/*
 * An hwmon driver for the Analog Devices AD7414
 *
 * Copyright 2006 Stefan Roese <sr at denx.de>, DENX Software Engineering
 *
 * Copyright (c) 2008 PIKA Technologies
 *   Sean MacLennan <smaclennan@pikatech.com>
 *
 * Copyright (c) 2008 Spansion Inc.
 *   Frank Edelhaeuser <frank.edelhaeuser at spansion.com>
 *   (converted to "new style" I2C driver model, removed checkpatch.pl warnings)
 *
 * Based on ad7418.c
 * Copyright 2006 Tower Technologies, Alessandro Zummo <a.zummo at towertech.it>
 *
 * 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.
 */

#include <linux/module.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/slab.h>


/* AD7414 registers */
#define AD7414_REG_TEMP         0x00
#define AD7414_REG_CONF         0x01
#define AD7414_REG_T_HIGH       0x02
#define AD7414_REG_T_LOW        0x03

static u8 AD7414_REG_LIMIT[] = { AD7414_REG_T_HIGH, AD7414_REG_T_LOW };

struct ad7414_data {
        struct i2c_client       *client;
        struct mutex            lock;   /* atomic read data updates */
        char                    valid;  /* !=0 if following fields are valid */
        unsigned long           next_update;    /* In jiffies */
        s16                     temp_input;     /* Register values */
        s8                      temps[ARRAY_SIZE(AD7414_REG_LIMIT)];
};

/* REG: (0.25C/bit, two's complement) << 6 */
static inline int ad7414_temp_from_reg(s16 reg)
{
        /*
         * use integer division instead of equivalent right shift to
         * guarantee arithmetic shift and preserve the sign
         */
        return ((int)reg / 64) * 250;
}

static inline int ad7414_read(struct i2c_client *client, u8 reg)
{
        if (reg == AD7414_REG_TEMP)
                return i2c_smbus_read_word_swapped(client, reg);
        else
                return i2c_smbus_read_byte_data(client, reg);
}

static inline int ad7414_write(struct i2c_client *client, u8 reg, u8 value)
{
        return i2c_smbus_write_byte_data(client, reg, value);
}

static struct ad7414_data *ad7414_update_device(struct device *dev)
{
        struct ad7414_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;

        mutex_lock(&data->lock);

        if (time_after(jiffies, data->next_update) || !data->valid) {
                int value, i;

                dev_dbg(&client->dev, "starting ad7414 update\n");

                value = ad7414_read(client, AD7414_REG_TEMP);
                if (value < 0)
                        dev_dbg(&client->dev, "AD7414_REG_TEMP err %d\n",
                                value);
                else
                        data->temp_input = value;

                for (i = 0; i < ARRAY_SIZE(AD7414_REG_LIMIT); ++i) {
                        value = ad7414_read(client, AD7414_REG_LIMIT[i]);
                        if (value < 0)
                                dev_dbg(&client->dev, "AD7414 reg %d err %d\n",
                                        AD7414_REG_LIMIT[i], value);
                        else
                                data->temps[i] = value;
                }

                data->next_update = jiffies + HZ + HZ / 2;
                data->valid = 1;
        }

        mutex_unlock(&data->lock);

        return data;
}

static ssize_t show_temp_input(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct ad7414_data *data = ad7414_update_device(dev);
        return sprintf(buf, "%d\n", ad7414_temp_from_reg(data->temp_input));
}
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);

static ssize_t show_max_min(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        int index = to_sensor_dev_attr(attr)->index;
        struct ad7414_data *data = ad7414_update_device(dev);
        return sprintf(buf, "%d\n", data->temps[index] * 1000);
}

static ssize_t set_max_min(struct device *dev,
                           struct device_attribute *attr,
                           const char *buf, size_t count)
{
        struct ad7414_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int index = to_sensor_dev_attr(attr)->index;
        u8 reg = AD7414_REG_LIMIT[index];
        long temp;
        int ret = kstrtol(buf, 10, &temp);

        if (ret < 0)
                return ret;

        temp = clamp_val(temp, -40000, 85000);
        temp = (temp + (temp < 0 ? -500 : 500)) / 1000;

        mutex_lock(&data->lock);
        data->temps[index] = temp;
        ad7414_write(client, reg, temp);
        mutex_unlock(&data->lock);
        return count;
}

static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
                          show_max_min, set_max_min, 0);
static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
                          show_max_min, set_max_min, 1);

static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        int bitnr = to_sensor_dev_attr(attr)->index;
        struct ad7414_data *data = ad7414_update_device(dev);
        int value = (data->temp_input >> bitnr) & 1;
        return sprintf(buf, "%d\n", value);
}

static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 3);
static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 4);

static struct attribute *ad7414_attrs[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_min.dev_attr.attr,
        &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
        &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
        NULL
};

ATTRIBUTE_GROUPS(ad7414);

static int ad7414_probe(struct i2c_client *client,
                        const struct i2c_device_id *dev_id)
{
        struct device *dev = &client->dev;
        struct ad7414_data *data;
        struct device *hwmon_dev;
        int conf;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                                     I2C_FUNC_SMBUS_READ_WORD_DATA))
                return -EOPNOTSUPP;

        data = devm_kzalloc(dev, sizeof(struct ad7414_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->client = client;
        mutex_init(&data->lock);

        dev_info(&client->dev, "chip found\n");

        /* Make sure the chip is powered up. */
        conf = i2c_smbus_read_byte_data(client, AD7414_REG_CONF);
        if (conf < 0)
                dev_warn(dev, "ad7414_probe unable to read config register.\n");
        else {
                conf &= ~(1 << 7);
                i2c_smbus_write_byte_data(client, AD7414_REG_CONF, conf);
        }

        hwmon_dev = devm_hwmon_device_register_with_groups(dev,
                                                           client->name,
                                                           data, ad7414_groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id ad7414_id[] = {
        { "ad7414", 0 },
        {}
};
MODULE_DEVICE_TABLE(i2c, ad7414_id);

static struct i2c_driver ad7414_driver = {
        .driver = {
                .name   = "ad7414",
        },
        .probe  = ad7414_probe,
        .id_table = ad7414_id,
};

module_i2c_driver(ad7414_driver);

MODULE_AUTHOR("Stefan Roese <sr at denx.de>, "
              "Frank Edelhaeuser <frank.edelhaeuser at spansion.com>");

MODULE_DESCRIPTION("AD7414 driver");
MODULE_LICENSE("GPL");