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/of.h>
 #include <linux/of_device.h>

 #include <linux/platform_data/ntc_thermistor.h>

 #include <linux/iio/iio.h>
 #include <linux/iio/machine.h>
 #include <linux/iio/driver.h>
 #include <linux/iio/consumer.h>

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

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

 /* Order matters, ntc_match references the entries by index */
 static const struct platform_device_id ntc_thermistor_id[] = {
 	{ "ncp15wb473", TYPE_NCPXXWB473 },
 	{ "ncp18wb473", TYPE_NCPXXWB473 },
 	{ "ncp21wb473", TYPE_NCPXXWB473 },
 	{ "ncp03wb473", TYPE_NCPXXWB473 },
 	{ "ncp15wl333", TYPE_NCPXXWL333 },
 	{ "b57330v2103", TYPE_B57330V2103},
 	{ "ncp03wf104", TYPE_NCPXXWF104 },
 	{ "ncp15xh103", TYPE_NCPXXXH103 },
 	{ },
 };

 /*
  * 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
  */
 static 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 },
 };
 static 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 },
 };

 static const struct ntc_compensation ncpXXwf104[] = {
 	{ .temp_c	= -40, .ohm	= 4397119 },
 	{ .temp_c	= -35, .ohm	= 3088599 },
 	{ .temp_c	= -30, .ohm	= 2197225 },
 	{ .temp_c	= -25, .ohm	= 1581881 },
 	{ .temp_c	= -20, .ohm	= 1151037 },
 	{ .temp_c	= -15, .ohm	= 846579 },
 	{ .temp_c	= -10, .ohm	= 628988 },
 	{ .temp_c	= -5, .ohm	= 471632 },
 	{ .temp_c	= 0, .ohm	= 357012 },
 	{ .temp_c	= 5, .ohm	= 272500 },
 	{ .temp_c	= 10, .ohm	= 209710 },
 	{ .temp_c	= 15, .ohm	= 162651 },
 	{ .temp_c	= 20, .ohm	= 127080 },
 	{ .temp_c	= 25, .ohm	= 100000 },
 	{ .temp_c	= 30, .ohm	= 79222 },
 	{ .temp_c	= 35, .ohm	= 63167 },
 	{ .temp_c	= 40, .ohm	= 50677 },
 	{ .temp_c	= 45, .ohm	= 40904 },
 	{ .temp_c	= 50, .ohm	= 33195 },
 	{ .temp_c	= 55, .ohm	= 27091 },
 	{ .temp_c	= 60, .ohm	= 22224 },
 	{ .temp_c	= 65, .ohm	= 18323 },
 	{ .temp_c	= 70, .ohm	= 15184 },
 	{ .temp_c	= 75, .ohm	= 12635 },
 	{ .temp_c	= 80, .ohm	= 10566 },
 	{ .temp_c	= 85, .ohm	= 8873 },
 	{ .temp_c	= 90, .ohm	= 7481 },
 	{ .temp_c	= 95, .ohm	= 6337 },
 	{ .temp_c	= 100, .ohm	= 5384 },
 	{ .temp_c	= 105, .ohm	= 4594 },
 	{ .temp_c	= 110, .ohm	= 3934 },
 	{ .temp_c	= 115, .ohm	= 3380 },
 	{ .temp_c	= 120, .ohm	= 2916 },
 	{ .temp_c	= 125, .ohm	= 2522 },
 };

 static const struct ntc_compensation ncpXXxh103[] = {
 	{ .temp_c	= -40, .ohm	= 247565 },
 	{ .temp_c	= -35, .ohm	= 181742 },
 	{ .temp_c	= -30, .ohm	= 135128 },
 	{ .temp_c	= -25, .ohm	= 101678 },
 	{ .temp_c	= -20, .ohm	= 77373 },
 	{ .temp_c	= -15, .ohm	= 59504 },
 	{ .temp_c	= -10, .ohm	= 46222 },
 	{ .temp_c	= -5, .ohm	= 36244 },
 	{ .temp_c	= 0, .ohm	= 28674 },
 	{ .temp_c	= 5, .ohm	= 22878 },
 	{ .temp_c	= 10, .ohm	= 18399 },
 	{ .temp_c	= 15, .ohm	= 14910 },
 	{ .temp_c	= 20, .ohm	= 12169 },
 	{ .temp_c	= 25, .ohm	= 10000 },
 	{ .temp_c	= 30, .ohm	= 8271 },
 	{ .temp_c	= 35, .ohm	= 6883 },
 	{ .temp_c	= 40, .ohm	= 5762 },
 	{ .temp_c	= 45, .ohm	= 4851 },
 	{ .temp_c	= 50, .ohm	= 4105 },
 	{ .temp_c	= 55, .ohm	= 3492 },
 	{ .temp_c	= 60, .ohm	= 2985 },
 	{ .temp_c	= 65, .ohm	= 2563 },
 	{ .temp_c	= 70, .ohm	= 2211 },
 	{ .temp_c	= 75, .ohm	= 1915 },
 	{ .temp_c	= 80, .ohm	= 1666 },
 	{ .temp_c	= 85, .ohm	= 1454 },
 	{ .temp_c	= 90, .ohm	= 1275 },
 	{ .temp_c	= 95, .ohm	= 1121 },
 	{ .temp_c	= 100, .ohm	= 990 },
 	{ .temp_c	= 105, .ohm	= 876 },
 	{ .temp_c	= 110, .ohm	= 779 },
 	{ .temp_c	= 115, .ohm	= 694 },
 	{ .temp_c	= 120, .ohm	= 620 },
 	{ .temp_c	= 125, .ohm	= 556 },
 };

 /*
  * The following compensation table is from the specification of EPCOS NTC
  * Thermistors Datasheet
  */
 static const struct ntc_compensation b57330v2103[] = {
 	{ .temp_c	= -40, .ohm	= 190030 },
 	{ .temp_c	= -35, .ohm	= 145360 },
 	{ .temp_c	= -30, .ohm	= 112060 },
 	{ .temp_c	= -25, .ohm	= 87041 },
 	{ .temp_c	= -20, .ohm	= 68104 },
 	{ .temp_c	= -15, .ohm	= 53665 },
 	{ .temp_c	= -10, .ohm	= 42576 },
 	{ .temp_c	= -5, .ohm	= 34001 },
 	{ .temp_c	= 0, .ohm	= 27326 },
 	{ .temp_c	= 5, .ohm	= 22096 },
 	{ .temp_c	= 10, .ohm	= 17973 },
 	{ .temp_c	= 15, .ohm	= 14703 },
 	{ .temp_c	= 20, .ohm	= 12090 },
 	{ .temp_c	= 25, .ohm	= 10000 },
 	{ .temp_c	= 30, .ohm	= 8311 },
 	{ .temp_c	= 35, .ohm	= 6941 },
 	{ .temp_c	= 40, .ohm	= 5825 },
 	{ .temp_c	= 45, .ohm	= 4911 },
 	{ .temp_c	= 50, .ohm	= 4158 },
 	{ .temp_c	= 55, .ohm	= 3536 },
 	{ .temp_c	= 60, .ohm	= 3019 },
 	{ .temp_c	= 65, .ohm	= 2588 },
 	{ .temp_c	= 70, .ohm	= 2227 },
 	{ .temp_c	= 75, .ohm	= 1924 },
 	{ .temp_c	= 80, .ohm	= 1668 },
 	{ .temp_c	= 85, .ohm	= 1451 },
 	{ .temp_c	= 90, .ohm	= 1266 },
 	{ .temp_c	= 95, .ohm	= 1108 },
 	{ .temp_c	= 100, .ohm	= 973 },
 	{ .temp_c	= 105, .ohm	= 857 },
 	{ .temp_c	= 110, .ohm	= 757 },
 	{ .temp_c	= 115, .ohm	= 671 },
 	{ .temp_c	= 120, .ohm	= 596 },
 	{ .temp_c	= 125, .ohm	= 531 },
 };

 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];
 	struct thermal_zone_device *tz;
 };

 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO)
 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
 {
 	struct iio_channel *channel = pdata->chan;
 	int raw, uv, ret;

 	ret = iio_read_channel_raw(channel, &raw);
 	if (ret < 0) {
 		pr_err("read channel() error: %d\n", ret);
 		return ret;
 	}

 	ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
 	if (ret < 0) {
 		/* Assume 12 bit ADC with vref at pullup_uv */
 		uv = (pdata->pullup_uv * (s64)raw) >> 12;
 	}

 	return uv;
 }

 static const struct of_device_id ntc_match[] = {
 	{ .compatible = "murata,ncp15wb473",
 		.data = &ntc_thermistor_id[0] },
 	{ .compatible = "murata,ncp18wb473",
 		.data = &ntc_thermistor_id[1] },
 	{ .compatible = "murata,ncp21wb473",
 		.data = &ntc_thermistor_id[2] },
 	{ .compatible = "murata,ncp03wb473",
 		.data = &ntc_thermistor_id[3] },
 	{ .compatible = "murata,ncp15wl333",
 		.data = &ntc_thermistor_id[4] },
 	{ .compatible = "epcos,b57330v2103",
 		.data = &ntc_thermistor_id[5]},
 	{ .compatible = "murata,ncp03wf104",
 		.data = &ntc_thermistor_id[6] },
 	{ .compatible = "murata,ncp15xh103",
 		.data = &ntc_thermistor_id[7] },

 	/* Usage of vendor name "ntc" is deprecated */
 	{ .compatible = "ntc,ncp15wb473",
 		.data = &ntc_thermistor_id[0] },
 	{ .compatible = "ntc,ncp18wb473",
 		.data = &ntc_thermistor_id[1] },
 	{ .compatible = "ntc,ncp21wb473",
 		.data = &ntc_thermistor_id[2] },
 	{ .compatible = "ntc,ncp03wb473",
 		.data = &ntc_thermistor_id[3] },
 	{ .compatible = "ntc,ncp15wl333",
 		.data = &ntc_thermistor_id[4] },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, ntc_match);

 static struct ntc_thermistor_platform_data *
 ntc_thermistor_parse_dt(struct platform_device *pdev)
 {
 	struct iio_channel *chan;
 	enum iio_chan_type type;
 	struct device_node *np = pdev->dev.of_node;
 	struct ntc_thermistor_platform_data *pdata;
 	int ret;

 	if (!np)
 		return NULL;

 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
 		return ERR_PTR(-ENOMEM);

 	chan = iio_channel_get(&pdev->dev, NULL);
 	if (IS_ERR(chan))
 		return ERR_CAST(chan);

 	ret = iio_get_channel_type(chan, &type);
 	if (ret < 0)
 		return ERR_PTR(ret);

 	if (type != IIO_VOLTAGE)
 		return ERR_PTR(-EINVAL);

 	if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv))
 		return ERR_PTR(-ENODEV);
 	if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
 		return ERR_PTR(-ENODEV);
 	if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
 		return ERR_PTR(-ENODEV);

 	if (of_find_property(np, "connected-positive", NULL))
 		pdata->connect = NTC_CONNECTED_POSITIVE;
 	else /* status change should be possible if not always on. */
 		pdata->connect = NTC_CONNECTED_GROUND;

 	pdata->chan = chan;
 	pdata->read_uv = ntc_adc_iio_read;

 	return pdata;
 }
 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
 {
 	if (pdata->chan)
 		iio_channel_release(pdata->chan);
 }
 #else
 static struct ntc_thermistor_platform_data *
 ntc_thermistor_parse_dt(struct platform_device *pdev)
 {
 	return NULL;
 }

 #define ntc_match	NULL

 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
 { }
 #endif

 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 int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
 {
 	struct ntc_thermistor_platform_data *pdata = data->pdata;
 	u32 puv = pdata->pullup_uv;
 	u64 n, puo, pdo;
 	puo = pdata->pullup_ohm;
 	pdo = pdata->pulldown_ohm;

 	if (uv == 0)
 		return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 			INT_MAX : 0;
 	if (uv >= puv)
 		return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 			0 : INT_MAX;

 	if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0)
 		n = div_u64(pdo * (puv - uv), uv);
 	else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0)
 		n = div_u64(puo * uv, puv - uv);
 	else if (pdata->connect == NTC_CONNECTED_POSITIVE)
 		n = div64_u64_safe(pdo * puo * (puv - uv),
 				puo * uv - pdo * (puv - uv));
 	else
 		n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv);

 	if (n > INT_MAX)
 		n = INT_MAX;
 	return n;
 }

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

 	/*
 	 * Handle special cases: Resistance is higher than or equal to
 	 * resistance in first table entry, or resistance is lower or equal
 	 * to resistance in last table entry.
 	 * In these cases, return i_low == i_high, either pointing to the
 	 * beginning or to the end of the table depending on the condition.
 	 */
 	if (ohm >= data->comp[0].ohm) {
 		*i_low = 0;
 		*i_high = 0;
 		return;
 	}
 	if (ohm <= data->comp[data->n_comp - 1].ohm) {
 		*i_low = data->n_comp - 1;
 		*i_high = data->n_comp - 1;
 		return;
 	}

 	/* Do a binary search on compensation table */
 	start = 0;
 	end = data->n_comp;
 	while (start < end) {
 		mid = start + (end - start) / 2;
 		/*
 		 * start <= mid < end
 		 * data->comp[start].ohm > ohm >= data->comp[end].ohm
 		 *
 		 * We could check for "ohm == data->comp[mid].ohm" here, but
 		 * that is a quite unlikely condition, and we would have to
 		 * check again after updating start. Check it at the end instead
 		 * for simplicity.
 		 */
 		if (ohm >= data->comp[mid].ohm) {
 			end = mid;
 		} else {
 			start = mid + 1;
 			/*
 			 * ohm >= data->comp[start].ohm might be true here,
 			 * since we set start to mid + 1. In that case, we are
 			 * done. We could keep going, but the condition is quite
 			 * likely to occur, so it is worth checking for it.
 			 */
 			if (ohm >= data->comp[start].ohm)
 				end = start;
 		}
 		/*
 		 * start <= end
 		 * data->comp[start].ohm >= ohm >= data->comp[end].ohm
 		 */
 	}
 	/*
 	 * start == end
 	 * ohm >= data->comp[end].ohm
 	 */
 	*i_low = end;
 	if (ohm == data->comp[end].ohm)
 		*i_high = end;
 	else
 		*i_high = end - 1;
 }

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

 	lookup_comp(data, ohm, &low, &high);
 	if (low == high) {
 		/* Unable to use linear approximation */
 		temp = data->comp[low].temp_c * 1000;
 	} 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 temp;
 }

 static int ntc_thermistor_get_ohm(struct ntc_data *data)
 {
 	int read_uv;

 	if (data->pdata->read_ohm)
 		return data->pdata->read_ohm();

 	if (data->pdata->read_uv) {
 		read_uv = data->pdata->read_uv(data->pdata);
 		if (read_uv < 0)
 			return read_uv;
 		return get_ohm_of_thermistor(data, read_uv);
 	}
 	return -EINVAL;
 }

 static int ntc_read_temp(void *dev, int *temp)
 {
 	struct ntc_data *data = dev_get_drvdata(dev);
 	int ohm;

 	ohm = ntc_thermistor_get_ohm(data);
 	if (ohm < 0)
 		return ohm;

 	*temp = get_temp_mc(data, ohm);

 	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 ohm;

 	ohm = ntc_thermistor_get_ohm(data);
 	if (ohm < 0)
 		return ohm;

 	return sprintf(buf, "%d\n", get_temp_mc(data, ohm));
 }

 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 const struct thermal_zone_of_device_ops ntc_of_thermal_ops = {
 	.get_temp = ntc_read_temp,
 };

 static int ntc_thermistor_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *of_id =
 			of_match_device(of_match_ptr(ntc_match), &pdev->dev);
 	const struct platform_device_id *pdev_id;
 	struct ntc_thermistor_platform_data *pdata;
 	struct ntc_data *data;
 	int ret;

 	pdata = ntc_thermistor_parse_dt(pdev);
 	if (IS_ERR(pdata))
 		return PTR_ERR(pdata);
 	else if (pdata == NULL)
 		pdata = dev_get_platdata(&pdev->dev);

 	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 = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);

 	data->dev = &pdev->dev;
 	data->pdata = pdata;
 	strlcpy(data->name, pdev_id->name, sizeof(data->name));

 	switch (pdev_id->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;
 	case TYPE_B57330V2103:
 		data->comp = b57330v2103;
 		data->n_comp = ARRAY_SIZE(b57330v2103);
 		break;
 	case TYPE_NCPXXWF104:
 		data->comp = ncpXXwf104;
 		data->n_comp = ARRAY_SIZE(ncpXXwf104);
 		break;
 	case TYPE_NCPXXXH103:
 		data->comp = ncpXXxh103;
 		data->n_comp = ARRAY_SIZE(ncpXXxh103);
 		break;
 	default:
 		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
 				pdev_id->driver_data, pdev_id->name);
 		return -EINVAL;
 	}

 	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");
 		return ret;
 	}

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

 	dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
 								pdev_id->name);

 	data->tz = thermal_zone_of_sensor_register(data->dev, 0, data->dev,
 						   &ntc_of_thermal_ops);
 	if (IS_ERR(data->tz)) {
 		dev_dbg(&pdev->dev, "Failed to register to thermal fw.\n");
 		data->tz = NULL;
 	}

 	return 0;
 err_after_sysfs:
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 	ntc_iio_channel_release(pdata);
 	return ret;
 }

 static int ntc_thermistor_remove(struct platform_device *pdev)
 {
 	struct ntc_data *data = platform_get_drvdata(pdev);
 	struct ntc_thermistor_platform_data *pdata = data->pdata;

 	hwmon_device_unregister(data->hwmon_dev);
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 	ntc_iio_channel_release(pdata);

 	thermal_zone_of_sensor_unregister(data->dev, data->tz);

 	return 0;
 }

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

 module_platform_driver(ntc_thermistor_driver);

 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/of.h>
	#include <linux/of_device.h>

	#include <linux/platform_data/ntc_thermistor.h>

	#include <linux/iio/iio.h>
	#include <linux/iio/machine.h>
	#include <linux/iio/driver.h>
	#include <linux/iio/consumer.h>

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

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

	/* Order matters, ntc_match references the entries by index */
	static const struct platform_device_id ntc_thermistor_id[] = {
	{ "ncp15wb473", TYPE_NCPXXWB473 },
	{ "ncp18wb473", TYPE_NCPXXWB473 },
	{ "ncp21wb473", TYPE_NCPXXWB473 },
	{ "ncp03wb473", TYPE_NCPXXWB473 },
	{ "ncp15wl333", TYPE_NCPXXWL333 },
	{ "b57330v2103", TYPE_B57330V2103},
	{ "ncp03wf104", TYPE_NCPXXWF104 },
	{ "ncp15xh103", TYPE_NCPXXXH103 },
	{ },
	};

	/*
	* 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
	*/
	static 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 },
	};
	static 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 },
	};

	static const struct ntc_compensation ncpXXwf104[] = {
	{ .temp_c = -40, .ohm = 4397119 },
	{ .temp_c = -35, .ohm = 3088599 },
	{ .temp_c = -30, .ohm = 2197225 },
	{ .temp_c = -25, .ohm = 1581881 },
	{ .temp_c = -20, .ohm = 1151037 },
	{ .temp_c = -15, .ohm = 846579 },
	{ .temp_c = -10, .ohm = 628988 },
	{ .temp_c = -5, .ohm = 471632 },
	{ .temp_c = 0, .ohm = 357012 },
	{ .temp_c = 5, .ohm = 272500 },
	{ .temp_c = 10, .ohm = 209710 },
	{ .temp_c = 15, .ohm = 162651 },
	{ .temp_c = 20, .ohm = 127080 },
	{ .temp_c = 25, .ohm = 100000 },
	{ .temp_c = 30, .ohm = 79222 },
	{ .temp_c = 35, .ohm = 63167 },
	{ .temp_c = 40, .ohm = 50677 },
	{ .temp_c = 45, .ohm = 40904 },
	{ .temp_c = 50, .ohm = 33195 },
	{ .temp_c = 55, .ohm = 27091 },
	{ .temp_c = 60, .ohm = 22224 },
	{ .temp_c = 65, .ohm = 18323 },
	{ .temp_c = 70, .ohm = 15184 },
	{ .temp_c = 75, .ohm = 12635 },
	{ .temp_c = 80, .ohm = 10566 },
	{ .temp_c = 85, .ohm = 8873 },
	{ .temp_c = 90, .ohm = 7481 },
	{ .temp_c = 95, .ohm = 6337 },
	{ .temp_c = 100, .ohm = 5384 },
	{ .temp_c = 105, .ohm = 4594 },
	{ .temp_c = 110, .ohm = 3934 },
	{ .temp_c = 115, .ohm = 3380 },
	{ .temp_c = 120, .ohm = 2916 },
	{ .temp_c = 125, .ohm = 2522 },
	};

	static const struct ntc_compensation ncpXXxh103[] = {
	{ .temp_c = -40, .ohm = 247565 },
	{ .temp_c = -35, .ohm = 181742 },
	{ .temp_c = -30, .ohm = 135128 },
	{ .temp_c = -25, .ohm = 101678 },
	{ .temp_c = -20, .ohm = 77373 },
	{ .temp_c = -15, .ohm = 59504 },
	{ .temp_c = -10, .ohm = 46222 },
	{ .temp_c = -5, .ohm = 36244 },
	{ .temp_c = 0, .ohm = 28674 },
	{ .temp_c = 5, .ohm = 22878 },
	{ .temp_c = 10, .ohm = 18399 },
	{ .temp_c = 15, .ohm = 14910 },
	{ .temp_c = 20, .ohm = 12169 },
	{ .temp_c = 25, .ohm = 10000 },
	{ .temp_c = 30, .ohm = 8271 },
	{ .temp_c = 35, .ohm = 6883 },
	{ .temp_c = 40, .ohm = 5762 },
	{ .temp_c = 45, .ohm = 4851 },
	{ .temp_c = 50, .ohm = 4105 },
	{ .temp_c = 55, .ohm = 3492 },
	{ .temp_c = 60, .ohm = 2985 },
	{ .temp_c = 65, .ohm = 2563 },
	{ .temp_c = 70, .ohm = 2211 },
	{ .temp_c = 75, .ohm = 1915 },
	{ .temp_c = 80, .ohm = 1666 },
	{ .temp_c = 85, .ohm = 1454 },
	{ .temp_c = 90, .ohm = 1275 },
	{ .temp_c = 95, .ohm = 1121 },
	{ .temp_c = 100, .ohm = 990 },
	{ .temp_c = 105, .ohm = 876 },
	{ .temp_c = 110, .ohm = 779 },
	{ .temp_c = 115, .ohm = 694 },
	{ .temp_c = 120, .ohm = 620 },
	{ .temp_c = 125, .ohm = 556 },
	};

	/*
	* The following compensation table is from the specification of EPCOS NTC
	* Thermistors Datasheet
	*/
	static const struct ntc_compensation b57330v2103[] = {
	{ .temp_c = -40, .ohm = 190030 },
	{ .temp_c = -35, .ohm = 145360 },
	{ .temp_c = -30, .ohm = 112060 },
	{ .temp_c = -25, .ohm = 87041 },
	{ .temp_c = -20, .ohm = 68104 },
	{ .temp_c = -15, .ohm = 53665 },
	{ .temp_c = -10, .ohm = 42576 },
	{ .temp_c = -5, .ohm = 34001 },
	{ .temp_c = 0, .ohm = 27326 },
	{ .temp_c = 5, .ohm = 22096 },
	{ .temp_c = 10, .ohm = 17973 },
	{ .temp_c = 15, .ohm = 14703 },
	{ .temp_c = 20, .ohm = 12090 },
	{ .temp_c = 25, .ohm = 10000 },
	{ .temp_c = 30, .ohm = 8311 },
	{ .temp_c = 35, .ohm = 6941 },
	{ .temp_c = 40, .ohm = 5825 },
	{ .temp_c = 45, .ohm = 4911 },
	{ .temp_c = 50, .ohm = 4158 },
	{ .temp_c = 55, .ohm = 3536 },
	{ .temp_c = 60, .ohm = 3019 },
	{ .temp_c = 65, .ohm = 2588 },
	{ .temp_c = 70, .ohm = 2227 },
	{ .temp_c = 75, .ohm = 1924 },
	{ .temp_c = 80, .ohm = 1668 },
	{ .temp_c = 85, .ohm = 1451 },
	{ .temp_c = 90, .ohm = 1266 },
	{ .temp_c = 95, .ohm = 1108 },
	{ .temp_c = 100, .ohm = 973 },
	{ .temp_c = 105, .ohm = 857 },
	{ .temp_c = 110, .ohm = 757 },
	{ .temp_c = 115, .ohm = 671 },
	{ .temp_c = 120, .ohm = 596 },
	{ .temp_c = 125, .ohm = 531 },
	};

	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];
	struct thermal_zone_device *tz;
	};

	#if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO)
	static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
	{
	struct iio_channel *channel = pdata->chan;
	int raw, uv, ret;

	ret = iio_read_channel_raw(channel, &raw);
	if (ret < 0) {
	pr_err("read channel() error: %d\n", ret);
	return ret;
	}

	ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
	if (ret < 0) {
	/* Assume 12 bit ADC with vref at pullup_uv */
	uv = (pdata->pullup_uv * (s64)raw) >> 12;
	}

	return uv;
	}

	static const struct of_device_id ntc_match[] = {
	{ .compatible = "murata,ncp15wb473",
	.data = &ntc_thermistor_id[0] },
	{ .compatible = "murata,ncp18wb473",
	.data = &ntc_thermistor_id[1] },
	{ .compatible = "murata,ncp21wb473",
	.data = &ntc_thermistor_id[2] },
	{ .compatible = "murata,ncp03wb473",
	.data = &ntc_thermistor_id[3] },
	{ .compatible = "murata,ncp15wl333",
	.data = &ntc_thermistor_id[4] },
	{ .compatible = "epcos,b57330v2103",
	.data = &ntc_thermistor_id[5]},
	{ .compatible = "murata,ncp03wf104",
	.data = &ntc_thermistor_id[6] },
	{ .compatible = "murata,ncp15xh103",
	.data = &ntc_thermistor_id[7] },

	/* Usage of vendor name "ntc" is deprecated */
	{ .compatible = "ntc,ncp15wb473",
	.data = &ntc_thermistor_id[0] },
	{ .compatible = "ntc,ncp18wb473",
	.data = &ntc_thermistor_id[1] },
	{ .compatible = "ntc,ncp21wb473",
	.data = &ntc_thermistor_id[2] },
	{ .compatible = "ntc,ncp03wb473",
	.data = &ntc_thermistor_id[3] },
	{ .compatible = "ntc,ncp15wl333",
	.data = &ntc_thermistor_id[4] },
	{ },
	};
	MODULE_DEVICE_TABLE(of, ntc_match);

	static struct ntc_thermistor_platform_data *
	ntc_thermistor_parse_dt(struct platform_device *pdev)
	{
	struct iio_channel *chan;
	enum iio_chan_type type;
	struct device_node *np = pdev->dev.of_node;
	struct ntc_thermistor_platform_data *pdata;
	int ret;

	if (!np)
	return NULL;

	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
	if (!pdata)
	return ERR_PTR(-ENOMEM);

	chan = iio_channel_get(&pdev->dev, NULL);
	if (IS_ERR(chan))
	return ERR_CAST(chan);

	ret = iio_get_channel_type(chan, &type);
	if (ret < 0)
	return ERR_PTR(ret);

	if (type != IIO_VOLTAGE)
	return ERR_PTR(-EINVAL);

	if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv))
	return ERR_PTR(-ENODEV);
	if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
	return ERR_PTR(-ENODEV);
	if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
	return ERR_PTR(-ENODEV);

	if (of_find_property(np, "connected-positive", NULL))
	pdata->connect = NTC_CONNECTED_POSITIVE;
	else /* status change should be possible if not always on. */
	pdata->connect = NTC_CONNECTED_GROUND;

	pdata->chan = chan;
	pdata->read_uv = ntc_adc_iio_read;

	return pdata;
	}
	static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
	{
	if (pdata->chan)
	iio_channel_release(pdata->chan);
	}
	#else
	static struct ntc_thermistor_platform_data *
	ntc_thermistor_parse_dt(struct platform_device *pdev)
	{
	return NULL;
	}

	#define ntc_match NULL

	static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
	{ }
	#endif

	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 int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
	{
	struct ntc_thermistor_platform_data *pdata = data->pdata;
	u32 puv = pdata->pullup_uv;
	u64 n, puo, pdo;
	puo = pdata->pullup_ohm;
	pdo = pdata->pulldown_ohm;

	if (uv == 0)
	return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
	INT_MAX : 0;
	if (uv >= puv)
	return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
	0 : INT_MAX;

	if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0)
	n = div_u64(pdo * (puv - uv), uv);
	else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0)
	n = div_u64(puo * uv, puv - uv);
	else if (pdata->connect == NTC_CONNECTED_POSITIVE)
	n = div64_u64_safe(pdo * puo * (puv - uv),
	puo * uv - pdo * (puv - uv));
	else
	n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv);

	if (n > INT_MAX)
	n = INT_MAX;
	return n;
	}

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

	/*
	* Handle special cases: Resistance is higher than or equal to
	* resistance in first table entry, or resistance is lower or equal
	* to resistance in last table entry.
	* In these cases, return i_low == i_high, either pointing to the
	* beginning or to the end of the table depending on the condition.
	*/
	if (ohm >= data->comp[0].ohm) {
	*i_low = 0;
	*i_high = 0;
	return;
	}
	if (ohm <= data->comp[data->n_comp - 1].ohm) {
	*i_low = data->n_comp - 1;
	*i_high = data->n_comp - 1;
	return;
	}

	/* Do a binary search on compensation table */
	start = 0;
	end = data->n_comp;
	while (start < end) {
	mid = start + (end - start) / 2;
	/*
	* start <= mid < end
	* data->comp[start].ohm > ohm >= data->comp[end].ohm
	*
	* We could check for "ohm == data->comp[mid].ohm" here, but
	* that is a quite unlikely condition, and we would have to
	* check again after updating start. Check it at the end instead
	* for simplicity.
	*/
	if (ohm >= data->comp[mid].ohm) {
	end = mid;
	} else {
	start = mid + 1;
	/*
	* ohm >= data->comp[start].ohm might be true here,
	* since we set start to mid + 1. In that case, we are
	* done. We could keep going, but the condition is quite
	* likely to occur, so it is worth checking for it.
	*/
	if (ohm >= data->comp[start].ohm)
	end = start;
	}
	/*
	* start <= end
	* data->comp[start].ohm >= ohm >= data->comp[end].ohm
	*/
	}
	/*
	* start == end
	* ohm >= data->comp[end].ohm
	*/
	*i_low = end;
	if (ohm == data->comp[end].ohm)
	*i_high = end;
	else
	*i_high = end - 1;
	}

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

	lookup_comp(data, ohm, &low, &high);
	if (low == high) {
	/* Unable to use linear approximation */
	temp = data->comp[low].temp_c * 1000;
	} 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 temp;
	}

	static int ntc_thermistor_get_ohm(struct ntc_data *data)
	{
	int read_uv;

	if (data->pdata->read_ohm)
	return data->pdata->read_ohm();

	if (data->pdata->read_uv) {
	read_uv = data->pdata->read_uv(data->pdata);
	if (read_uv < 0)
	return read_uv;
	return get_ohm_of_thermistor(data, read_uv);
	}
	return -EINVAL;
	}

	static int ntc_read_temp(void dev, int temp)
	{
	struct ntc_data *data = dev_get_drvdata(dev);
	int ohm;

	ohm = ntc_thermistor_get_ohm(data);
	if (ohm < 0)
	return ohm;

	*temp = get_temp_mc(data, ohm);

	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 ohm;

	ohm = ntc_thermistor_get_ohm(data);
	if (ohm < 0)
	return ohm;

	return sprintf(buf, "%d\n", get_temp_mc(data, ohm));
	}

	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 const struct thermal_zone_of_device_ops ntc_of_thermal_ops = {
	.get_temp = ntc_read_temp,
	};

	static int ntc_thermistor_probe(struct platform_device *pdev)
	{
	const struct of_device_id *of_id =
	of_match_device(of_match_ptr(ntc_match), &pdev->dev);
	const struct platform_device_id *pdev_id;
	struct ntc_thermistor_platform_data *pdata;
	struct ntc_data *data;
	int ret;

	pdata = ntc_thermistor_parse_dt(pdev);
	if (IS_ERR(pdata))
	return PTR_ERR(pdata);
	else if (pdata == NULL)
	pdata = dev_get_platdata(&pdev->dev);

	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 = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);

	data->dev = &pdev->dev;
	data->pdata = pdata;
	strlcpy(data->name, pdev_id->name, sizeof(data->name));

	switch (pdev_id->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;
	case TYPE_B57330V2103:
	data->comp = b57330v2103;
	data->n_comp = ARRAY_SIZE(b57330v2103);
	break;
	case TYPE_NCPXXWF104:
	data->comp = ncpXXwf104;
	data->n_comp = ARRAY_SIZE(ncpXXwf104);
	break;
	case TYPE_NCPXXXH103:
	data->comp = ncpXXxh103;
	data->n_comp = ARRAY_SIZE(ncpXXxh103);
	break;
	default:
	dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
	pdev_id->driver_data, pdev_id->name);
	return -EINVAL;
	}

	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");
	return ret;
	}

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

	dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
	pdev_id->name);

	data->tz = thermal_zone_of_sensor_register(data->dev, 0, data->dev,
	&ntc_of_thermal_ops);
	if (IS_ERR(data->tz)) {
	dev_dbg(&pdev->dev, "Failed to register to thermal fw.\n");
	data->tz = NULL;
	}

	return 0;
	err_after_sysfs:
	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
	ntc_iio_channel_release(pdata);
	return ret;
	}

	static int ntc_thermistor_remove(struct platform_device *pdev)
	{
	struct ntc_data *data = platform_get_drvdata(pdev);
	struct ntc_thermistor_platform_data *pdata = data->pdata;

	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
	ntc_iio_channel_release(pdata);

	thermal_zone_of_sensor_unregister(data->dev, data->tz);

	return 0;
	}

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

	module_platform_driver(ntc_thermistor_driver);

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