/*
 *  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 */

        u16 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);