/*
 * 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 <jdelvare@suse.de>
 *
 * The DS1621 device is a digital temperature/thermometer with 9-bit
 * resolution, a thermal alarm output (Tout), and user-defined minimum
 * and maximum temperature thresholds (TH and TL).
 *
 * The DS1625, DS1631, DS1721, and DS1731 are pin compatible with the DS1621
 * and similar in operation, with slight variations as noted in the device
 * datasheets (please refer to www.maximintegrated.com for specific
 * device information).
 *
 * Since the DS1621 was the first chipset supported by this driver,
 * most comments will refer to this chipset, but are actually general
 * and concern all supported chipsets, unless mentioned otherwise.
 *
 * 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/kernel.h>

/* Supported devices */
enum chips { ds1621, ds1625, ds1631, ds1721, ds1731 };

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

/*
 * The Configuration/Status register
 *
 * - DS1621:
 *   7    6    5    4    3    2    1    0
 * |Done|THF |TLF |NVB | X  | X  |POL |1SHOT|
 *
 * - DS1625:
 *   7    6    5    4    3    2    1    0
 * |Done|THF |TLF |NVB | 1  | 0  |POL |1SHOT|
 *
 * - DS1631, DS1731:
 *   7    6    5    4    3    2    1    0
 * |Done|THF |TLF |NVB | R1 | R0 |POL |1SHOT|
 *
 * - DS1721:
 *   7    6    5    4    3    2    1    0
 * |Done| X  | X  | U  | R1 | R0 |POL |1SHOT|
 *
 * Where:
 * - 'X' is Reserved
 * - 'U' is Undefined
 */
#define DS1621_REG_CONFIG_NVB           0x10
#define DS1621_REG_CONFIG_RESOL         0x0C
#define DS1621_REG_CONFIG_POLARITY      0x02
#define DS1621_REG_CONFIG_1SHOT         0x01
#define DS1621_REG_CONFIG_DONE          0x80

#define DS1621_REG_CONFIG_RESOL_SHIFT   2

/* ds1721 conversion rates: {C/LSB, time(ms), resolution bit setting} */
static const unsigned short ds1721_convrates[] = {
        94,     /*  9-bits (0.5,  93.75, RES[0..1] = 0 */
        188,    /* 10-bits (0.25, 187.5, RES[0..1] = 1 */
        375,    /* 11-bits (0.125,  375, RES[0..1] = 2 */
        750,    /* 12-bits (0.0625, 750, RES[0..1] = 3 */
};

#define DS1621_CONVERSION_MAX   750
#define DS1625_CONVERSION_MAX   500

#define DS1621_TEMP_MAX 125000
#define DS1621_TEMP_MIN (-55000)

/* The DS1621 temperature 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 DS1721_COM_START                0x51 /* 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 i2c_client *client;
        struct mutex update_lock;
        char valid;                     /* !=0 if following fields are valid */
        unsigned long last_updated;     /* In jiffies */
        enum chips kind;                /* device type */

        u16 temp[3];                    /* Register values, word */
        u8 conf;                        /* Register encoding, combined */
        u8 zbits;                       /* Resolution encoded as number of
                                         * zero bits */
        u16 update_interval;            /* Conversion rate in milliseconds */
};

static inline int DS1621_TEMP_FROM_REG(u16 reg)
{
        return DIV_ROUND_CLOSEST(((s16)reg / 16) * 625, 10);
}

/*
 * TEMP: 0.001C/bit (-55C to +125C)
 * REG:
 *  - 1621, 1625: 0.5C/bit, 7 zero-bits
 *  - 1631, 1721, 1731: 0.0625C/bit, 4 zero-bits
 */
static inline u16 DS1621_TEMP_TO_REG(long temp, u8 zbits)
{
        temp = clamp_val(temp, DS1621_TEMP_MIN, DS1621_TEMP_MAX);
        temp = DIV_ROUND_CLOSEST(temp * (1 << (8 - zbits)), 1000) << zbits;
        return temp;
}

static void ds1621_init_client(struct ds1621_data *data,
                               struct i2c_client *client)
{
        u8 conf, new_conf, sreg, resol;

        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);

        switch (data->kind) {
        case ds1625:
                data->update_interval = DS1625_CONVERSION_MAX;
                data->zbits = 7;
                sreg = DS1621_COM_START;
                break;
        case ds1631:
        case ds1721:
        case ds1731:
                resol = (new_conf & DS1621_REG_CONFIG_RESOL) >>
                         DS1621_REG_CONFIG_RESOL_SHIFT;
                data->update_interval = ds1721_convrates[resol];
                data->zbits = 7 - resol;
                sreg = DS1721_COM_START;
                break;
        default:
                data->update_interval = DS1621_CONVERSION_MAX;
                data->zbits = 7;
                sreg = DS1621_COM_START;
                break;
        }

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

static struct ds1621_data *ds1621_update_client(struct device *dev)
{
        struct ds1621_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        u8 new_conf;

        mutex_lock(&data->update_lock);

        if (time_after(jiffies, data->last_updated + data->update_interval) ||
            !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] = i2c_smbus_read_word_swapped(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",
                       DS1621_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 ds1621_data *data = dev_get_drvdata(dev);
        long val;
        int err;

        err = kstrtol(buf, 10, &val);
        if (err)
                return err;

        mutex_lock(&data->update_lock);
        data->temp[attr->index] = DS1621_TEMP_TO_REG(val, data->zbits);
        i2c_smbus_write_word_swapped(data->client, DS1621_REG_TEMP[attr->index],
                                     data->temp[attr->index]);
        mutex_unlock(&data->update_lock);
        return count;
}

static ssize_t alarms_show(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 ssize_t update_interval_show(struct device *dev,
                                    struct device_attribute *da, char *buf)
{
        struct ds1621_data *data = dev_get_drvdata(dev);
        return scnprintf(buf, PAGE_SIZE, "%hu\n", data->update_interval);
}

static ssize_t update_interval_store(struct device *dev,
                                     struct device_attribute *da,
                                     const char *buf, size_t count)
{
        struct ds1621_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        unsigned long convrate;
        s32 err;
        int resol = 0;

        err = kstrtoul(buf, 10, &convrate);
        if (err)
                return err;

        /* Convert rate into resolution bits */
        while (resol < (ARRAY_SIZE(ds1721_convrates) - 1) &&
               convrate > ds1721_convrates[resol])
                resol++;

        mutex_lock(&data->update_lock);
        data->conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);
        data->conf &= ~DS1621_REG_CONFIG_RESOL;
        data->conf |= (resol << DS1621_REG_CONFIG_RESOL_SHIFT);
        i2c_smbus_write_byte_data(client, DS1621_REG_CONF, data->conf);
        data->update_interval = ds1721_convrates[resol];
        data->zbits = 7 - resol;
        mutex_unlock(&data->update_lock);

        return count;
}

static DEVICE_ATTR_RO(alarms);
static DEVICE_ATTR_RW(update_interval);

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,
        &dev_attr_update_interval.attr,
        NULL
};

static umode_t ds1621_attribute_visible(struct kobject *kobj,
                                        struct attribute *attr, int index)
{
        struct device *dev = container_of(kobj, struct device, kobj);
        struct ds1621_data *data = dev_get_drvdata(dev);

        if (attr == &dev_attr_update_interval.attr)
                if (data->kind == ds1621 || data->kind == ds1625)
                        /* shhh, we're hiding update_interval */
                        return 0;
        return attr->mode;
}

static const struct attribute_group ds1621_group = {
        .attrs = ds1621_attributes,
        .is_visible = ds1621_attribute_visible
};
__ATTRIBUTE_GROUPS(ds1621);

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

        data = devm_kzalloc(&client->dev, sizeof(struct ds1621_data),
                            GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        mutex_init(&data->update_lock);

        data->kind = id->driver_data;
        data->client = client;

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

        hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
                                                           client->name, data,
                                                           ds1621_groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id ds1621_id[] = {
        { "ds1621", ds1621 },
        { "ds1625", ds1625 },
        { "ds1631", ds1631 },
        { "ds1721", ds1721 },
        { "ds1731", ds1731 },
        { }
};
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,
        .id_table       = ds1621_id,
};

module_i2c_driver(ds1621_driver);

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