/*
   *  ds620.c - Support for temperature sensor and thermostat DS620
   *
   *  Copyright (C) 2010, 2011 Roland Stigge <stigge@antcom.de>
   *
   *  based on ds1621.c by Christian W. Zuckschwerdt  <zany@triq.net>
   *
   *  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/i2c/ds620.h>
  
  /*
   * Many DS620 constants specified below
   *  15   14   13   12   11   10   09    08
   * |Done|NVB |THF |TLF |R1  |R0  |AUTOC|1SHOT|
   *
   *  07   06   05   04   03   02   01    00
   * |PO2 |PO1 |A2  |A1  |A0  |    |     |     |
   */
  #define DS620_REG_CONFIG_DONE		0x8000
  #define DS620_REG_CONFIG_NVB		0x4000
  #define DS620_REG_CONFIG_THF		0x2000
  #define DS620_REG_CONFIG_TLF		0x1000
  #define DS620_REG_CONFIG_R1		0x0800
  #define DS620_REG_CONFIG_R0		0x0400
  #define DS620_REG_CONFIG_AUTOC		0x0200
  #define DS620_REG_CONFIG_1SHOT		0x0100
  #define DS620_REG_CONFIG_PO2		0x0080
  #define DS620_REG_CONFIG_PO1		0x0040
  #define DS620_REG_CONFIG_A2		0x0020
  #define DS620_REG_CONFIG_A1		0x0010
  #define DS620_REG_CONFIG_A0		0x0008
  
  /* The DS620 registers */
  static const u8 DS620_REG_TEMP[3] = {
  	0xAA,			/* input, word, RO */
  	0xA2,			/* min, word, RW */
  	0xA0,			/* max, word, RW */
  };
  
  #define DS620_REG_CONF		0xAC	/* word, RW */
  #define DS620_COM_START		0x51	/* no data */
  #define DS620_COM_STOP		0x22	/* no data */
  
  /* Each client has this additional data */
  struct ds620_data {
  	struct device *hwmon_dev;
  	struct mutex update_lock;
  	char valid;		/* !=0 if following fields are valid */
  	unsigned long last_updated;	/* In jiffies */
  
  	s16 temp[3];		/* Register values, word */
  };
  
  static void ds620_init_client(struct i2c_client *client)
  {
  	struct ds620_platform_data *ds620_info = dev_get_platdata(&client->dev);
  	u16 conf, new_conf;
  
  	new_conf = conf =
  	    i2c_smbus_read_word_swapped(client, DS620_REG_CONF);
  
  	/* switch to continuous conversion mode */
  	new_conf &= ~DS620_REG_CONFIG_1SHOT;
  	/* already high at power-on, but don't trust the BIOS! */
  	new_conf |= DS620_REG_CONFIG_PO2;
  	/* thermostat mode according to platform data */
  	if (ds620_info && ds620_info->pomode == 1)
  		new_conf &= ~DS620_REG_CONFIG_PO1; /* PO_LOW */
  	else if (ds620_info && ds620_info->pomode == 2)
  		new_conf |= DS620_REG_CONFIG_PO1; /* PO_HIGH */
  	else
  		new_conf &= ~DS620_REG_CONFIG_PO2; /* always low */
  	/* with highest precision */
  	new_conf |= DS620_REG_CONFIG_R1 | DS620_REG_CONFIG_R0;
  
  	if (conf != new_conf)
  		i2c_smbus_write_word_swapped(client, DS620_REG_CONF, new_conf);
  
  	/* start conversion */
  	i2c_smbus_write_byte(client, DS620_COM_START);
  }
  
  static struct ds620_data *ds620_update_client(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct ds620_data *data = i2c_get_clientdata(client);
  	struct ds620_data *ret = data;
  
  	mutex_lock(&data->update_lock);
  
  	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
  	    || !data->valid) {
  		int i;
  		int res;
  
  		dev_dbg(&client->dev, "Starting ds620 update
  ");
  
  		for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
  			res = i2c_smbus_read_word_swapped(client,
  							  DS620_REG_TEMP[i]);
  			if (res < 0) {
  				ret = ERR_PTR(res);
  				goto abort;
  			}
  
  			data->temp[i] = res;
  		}
  
  		data->last_updated = jiffies;
  		data->valid = 1;
  	}
  abort:
  	mutex_unlock(&data->update_lock);
  
  	return ret;
  }
  
  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 ds620_data *data = ds620_update_client(dev);
  
  	if (IS_ERR(data))
  		return PTR_ERR(data);
  
  	return sprintf(buf, "%d
  ", ((data->temp[attr->index] / 8) * 625) / 10);
  }
  
  static ssize_t set_temp(struct device *dev, struct device_attribute *da,
  			const char *buf, size_t count)
  {
  	int res;
  	long val;
  
  	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
  	struct i2c_client *client = to_i2c_client(dev);
  	struct ds620_data *data = i2c_get_clientdata(client);
  
  	res = kstrtol(buf, 10, &val);
  
  	if (res)
  		return res;
  
  	val = (val * 10 / 625) * 8;
  
  	mutex_lock(&data->update_lock);
  	data->temp[attr->index] = val;
  	i2c_smbus_write_word_swapped(client, DS620_REG_TEMP[attr->index],
  				     data->temp[attr->index]);
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  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 ds620_data *data = ds620_update_client(dev);
  	struct i2c_client *client = to_i2c_client(dev);
  	u16 conf, new_conf;
  	int res;
  
  	if (IS_ERR(data))
  		return PTR_ERR(data);
  
  	/* reset alarms if necessary */
  	res = i2c_smbus_read_word_swapped(client, DS620_REG_CONF);
  	if (res < 0)
  		return res;
  
  	new_conf = conf = res;
  	new_conf &= ~attr->index;
  	if (conf != new_conf) {
  		res = i2c_smbus_write_word_swapped(client, DS620_REG_CONF,
  						   new_conf);
  		if (res < 0)
  			return res;
  	}
  
  	return sprintf(buf, "%d
  ", !!(conf & attr->index));
  }
  
  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,
  			  DS620_REG_CONFIG_TLF);
  static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL,
  			  DS620_REG_CONFIG_THF);
  
  static struct attribute *ds620_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,
  	NULL
  };
  
  static const struct attribute_group ds620_group = {
  	.attrs = ds620_attributes,
  };
  
  static int ds620_probe(struct i2c_client *client,
  		       const struct i2c_device_id *id)
  {
  	struct ds620_data *data;
  	int err;
  
  	data = devm_kzalloc(&client->dev, sizeof(struct ds620_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, data);
  	mutex_init(&data->update_lock);
  
  	/* Initialize the DS620 chip */
  	ds620_init_client(client);
  
  	/* Register sysfs hooks */
  	err = sysfs_create_group(&client->dev.kobj, &ds620_group);
  	if (err)
  		return err;
  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		err = PTR_ERR(data->hwmon_dev);
  		goto exit_remove_files;
  	}
  
  	dev_info(&client->dev, "temperature sensor found
  ");
  
  	return 0;
  
  exit_remove_files:
  	sysfs_remove_group(&client->dev.kobj, &ds620_group);
  	return err;
  }
  
  static int ds620_remove(struct i2c_client *client)
  {
  	struct ds620_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  	sysfs_remove_group(&client->dev.kobj, &ds620_group);
  
  	return 0;
  }
  
  static const struct i2c_device_id ds620_id[] = {
  	{"ds620", 0},
  	{}
  };
  
  MODULE_DEVICE_TABLE(i2c, ds620_id);
  
  /* This is the driver that will be inserted */
  static struct i2c_driver ds620_driver = {
  	.class = I2C_CLASS_HWMON,
  	.driver = {
  		   .name = "ds620",
  	},
  	.probe = ds620_probe,
  	.remove = ds620_remove,
  	.id_table = ds620_id,
  };
  
  module_i2c_driver(ds620_driver);
  
  MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
  MODULE_DESCRIPTION("DS620 driver");
  MODULE_LICENSE("GPL");