/*
 * Driver for +/-1 degree C, SMBus-Compatible Remote/Local Temperature Sensor
 * with Overtemperature Alarm
 *
 * Copyright (C) 2011 AppearTV AS
 *
 * Derived from:
 *
 *  Based on the max1619 driver.
 *  Copyright (C) 2003-2004 Alexey Fisher <fishor@mail.ru>
 *                          Jean Delvare <khali@linux-fr.org>
 *
 * The MAX6642 is a sensor chip made by Maxim.
 * It reports up to two temperatures (its own plus up to
 * one external one). Complete datasheet can be
 * obtained from Maxim's website at:
 *   http://datasheets.maxim-ic.com/en/ds/MAX6642.pdf
 *
 * 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>

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

/*
 * The MAX6642 registers
 */

#define MAX6642_REG_R_MAN_ID            0xFE
#define MAX6642_REG_R_CONFIG            0x03
#define MAX6642_REG_W_CONFIG            0x09
#define MAX6642_REG_R_STATUS            0x02
#define MAX6642_REG_R_LOCAL_TEMP        0x00
#define MAX6642_REG_R_LOCAL_TEMPL       0x11
#define MAX6642_REG_R_LOCAL_HIGH        0x05
#define MAX6642_REG_W_LOCAL_HIGH        0x0B
#define MAX6642_REG_R_REMOTE_TEMP       0x01
#define MAX6642_REG_R_REMOTE_TEMPL      0x10
#define MAX6642_REG_R_REMOTE_HIGH       0x07
#define MAX6642_REG_W_REMOTE_HIGH       0x0D

/*
 * Conversions
 */

static int temp_from_reg10(int val)
{
        return val * 250;
}

static int temp_from_reg(int val)
{
        return val * 1000;
}

static int temp_to_reg(int val)
{
        return val / 1000;
}

/*
 * Client data (each client gets its own)
 */

struct max6642_data {
        struct device *hwmon_dev;
        struct mutex update_lock;
        bool valid; /* zero until following fields are valid */
        unsigned long last_updated; /* in jiffies */

        /* registers values */
        u16 temp_input[2]; /* local/remote */
        u16 temp_high[2]; /* local/remote */
        u8 alarms;
};

/*
 * Real code
 */

static void max6642_init_client(struct i2c_client *client)
{
        u8 config;
        struct max6642_data *data = i2c_get_clientdata(client);

        /*
         * Start the conversions.
         */
        config = i2c_smbus_read_byte_data(client, MAX6642_REG_R_CONFIG);
        if (config & 0x40)
                i2c_smbus_write_byte_data(client, MAX6642_REG_W_CONFIG,
                                          config & 0xBF); /* run */

        data->temp_high[0] = i2c_smbus_read_byte_data(client,
                                MAX6642_REG_R_LOCAL_HIGH);
        data->temp_high[1] = i2c_smbus_read_byte_data(client,
                                MAX6642_REG_R_REMOTE_HIGH);
}

/* Return 0 if detection is successful, -ENODEV otherwise */
static int max6642_detect(struct i2c_client *client,
                          struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = client->adapter;
        u8 reg_config, reg_status, man_id;

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

        /* identification */
        man_id = i2c_smbus_read_byte_data(client, MAX6642_REG_R_MAN_ID);
        if (man_id != 0x4D)
                return -ENODEV;

        /* sanity check */
        if (i2c_smbus_read_byte_data(client, 0x04) != 0x4D
            || i2c_smbus_read_byte_data(client, 0x06) != 0x4D
            || i2c_smbus_read_byte_data(client, 0xff) != 0x4D)
                return -ENODEV;

        /*
         * We read the config and status register, the 4 lower bits in the
         * config register should be zero and bit 5, 3, 1 and 0 should be
         * zero in the status register.
         */
        reg_config = i2c_smbus_read_byte_data(client, MAX6642_REG_R_CONFIG);
        if ((reg_config & 0x0f) != 0x00)
                return -ENODEV;

        /* in between, another round of sanity checks */
        if (i2c_smbus_read_byte_data(client, 0x04) != reg_config
            || i2c_smbus_read_byte_data(client, 0x06) != reg_config
            || i2c_smbus_read_byte_data(client, 0xff) != reg_config)
                return -ENODEV;

        reg_status = i2c_smbus_read_byte_data(client, MAX6642_REG_R_STATUS);
        if ((reg_status & 0x2b) != 0x00)
                return -ENODEV;

        strlcpy(info->type, "max6642", I2C_NAME_SIZE);

        return 0;
}

static struct max6642_data *max6642_update_device(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct max6642_data *data = i2c_get_clientdata(client);
        u16 val, tmp;

        mutex_lock(&data->update_lock);

        if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
                dev_dbg(&client->dev, "Updating max6642 data.\n");
                val = i2c_smbus_read_byte_data(client,
                                        MAX6642_REG_R_LOCAL_TEMPL);
                tmp = (val >> 6) & 3;
                val = i2c_smbus_read_byte_data(client,
                                        MAX6642_REG_R_LOCAL_TEMP);
                val = (val << 2) | tmp;
                data->temp_input[0] = val;
                val = i2c_smbus_read_byte_data(client,
                                        MAX6642_REG_R_REMOTE_TEMPL);
                tmp = (val >> 6) & 3;
                val = i2c_smbus_read_byte_data(client,
                                        MAX6642_REG_R_REMOTE_TEMP);
                val = (val << 2) | tmp;
                data->temp_input[1] = val;
                data->alarms = i2c_smbus_read_byte_data(client,
                                        MAX6642_REG_R_STATUS);

                data->last_updated = jiffies;
                data->valid = 1;
        }

        mutex_unlock(&data->update_lock);

        return data;
}

/*
 * Sysfs stuff
 */

static ssize_t show_temp_max10(struct device *dev,
                               struct device_attribute *dev_attr, char *buf)
{
        struct max6642_data *data = max6642_update_device(dev);
        struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

        return sprintf(buf, "%d\n",
                       temp_from_reg10(data->temp_input[attr->index]));
}

static ssize_t show_temp_max(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct max6642_data *data = max6642_update_device(dev);
        struct sensor_device_attribute_2 *attr2 = to_sensor_dev_attr_2(attr);

        return sprintf(buf, "%d\n", temp_from_reg(data->temp_high[attr2->nr]));
}

static ssize_t set_temp_max(struct device *dev, struct device_attribute *attr,
                            const char *buf, size_t count)
{
        unsigned long val;
        int err;
        struct i2c_client *client = to_i2c_client(dev);
        struct max6642_data *data = i2c_get_clientdata(client);
        struct sensor_device_attribute_2 *attr2 = to_sensor_dev_attr_2(attr);

        err = strict_strtoul(buf, 10, &val);
        if (err < 0)
                return err;

        mutex_lock(&data->update_lock);
        data->temp_high[attr2->nr] = SENSORS_LIMIT(temp_to_reg(val), 0, 255);
        i2c_smbus_write_byte_data(client, attr2->index,
                                  data->temp_high[attr2->nr]);
        mutex_unlock(&data->update_lock);
        return count;
}

static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        int bitnr = to_sensor_dev_attr(attr)->index;
        struct max6642_data *data = max6642_update_device(dev);
        return sprintf(buf, "%d\n", (data->alarms >> bitnr) & 1);
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_max10, NULL, 0);
static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_max10, NULL, 1);
static SENSOR_DEVICE_ATTR_2(temp1_max, S_IWUSR | S_IRUGO, show_temp_max,
                            set_temp_max, 0, MAX6642_REG_W_LOCAL_HIGH);
static SENSOR_DEVICE_ATTR_2(temp2_max, S_IWUSR | S_IRUGO, show_temp_max,
                            set_temp_max, 1, MAX6642_REG_W_REMOTE_HIGH);
static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_alarm, NULL, 2);
static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 6);
static SENSOR_DEVICE_ATTR(temp2_max_alarm, S_IRUGO, show_alarm, NULL, 4);

static struct attribute *max6642_attributes[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_temp2_input.dev_attr.attr,
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp2_max.dev_attr.attr,

        &sensor_dev_attr_temp2_fault.dev_attr.attr,
        &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
        &sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
        NULL
};

static const struct attribute_group max6642_group = {
        .attrs = max6642_attributes,
};

static int max6642_probe(struct i2c_client *new_client,
                         const struct i2c_device_id *id)
{
        struct max6642_data *data;
        int err;

        data = kzalloc(sizeof(struct max6642_data), GFP_KERNEL);
        if (!data) {
                err = -ENOMEM;
                goto exit;
        }

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

        /* Initialize the MAX6642 chip */
        max6642_init_client(new_client);

        /* Register sysfs hooks */
        err = sysfs_create_group(&new_client->dev.kobj, &max6642_group);
        if (err)
                goto exit_free;

        data->hwmon_dev = hwmon_device_register(&new_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(&new_client->dev.kobj, &max6642_group);
exit_free:
        kfree(data);
exit:
        return err;
}

static int max6642_remove(struct i2c_client *client)
{
        struct max6642_data *data = i2c_get_clientdata(client);

        hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&client->dev.kobj, &max6642_group);

        kfree(data);
        return 0;
}

/*
 * Driver data (common to all clients)
 */

static const struct i2c_device_id max6642_id[] = {
        { "max6642", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, max6642_id);

static struct i2c_driver max6642_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "max6642",
        },
        .probe          = max6642_probe,
        .remove         = max6642_remove,
        .id_table       = max6642_id,
        .detect         = max6642_detect,
        .address_list   = normal_i2c,
};

static int __init max6642_init(void)
{
        return i2c_add_driver(&max6642_driver);
}

static void __exit max6642_exit(void)
{
        i2c_del_driver(&max6642_driver);
}

MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
MODULE_DESCRIPTION("MAX6642 sensor driver");
MODULE_LICENSE("GPL");

module_init(max6642_init);
module_exit(max6642_exit);