drivers/hwmon/ntc_thermistor.c - kernel/msm-4.9 - Gitiles

 /*
  * ntc_thermistor.c - NTC Thermistors
  *
  *  Copyright (C) 2010 Samsung Electronics
  *  MyungJoo Ham <myungjoo.ham@samsung.com>
  *
  * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
  */

 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/math64.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>

 #include <linux/platform_data/ntc_thermistor.h>

 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>

 struct ntc_compensation {
 	int		temp_C;
 	unsigned int	ohm;
 };

 /*
  * A compensation table should be sorted by the values of .ohm
  * in descending order.
  * The following compensation tables are from the specification of Murata NTC
  * Thermistors Datasheet
  */
 const struct ntc_compensation ncpXXwb473[] = {
 	{ .temp_C	= -40, .ohm	= 1747920 },
 	{ .temp_C	= -35, .ohm	= 1245428 },
 	{ .temp_C	= -30, .ohm	= 898485 },
 	{ .temp_C	= -25, .ohm	= 655802 },
 	{ .temp_C	= -20, .ohm	= 483954 },
 	{ .temp_C	= -15, .ohm	= 360850 },
 	{ .temp_C	= -10, .ohm	= 271697 },
 	{ .temp_C	= -5, .ohm	= 206463 },
 	{ .temp_C	= 0, .ohm	= 158214 },
 	{ .temp_C	= 5, .ohm	= 122259 },
 	{ .temp_C	= 10, .ohm	= 95227 },
 	{ .temp_C	= 15, .ohm	= 74730 },
 	{ .temp_C	= 20, .ohm	= 59065 },
 	{ .temp_C	= 25, .ohm	= 47000 },
 	{ .temp_C	= 30, .ohm	= 37643 },
 	{ .temp_C	= 35, .ohm	= 30334 },
 	{ .temp_C	= 40, .ohm	= 24591 },
 	{ .temp_C	= 45, .ohm	= 20048 },
 	{ .temp_C	= 50, .ohm	= 16433 },
 	{ .temp_C	= 55, .ohm	= 13539 },
 	{ .temp_C	= 60, .ohm	= 11209 },
 	{ .temp_C	= 65, .ohm	= 9328 },
 	{ .temp_C	= 70, .ohm	= 7798 },
 	{ .temp_C	= 75, .ohm	= 6544 },
 	{ .temp_C	= 80, .ohm	= 5518 },
 	{ .temp_C	= 85, .ohm	= 4674 },
 	{ .temp_C	= 90, .ohm	= 3972 },
 	{ .temp_C	= 95, .ohm	= 3388 },
 	{ .temp_C	= 100, .ohm	= 2902 },
 	{ .temp_C	= 105, .ohm	= 2494 },
 	{ .temp_C	= 110, .ohm	= 2150 },
 	{ .temp_C	= 115, .ohm	= 1860 },
 	{ .temp_C	= 120, .ohm	= 1615 },
 	{ .temp_C	= 125, .ohm	= 1406 },
 };
 const struct ntc_compensation ncpXXwl333[] = {
 	{ .temp_C	= -40, .ohm	= 1610154 },
 	{ .temp_C	= -35, .ohm	= 1130850 },
 	{ .temp_C	= -30, .ohm	= 802609 },
 	{ .temp_C	= -25, .ohm	= 575385 },
 	{ .temp_C	= -20, .ohm	= 416464 },
 	{ .temp_C	= -15, .ohm	= 304219 },
 	{ .temp_C	= -10, .ohm	= 224193 },
 	{ .temp_C	= -5, .ohm	= 166623 },
 	{ .temp_C	= 0, .ohm	= 124850 },
 	{ .temp_C	= 5, .ohm	= 94287 },
 	{ .temp_C	= 10, .ohm	= 71747 },
 	{ .temp_C	= 15, .ohm	= 54996 },
 	{ .temp_C	= 20, .ohm	= 42455 },
 	{ .temp_C	= 25, .ohm	= 33000 },
 	{ .temp_C	= 30, .ohm	= 25822 },
 	{ .temp_C	= 35, .ohm	= 20335 },
 	{ .temp_C	= 40, .ohm	= 16115 },
 	{ .temp_C	= 45, .ohm	= 12849 },
 	{ .temp_C	= 50, .ohm	= 10306 },
 	{ .temp_C	= 55, .ohm	= 8314 },
 	{ .temp_C	= 60, .ohm	= 6746 },
 	{ .temp_C	= 65, .ohm	= 5503 },
 	{ .temp_C	= 70, .ohm	= 4513 },
 	{ .temp_C	= 75, .ohm	= 3721 },
 	{ .temp_C	= 80, .ohm	= 3084 },
 	{ .temp_C	= 85, .ohm	= 2569 },
 	{ .temp_C	= 90, .ohm	= 2151 },
 	{ .temp_C	= 95, .ohm	= 1809 },
 	{ .temp_C	= 100, .ohm	= 1529 },
 	{ .temp_C	= 105, .ohm	= 1299 },
 	{ .temp_C	= 110, .ohm	= 1108 },
 	{ .temp_C	= 115, .ohm	= 949 },
 	{ .temp_C	= 120, .ohm	= 817 },
 	{ .temp_C	= 125, .ohm	= 707 },
 };

 struct ntc_data {
 	struct device *hwmon_dev;
 	struct ntc_thermistor_platform_data *pdata;
 	const struct ntc_compensation *comp;
 	struct device *dev;
 	int n_comp;
 	char name[PLATFORM_NAME_SIZE];
 };

 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 {
 	if (divisor == 0 && dividend == 0)
 		return 0;
 	if (divisor == 0)
 		return UINT_MAX;
 	return div64_u64(dividend, divisor);
 }

 static unsigned int get_ohm_of_thermistor(struct ntc_data *data,
 		unsigned int uV)
 {
 	struct ntc_thermistor_platform_data *pdata = data->pdata;
 	u64 mV = uV / 1000;
 	u64 pmV = pdata->pullup_uV / 1000;
 	u64 N, puO, pdO;
 	puO = pdata->pullup_ohm;
 	pdO = pdata->pulldown_ohm;

 	if (mV == 0) {
 		if (pdata->connect == NTC_CONNECTED_POSITIVE)
 			return UINT_MAX;
 		return 0;
 	}
 	if (mV >= pmV)
 		return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 			0 : UINT_MAX;

 	if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0)
 		N = div64_u64_safe(pdO * (pmV - mV), mV);
 	else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0)
 		N = div64_u64_safe(puO * mV, pmV - mV);
 	else if (pdata->connect == NTC_CONNECTED_POSITIVE)
 		N = div64_u64_safe(pdO * puO * (pmV - mV),
 				puO * mV - pdO * (pmV - mV));
 	else
 		N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV);

 	return (unsigned int) N;
 }

 static int lookup_comp(struct ntc_data *data,
 		unsigned int ohm, int *i_low, int *i_high)
 {
 	int start, end, mid = -1;

 	/* Do a binary search on compensation table */
 	start = 0;
 	end = data->n_comp;

 	while (end > start) {
 		mid = start + (end - start) / 2;
 		if (data->comp[mid].ohm < ohm)
 			end = mid;
 		else if (data->comp[mid].ohm > ohm)
 			start = mid + 1;
 		else
 			break;
 	}

 	if (mid == 0) {
 		if (data->comp[mid].ohm > ohm) {
 			*i_high = mid;
 			*i_low = mid + 1;
 			return 0;
 		} else {
 			*i_low = mid;
 			*i_high = -1;
 			return -EINVAL;
 		}
 	}
 	if (mid == (data->n_comp - 1)) {
 		if (data->comp[mid].ohm <= ohm) {
 			*i_low = mid;
 			*i_high = mid - 1;
 			return 0;
 		} else {
 			*i_low = -1;
 			*i_high = mid;
 			return -EINVAL;
 		}
 	}

 	if (data->comp[mid].ohm <= ohm) {
 		*i_low = mid;
 		*i_high = mid - 1;
 	}
 	if (data->comp[mid].ohm > ohm) {
 		*i_low = mid + 1;
 		*i_high = mid;
 	}

 	return 0;
 }

 static int get_temp_mC(struct ntc_data *data, unsigned int ohm, int *temp)
 {
 	int low, high;
 	int ret;

 	ret = lookup_comp(data, ohm, &low, &high);
 	if (ret) {
 		/* Unable to use linear approximation */
 		if (low != -1)
 			*temp = data->comp[low].temp_C * 1000;
 		else if (high != -1)
 			*temp = data->comp[high].temp_C * 1000;
 		else
 			return ret;
 	} else {
 		*temp = data->comp[low].temp_C * 1000 +
 			((data->comp[high].temp_C - data->comp[low].temp_C) *
 			 1000 * ((int)ohm - (int)data->comp[low].ohm)) /
 			((int)data->comp[high].ohm - (int)data->comp[low].ohm);
 	}

 	return 0;
 }

 static int ntc_thermistor_read(struct ntc_data *data, int *temp)
 {
 	int ret;
 	int read_ohm, read_uV;
 	unsigned int ohm = 0;

 	if (data->pdata->read_ohm) {
 		read_ohm = data->pdata->read_ohm();
 		if (read_ohm < 0)
 			return read_ohm;
 		ohm = (unsigned int)read_ohm;
 	}

 	if (data->pdata->read_uV) {
 		read_uV = data->pdata->read_uV();
 		if (read_uV < 0)
 			return read_uV;
 		ohm = get_ohm_of_thermistor(data, (unsigned int)read_uV);
 	}

 	ret = get_temp_mC(data, ohm, temp);
 	if (ret) {
 		dev_dbg(data->dev, "Sensor reading function not available.\n");
 		return ret;
 	}

 	return 0;
 }

 static ssize_t ntc_show_name(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct ntc_data *data = dev_get_drvdata(dev);

 	return sprintf(buf, "%s\n", data->name);
 }

 static ssize_t ntc_show_type(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	return sprintf(buf, "4\n");
 }

 static ssize_t ntc_show_temp(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct ntc_data *data = dev_get_drvdata(dev);
 	int temp, ret;

 	ret = ntc_thermistor_read(data, &temp);
 	if (ret)
 		return ret;
 	return sprintf(buf, "%d\n", temp);
 }

 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);

 static struct attribute *ntc_attributes[] = {
 	&dev_attr_name.attr,
 	&sensor_dev_attr_temp1_type.dev_attr.attr,
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group ntc_attr_group = {
 	.attrs = ntc_attributes,
 };

 static int __devinit ntc_thermistor_probe(struct platform_device *pdev)
 {
 	struct ntc_data *data;
 	struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
 	int ret = 0;

 	if (!pdata) {
 		dev_err(&pdev->dev, "No platform init data supplied.\n");
 		return -ENODEV;
 	}

 	/* Either one of the two is required. */
 	if (!pdata->read_uV && !pdata->read_ohm) {
 		dev_err(&pdev->dev, "Both read_uV and read_ohm missing."
 				"Need either one of the two.\n");
 		return -EINVAL;
 	}

 	if (pdata->read_uV && pdata->read_ohm) {
 		dev_warn(&pdev->dev, "Only one of read_uV and read_ohm "
 				"is needed; ignoring read_uV.\n");
 		pdata->read_uV = NULL;
 	}

 	if (pdata->read_uV && (pdata->pullup_uV == 0 ||
 				(pdata->pullup_ohm == 0 && pdata->connect ==
 				 NTC_CONNECTED_GROUND) ||
 				(pdata->pulldown_ohm == 0 && pdata->connect ==
 				 NTC_CONNECTED_POSITIVE) ||
 				(pdata->connect != NTC_CONNECTED_POSITIVE &&
 				 pdata->connect != NTC_CONNECTED_GROUND))) {
 		dev_err(&pdev->dev, "Required data to use read_uV not "
 				"supplied.\n");
 		return -EINVAL;
 	}

 	data = kzalloc(sizeof(struct ntc_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->dev = &pdev->dev;
 	data->pdata = pdata;
 	strncpy(data->name, pdev->id_entry->name, PLATFORM_NAME_SIZE);

 	switch (pdev->id_entry->driver_data) {
 	case TYPE_NCPXXWB473:
 		data->comp = ncpXXwb473;
 		data->n_comp = ARRAY_SIZE(ncpXXwb473);
 		break;
 	case TYPE_NCPXXWL333:
 		data->comp = ncpXXwl333;
 		data->n_comp = ARRAY_SIZE(ncpXXwl333);
 		break;
 	default:
 		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
 				pdev->id_entry->driver_data,
 				pdev->id_entry->name);
 		ret = -EINVAL;
 		goto err;
 	}

 	platform_set_drvdata(pdev, data);

 	ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
 	if (ret) {
 		dev_err(data->dev, "unable to create sysfs files\n");
 		goto err;
 	}

 	data->hwmon_dev = hwmon_device_register(data->dev);
 	if (IS_ERR_OR_NULL(data->hwmon_dev)) {
 		dev_err(data->dev, "unable to register as hwmon device.\n");
 		ret = -EINVAL;
 		goto err_after_sysfs;
 	}

 	dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
 			pdev->name, pdev->id, pdev->id_entry->name,
 			pdev->id_entry->driver_data);
 	return 0;
 err_after_sysfs:
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 err:
 	kfree(data);
 	return ret;
 }

 static int __devexit ntc_thermistor_remove(struct platform_device *pdev)
 {
 	struct ntc_data *data = platform_get_drvdata(pdev);

 	hwmon_device_unregister(data->hwmon_dev);
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 	platform_set_drvdata(pdev, NULL);

 	kfree(data);

 	return 0;
 }

 static const struct platform_device_id ntc_thermistor_id[] = {
 	{ "ncp15wb473", TYPE_NCPXXWB473 },
 	{ "ncp18wb473", TYPE_NCPXXWB473 },
 	{ "ncp21wb473", TYPE_NCPXXWB473 },
 	{ "ncp03wb473", TYPE_NCPXXWB473 },
 	{ "ncp15wl333", TYPE_NCPXXWL333 },
 	{ },
 };

 static struct platform_driver ntc_thermistor_driver = {
 	.driver = {
 		.name = "ntc-thermistor",
 		.owner = THIS_MODULE,
 	},
 	.probe = ntc_thermistor_probe,
 	.remove = __devexit_p(ntc_thermistor_remove),
 	.id_table = ntc_thermistor_id,
 };

 static int __init ntc_thermistor_init(void)
 {
 	return platform_driver_register(&ntc_thermistor_driver);
 }

 module_init(ntc_thermistor_init);

 static void __exit ntc_thermistor_cleanup(void)
 {
 	platform_driver_unregister(&ntc_thermistor_driver);
 }

 module_exit(ntc_thermistor_cleanup);

 MODULE_DESCRIPTION("NTC Thermistor Driver");
 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:ntc-thermistor");
	/*
	* ntc_thermistor.c - NTC Thermistors
	*
	* Copyright (C) 2010 Samsung Electronics
	* MyungJoo Ham <myungjoo.ham@samsung.com>
	*
	* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*
	*/

	#include <linux/slab.h>
	#include <linux/module.h>
	#include <linux/pm_runtime.h>
	#include <linux/math64.h>
	#include <linux/platform_device.h>
	#include <linux/err.h>

	#include <linux/platform_data/ntc_thermistor.h>

	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>

	struct ntc_compensation {
	int temp_C;
	unsigned int ohm;
	};

	/*
	* A compensation table should be sorted by the values of .ohm
	* in descending order.
	* The following compensation tables are from the specification of Murata NTC
	* Thermistors Datasheet
	*/
	const struct ntc_compensation ncpXXwb473[] = {
	{ .temp_C = -40, .ohm = 1747920 },
	{ .temp_C = -35, .ohm = 1245428 },
	{ .temp_C = -30, .ohm = 898485 },
	{ .temp_C = -25, .ohm = 655802 },
	{ .temp_C = -20, .ohm = 483954 },
	{ .temp_C = -15, .ohm = 360850 },
	{ .temp_C = -10, .ohm = 271697 },
	{ .temp_C = -5, .ohm = 206463 },
	{ .temp_C = 0, .ohm = 158214 },
	{ .temp_C = 5, .ohm = 122259 },
	{ .temp_C = 10, .ohm = 95227 },
	{ .temp_C = 15, .ohm = 74730 },
	{ .temp_C = 20, .ohm = 59065 },
	{ .temp_C = 25, .ohm = 47000 },
	{ .temp_C = 30, .ohm = 37643 },
	{ .temp_C = 35, .ohm = 30334 },
	{ .temp_C = 40, .ohm = 24591 },
	{ .temp_C = 45, .ohm = 20048 },
	{ .temp_C = 50, .ohm = 16433 },
	{ .temp_C = 55, .ohm = 13539 },
	{ .temp_C = 60, .ohm = 11209 },
	{ .temp_C = 65, .ohm = 9328 },
	{ .temp_C = 70, .ohm = 7798 },
	{ .temp_C = 75, .ohm = 6544 },
	{ .temp_C = 80, .ohm = 5518 },
	{ .temp_C = 85, .ohm = 4674 },
	{ .temp_C = 90, .ohm = 3972 },
	{ .temp_C = 95, .ohm = 3388 },
	{ .temp_C = 100, .ohm = 2902 },
	{ .temp_C = 105, .ohm = 2494 },
	{ .temp_C = 110, .ohm = 2150 },
	{ .temp_C = 115, .ohm = 1860 },
	{ .temp_C = 120, .ohm = 1615 },
	{ .temp_C = 125, .ohm = 1406 },
	};
	const struct ntc_compensation ncpXXwl333[] = {
	{ .temp_C = -40, .ohm = 1610154 },
	{ .temp_C = -35, .ohm = 1130850 },
	{ .temp_C = -30, .ohm = 802609 },
	{ .temp_C = -25, .ohm = 575385 },
	{ .temp_C = -20, .ohm = 416464 },
	{ .temp_C = -15, .ohm = 304219 },
	{ .temp_C = -10, .ohm = 224193 },
	{ .temp_C = -5, .ohm = 166623 },
	{ .temp_C = 0, .ohm = 124850 },
	{ .temp_C = 5, .ohm = 94287 },
	{ .temp_C = 10, .ohm = 71747 },
	{ .temp_C = 15, .ohm = 54996 },
	{ .temp_C = 20, .ohm = 42455 },
	{ .temp_C = 25, .ohm = 33000 },
	{ .temp_C = 30, .ohm = 25822 },
	{ .temp_C = 35, .ohm = 20335 },
	{ .temp_C = 40, .ohm = 16115 },
	{ .temp_C = 45, .ohm = 12849 },
	{ .temp_C = 50, .ohm = 10306 },
	{ .temp_C = 55, .ohm = 8314 },
	{ .temp_C = 60, .ohm = 6746 },
	{ .temp_C = 65, .ohm = 5503 },
	{ .temp_C = 70, .ohm = 4513 },
	{ .temp_C = 75, .ohm = 3721 },
	{ .temp_C = 80, .ohm = 3084 },
	{ .temp_C = 85, .ohm = 2569 },
	{ .temp_C = 90, .ohm = 2151 },
	{ .temp_C = 95, .ohm = 1809 },
	{ .temp_C = 100, .ohm = 1529 },
	{ .temp_C = 105, .ohm = 1299 },
	{ .temp_C = 110, .ohm = 1108 },
	{ .temp_C = 115, .ohm = 949 },
	{ .temp_C = 120, .ohm = 817 },
	{ .temp_C = 125, .ohm = 707 },
	};

	struct ntc_data {
	struct device *hwmon_dev;
	struct ntc_thermistor_platform_data *pdata;
	const struct ntc_compensation *comp;
	struct device *dev;
	int n_comp;
	char name[PLATFORM_NAME_SIZE];
	};

	static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
	{
	if (divisor == 0 && dividend == 0)
	return 0;
	if (divisor == 0)
	return UINT_MAX;
	return div64_u64(dividend, divisor);
	}

	static unsigned int get_ohm_of_thermistor(struct ntc_data *data,
	unsigned int uV)
	{
	struct ntc_thermistor_platform_data *pdata = data->pdata;
	u64 mV = uV / 1000;
	u64 pmV = pdata->pullup_uV / 1000;
	u64 N, puO, pdO;
	puO = pdata->pullup_ohm;
	pdO = pdata->pulldown_ohm;

	if (mV == 0) {
	if (pdata->connect == NTC_CONNECTED_POSITIVE)
	return UINT_MAX;
	return 0;
	}
	if (mV >= pmV)
	return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
	0 : UINT_MAX;

	if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0)
	N = div64_u64_safe(pdO * (pmV - mV), mV);
	else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0)
	N = div64_u64_safe(puO * mV, pmV - mV);
	else if (pdata->connect == NTC_CONNECTED_POSITIVE)
	N = div64_u64_safe(pdO * puO * (pmV - mV),
	puO * mV - pdO * (pmV - mV));
	else
	N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV);

	return (unsigned int) N;
	}

	static int lookup_comp(struct ntc_data *data,
	unsigned int ohm, int i_low, int i_high)
	{
	int start, end, mid = -1;

	/* Do a binary search on compensation table */
	start = 0;
	end = data->n_comp;

	while (end > start) {
	mid = start + (end - start) / 2;
	if (data->comp[mid].ohm < ohm)
	end = mid;
	else if (data->comp[mid].ohm > ohm)
	start = mid + 1;
	else
	break;
	}

	if (mid == 0) {
	if (data->comp[mid].ohm > ohm) {
	*i_high = mid;
	*i_low = mid + 1;
	return 0;
	} else {
	*i_low = mid;
	*i_high = -1;
	return -EINVAL;
	}
	}
	if (mid == (data->n_comp - 1)) {
	if (data->comp[mid].ohm <= ohm) {
	*i_low = mid;
	*i_high = mid - 1;
	return 0;
	} else {
	*i_low = -1;
	*i_high = mid;
	return -EINVAL;
	}
	}

	if (data->comp[mid].ohm <= ohm) {
	*i_low = mid;
	*i_high = mid - 1;
	}
	if (data->comp[mid].ohm > ohm) {
	*i_low = mid + 1;
	*i_high = mid;
	}

	return 0;
	}

	static int get_temp_mC(struct ntc_data data, unsigned int ohm, int temp)
	{
	int low, high;
	int ret;

	ret = lookup_comp(data, ohm, &low, &high);
	if (ret) {
	/* Unable to use linear approximation */
	if (low != -1)
	temp = data->comp[low].temp_C 1000;
	else if (high != -1)
	temp = data->comp[high].temp_C 1000;
	else
	return ret;
	} else {
	temp = data->comp[low].temp_C 1000 +
	((data->comp[high].temp_C - data->comp[low].temp_C) *
	1000 * ((int)ohm - (int)data->comp[low].ohm)) /
	((int)data->comp[high].ohm - (int)data->comp[low].ohm);
	}

	return 0;
	}

	static int ntc_thermistor_read(struct ntc_data data, int temp)
	{
	int ret;
	int read_ohm, read_uV;
	unsigned int ohm = 0;

	if (data->pdata->read_ohm) {
	read_ohm = data->pdata->read_ohm();
	if (read_ohm < 0)
	return read_ohm;
	ohm = (unsigned int)read_ohm;
	}

	if (data->pdata->read_uV) {
	read_uV = data->pdata->read_uV();
	if (read_uV < 0)
	return read_uV;
	ohm = get_ohm_of_thermistor(data, (unsigned int)read_uV);
	}

	ret = get_temp_mC(data, ohm, temp);
	if (ret) {
	dev_dbg(data->dev, "Sensor reading function not available.\n");
	return ret;
	}

	return 0;
	}

	static ssize_t ntc_show_name(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct ntc_data *data = dev_get_drvdata(dev);

	return sprintf(buf, "%s\n", data->name);
	}

	static ssize_t ntc_show_type(struct device *dev,
	struct device_attribute attr, char buf)
	{
	return sprintf(buf, "4\n");
	}

	static ssize_t ntc_show_temp(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct ntc_data *data = dev_get_drvdata(dev);
	int temp, ret;

	ret = ntc_thermistor_read(data, &temp);
	if (ret)
	return ret;
	return sprintf(buf, "%d\n", temp);
	}

	static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
	static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);

	static struct attribute *ntc_attributes[] = {
	&dev_attr_name.attr,
	&sensor_dev_attr_temp1_type.dev_attr.attr,
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group ntc_attr_group = {
	.attrs = ntc_attributes,
	};

	static int __devinit ntc_thermistor_probe(struct platform_device *pdev)
	{
	struct ntc_data *data;
	struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
	int ret = 0;

	if (!pdata) {
	dev_err(&pdev->dev, "No platform init data supplied.\n");
	return -ENODEV;
	}

	/* Either one of the two is required. */
	if (!pdata->read_uV && !pdata->read_ohm) {
	dev_err(&pdev->dev, "Both read_uV and read_ohm missing."
	"Need either one of the two.\n");
	return -EINVAL;
	}

	if (pdata->read_uV && pdata->read_ohm) {
	dev_warn(&pdev->dev, "Only one of read_uV and read_ohm "
	"is needed; ignoring read_uV.\n");
	pdata->read_uV = NULL;
	}

	if (pdata->read_uV && (pdata->pullup_uV == 0 \|\|
	(pdata->pullup_ohm == 0 && pdata->connect ==
	NTC_CONNECTED_GROUND) \|\|
	(pdata->pulldown_ohm == 0 && pdata->connect ==
	NTC_CONNECTED_POSITIVE) \|\|
	(pdata->connect != NTC_CONNECTED_POSITIVE &&
	pdata->connect != NTC_CONNECTED_GROUND))) {
	dev_err(&pdev->dev, "Required data to use read_uV not "
	"supplied.\n");
	return -EINVAL;
	}

	data = kzalloc(sizeof(struct ntc_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->dev = &pdev->dev;
	data->pdata = pdata;
	strncpy(data->name, pdev->id_entry->name, PLATFORM_NAME_SIZE);

	switch (pdev->id_entry->driver_data) {
	case TYPE_NCPXXWB473:
	data->comp = ncpXXwb473;
	data->n_comp = ARRAY_SIZE(ncpXXwb473);
	break;
	case TYPE_NCPXXWL333:
	data->comp = ncpXXwl333;
	data->n_comp = ARRAY_SIZE(ncpXXwl333);
	break;
	default:
	dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
	pdev->id_entry->driver_data,
	pdev->id_entry->name);
	ret = -EINVAL;
	goto err;
	}

	platform_set_drvdata(pdev, data);

	ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
	if (ret) {
	dev_err(data->dev, "unable to create sysfs files\n");
	goto err;
	}

	data->hwmon_dev = hwmon_device_register(data->dev);
	if (IS_ERR_OR_NULL(data->hwmon_dev)) {
	dev_err(data->dev, "unable to register as hwmon device.\n");
	ret = -EINVAL;
	goto err_after_sysfs;
	}

	dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
	pdev->name, pdev->id, pdev->id_entry->name,
	pdev->id_entry->driver_data);
	return 0;
	err_after_sysfs:
	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
	err:
	kfree(data);
	return ret;
	}

	static int __devexit ntc_thermistor_remove(struct platform_device *pdev)
	{
	struct ntc_data *data = platform_get_drvdata(pdev);

	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
	platform_set_drvdata(pdev, NULL);

	kfree(data);

	return 0;
	}

	static const struct platform_device_id ntc_thermistor_id[] = {
	{ "ncp15wb473", TYPE_NCPXXWB473 },
	{ "ncp18wb473", TYPE_NCPXXWB473 },
	{ "ncp21wb473", TYPE_NCPXXWB473 },
	{ "ncp03wb473", TYPE_NCPXXWB473 },
	{ "ncp15wl333", TYPE_NCPXXWL333 },
	{ },
	};

	static struct platform_driver ntc_thermistor_driver = {
	.driver = {
	.name = "ntc-thermistor",
	.owner = THIS_MODULE,
	},
	.probe = ntc_thermistor_probe,
	.remove = __devexit_p(ntc_thermistor_remove),
	.id_table = ntc_thermistor_id,
	};

	static int __init ntc_thermistor_init(void)
	{
	return platform_driver_register(&ntc_thermistor_driver);
	}

	module_init(ntc_thermistor_init);

	static void __exit ntc_thermistor_cleanup(void)
	{
	platform_driver_unregister(&ntc_thermistor_driver);
	}

	module_exit(ntc_thermistor_cleanup);

	MODULE_DESCRIPTION("NTC Thermistor Driver");
	MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:ntc-thermistor");