/*
   * ds1621.c - Part of lm_sensors, Linux kernel modules for hardware
   *	      monitoring
   * Christian W. Zuckschwerdt  <zany@triq.net>  2000-11-23
   * based on lm75.c by Frodo Looijaard <frodol@dds.nl>
   * Ported to Linux 2.6 by Aurelien Jarno <aurelien@aurel32.net> with
   * the help of Jean Delvare <jdelvare@suse.de>
   *
   * The DS1621 device is a digital temperature/thermometer with 9-bit
   * resolution, a thermal alarm output (Tout), and user-defined minimum
   * and maximum temperature thresholds (TH and TL).
   *
   * The DS1625, DS1631, DS1721, and DS1731 are pin compatible with the DS1621
   * and similar in operation, with slight variations as noted in the device
   * datasheets (please refer to www.maximintegrated.com for specific
   * device information).
   *
   * Since the DS1621 was the first chipset supported by this driver,
   * most comments will refer to this chipset, but are actually general
   * and concern all supported chipsets, unless mentioned otherwise.
   *
   * 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>
  #include <linux/kernel.h>
  
  /* Supported devices */
  enum chips { ds1621, ds1625, ds1631, ds1721, ds1731 };
  
  /* Insmod parameters */
  static int polarity = -1;
  module_param(polarity, int, 0);
  MODULE_PARM_DESC(polarity, "Output's polarity: 0 = active high, 1 = active low");
  
  /*
   * The Configuration/Status register
   *
   * - DS1621:
   *   7    6    5    4    3    2    1    0
   * |Done|THF |TLF |NVB | X  | X  |POL |1SHOT|
   *
   * - DS1625:
   *   7    6    5    4    3    2    1    0
   * |Done|THF |TLF |NVB | 1  | 0  |POL |1SHOT|
   *
   * - DS1631, DS1731:
   *   7    6    5    4    3    2    1    0
   * |Done|THF |TLF |NVB | R1 | R0 |POL |1SHOT|
   *
   * - DS1721:
   *   7    6    5    4    3    2    1    0
   * |Done| X  | X  | U  | R1 | R0 |POL |1SHOT|
   *
   * Where:
   * - 'X' is Reserved
   * - 'U' is Undefined
   */
  #define DS1621_REG_CONFIG_NVB		0x10
  #define DS1621_REG_CONFIG_RESOL		0x0C
  #define DS1621_REG_CONFIG_POLARITY	0x02
  #define DS1621_REG_CONFIG_1SHOT		0x01
  #define DS1621_REG_CONFIG_DONE		0x80
  
  #define DS1621_REG_CONFIG_RESOL_SHIFT	2
  
  /* ds1721 conversion rates: {C/LSB, time(ms), resolution bit setting} */
  static const unsigned short ds1721_convrates[] = {
  	94,	/*  9-bits (0.5,  93.75, RES[0..1] = 0 */
  	188,	/* 10-bits (0.25, 187.5, RES[0..1] = 1 */
  	375,	/* 11-bits (0.125,  375, RES[0..1] = 2 */
  	750,	/* 12-bits (0.0625, 750, RES[0..1] = 3 */
  };
  
  #define DS1621_CONVERSION_MAX	750
  #define DS1625_CONVERSION_MAX	500
  
  #define DS1621_TEMP_MAX	125000
  #define DS1621_TEMP_MIN	(-55000)
  
  /* The DS1621 temperature registers */
  static const u8 DS1621_REG_TEMP[3] = {
  	0xAA,		/* input, word, RO */
  	0xA2,		/* min, word, RW */
  	0xA1,		/* max, word, RW */
  };
  #define DS1621_REG_CONF			0xAC /* byte, RW */
  #define DS1621_COM_START		0xEE /* no data */
  #define DS1721_COM_START		0x51 /* no data */
  #define DS1621_COM_STOP			0x22 /* no data */
  
  /* The DS1621 configuration register */
  #define DS1621_ALARM_TEMP_HIGH		0x40
  #define DS1621_ALARM_TEMP_LOW		0x20
  
  /* Conversions */
  #define ALARMS_FROM_REG(val) ((val) & \
  			(DS1621_ALARM_TEMP_HIGH | DS1621_ALARM_TEMP_LOW))
  
  /* Each client has this additional data */
  struct ds1621_data {
  	struct i2c_client *client;
  	struct mutex update_lock;
  	char valid;			/* !=0 if following fields are valid */
  	unsigned long last_updated;	/* In jiffies */
  	enum chips kind;		/* device type */
  
  	u16 temp[3];			/* Register values, word */
  	u8 conf;			/* Register encoding, combined */
  	u8 zbits;			/* Resolution encoded as number of
  					 * zero bits */
  	u16 update_interval;		/* Conversion rate in milliseconds */
  };
  
  static inline int DS1621_TEMP_FROM_REG(u16 reg)
  {
  	return DIV_ROUND_CLOSEST(((s16)reg / 16) * 625, 10);
  }
  
  /*
   * TEMP: 0.001C/bit (-55C to +125C)
   * REG:
   *  - 1621, 1625: 0.5C/bit, 7 zero-bits
   *  - 1631, 1721, 1731: 0.0625C/bit, 4 zero-bits
   */
  static inline u16 DS1621_TEMP_TO_REG(long temp, u8 zbits)
  {
  	temp = clamp_val(temp, DS1621_TEMP_MIN, DS1621_TEMP_MAX);
  	temp = DIV_ROUND_CLOSEST(temp * (1 << (8 - zbits)), 1000) << zbits;
  	return temp;
  }
  
  static void ds1621_init_client(struct ds1621_data *data,
  			       struct i2c_client *client)
  {
  	u8 conf, new_conf, sreg, resol;
  
  	new_conf = conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
  	/* switch to continuous conversion mode */
  	new_conf &= ~DS1621_REG_CONFIG_1SHOT;
  
  	/* setup output polarity */
  	if (polarity == 0)
  		new_conf &= ~DS1621_REG_CONFIG_POLARITY;
  	else if (polarity == 1)
  		new_conf |= DS1621_REG_CONFIG_POLARITY;
  
  	if (conf != new_conf)
  		i2c_smbus_write_byte_data(client, DS1621_REG_CONF, new_conf);
  
  	switch (data->kind) {
  	case ds1625:
  		data->update_interval = DS1625_CONVERSION_MAX;
  		data->zbits = 7;
  		sreg = DS1621_COM_START;
  		break;
  	case ds1631:
  	case ds1721:
  	case ds1731:
  		resol = (new_conf & DS1621_REG_CONFIG_RESOL) >>
  			 DS1621_REG_CONFIG_RESOL_SHIFT;
  		data->update_interval = ds1721_convrates[resol];
  		data->zbits = 7 - resol;
  		sreg = DS1721_COM_START;
  		break;
  	default:
  		data->update_interval = DS1621_CONVERSION_MAX;
  		data->zbits = 7;
  		sreg = DS1621_COM_START;
  		break;
  	}
  
  	/* start conversion */
  	i2c_smbus_write_byte(client, sreg);
  }
  
  static struct ds1621_data *ds1621_update_client(struct device *dev)
  {
  	struct ds1621_data *data = dev_get_drvdata(dev);
  	struct i2c_client *client = data->client;
  	u8 new_conf;
  
  	mutex_lock(&data->update_lock);
  
  	if (time_after(jiffies, data->last_updated + data->update_interval) ||
  	    !data->valid) {
  		int i;
  
  		dev_dbg(&client->dev, "Starting ds1621 update
  ");
  
  		data->conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
  
  		for (i = 0; i < ARRAY_SIZE(data->temp); i++)
  			data->temp[i] = i2c_smbus_read_word_swapped(client,
  							 DS1621_REG_TEMP[i]);
  
  		/* reset alarms if necessary */
  		new_conf = data->conf;
  		if (data->temp[0] > data->temp[1])	/* input > min */
  			new_conf &= ~DS1621_ALARM_TEMP_LOW;
  		if (data->temp[0] < data->temp[2])	/* input < max */
  			new_conf &= ~DS1621_ALARM_TEMP_HIGH;
  		if (data->conf != new_conf)
  			i2c_smbus_write_byte_data(client, DS1621_REG_CONF,
  						  new_conf);
  
  		data->last_updated = jiffies;
  		data->valid = 1;
  	}
  
  	mutex_unlock(&data->update_lock);
  
  	return data;
  }
  
  static ssize_t show_temp(struct device *dev, struct device_attribute *da,
  			 char *buf)
  {
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  	struct ds1621_data *data = ds1621_update_client(dev);
  	return sprintf(buf, "%d
  ",
  		       DS1621_TEMP_FROM_REG(data->temp[attr->index]));
  }
  
  static ssize_t set_temp(struct device *dev, struct device_attribute *da,
  			const char *buf, size_t count)
  {
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  	struct ds1621_data *data = dev_get_drvdata(dev);
  	long val;
  	int err;
  
  	err = kstrtol(buf, 10, &val);
  	if (err)
  		return err;
  
  	mutex_lock(&data->update_lock);
  	data->temp[attr->index] = DS1621_TEMP_TO_REG(val, data->zbits);
  	i2c_smbus_write_word_swapped(data->client, DS1621_REG_TEMP[attr->index],
  				     data->temp[attr->index]);
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  static ssize_t show_alarms(struct device *dev, struct device_attribute *da,
  			   char *buf)
  {
  	struct ds1621_data *data = ds1621_update_client(dev);
  	return sprintf(buf, "%d
  ", ALARMS_FROM_REG(data->conf));
  }
  
  static ssize_t show_alarm(struct device *dev, struct device_attribute *da,
  			  char *buf)
  {
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  	struct ds1621_data *data = ds1621_update_client(dev);
  	return sprintf(buf, "%d
  ", !!(data->conf & attr->index));
  }
  
  static ssize_t show_convrate(struct device *dev, struct device_attribute *da,
  			  char *buf)
  {
  	struct ds1621_data *data = dev_get_drvdata(dev);
  	return scnprintf(buf, PAGE_SIZE, "%hu
  ", data->update_interval);
  }
  
  static ssize_t set_convrate(struct device *dev, struct device_attribute *da,
  			    const char *buf, size_t count)
  {
  	struct ds1621_data *data = dev_get_drvdata(dev);
  	struct i2c_client *client = data->client;
  	unsigned long convrate;
  	s32 err;
  	int resol = 0;
  
  	err = kstrtoul(buf, 10, &convrate);
  	if (err)
  		return err;
  
  	/* Convert rate into resolution bits */
  	while (resol < (ARRAY_SIZE(ds1721_convrates) - 1) &&
  	       convrate > ds1721_convrates[resol])
  		resol++;
  
  	mutex_lock(&data->update_lock);
  	data->conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
  	data->conf &= ~DS1621_REG_CONFIG_RESOL;
  	data->conf |= (resol << DS1621_REG_CONFIG_RESOL_SHIFT);
  	i2c_smbus_write_byte_data(client, DS1621_REG_CONF, data->conf);
  	data->update_interval = ds1721_convrates[resol];
  	data->zbits = 7 - resol;
  	mutex_unlock(&data->update_lock);
  
  	return count;
  }
  
  static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
  static DEVICE_ATTR(update_interval, S_IWUSR | S_IRUGO, show_convrate,
  		   set_convrate);
  
  static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
  static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp, 1);
  static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp, 2);
  static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL,
  		DS1621_ALARM_TEMP_LOW);
  static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL,
  		DS1621_ALARM_TEMP_HIGH);
  
  static struct attribute *ds1621_attributes[] = {
  	&sensor_dev_attr_temp1_input.dev_attr.attr,
  	&sensor_dev_attr_temp1_min.dev_attr.attr,
  	&sensor_dev_attr_temp1_max.dev_attr.attr,
  	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
  	&dev_attr_alarms.attr,
  	&dev_attr_update_interval.attr,
  	NULL
  };
  
  static umode_t ds1621_attribute_visible(struct kobject *kobj,
  					struct attribute *attr, int index)
  {
  	struct device *dev = container_of(kobj, struct device, kobj);
  	struct ds1621_data *data = dev_get_drvdata(dev);
  
  	if (attr == &dev_attr_update_interval.attr)
  		if (data->kind == ds1621 || data->kind == ds1625)
  			/* shhh, we're hiding update_interval */
  			return 0;
  	return attr->mode;
  }
  
  static const struct attribute_group ds1621_group = {
  	.attrs = ds1621_attributes,
  	.is_visible = ds1621_attribute_visible
  };
  __ATTRIBUTE_GROUPS(ds1621);
  
  static int ds1621_probe(struct i2c_client *client,
  			const struct i2c_device_id *id)
  {
  	struct ds1621_data *data;
  	struct device *hwmon_dev;
  
  	data = devm_kzalloc(&client->dev, sizeof(struct ds1621_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	mutex_init(&data->update_lock);
  
  	data->kind = id->driver_data;
  	data->client = client;
  
  	/* Initialize the DS1621 chip */
  	ds1621_init_client(data, client);
  
  	hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
  							   client->name, data,
  							   ds1621_groups);
  	return PTR_ERR_OR_ZERO(hwmon_dev);
  }
  
  static const struct i2c_device_id ds1621_id[] = {
  	{ "ds1621", ds1621 },
  	{ "ds1625", ds1625 },
  	{ "ds1631", ds1631 },
  	{ "ds1721", ds1721 },
  	{ "ds1731", ds1731 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, ds1621_id);
  
  /* This is the driver that will be inserted */
  static struct i2c_driver ds1621_driver = {
  	.class		= I2C_CLASS_HWMON,
  	.driver = {
  		.name	= "ds1621",
  	},
  	.probe		= ds1621_probe,
  	.id_table	= ds1621_id,
  };
  
  module_i2c_driver(ds1621_driver);
  
  MODULE_AUTHOR("Christian W. Zuckschwerdt <zany@triq.net>");
  MODULE_DESCRIPTION("DS1621 driver");
  MODULE_LICENSE("GPL");