/*
   * emc2103.c - Support for SMSC EMC2103
   * Copyright (c) 2010 SMSC
   *
   * 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>
  
  /* Addresses scanned */
  static const unsigned short normal_i2c[] = { 0x2E, I2C_CLIENT_END };
  
  static const u8 REG_TEMP[4] = { 0x00, 0x02, 0x04, 0x06 };
  static const u8 REG_TEMP_MIN[4] = { 0x3c, 0x38, 0x39, 0x3a };
  static const u8 REG_TEMP_MAX[4] = { 0x34, 0x30, 0x31, 0x32 };
  
  #define REG_CONF1		0x20
  #define REG_TEMP_MAX_ALARM	0x24
  #define REG_TEMP_MIN_ALARM	0x25
  #define REG_FAN_CONF1		0x42
  #define REG_FAN_TARGET_LO	0x4c
  #define REG_FAN_TARGET_HI	0x4d
  #define REG_FAN_TACH_HI		0x4e
  #define REG_FAN_TACH_LO		0x4f
  #define REG_PRODUCT_ID		0xfd
  #define REG_MFG_ID		0xfe
  
  /* equation 4 from datasheet: rpm = (3932160 * multipler) / count */
  #define FAN_RPM_FACTOR		3932160
  
  /*
   * 2103-2 and 2103-4's 3rd temperature sensor can be connected to two diodes
   * in anti-parallel mode, and in this configuration both can be read
   * independently (so we have 4 temperature inputs).  The device can't
   * detect if it's connected in this mode, so we have to manually enable
   * it.  Default is to leave the device in the state it's already in (-1).
   * This parameter allows APD mode to be optionally forced on or off
   */
  static int apd = -1;
  module_param(apd, bint, 0);
  MODULE_PARM_DESC(init, "Set to zero to disable anti-parallel diode mode");
  
  struct temperature {
  	s8	degrees;
  	u8	fraction;	/* 0-7 multiples of 0.125 */
  };
  
  struct emc2103_data {
  	struct device		*hwmon_dev;
  	struct mutex		update_lock;
  	bool			valid;		/* registers are valid */
  	bool			fan_rpm_control;
  	int			temp_count;	/* num of temp sensors */
  	unsigned long		last_updated;	/* in jiffies */
  	struct temperature	temp[4];	/* internal + 3 external */
  	s8			temp_min[4];	/* no fractional part */
  	s8			temp_max[4];    /* no fractional part */
  	u8			temp_min_alarm;
  	u8			temp_max_alarm;
  	u8			fan_multiplier;
  	u16			fan_tach;
  	u16			fan_target;
  };
  
  static int read_u8_from_i2c(struct i2c_client *client, u8 i2c_reg, u8 *output)
  {
  	int status = i2c_smbus_read_byte_data(client, i2c_reg);
  	if (status < 0) {
  		dev_warn(&client->dev, "reg 0x%02x, err %d
  ",
  			i2c_reg, status);
  	} else {
  		*output = status;
  	}
  	return status;
  }
  
  static void read_temp_from_i2c(struct i2c_client *client, u8 i2c_reg,
  			       struct temperature *temp)
  {
  	u8 degrees, fractional;
  
  	if (read_u8_from_i2c(client, i2c_reg, &degrees) < 0)
  		return;
  
  	if (read_u8_from_i2c(client, i2c_reg + 1, &fractional) < 0)
  		return;
  
  	temp->degrees = degrees;
  	temp->fraction = (fractional & 0xe0) >> 5;
  }
  
  static void read_fan_from_i2c(struct i2c_client *client, u16 *output,
  			      u8 hi_addr, u8 lo_addr)
  {
  	u8 high_byte, lo_byte;
  
  	if (read_u8_from_i2c(client, hi_addr, &high_byte) < 0)
  		return;
  
  	if (read_u8_from_i2c(client, lo_addr, &lo_byte) < 0)
  		return;
  
  	*output = ((u16)high_byte << 5) | (lo_byte >> 3);
  }
  
  static void write_fan_target_to_i2c(struct i2c_client *client, u16 new_target)
  {
  	u8 high_byte = (new_target & 0x1fe0) >> 5;
  	u8 low_byte = (new_target & 0x001f) << 3;
  	i2c_smbus_write_byte_data(client, REG_FAN_TARGET_LO, low_byte);
  	i2c_smbus_write_byte_data(client, REG_FAN_TARGET_HI, high_byte);
  }
  
  static void read_fan_config_from_i2c(struct i2c_client *client)
  
  {
  	struct emc2103_data *data = i2c_get_clientdata(client);
  	u8 conf1;
  
  	if (read_u8_from_i2c(client, REG_FAN_CONF1, &conf1) < 0)
  		return;
  
  	data->fan_multiplier = 1 << ((conf1 & 0x60) >> 5);
  	data->fan_rpm_control = (conf1 & 0x80) != 0;
  }
  
  static struct emc2103_data *emc2103_update_device(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct emc2103_data *data = i2c_get_clientdata(client);
  
  	mutex_lock(&data->update_lock);
  
  	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
  	    || !data->valid) {
  		int i;
  
  		for (i = 0; i < data->temp_count; i++) {
  			read_temp_from_i2c(client, REG_TEMP[i], &data->temp[i]);
  			read_u8_from_i2c(client, REG_TEMP_MIN[i],
  				&data->temp_min[i]);
  			read_u8_from_i2c(client, REG_TEMP_MAX[i],
  				&data->temp_max[i]);
  		}
  
  		read_u8_from_i2c(client, REG_TEMP_MIN_ALARM,
  			&data->temp_min_alarm);
  		read_u8_from_i2c(client, REG_TEMP_MAX_ALARM,
  			&data->temp_max_alarm);
  
  		read_fan_from_i2c(client, &data->fan_tach,
  			REG_FAN_TACH_HI, REG_FAN_TACH_LO);
  		read_fan_from_i2c(client, &data->fan_target,
  			REG_FAN_TARGET_HI, REG_FAN_TARGET_LO);
  		read_fan_config_from_i2c(client);
  
  		data->last_updated = jiffies;
  		data->valid = true;
  	}
  
  	mutex_unlock(&data->update_lock);
  
  	return data;
  }
  
  static ssize_t
  show_temp(struct device *dev, struct device_attribute *da, char *buf)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct emc2103_data *data = emc2103_update_device(dev);
  	int millidegrees = data->temp[nr].degrees * 1000
  		+ data->temp[nr].fraction * 125;
  	return sprintf(buf, "%d
  ", millidegrees);
  }
  
  static ssize_t
  show_temp_min(struct device *dev, struct device_attribute *da, char *buf)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct emc2103_data *data = emc2103_update_device(dev);
  	int millidegrees = data->temp_min[nr] * 1000;
  	return sprintf(buf, "%d
  ", millidegrees);
  }
  
  static ssize_t
  show_temp_max(struct device *dev, struct device_attribute *da, char *buf)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct emc2103_data *data = emc2103_update_device(dev);
  	int millidegrees = data->temp_max[nr] * 1000;
  	return sprintf(buf, "%d
  ", millidegrees);
  }
  
  static ssize_t
  show_temp_fault(struct device *dev, struct device_attribute *da, char *buf)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct emc2103_data *data = emc2103_update_device(dev);
  	bool fault = (data->temp[nr].degrees == -128);
  	return sprintf(buf, "%d
  ", fault ? 1 : 0);
  }
  
  static ssize_t
  show_temp_min_alarm(struct device *dev, struct device_attribute *da, char *buf)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct emc2103_data *data = emc2103_update_device(dev);
  	bool alarm = data->temp_min_alarm & (1 << nr);
  	return sprintf(buf, "%d
  ", alarm ? 1 : 0);
  }
  
  static ssize_t
  show_temp_max_alarm(struct device *dev, struct device_attribute *da, char *buf)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct emc2103_data *data = emc2103_update_device(dev);
  	bool alarm = data->temp_max_alarm & (1 << nr);
  	return sprintf(buf, "%d
  ", alarm ? 1 : 0);
  }
  
  static ssize_t set_temp_min(struct device *dev, struct device_attribute *da,
  			    const char *buf, size_t count)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct i2c_client *client = to_i2c_client(dev);
  	struct emc2103_data *data = i2c_get_clientdata(client);
  	long val;
  
  	int result = kstrtol(buf, 10, &val);
  	if (result < 0)
  		return result;
  
  	val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), -63, 127);
  
  	mutex_lock(&data->update_lock);
  	data->temp_min[nr] = val;
  	i2c_smbus_write_byte_data(client, REG_TEMP_MIN[nr], val);
  	mutex_unlock(&data->update_lock);
  
  	return count;
  }
  
  static ssize_t set_temp_max(struct device *dev, struct device_attribute *da,
  			    const char *buf, size_t count)
  {
  	int nr = to_sensor_dev_attr(da)->index;
  	struct i2c_client *client = to_i2c_client(dev);
  	struct emc2103_data *data = i2c_get_clientdata(client);
  	long val;
  
  	int result = kstrtol(buf, 10, &val);
  	if (result < 0)
  		return result;
  
  	val = clamp_val(DIV_ROUND_CLOSEST(val, 1000), -63, 127);
  
  	mutex_lock(&data->update_lock);
  	data->temp_max[nr] = val;
  	i2c_smbus_write_byte_data(client, REG_TEMP_MAX[nr], val);
  	mutex_unlock(&data->update_lock);
  
  	return count;
  }
  
  static ssize_t
  show_fan(struct device *dev, struct device_attribute *da, char *buf)
  {
  	struct emc2103_data *data = emc2103_update_device(dev);
  	int rpm = 0;
  	if (data->fan_tach != 0)
  		rpm = (FAN_RPM_FACTOR * data->fan_multiplier) / data->fan_tach;
  	return sprintf(buf, "%d
  ", rpm);
  }
  
  static ssize_t
  show_fan_div(struct device *dev, struct device_attribute *da, char *buf)
  {
  	struct emc2103_data *data = emc2103_update_device(dev);
  	int fan_div = 8 / data->fan_multiplier;
  	return sprintf(buf, "%d
  ", fan_div);
  }
  
  /*
   * Note: we also update the fan target here, because its value is
   * determined in part by the fan clock divider.  This follows the principle
   * of least surprise; the user doesn't expect the fan target to change just
   * because the divider changed.
   */
  static ssize_t set_fan_div(struct device *dev, struct device_attribute *da,
  			   const char *buf, size_t count)
  {
  	struct emc2103_data *data = emc2103_update_device(dev);
  	struct i2c_client *client = to_i2c_client(dev);
  	int new_range_bits, old_div = 8 / data->fan_multiplier;
  	long new_div;
  
  	int status = kstrtol(buf, 10, &new_div);
  	if (status < 0)
  		return status;
  
  	if (new_div == old_div) /* No change */
  		return count;
  
  	switch (new_div) {
  	case 1:
  		new_range_bits = 3;
  		break;
  	case 2:
  		new_range_bits = 2;
  		break;
  	case 4:
  		new_range_bits = 1;
  		break;
  	case 8:
  		new_range_bits = 0;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	mutex_lock(&data->update_lock);
  
  	status = i2c_smbus_read_byte_data(client, REG_FAN_CONF1);
  	if (status < 0) {
  		dev_dbg(&client->dev, "reg 0x%02x, err %d
  ",
  			REG_FAN_CONF1, status);
  		mutex_unlock(&data->update_lock);
  		return -EIO;
  	}
  	status &= 0x9F;
  	status |= (new_range_bits << 5);
  	i2c_smbus_write_byte_data(client, REG_FAN_CONF1, status);
  
  	data->fan_multiplier = 8 / new_div;
  
  	/* update fan target if high byte is not disabled */
  	if ((data->fan_target & 0x1fe0) != 0x1fe0) {
  		u16 new_target = (data->fan_target * old_div) / new_div;
  		data->fan_target = min(new_target, (u16)0x1fff);
  		write_fan_target_to_i2c(client, data->fan_target);
  	}
  
  	/* invalidate data to force re-read from hardware */
  	data->valid = false;
  
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  static ssize_t
  show_fan_target(struct device *dev, struct device_attribute *da, char *buf)
  {
  	struct emc2103_data *data = emc2103_update_device(dev);
  	int rpm = 0;
  
  	/* high byte of 0xff indicates disabled so return 0 */
  	if ((data->fan_target != 0) && ((data->fan_target & 0x1fe0) != 0x1fe0))
  		rpm = (FAN_RPM_FACTOR * data->fan_multiplier)
  			/ data->fan_target;
  
  	return sprintf(buf, "%d
  ", rpm);
  }
  
  static ssize_t set_fan_target(struct device *dev, struct device_attribute *da,
  			      const char *buf, size_t count)
  {
  	struct emc2103_data *data = emc2103_update_device(dev);
  	struct i2c_client *client = to_i2c_client(dev);
  	unsigned long rpm_target;
  
  	int result = kstrtoul(buf, 10, &rpm_target);
  	if (result < 0)
  		return result;
  
  	/* Datasheet states 16384 as maximum RPM target (table 3.2) */
  	rpm_target = clamp_val(rpm_target, 0, 16384);
  
  	mutex_lock(&data->update_lock);
  
  	if (rpm_target == 0)
  		data->fan_target = 0x1fff;
  	else
  		data->fan_target = clamp_val(
  			(FAN_RPM_FACTOR * data->fan_multiplier) / rpm_target,
  			0, 0x1fff);
  
  	write_fan_target_to_i2c(client, data->fan_target);
  
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  static ssize_t
  show_fan_fault(struct device *dev, struct device_attribute *da, char *buf)
  {
  	struct emc2103_data *data = emc2103_update_device(dev);
  	bool fault = ((data->fan_tach & 0x1fe0) == 0x1fe0);
  	return sprintf(buf, "%d
  ", fault ? 1 : 0);
  }
  
  static ssize_t
  show_pwm_enable(struct device *dev, struct device_attribute *da, char *buf)
  {
  	struct emc2103_data *data = emc2103_update_device(dev);
  	return sprintf(buf, "%d
  ", data->fan_rpm_control ? 3 : 0);
  }
  
  static ssize_t set_pwm_enable(struct device *dev, struct device_attribute *da,
  			      const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct emc2103_data *data = i2c_get_clientdata(client);
  	long new_value;
  	u8 conf_reg;
  
  	int result = kstrtol(buf, 10, &new_value);
  	if (result < 0)
  		return result;
  
  	mutex_lock(&data->update_lock);
  	switch (new_value) {
  	case 0:
  		data->fan_rpm_control = false;
  		break;
  	case 3:
  		data->fan_rpm_control = true;
  		break;
  	default:
  		count = -EINVAL;
  		goto err;
  	}
  
  	result = read_u8_from_i2c(client, REG_FAN_CONF1, &conf_reg);
  	if (result) {
  		count = result;
  		goto err;
  	}
  
  	if (data->fan_rpm_control)
  		conf_reg |= 0x80;
  	else
  		conf_reg &= ~0x80;
  
  	i2c_smbus_write_byte_data(client, REG_FAN_CONF1, conf_reg);
  err:
  	mutex_unlock(&data->update_lock);
  	return count;
  }
  
  static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
  static SENSOR_DEVICE_ATTR(temp1_min, S_IRUGO | S_IWUSR, show_temp_min,
  	set_temp_min, 0);
  static SENSOR_DEVICE_ATTR(temp1_max, S_IRUGO | S_IWUSR, show_temp_max,
  	set_temp_max, 0);
  static SENSOR_DEVICE_ATTR(temp1_fault, S_IRUGO, show_temp_fault, NULL, 0);
  static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_temp_min_alarm,
  	NULL, 0);
  static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_temp_max_alarm,
  	NULL, 0);
  
  static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp, NULL, 1);
  static SENSOR_DEVICE_ATTR(temp2_min, S_IRUGO | S_IWUSR, show_temp_min,
  	set_temp_min, 1);
  static SENSOR_DEVICE_ATTR(temp2_max, S_IRUGO | S_IWUSR, show_temp_max,
  	set_temp_max, 1);
  static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_temp_fault, NULL, 1);
  static SENSOR_DEVICE_ATTR(temp2_min_alarm, S_IRUGO, show_temp_min_alarm,
  	NULL, 1);
  static SENSOR_DEVICE_ATTR(temp2_max_alarm, S_IRUGO, show_temp_max_alarm,
  	NULL, 1);
  
  static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, show_temp, NULL, 2);
  static SENSOR_DEVICE_ATTR(temp3_min, S_IRUGO | S_IWUSR, show_temp_min,
  	set_temp_min, 2);
  static SENSOR_DEVICE_ATTR(temp3_max, S_IRUGO | S_IWUSR, show_temp_max,
  	set_temp_max, 2);
  static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_temp_fault, NULL, 2);
  static SENSOR_DEVICE_ATTR(temp3_min_alarm, S_IRUGO, show_temp_min_alarm,
  	NULL, 2);
  static SENSOR_DEVICE_ATTR(temp3_max_alarm, S_IRUGO, show_temp_max_alarm,
  	NULL, 2);
  
  static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, show_temp, NULL, 3);
  static SENSOR_DEVICE_ATTR(temp4_min, S_IRUGO | S_IWUSR, show_temp_min,
  	set_temp_min, 3);
  static SENSOR_DEVICE_ATTR(temp4_max, S_IRUGO | S_IWUSR, show_temp_max,
  	set_temp_max, 3);
  static SENSOR_DEVICE_ATTR(temp4_fault, S_IRUGO, show_temp_fault, NULL, 3);
  static SENSOR_DEVICE_ATTR(temp4_min_alarm, S_IRUGO, show_temp_min_alarm,
  	NULL, 3);
  static SENSOR_DEVICE_ATTR(temp4_max_alarm, S_IRUGO, show_temp_max_alarm,
  	NULL, 3);
  
  static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
  static DEVICE_ATTR(fan1_div, S_IRUGO | S_IWUSR, show_fan_div, set_fan_div);
  static DEVICE_ATTR(fan1_target, S_IRUGO | S_IWUSR, show_fan_target,
  	set_fan_target);
  static DEVICE_ATTR(fan1_fault, S_IRUGO, show_fan_fault, NULL);
  
  static DEVICE_ATTR(pwm1_enable, S_IRUGO | S_IWUSR, show_pwm_enable,
  	set_pwm_enable);
  
  /* sensors present on all models */
  static struct attribute *emc2103_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_fault.dev_attr.attr,
  	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp2_input.dev_attr.attr,
  	&sensor_dev_attr_temp2_min.dev_attr.attr,
  	&sensor_dev_attr_temp2_max.dev_attr.attr,
  	&sensor_dev_attr_temp2_fault.dev_attr.attr,
  	&sensor_dev_attr_temp2_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
  	&dev_attr_fan1_input.attr,
  	&dev_attr_fan1_div.attr,
  	&dev_attr_fan1_target.attr,
  	&dev_attr_fan1_fault.attr,
  	&dev_attr_pwm1_enable.attr,
  	NULL
  };
  
  /* extra temperature sensors only present on 2103-2 and 2103-4 */
  static struct attribute *emc2103_attributes_temp3[] = {
  	&sensor_dev_attr_temp3_input.dev_attr.attr,
  	&sensor_dev_attr_temp3_min.dev_attr.attr,
  	&sensor_dev_attr_temp3_max.dev_attr.attr,
  	&sensor_dev_attr_temp3_fault.dev_attr.attr,
  	&sensor_dev_attr_temp3_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp3_max_alarm.dev_attr.attr,
  	NULL
  };
  
  /* extra temperature sensors only present on 2103-2 and 2103-4 in APD mode */
  static struct attribute *emc2103_attributes_temp4[] = {
  	&sensor_dev_attr_temp4_input.dev_attr.attr,
  	&sensor_dev_attr_temp4_min.dev_attr.attr,
  	&sensor_dev_attr_temp4_max.dev_attr.attr,
  	&sensor_dev_attr_temp4_fault.dev_attr.attr,
  	&sensor_dev_attr_temp4_min_alarm.dev_attr.attr,
  	&sensor_dev_attr_temp4_max_alarm.dev_attr.attr,
  	NULL
  };
  
  static const struct attribute_group emc2103_group = {
  	.attrs = emc2103_attributes,
  };
  
  static const struct attribute_group emc2103_temp3_group = {
  	.attrs = emc2103_attributes_temp3,
  };
  
  static const struct attribute_group emc2103_temp4_group = {
  	.attrs = emc2103_attributes_temp4,
  };
  
  static int
  emc2103_probe(struct i2c_client *client, const struct i2c_device_id *id)
  {
  	struct emc2103_data *data;
  	int status;
  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  		return -EIO;
  
  	data = devm_kzalloc(&client->dev, sizeof(struct emc2103_data),
  			    GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, data);
  	mutex_init(&data->update_lock);
  
  	/* 2103-2 and 2103-4 have 3 external diodes, 2103-1 has 1 */
  	status = i2c_smbus_read_byte_data(client, REG_PRODUCT_ID);
  	if (status == 0x24) {
  		/* 2103-1 only has 1 external diode */
  		data->temp_count = 2;
  	} else {
  		/* 2103-2 and 2103-4 have 3 or 4 external diodes */
  		status = i2c_smbus_read_byte_data(client, REG_CONF1);
  		if (status < 0) {
  			dev_dbg(&client->dev, "reg 0x%02x, err %d
  ", REG_CONF1,
  				status);
  			return status;
  		}
  
  		/* detect current state of hardware */
  		data->temp_count = (status & 0x01) ? 4 : 3;
  
  		/* force APD state if module parameter is set */
  		if (apd == 0) {
  			/* force APD mode off */
  			data->temp_count = 3;
  			status &= ~(0x01);
  			i2c_smbus_write_byte_data(client, REG_CONF1, status);
  		} else if (apd == 1) {
  			/* force APD mode on */
  			data->temp_count = 4;
  			status |= 0x01;
  			i2c_smbus_write_byte_data(client, REG_CONF1, status);
  		}
  	}
  
  	/* Register sysfs hooks */
  	status = sysfs_create_group(&client->dev.kobj, &emc2103_group);
  	if (status)
  		return status;
  
  	if (data->temp_count >= 3) {
  		status = sysfs_create_group(&client->dev.kobj,
  			&emc2103_temp3_group);
  		if (status)
  			goto exit_remove;
  	}
  
  	if (data->temp_count == 4) {
  		status = sysfs_create_group(&client->dev.kobj,
  			&emc2103_temp4_group);
  		if (status)
  			goto exit_remove_temp3;
  	}
  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		status = PTR_ERR(data->hwmon_dev);
  		goto exit_remove_temp4;
  	}
  
  	dev_info(&client->dev, "%s: sensor '%s'
  ",
  		 dev_name(data->hwmon_dev), client->name);
  
  	return 0;
  
  exit_remove_temp4:
  	if (data->temp_count == 4)
  		sysfs_remove_group(&client->dev.kobj, &emc2103_temp4_group);
  exit_remove_temp3:
  	if (data->temp_count >= 3)
  		sysfs_remove_group(&client->dev.kobj, &emc2103_temp3_group);
  exit_remove:
  	sysfs_remove_group(&client->dev.kobj, &emc2103_group);
  	return status;
  }
  
  static int emc2103_remove(struct i2c_client *client)
  {
  	struct emc2103_data *data = i2c_get_clientdata(client);
  
  	hwmon_device_unregister(data->hwmon_dev);
  
  	if (data->temp_count == 4)
  		sysfs_remove_group(&client->dev.kobj, &emc2103_temp4_group);
  
  	if (data->temp_count >= 3)
  		sysfs_remove_group(&client->dev.kobj, &emc2103_temp3_group);
  
  	sysfs_remove_group(&client->dev.kobj, &emc2103_group);
  
  	return 0;
  }
  
  static const struct i2c_device_id emc2103_ids[] = {
  	{ "emc2103", 0, },
  	{ /* LIST END */ }
  };
  MODULE_DEVICE_TABLE(i2c, emc2103_ids);
  
  /* Return 0 if detection is successful, -ENODEV otherwise */
  static int
  emc2103_detect(struct i2c_client *new_client, struct i2c_board_info *info)
  {
  	struct i2c_adapter *adapter = new_client->adapter;
  	int manufacturer, product;
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  		return -ENODEV;
  
  	manufacturer = i2c_smbus_read_byte_data(new_client, REG_MFG_ID);
  	if (manufacturer != 0x5D)
  		return -ENODEV;
  
  	product = i2c_smbus_read_byte_data(new_client, REG_PRODUCT_ID);
  	if ((product != 0x24) && (product != 0x26))
  		return -ENODEV;
  
  	strlcpy(info->type, "emc2103", I2C_NAME_SIZE);
  
  	return 0;
  }
  
  static struct i2c_driver emc2103_driver = {
  	.class		= I2C_CLASS_HWMON,
  	.driver = {
  		.name	= "emc2103",
  	},
  	.probe		= emc2103_probe,
  	.remove		= emc2103_remove,
  	.id_table	= emc2103_ids,
  	.detect		= emc2103_detect,
  	.address_list	= normal_i2c,
  };
  
  module_i2c_driver(emc2103_driver);
  
  MODULE_AUTHOR("Steve Glendinning <steve.glendinning@shawell.net>");
  MODULE_DESCRIPTION("SMSC EMC2103 hwmon driver");
  MODULE_LICENSE("GPL");