_word_data(client, 4);
  	if (i2c_smbus_read_word_data(client, 6) != min
  	 || i2c_smbus_read_word_data(client, 7) != min)
  		return -ENODEV;
  
  	strlcpy(info->type, "lm77", I2C_NAME_SIZE);
  
  	return 0;
  }
  
  static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id)
  {
  	struct device *dev = &client->dev;
  	struct lm77_data *data;
  	int err;
  
  	data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, data);
  	data->valid = 0;
  	mutex_init(&data->update_lock);
  
  	/* Initialize the LM77 chip */
  	lm77_init_client(client);
  
  	/* Register sysfs hooks */
  	err = sysfs_create_group(&dev->kobj, &lm77_group);
  	if (err)
  		return err;
  
  	data->hwmon_dev = hwmon_device_register(dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		goto exit_remove;
  	}
  
  	return 0;
  
  exit_remove:
  	sysfs_remove_group(&dev->kobj, &lm77_group);
  	return err;
  }
  
  static int lm77_remove(struct i2c_client *client)
  {
  	struct lm77_data *data = i2c_get_clientdata(client);
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&client->dev.kobj, &lm77_group);
  	return 0;
  }
  
  /*
   * All registers are word-sized, except for the configuration register.
   * The LM77 uses the high-byte first convention.
   */
  static u16 lm77_read_value(struct i2c_client *client, u8 reg)
  {
  	if (reg == LM77_REG_CONF)
  		return i2c_smbus_read_byte_data(client, reg);
  	else
  		return i2c_smbus_read_word_swapped(client, reg);
  }
  
  static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
  {
  	if (reg == LM77_REG_CONF)
  		return i2c_smbus_write_byte_data(client, reg, value);
  	else
  		return i2c_smbus_write_word_swapped(client, reg, value);
  }
  
  static void lm77_init_client(struct i2c_client *client)
  {
  	/* Initialize the LM77 chip - turn off shutdown mode */
  	int conf = lm77_read_value(client, LM77_REG_CONF);
  	if (conf & 1)
  		lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
  }
  
  static struct lm77_data *lm77_update_device(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct lm77_data *data = i2c_get_clientdata(client);
  
  	mutex_lock(&data->update_lock);
  
  	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
  	    || !data->valid) {
  		dev_dbg(&client->dev, "Starting lm77 update
  ");
  		data->temp_input =
  			LM77_TEMP_FROM_REG(lm77_read_value(client,
  							   LM77_REG_TEMP));
  		data->temp_hyst =
  			LM77_TEMP_FROM_REG(lm77_read_value(client,
  							   LM77_REG_TEMP_HYST));
  		data->temp_crit =
  			LM77_TEMP_FROM_REG(lm77_read_value(client,
  							   LM77_REG_TEMP_CRIT));
  		data->temp_min =
  			LM77_TEMP_FROM_REG(lm77_read_value(client,
  							   LM77_REG_TEMP_MIN));
  		data->temp_max =
  			LM77_TEMP_FROM_REG(lm77_read_value(client,
  							   LM77_REG_TEMP_MAX));
  		data->alarms =
  			lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
  		data->last_updated = jiffies;
  		data->valid = 1;
  	}
  
  	mutex_unlock(&data->update_lock);
  
  	return data;
  }
  
  module_i2c_driver(lm77_driver);
  
  MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
  MODULE_DESCRIPTION("LM77 driver");
  MODULE_LICENSE("GPL");