hwmon: Driver for NTC Thermistors (f22aaaa7) · Commits · 戴 / test

Documentation/hwmon/ntc_thermistor

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		Kernel driver ntc_thermistor
		=================

		Supported thermistors:
		* Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, NCP15WL333
		Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473', 'ncp15wl333'
		Datasheet: Publicly available at Murata

		Other NTC thermistors can be supported simply by adding compensation
		tables; e.g., NCP15WL333 support is added by the table ncpXXwl333.

		Authors:
		MyungJoo Ham <myungjoo.ham@samsung.com>

		Description
		-----------

		The NTC thermistor is a simple thermistor that requires users to provide the
		resistance and lookup the corresponding compensation table to get the
		temperature input.

		The NTC driver provides lookup tables with a linear approximation function
		and four circuit models with an option not to use any of the four models.

		The four circuit models provided are:

		$: resister, [TH]: the thermistor

		1. connect = NTC_CONNECTED_POSITIVE, pullup_ohm > 0

		[pullup_uV]
		\| \|
		[TH] $ (pullup_ohm)
		\| \|
		+----+-----------------------[read_uV]
		\|
		$ (pulldown_ohm)
		\|
		--- (ground)

		2. connect = NTC_CONNECTED_POSITIVE, pullup_ohm = 0 (not-connected)

		[pullup_uV]
		\|
		[TH]
		\|
		+----------------------------[read_uV]
		\|
		$ (pulldown_ohm)
		\|
		--- (ground)

		3. connect = NTC_CONNECTED_GROUND, pulldown_ohm > 0

		[pullup_uV]
		\|
		$ (pullup_ohm)
		\|
		+----+-----------------------[read_uV]
		\| \|
		[TH] $ (pulldown_ohm)
		\| \|
		-------- (ground)

		4. connect = NTC_CONNECTED_GROUND, pulldown_ohm = 0 (not-connected)

		[pullup_uV]
		\|
		$ (pullup_ohm)
		\|
		+----------------------------[read_uV]
		\|
		[TH]
		\|
		--- (ground)

		When one of the four circuit models is used, read_uV, pullup_uV, pullup_ohm,
		pulldown_ohm, and connect should be provided. When none of the four models
		are suitable or the user can get the resistance directly, the user should
		provide read_ohm and _not_ provide the others.

		Sysfs Interface
		---------------
		name the mandatory global attribute, the thermistor name.

		temp1_type always 4 (thermistor)
		RO

		temp1_input measure the temperature and provide the measured value.
		(reading this file initiates the reading procedure.)
		RO

		Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.

drivers/hwmon/Kconfig

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		@@ -777,6 +777,20 @@ config SENSORS_MAX6650
		This driver can also be built as a module. If so, the module
		will be called max6650.

		config SENSORS_NTC_THERMISTOR
		tristate "NTC thermistor support"
		depends on EXPERIMENTAL
		help
		This driver supports NTC thermistors sensor reading and its
		interpretation. The driver can also monitor the temperature and
		send notifications about the temperature.

		Currently, this driver supports
		NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, and NCP15WL333.

		This driver can also be built as a module. If so, the module
		will be called ntc-thermistor.

		config SENSORS_PC87360
		tristate "National Semiconductor PC87360 family"
		select HWMON_VID

drivers/hwmon/Makefile

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		@@ -92,6 +92,7 @@ obj-$(CONFIG_SENSORS_MAX6639) += max6639.o
		obj-$(CONFIG_SENSORS_MAX6642) += max6642.o
		obj-$(CONFIG_SENSORS_MAX6650) += max6650.o
		obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
		obj-$(CONFIG_SENSORS_NTC_THERMISTOR) += ntc_thermistor.o
		obj-$(CONFIG_SENSORS_PC87360) += pc87360.o
		obj-$(CONFIG_SENSORS_PC87427) += pc87427.o
		obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o

drivers/hwmon/ntc_thermistor.c

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		/*
		* 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");

include/linux/platform_data/ntc_thermistor.h

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Original line number	Diff line number	Diff line
		/*
		* ntc_thermistor.h - 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
		*/
		#ifndef _LINUX_NTC_H
		#define _LINUX_NTC_H

		enum ntc_thermistor_type {
		TYPE_NCPXXWB473,
		TYPE_NCPXXWL333,
		};

		struct ntc_thermistor_platform_data {
		/*
		* One (not both) of read_uV and read_ohm should be provided and only
		* one of the two should be provided.
		* Both functions should return negative value for an error case.
		*
		* pullup_uV, pullup_ohm, pulldown_ohm, and connect are required to use
		* read_uV()
		*
		* How to setup pullup_ohm, pulldown_ohm, and connect is
		* described at Documentation/hwmon/ntc
		*
		* pullup/down_ohm: 0 for infinite / not-connected
		*/
		int (*read_uV)(void);
		unsigned int pullup_uV;

		unsigned int pullup_ohm;
		unsigned int pulldown_ohm;
		enum { NTC_CONNECTED_POSITIVE, NTC_CONNECTED_GROUND } connect;

		int (*read_ohm)(void);
		};

		#endif /* _LINUX_NTC_H */

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