/*
 * adm9240.c    Part of lm_sensors, Linux kernel modules for hardware
 *              monitoring
 *
 * Copyright (C) 1999   Frodo Looijaard <frodol@dds.nl>
 *                      Philip Edelbrock <phil@netroedge.com>
 * Copyright (C) 2003   Michiel Rook <michiel@grendelproject.nl>
 * Copyright (C) 2005   Grant Coady <gcoady.lk@gmail.com> with valuable
 *                              guidance from Jean Delvare
 *
 * Driver supports      Analog Devices          ADM9240
 *                      Dallas Semiconductor    DS1780
 *                      National Semiconductor  LM81
 *
 * ADM9240 is the reference, DS1780 and LM81 are register compatibles
 *
 * Voltage      Six inputs are scaled by chip, VID also reported
 * Temperature  Chip temperature to 0.5'C, maximum and max_hysteris
 * Fans         2 fans, low speed alarm, automatic fan clock divider
 * Alarms       16-bit map of active alarms
 * Analog Out   0..1250 mV output
 *
 * Chassis Intrusion: clear CI latch with 'echo 0 > intrusion0_alarm'
 *
 * Test hardware: Intel SE440BX-2 desktop motherboard --Grant
 *
 * LM81 extended temp reading not implemented
 *
 * 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/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon-sysfs.h>
#include <linux/hwmon.h>
#include <linux/hwmon-vid.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/jiffies.h>

/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x2c, 0x2d, 0x2e, 0x2f,
                                        I2C_CLIENT_END };

enum chips { adm9240, ds1780, lm81 };

/* ADM9240 registers */
#define ADM9240_REG_MAN_ID              0x3e
#define ADM9240_REG_DIE_REV             0x3f
#define ADM9240_REG_CONFIG              0x40

#define ADM9240_REG_IN(nr)              (0x20 + (nr))   /* 0..5 */
#define ADM9240_REG_IN_MAX(nr)          (0x2b + (nr) * 2)
#define ADM9240_REG_IN_MIN(nr)          (0x2c + (nr) * 2)
#define ADM9240_REG_FAN(nr)             (0x28 + (nr))   /* 0..1 */
#define ADM9240_REG_FAN_MIN(nr)         (0x3b + (nr))
#define ADM9240_REG_INT(nr)             (0x41 + (nr))
#define ADM9240_REG_INT_MASK(nr)        (0x43 + (nr))
#define ADM9240_REG_TEMP                0x27
#define ADM9240_REG_TEMP_MAX(nr)        (0x39 + (nr)) /* 0, 1 = high, hyst */
#define ADM9240_REG_ANALOG_OUT          0x19
#define ADM9240_REG_CHASSIS_CLEAR       0x46
#define ADM9240_REG_VID_FAN_DIV         0x47
#define ADM9240_REG_I2C_ADDR            0x48
#define ADM9240_REG_VID4                0x49
#define ADM9240_REG_TEMP_CONF           0x4b

/* generalised scaling with integer rounding */
static inline int SCALE(long val, int mul, int div)
{
        if (val < 0)
                return (val * mul - div / 2) / div;
        else
                return (val * mul + div / 2) / div;
}

/* adm9240 internally scales voltage measurements */
static const u16 nom_mv[] = { 2500, 2700, 3300, 5000, 12000, 2700 };

static inline unsigned int IN_FROM_REG(u8 reg, int n)
{
        return SCALE(reg, nom_mv[n], 192);
}

static inline u8 IN_TO_REG(unsigned long val, int n)
{
        return clamp_val(SCALE(val, 192, nom_mv[n]), 0, 255);
}

/* temperature range: -40..125, 127 disables temperature alarm */
static inline s8 TEMP_TO_REG(long val)
{
        return clamp_val(SCALE(val, 1, 1000), -40, 127);
}

/* two fans, each with low fan speed limit */
static inline unsigned int FAN_FROM_REG(u8 reg, u8 div)
{
        if (!reg) /* error */
                return -1;

        if (reg == 255)
                return 0;

        return SCALE(1350000, 1, reg * div);
}

/* analog out 0..1250mV */
static inline u8 AOUT_TO_REG(unsigned long val)
{
        return clamp_val(SCALE(val, 255, 1250), 0, 255);
}

static inline unsigned int AOUT_FROM_REG(u8 reg)
{
        return SCALE(reg, 1250, 255);
}

static int adm9240_probe(struct i2c_client *client,
                         const struct i2c_device_id *id);
static int adm9240_detect(struct i2c_client *client,
                          struct i2c_board_info *info);
static void adm9240_init_client(struct i2c_client *client);
static int adm9240_remove(struct i2c_client *client);
static struct adm9240_data *adm9240_update_device(struct device *dev);

/* driver data */
static const struct i2c_device_id adm9240_id[] = {
        { "adm9240", adm9240 },
        { "ds1780", ds1780 },
        { "lm81", lm81 },
        { }
};
MODULE_DEVICE_TABLE(i2c, adm9240_id);

static struct i2c_driver adm9240_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "adm9240",
        },
        .probe          = adm9240_probe,
        .remove         = adm9240_remove,
        .id_table       = adm9240_id,
        .detect         = adm9240_detect,
        .address_list   = normal_i2c,
};

/* per client data */
struct adm9240_data {
        struct device *hwmon_dev;
        struct mutex update_lock;
        char valid;
        unsigned long last_updated_measure;
        unsigned long last_updated_config;

        u8 in[6];               /* ro   in0_input */
        u8 in_max[6];           /* rw   in0_max */
        u8 in_min[6];           /* rw   in0_min */
        u8 fan[2];              /* ro   fan1_input */
        u8 fan_min[2];          /* rw   fan1_min */
        u8 fan_div[2];          /* rw   fan1_div, read-only accessor */
        s16 temp;               /* ro   temp1_input, 9-bit sign-extended */
        s8 temp_max[2];         /* rw   0 -> temp_max, 1 -> temp_max_hyst */
        u16 alarms;             /* ro   alarms */
        u8 aout;                /* rw   aout_output */
        u8 vid;                 /* ro   vid */
        u8 vrm;                 /* --   vrm set on startup, no accessor */
};

/*** sysfs accessors ***/

/* temperature */
static ssize_t show_temp(struct device *dev, struct device_attribute *dummy,
                char *buf)
{
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", data->temp * 500); /* 9-bit value */
}

static ssize_t show_max(struct device *dev, struct device_attribute *devattr,
                char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", data->temp_max[attr->index] * 1000);
}

static ssize_t set_max(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 adm9240_data *data = i2c_get_clientdata(client);
        long val;
        int err;

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

        mutex_lock(&data->update_lock);
        data->temp_max[attr->index] = TEMP_TO_REG(val);
        i2c_smbus_write_byte_data(client, ADM9240_REG_TEMP_MAX(attr->index),
                        data->temp_max[attr->index]);
        mutex_unlock(&data->update_lock);
        return count;
}

static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL);
static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
                show_max, set_max, 0);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
                show_max, set_max, 1);

/* voltage */
static ssize_t show_in(struct device *dev, struct device_attribute *devattr,
                char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", IN_FROM_REG(data->in[attr->index],
                                attr->index));
}

static ssize_t show_in_min(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", IN_FROM_REG(data->in_min[attr->index],
                                attr->index));
}

static ssize_t show_in_max(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", IN_FROM_REG(data->in_max[attr->index],
                                attr->index));
}

static ssize_t set_in_min(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 adm9240_data *data = i2c_get_clientdata(client);
        unsigned long val;
        int err;

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

        mutex_lock(&data->update_lock);
        data->in_min[attr->index] = IN_TO_REG(val, attr->index);
        i2c_smbus_write_byte_data(client, ADM9240_REG_IN_MIN(attr->index),
                        data->in_min[attr->index]);
        mutex_unlock(&data->update_lock);
        return count;
}

static ssize_t set_in_max(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 adm9240_data *data = i2c_get_clientdata(client);
        unsigned long val;
        int err;

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

        mutex_lock(&data->update_lock);
        data->in_max[attr->index] = IN_TO_REG(val, attr->index);
        i2c_smbus_write_byte_data(client, ADM9240_REG_IN_MAX(attr->index),
                        data->in_max[attr->index]);
        mutex_unlock(&data->update_lock);
        return count;
}

#define vin(nr)                                                 \
static SENSOR_DEVICE_ATTR(in##nr##_input, S_IRUGO,              \
                show_in, NULL, nr);                             \
static SENSOR_DEVICE_ATTR(in##nr##_min, S_IRUGO | S_IWUSR,      \
                show_in_min, set_in_min, nr);                   \
static SENSOR_DEVICE_ATTR(in##nr##_max, S_IRUGO | S_IWUSR,      \
                show_in_max, set_in_max, nr);

vin(0);
vin(1);
vin(2);
vin(3);
vin(4);
vin(5);

/* fans */
static ssize_t show_fan(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[attr->index],
                                1 << data->fan_div[attr->index]));
}

static ssize_t show_fan_min(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan_min[attr->index],
                                1 << data->fan_div[attr->index]));
}

static ssize_t show_fan_div(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", 1 << data->fan_div[attr->index]);
}

/* write new fan div, callers must hold data->update_lock */
static void adm9240_write_fan_div(struct i2c_client *client, int nr,
                u8 fan_div)
{
        u8 reg, old, shift = (nr + 2) * 2;

        reg = i2c_smbus_read_byte_data(client, ADM9240_REG_VID_FAN_DIV);
        old = (reg >> shift) & 3;
        reg &= ~(3 << shift);
        reg |= (fan_div << shift);
        i2c_smbus_write_byte_data(client, ADM9240_REG_VID_FAN_DIV, reg);
        dev_dbg(&client->dev,
                "fan%d clock divider changed from %u to %u\n",
                nr + 1, 1 << old, 1 << fan_div);
}

/*
 * set fan speed low limit:
 *
 * - value is zero: disable fan speed low limit alarm
 *
 * - value is below fan speed measurement range: enable fan speed low
 *   limit alarm to be asserted while fan speed too slow to measure
 *
 * - otherwise: select fan clock divider to suit fan speed low limit,
 *   measurement code may adjust registers to ensure fan speed reading
 */
static ssize_t set_fan_min(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 adm9240_data *data = i2c_get_clientdata(client);
        int nr = attr->index;
        u8 new_div;
        unsigned long val;
        int err;

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

        mutex_lock(&data->update_lock);

        if (!val) {
                data->fan_min[nr] = 255;
                new_div = data->fan_div[nr];

                dev_dbg(&client->dev, "fan%u low limit set disabled\n",
                                nr + 1);

        } else if (val < 1350000 / (8 * 254)) {
                new_div = 3;
                data->fan_min[nr] = 254;

                dev_dbg(&client->dev, "fan%u low limit set minimum %u\n",
                                nr + 1, FAN_FROM_REG(254, 1 << new_div));

        } else {
                unsigned int new_min = 1350000 / val;

                new_div = 0;
                while (new_min > 192 && new_div < 3) {
                        new_div++;
                        new_min /= 2;
                }
                if (!new_min) /* keep > 0 */
                        new_min++;

                data->fan_min[nr] = new_min;

                dev_dbg(&client->dev, "fan%u low limit set fan speed %u\n",
                                nr + 1, FAN_FROM_REG(new_min, 1 << new_div));
        }

        if (new_div != data->fan_div[nr]) {
                data->fan_div[nr] = new_div;
                adm9240_write_fan_div(client, nr, new_div);
        }
        i2c_smbus_write_byte_data(client, ADM9240_REG_FAN_MIN(nr),
                        data->fan_min[nr]);

        mutex_unlock(&data->update_lock);
        return count;
}

#define fan(nr)                                                 \
static SENSOR_DEVICE_ATTR(fan##nr##_input, S_IRUGO,             \
                show_fan, NULL, nr - 1);                        \
static SENSOR_DEVICE_ATTR(fan##nr##_div, S_IRUGO,               \
                show_fan_div, NULL, nr - 1);                    \
static SENSOR_DEVICE_ATTR(fan##nr##_min, S_IRUGO | S_IWUSR,     \
                show_fan_min, set_fan_min, nr - 1);

fan(1);
fan(2);

/* alarms */
static ssize_t show_alarms(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%u\n", data->alarms);
}
static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);

static ssize_t show_alarm(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        int bitnr = to_sensor_dev_attr(attr)->index;
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
}
static SENSOR_DEVICE_ATTR(in0_alarm, S_IRUGO, show_alarm, NULL, 0);
static SENSOR_DEVICE_ATTR(in1_alarm, S_IRUGO, show_alarm, NULL, 1);
static SENSOR_DEVICE_ATTR(in2_alarm, S_IRUGO, show_alarm, NULL, 2);
static SENSOR_DEVICE_ATTR(in3_alarm, S_IRUGO, show_alarm, NULL, 3);
static SENSOR_DEVICE_ATTR(in4_alarm, S_IRUGO, show_alarm, NULL, 8);
static SENSOR_DEVICE_ATTR(in5_alarm, S_IRUGO, show_alarm, NULL, 9);
static SENSOR_DEVICE_ATTR(temp1_alarm, S_IRUGO, show_alarm, NULL, 4);
static SENSOR_DEVICE_ATTR(fan1_alarm, S_IRUGO, show_alarm, NULL, 6);
static SENSOR_DEVICE_ATTR(fan2_alarm, S_IRUGO, show_alarm, NULL, 7);

/* vid */
static ssize_t show_vid(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", vid_from_reg(data->vid, data->vrm));
}
static DEVICE_ATTR(cpu0_vid, S_IRUGO, show_vid, NULL);

/* analog output */
static ssize_t show_aout(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct adm9240_data *data = adm9240_update_device(dev);
        return sprintf(buf, "%d\n", AOUT_FROM_REG(data->aout));
}

static ssize_t set_aout(struct device *dev,
                struct device_attribute *attr,
                const char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct adm9240_data *data = i2c_get_clientdata(client);
        long val;
        int err;

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

        mutex_lock(&data->update_lock);
        data->aout = AOUT_TO_REG(val);
        i2c_smbus_write_byte_data(client, ADM9240_REG_ANALOG_OUT, data->aout);
        mutex_unlock(&data->update_lock);
        return count;
}
static DEVICE_ATTR(aout_output, S_IRUGO | S_IWUSR, show_aout, set_aout);

static ssize_t chassis_clear(struct device *dev,
                struct device_attribute *attr,
                const char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct adm9240_data *data = i2c_get_clientdata(client);
        unsigned long val;

        if (kstrtoul(buf, 10, &val) || val != 0)
                return -EINVAL;

        mutex_lock(&data->update_lock);
        i2c_smbus_write_byte_data(client, ADM9240_REG_CHASSIS_CLEAR, 0x80);
        data->valid = 0;                /* Force cache refresh */
        mutex_unlock(&data->update_lock);
        dev_dbg(&client->dev, "chassis intrusion latch cleared\n");

        return count;
}
static SENSOR_DEVICE_ATTR(intrusion0_alarm, S_IRUGO | S_IWUSR, show_alarm,
                chassis_clear, 12);

static struct attribute *adm9240_attributes[] = {
        &sensor_dev_attr_in0_input.dev_attr.attr,
        &sensor_dev_attr_in0_min.dev_attr.attr,
        &sensor_dev_attr_in0_max.dev_attr.attr,
        &sensor_dev_attr_in0_alarm.dev_attr.attr,
        &sensor_dev_attr_in1_input.dev_attr.attr,
        &sensor_dev_attr_in1_min.dev_attr.attr,
        &sensor_dev_attr_in1_max.dev_attr.attr,
        &sensor_dev_attr_in1_alarm.dev_attr.attr,
        &sensor_dev_attr_in2_input.dev_attr.attr,
        &sensor_dev_attr_in2_min.dev_attr.attr,
        &sensor_dev_attr_in2_max.dev_attr.attr,
        &sensor_dev_attr_in2_alarm.dev_attr.attr,
        &sensor_dev_attr_in3_input.dev_attr.attr,
        &sensor_dev_attr_in3_min.dev_attr.attr,
        &sensor_dev_attr_in3_max.dev_attr.attr,
        &sensor_dev_attr_in3_alarm.dev_attr.attr,
        &sensor_dev_attr_in4_input.dev_attr.attr,
        &sensor_dev_attr_in4_min.dev_attr.attr,
        &sensor_dev_attr_in4_max.dev_attr.attr,
        &sensor_dev_attr_in4_alarm.dev_attr.attr,
        &sensor_dev_attr_in5_input.dev_attr.attr,
        &sensor_dev_attr_in5_min.dev_attr.attr,
        &sensor_dev_attr_in5_max.dev_attr.attr,
        &sensor_dev_attr_in5_alarm.dev_attr.attr,
        &dev_attr_temp1_input.attr,
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
        &sensor_dev_attr_temp1_alarm.dev_attr.attr,
        &sensor_dev_attr_fan1_input.dev_attr.attr,
        &sensor_dev_attr_fan1_div.dev_attr.attr,
        &sensor_dev_attr_fan1_min.dev_attr.attr,
        &sensor_dev_attr_fan1_alarm.dev_attr.attr,
        &sensor_dev_attr_fan2_input.dev_attr.attr,
        &sensor_dev_attr_fan2_div.dev_attr.attr,
        &sensor_dev_attr_fan2_min.dev_attr.attr,
        &sensor_dev_attr_fan2_alarm.dev_attr.attr,
        &dev_attr_alarms.attr,
        &dev_attr_aout_output.attr,
        &sensor_dev_attr_intrusion0_alarm.dev_attr.attr,
        &dev_attr_cpu0_vid.attr,
        NULL
};

static const struct attribute_group adm9240_group = {
        .attrs = adm9240_attributes,
};


/*** sensor chip detect and driver install ***/

/* Return 0 if detection is successful, -ENODEV otherwise */
static int adm9240_detect(struct i2c_client *new_client,
                          struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = new_client->adapter;
        const char *name = "";
        int address = new_client->addr;
        u8 man_id, die_rev;

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

        /* verify chip: reg address should match i2c address */
        if (i2c_smbus_read_byte_data(new_client, ADM9240_REG_I2C_ADDR)
                        != address) {
                dev_err(&adapter->dev, "detect fail: address match, 0x%02x\n",
                        address);
                return -ENODEV;
        }

        /* check known chip manufacturer */
        man_id = i2c_smbus_read_byte_data(new_client, ADM9240_REG_MAN_ID);
        if (man_id == 0x23) {
                name = "adm9240";
        } else if (man_id == 0xda) {
                name = "ds1780";
        } else if (man_id == 0x01) {
                name = "lm81";
        } else {
                dev_err(&adapter->dev, "detect fail: unknown manuf, 0x%02x\n",
                        man_id);
                return -ENODEV;
        }

        /* successful detect, print chip info */
        die_rev = i2c_smbus_read_byte_data(new_client, ADM9240_REG_DIE_REV);
        dev_info(&adapter->dev, "found %s revision %u\n",
                 man_id == 0x23 ? "ADM9240" :
                 man_id == 0xda ? "DS1780" : "LM81", die_rev);

        strlcpy(info->type, name, I2C_NAME_SIZE);

        return 0;
}

static int adm9240_probe(struct i2c_client *new_client,
                         const struct i2c_device_id *id)
{
        struct adm9240_data *data;
        int err;

        data = devm_kzalloc(&new_client->dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

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

        adm9240_init_client(new_client);

        /* populate sysfs filesystem */
        err = sysfs_create_group(&new_client->dev.kobj, &adm9240_group);
        if (err)
                return err;

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

        return 0;

exit_remove:
        sysfs_remove_group(&new_client->dev.kobj, &adm9240_group);
        return err;
}

static int adm9240_remove(struct i2c_client *client)
{
        struct adm9240_data *data = i2c_get_clientdata(client);

        hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&client->dev.kobj, &adm9240_group);

        return 0;
}

static void adm9240_init_client(struct i2c_client *client)
{
        struct adm9240_data *data = i2c_get_clientdata(client);
        u8 conf = i2c_smbus_read_byte_data(client, ADM9240_REG_CONFIG);
        u8 mode = i2c_smbus_read_byte_data(client, ADM9240_REG_TEMP_CONF) & 3;

        data->vrm = vid_which_vrm(); /* need this to report vid as mV */

        dev_info(&client->dev, "Using VRM: %d.%d\n", data->vrm / 10,
                        data->vrm % 10);

        if (conf & 1) { /* measurement cycle running: report state */

                dev_info(&client->dev, "status: config 0x%02x mode %u\n",
                                conf, mode);

        } else { /* cold start: open limits before starting chip */
                int i;

                for (i = 0; i < 6; i++) {
                        i2c_smbus_write_byte_data(client,
                                        ADM9240_REG_IN_MIN(i), 0);
                        i2c_smbus_write_byte_data(client,
                                        ADM9240_REG_IN_MAX(i), 255);
                }
                i2c_smbus_write_byte_data(client,
                                ADM9240_REG_FAN_MIN(0), 255);
                i2c_smbus_write_byte_data(client,
                                ADM9240_REG_FAN_MIN(1), 255);
                i2c_smbus_write_byte_data(client,
                                ADM9240_REG_TEMP_MAX(0), 127);
                i2c_smbus_write_byte_data(client,
                                ADM9240_REG_TEMP_MAX(1), 127);

                /* start measurement cycle */
                i2c_smbus_write_byte_data(client, ADM9240_REG_CONFIG, 1);

                dev_info(&client->dev,
                         "cold start: config was 0x%02x mode %u\n", conf, mode);
        }
}

static struct adm9240_data *adm9240_update_device(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct adm9240_data *data = i2c_get_clientdata(client);
        int i;

        mutex_lock(&data->update_lock);

        /* minimum measurement cycle: 1.75 seconds */
        if (time_after(jiffies, data->last_updated_measure + (HZ * 7 / 4))
                        || !data->valid) {

                for (i = 0; i < 6; i++) { /* read voltages */
                        data->in[i] = i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_IN(i));
                }
                data->alarms = i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_INT(0)) |
                                        i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_INT(1)) << 8;

                /*
                 * read temperature: assume temperature changes less than
                 * 0.5'C per two measurement cycles thus ignore possible
                 * but unlikely aliasing error on lsb reading. --Grant
                 */
                data->temp = ((i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_TEMP) << 8) |
                                        i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_TEMP_CONF)) / 128;

                for (i = 0; i < 2; i++) { /* read fans */
                        data->fan[i] = i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_FAN(i));

                        /* adjust fan clock divider on overflow */
                        if (data->valid && data->fan[i] == 255 &&
                                        data->fan_div[i] < 3) {

                                adm9240_write_fan_div(client, i,
                                                ++data->fan_div[i]);

                                /* adjust fan_min if active, but not to 0 */
                                if (data->fan_min[i] < 255 &&
                                                data->fan_min[i] >= 2)
                                        data->fan_min[i] /= 2;
                        }
                }
                data->last_updated_measure = jiffies;
        }

        /* minimum config reading cycle: 300 seconds */
        if (time_after(jiffies, data->last_updated_config + (HZ * 300))
                        || !data->valid) {

                for (i = 0; i < 6; i++) {
                        data->in_min[i] = i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_IN_MIN(i));
                        data->in_max[i] = i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_IN_MAX(i));
                }
                for (i = 0; i < 2; i++) {
                        data->fan_min[i] = i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_FAN_MIN(i));
                }
                data->temp_max[0] = i2c_smbus_read_byte_data(client,
                                ADM9240_REG_TEMP_MAX(0));
                data->temp_max[1] = i2c_smbus_read_byte_data(client,
                                ADM9240_REG_TEMP_MAX(1));

                /* read fan divs and 5-bit VID */
                i = i2c_smbus_read_byte_data(client, ADM9240_REG_VID_FAN_DIV);
                data->fan_div[0] = (i >> 4) & 3;
                data->fan_div[1] = (i >> 6) & 3;
                data->vid = i & 0x0f;
                data->vid |= (i2c_smbus_read_byte_data(client,
                                        ADM9240_REG_VID4) & 1) << 4;
                /* read analog out */
                data->aout = i2c_smbus_read_byte_data(client,
                                ADM9240_REG_ANALOG_OUT);

                data->last_updated_config = jiffies;
                data->valid = 1;
        }
        mutex_unlock(&data->update_lock);
        return data;
}

module_i2c_driver(adm9240_driver);

MODULE_AUTHOR("Michiel Rook <michiel@grendelproject.nl>, "
                "Grant Coady <gcoady.lk@gmail.com> and others");
MODULE_DESCRIPTION("ADM9240/DS1780/LM81 driver");
MODULE_LICENSE("GPL");