/*
 *  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 */
};

/*
 *  Temperature registers are word-sized.
 *  DS620 uses a high-byte first convention, which is exactly opposite to
 *  the SMBus standard.
 */
static int ds620_read_temp(struct i2c_client *client, u8 reg)
{
	int ret;

	ret = i2c_smbus_read_word_data(client, reg);
	if (ret < 0)
		return ret;
	return swab16(ret);
}

static int ds620_write_temp(struct i2c_client *client, u8 reg, u16 value)
{
	return i2c_smbus_write_word_data(client, reg, swab16(value));
}

static void ds620_init_client(struct i2c_client *client)
{
	struct ds620_platform_data *ds620_info = client->dev.platform_data;
	u16 conf, new_conf;

	new_conf = conf =
	    swab16(i2c_smbus_read_word_data(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_data(client, DS620_REG_CONF,
					  swab16(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\n");

		for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
			res = ds620_read_temp(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\n", ((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 = strict_strtol(buf, 10, &val);

	if (res)
		return res;

	val = (val * 10 / 625) * 8;

	mutex_lock(&data->update_lock);
	data->temp[attr->index] = val;
	ds620_write_temp(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_data(client, DS620_REG_CONF);
	if (res < 0)
		return res;

	conf = swab16(res);
	new_conf = conf;
	new_conf &= ~attr->index;
	if (conf != new_conf) {
		res = i2c_smbus_write_word_data(client, DS620_REG_CONF,
						swab16(new_conf));
		if (res < 0)
			return res;
	}

	return sprintf(buf, "%d\n", !!(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 = kzalloc(sizeof(struct ds620_data), GFP_KERNEL);
	if (!data) {
		err = -ENOMEM;
		goto exit;
	}

	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)
		goto exit_free;

	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\n");

	return 0;

exit_remove_files:
	sysfs_remove_group(&client->dev.kobj, &ds620_group);
exit_free:
	kfree(data);
exit:
	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);

	kfree(data);

	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,
};

static int __init ds620_init(void)
{
	return i2c_add_driver(&ds620_driver);
}

static void __exit ds620_exit(void)
{
	i2c_del_driver(&ds620_driver);
}

MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
MODULE_DESCRIPTION("DS620 driver");
MODULE_LICENSE("GPL");

module_init(ds620_init);
module_exit(ds620_exit);