/*
 * An hwmon driver for the Analog Devices AD7416/17/18
 * Copyright (C) 2006-07 Tower Technologies
 *
 * Author: Alessandro Zummo <a.zummo@towertech.it>
 *
 * Based on lm75.c
 * Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
 *
 * 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 - version 2.
 */

#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/delay.h>

#include "lm75.h"

#define DRV_VERSION "0.3"

/* Addresses to scan */
static unsigned short normal_i2c[] = { 0x28, I2C_CLIENT_END };
/* Insmod parameters */
I2C_CLIENT_INSMOD_3(ad7416, ad7417, ad7418);

/* AD7418 registers */
#define AD7418_REG_TEMP_IN      0x00
#define AD7418_REG_CONF         0x01
#define AD7418_REG_TEMP_HYST    0x02
#define AD7418_REG_TEMP_OS      0x03
#define AD7418_REG_ADC          0x04
#define AD7418_REG_CONF2        0x05

#define AD7418_REG_ADC_CH(x)    ((x) << 5)
#define AD7418_CH_TEMP          AD7418_REG_ADC_CH(0)

static const u8 AD7418_REG_TEMP[] = { AD7418_REG_TEMP_IN,
                                        AD7418_REG_TEMP_HYST,
                                        AD7418_REG_TEMP_OS };

struct ad7418_data {
        struct i2c_client       client;
        struct device           *hwmon_dev;
        struct attribute_group  attrs;
        enum chips              type;
        struct mutex            lock;
        int                     adc_max;        /* number of ADC channels */
        char                    valid;
        unsigned long           last_updated;   /* In jiffies */
        s16                     temp[3];        /* Register values */
        u16                     in[4];
};

static int ad7418_attach_adapter(struct i2c_adapter *adapter);
static int ad7418_detect(struct i2c_adapter *adapter, int address, int kind);
static int ad7418_detach_client(struct i2c_client *client);

static struct i2c_driver ad7418_driver = {
        .driver = {
                .name   = "ad7418",
        },
        .attach_adapter = ad7418_attach_adapter,
        .detach_client  = ad7418_detach_client,
};

/* All registers are word-sized, except for the configuration registers.
 * AD7418 uses a high-byte first convention. Do NOT use those functions to
 * access the configuration registers CONF and CONF2, as they are byte-sized.
 */
static inline int ad7418_read(struct i2c_client *client, u8 reg)
{
        return swab16(i2c_smbus_read_word_data(client, reg));
}

static inline int ad7418_write(struct i2c_client *client, u8 reg, u16 value)
{
        return i2c_smbus_write_word_data(client, reg, swab16(value));
}

static void ad7418_init_client(struct i2c_client *client)
{
        struct ad7418_data *data = i2c_get_clientdata(client);

        int reg = i2c_smbus_read_byte_data(client, AD7418_REG_CONF);
        if (reg < 0) {
                dev_err(&client->dev, "cannot read configuration register\n");
        } else {
                dev_info(&client->dev, "configuring for mode 1\n");
                i2c_smbus_write_byte_data(client, AD7418_REG_CONF, reg & 0xfe);

                if (data->type == ad7417 || data->type == ad7418)
                        i2c_smbus_write_byte_data(client,
                                                AD7418_REG_CONF2, 0x00);
        }
}

static struct ad7418_data *ad7418_update_device(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct ad7418_data *data = i2c_get_clientdata(client);

        mutex_lock(&data->lock);

        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
                || !data->valid) {
                u8 cfg;
                int i, ch;

                /* read config register and clear channel bits */
                cfg = i2c_smbus_read_byte_data(client, AD7418_REG_CONF);
                cfg &= 0x1F;

                i2c_smbus_write_byte_data(client, AD7418_REG_CONF,
                                                cfg | AD7418_CH_TEMP);
                udelay(30);

                for (i = 0; i < 3; i++) {
                        data->temp[i] = ad7418_read(client, AD7418_REG_TEMP[i]);
                }

                for (i = 0, ch = 4; i < data->adc_max; i++, ch--) {
                        i2c_smbus_write_byte_data(client,
                                        AD7418_REG_CONF,
                                        cfg | AD7418_REG_ADC_CH(ch));

                        udelay(15);
                        data->in[data->adc_max - 1 - i] =
                                ad7418_read(client, AD7418_REG_ADC);
                }

                /* restore old configuration value */
                ad7418_write(client, AD7418_REG_CONF, cfg);

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

        mutex_unlock(&data->lock);

        return data;
}

static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
                        char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct ad7418_data *data = ad7418_update_device(dev);
        return sprintf(buf, "%d\n",
                LM75_TEMP_FROM_REG(data->temp[attr->index]));
}

static ssize_t show_adc(struct device *dev, struct device_attribute *devattr,
                        char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct ad7418_data *data = ad7418_update_device(dev);

        return sprintf(buf, "%d\n",
                ((data->in[attr->index] >> 6) * 2500 + 512) / 1024);
}

static ssize_t set_temp(struct device *dev, struct device_attribute *devattr,
                        const char *buf, size_t count)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct i2c_client *client = to_i2c_client(dev);
        struct ad7418_data *data = i2c_get_clientdata(client);
        long temp = simple_strtol(buf, NULL, 10);

        mutex_lock(&data->lock);
        data->temp[attr->index] = LM75_TEMP_TO_REG(temp);
        ad7418_write(client, AD7418_REG_TEMP[attr->index], data->temp[attr->index]);
        mutex_unlock(&data->lock);
        return count;
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, 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(in1_input, S_IRUGO, show_adc, NULL, 0);
static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_adc, NULL, 1);
static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_adc, NULL, 2);
static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_adc, NULL, 3);

static int ad7418_attach_adapter(struct i2c_adapter *adapter)
{
        if (!(adapter->class & I2C_CLASS_HWMON))
                return 0;
        return i2c_probe(adapter, &addr_data, ad7418_detect);
}

static struct attribute *ad7416_attributes[] = {
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        NULL
};

static struct attribute *ad7417_attributes[] = {
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_in1_input.dev_attr.attr,
        &sensor_dev_attr_in2_input.dev_attr.attr,
        &sensor_dev_attr_in3_input.dev_attr.attr,
        &sensor_dev_attr_in4_input.dev_attr.attr,
        NULL
};

static struct attribute *ad7418_attributes[] = {
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_in1_input.dev_attr.attr,
        NULL
};

static int ad7418_detect(struct i2c_adapter *adapter, int address, int kind)
{
        struct i2c_client *client;
        struct ad7418_data *data;
        int err = 0;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                                        I2C_FUNC_SMBUS_WORD_DATA))
                goto exit;

        if (!(data = kzalloc(sizeof(struct ad7418_data), GFP_KERNEL))) {
                err = -ENOMEM;
                goto exit;
        }

        client = &data->client;
        client->addr = address;
        client->adapter = adapter;
        client->driver = &ad7418_driver;

        i2c_set_clientdata(client, data);

        mutex_init(&data->lock);

        /* AD7418 has a curious behaviour on registers 6 and 7. They
         * both always read 0xC071 and are not documented on the datasheet.
         * We use them to detect the chip.
         */
        if (kind <= 0) {
                int reg, reg6, reg7;

                /* the AD7416 lies within this address range, but I have
                 * no means to check.
                 */
                if (address >= 0x48 && address <= 0x4f) {
                        /* XXX add tests for AD7416 here */
                        /* data->type = ad7416; */
                }
                /* here we might have AD7417 or AD7418 */
                else if (address >= 0x28 && address <= 0x2f) {
                        reg6 = i2c_smbus_read_word_data(client, 0x06);
                        reg7 = i2c_smbus_read_word_data(client, 0x07);

                        if (address == 0x28 && reg6 == 0xC071 && reg7 == 0xC071)
                                data->type = ad7418;

                        /* XXX add tests for AD7417 here */


                        /* both AD7417 and AD7418 have bits 0-5 of
                         * the CONF2 register at 0
                         */
                        reg = i2c_smbus_read_byte_data(client,
                                                        AD7418_REG_CONF2);
                        if (reg & 0x3F)
                                data->type = any_chip; /* detection failed */
                }
        } else {
                dev_dbg(&adapter->dev, "detection forced\n");
        }

        if (kind > 0)
                data->type = kind;
        else if (kind < 0 && data->type == any_chip) {
                err = -ENODEV;
                goto exit_free;
        }

        switch (data->type) {
        case any_chip:
        case ad7416:
                data->adc_max = 0;
                data->attrs.attrs = ad7416_attributes;
                strlcpy(client->name, "ad7416", I2C_NAME_SIZE);
                break;

        case ad7417:
                data->adc_max = 4;
                data->attrs.attrs = ad7417_attributes;
                strlcpy(client->name, "ad7417", I2C_NAME_SIZE);
                break;

        case ad7418:
                data->adc_max = 1;
                data->attrs.attrs = ad7418_attributes;
                strlcpy(client->name, "ad7418", I2C_NAME_SIZE);
                break;
        }

        if ((err = i2c_attach_client(client)))
                goto exit_free;

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

        /* Initialize the AD7418 chip */
        ad7418_init_client(client);

        /* Register sysfs hooks */
        if ((err = sysfs_create_group(&client->dev.kobj, &data->attrs)))
                goto exit_detach;

        data->hwmon_dev = hwmon_device_register(&client->dev);
        if (IS_ERR(data->hwmon_dev)) {
                err = PTR_ERR(data->hwmon_dev);
                goto exit_remove;
        }

        return 0;

exit_remove:
        sysfs_remove_group(&client->dev.kobj, &data->attrs);
exit_detach:
        i2c_detach_client(client);
exit_free:
        kfree(data);
exit:
        return err;
}

static int ad7418_detach_client(struct i2c_client *client)
{
        struct ad7418_data *data = i2c_get_clientdata(client);
        hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&client->dev.kobj, &data->attrs);
        i2c_detach_client(client);
        kfree(data);
        return 0;
}

static int __init ad7418_init(void)
{
        return i2c_add_driver(&ad7418_driver);
}

static void __exit ad7418_exit(void)
{
        i2c_del_driver(&ad7418_driver);
}

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("AD7416/17/18 driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

module_init(ad7418_init);
module_exit(ad7418_exit);