/*
    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 <khali@linux-fr.org>

    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 "lm75.h"

/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
                                        0x4d, 0x4e, 0x4f, I2C_CLIENT_END };

/* Insmod parameters */
static int polarity = -1;
module_param(polarity, int, 0);
MODULE_PARM_DESC(polarity, "Output's polarity: 0 = active high, 1 = active low");

/* Many DS1621 constants specified below */
/* Config register used for detection         */
/*  7    6    5    4    3    2    1    0      */
/* |Done|THF |TLF |NVB | X  | X  |POL |1SHOT| */
#define DS1621_REG_CONFIG_NVB           0x10
#define DS1621_REG_CONFIG_POLARITY      0x02
#define DS1621_REG_CONFIG_1SHOT         0x01
#define DS1621_REG_CONFIG_DONE          0x80

/* The DS1621 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 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 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 */
        u8 conf;                        /* Register encoding, combined */
};

/* Temperature registers are word-sized.
   DS1621 uses a high-byte first convention, which is exactly opposite to
   the SMBus standard. */
static int ds1621_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 ds1621_write_temp(struct i2c_client *client, u8 reg, u16 value)
{
        return i2c_smbus_write_word_data(client, reg, swab16(value));
}

static void ds1621_init_client(struct i2c_client *client)
{
        u8 conf, new_conf;

        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);
        
        /* start conversion */
        i2c_smbus_write_byte(client, DS1621_COM_START);
}

static struct ds1621_data *ds1621_update_client(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct ds1621_data *data = i2c_get_clientdata(client);
        u8 new_conf;

        mutex_lock(&data->update_lock);

        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
            || !data->valid) {
                int i;

                dev_dbg(&client->dev, "Starting ds1621 update\n");

                data->conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);

                for (i = 0; i < ARRAY_SIZE(data->temp); i++)
                        data->temp[i] = ds1621_read_temp(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\n",
                       LM75_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 i2c_client *client = to_i2c_client(dev);
        struct ds1621_data *data = i2c_get_clientdata(client);
        u16 val = LM75_TEMP_TO_REG(simple_strtol(buf, NULL, 10));

        mutex_lock(&data->update_lock);
        data->temp[attr->index] = val;
        ds1621_write_temp(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\n", 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\n", !!(data->conf & attr->index));
}

static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
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,
        NULL
};

static const struct attribute_group ds1621_group = {
        .attrs = ds1621_attributes,
};


/* Return 0 if detection is successful, -ENODEV otherwise */
static int ds1621_detect(struct i2c_client *client,
                         struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = client->adapter;
        int conf, temp;
        int i;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA 
                                     | I2C_FUNC_SMBUS_WORD_DATA 
                                     | I2C_FUNC_SMBUS_WRITE_BYTE))
                return -ENODEV;

        /* Now, we do the remaining detection. It is lousy. */
        /* The NVB bit should be low if no EEPROM write has been  requested
           during the latest 10ms, which is highly improbable in our case. */
        conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
        if (conf < 0 || conf & DS1621_REG_CONFIG_NVB)
                return -ENODEV;
        /* The 7 lowest bits of a temperature should always be 0. */
        for (i = 0; i < ARRAY_SIZE(DS1621_REG_TEMP); i++) {
                temp = i2c_smbus_read_word_data(client, DS1621_REG_TEMP[i]);
                if (temp < 0 || (temp & 0x7f00))
                        return -ENODEV;
        }

        strlcpy(info->type, "ds1621", I2C_NAME_SIZE);

        return 0;
}

static int ds1621_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct ds1621_data *data;
        int err;

        data = kzalloc(sizeof(struct ds1621_data), GFP_KERNEL);
        if (!data) {
                err = -ENOMEM;
                goto exit;
        }

        i2c_set_clientdata(client, data);
        mutex_init(&data->update_lock);

        /* Initialize the DS1621 chip */
        ds1621_init_client(client);

        /* Register sysfs hooks */
        if ((err = sysfs_create_group(&client->dev.kobj, &ds1621_group)))
                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;
        }

        return 0;

      exit_remove_files:
        sysfs_remove_group(&client->dev.kobj, &ds1621_group);
      exit_free:
        kfree(data);
      exit:
        return err;
}

static int ds1621_remove(struct i2c_client *client)
{
        struct ds1621_data *data = i2c_get_clientdata(client);

        hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&client->dev.kobj, &ds1621_group);

        kfree(data);

        return 0;
}

static const struct i2c_device_id ds1621_id[] = {
        { "ds1621", 0 },
        { "ds1625", 0 },
        { }
};
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,
        .remove         = ds1621_remove,
        .id_table       = ds1621_id,
        .detect         = ds1621_detect,
        .address_list   = normal_i2c,
};

static int __init ds1621_init(void)
{
        return i2c_add_driver(&ds1621_driver);
}

static void __exit ds1621_exit(void)
{
        i2c_del_driver(&ds1621_driver);
}


MODULE_AUTHOR("Christian W. Zuckschwerdt <zany@triq.net>");
MODULE_DESCRIPTION("DS1621 driver");
MODULE_LICENSE("GPL");

module_init(ds1621_init);
module_exit(ds1621_exit);