2 * ntc_thermistor.c - NTC Thermistors
4 * Copyright (C) 2010 Samsung Electronics
5 * MyungJoo Ham <myungjoo.ham@samsung.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 #include <linux/slab.h>
24 #include <linux/module.h>
25 #include <linux/pm_runtime.h>
26 #include <linux/math64.h>
27 #include <linux/platform_device.h>
28 #include <linux/err.h>
30 #include <linux/platform_data/ntc_thermistor.h>
32 #include <linux/hwmon.h>
33 #include <linux/hwmon-sysfs.h>
35 struct ntc_compensation {
41 * A compensation table should be sorted by the values of .ohm
42 * in descending order.
43 * The following compensation tables are from the specification of Murata NTC
44 * Thermistors Datasheet
46 const struct ntc_compensation ncpXXwb473[] = {
47 { .temp_C = -40, .ohm = 1747920 },
48 { .temp_C = -35, .ohm = 1245428 },
49 { .temp_C = -30, .ohm = 898485 },
50 { .temp_C = -25, .ohm = 655802 },
51 { .temp_C = -20, .ohm = 483954 },
52 { .temp_C = -15, .ohm = 360850 },
53 { .temp_C = -10, .ohm = 271697 },
54 { .temp_C = -5, .ohm = 206463 },
55 { .temp_C = 0, .ohm = 158214 },
56 { .temp_C = 5, .ohm = 122259 },
57 { .temp_C = 10, .ohm = 95227 },
58 { .temp_C = 15, .ohm = 74730 },
59 { .temp_C = 20, .ohm = 59065 },
60 { .temp_C = 25, .ohm = 47000 },
61 { .temp_C = 30, .ohm = 37643 },
62 { .temp_C = 35, .ohm = 30334 },
63 { .temp_C = 40, .ohm = 24591 },
64 { .temp_C = 45, .ohm = 20048 },
65 { .temp_C = 50, .ohm = 16433 },
66 { .temp_C = 55, .ohm = 13539 },
67 { .temp_C = 60, .ohm = 11209 },
68 { .temp_C = 65, .ohm = 9328 },
69 { .temp_C = 70, .ohm = 7798 },
70 { .temp_C = 75, .ohm = 6544 },
71 { .temp_C = 80, .ohm = 5518 },
72 { .temp_C = 85, .ohm = 4674 },
73 { .temp_C = 90, .ohm = 3972 },
74 { .temp_C = 95, .ohm = 3388 },
75 { .temp_C = 100, .ohm = 2902 },
76 { .temp_C = 105, .ohm = 2494 },
77 { .temp_C = 110, .ohm = 2150 },
78 { .temp_C = 115, .ohm = 1860 },
79 { .temp_C = 120, .ohm = 1615 },
80 { .temp_C = 125, .ohm = 1406 },
82 const struct ntc_compensation ncpXXwl333[] = {
83 { .temp_C = -40, .ohm = 1610154 },
84 { .temp_C = -35, .ohm = 1130850 },
85 { .temp_C = -30, .ohm = 802609 },
86 { .temp_C = -25, .ohm = 575385 },
87 { .temp_C = -20, .ohm = 416464 },
88 { .temp_C = -15, .ohm = 304219 },
89 { .temp_C = -10, .ohm = 224193 },
90 { .temp_C = -5, .ohm = 166623 },
91 { .temp_C = 0, .ohm = 124850 },
92 { .temp_C = 5, .ohm = 94287 },
93 { .temp_C = 10, .ohm = 71747 },
94 { .temp_C = 15, .ohm = 54996 },
95 { .temp_C = 20, .ohm = 42455 },
96 { .temp_C = 25, .ohm = 33000 },
97 { .temp_C = 30, .ohm = 25822 },
98 { .temp_C = 35, .ohm = 20335 },
99 { .temp_C = 40, .ohm = 16115 },
100 { .temp_C = 45, .ohm = 12849 },
101 { .temp_C = 50, .ohm = 10306 },
102 { .temp_C = 55, .ohm = 8314 },
103 { .temp_C = 60, .ohm = 6746 },
104 { .temp_C = 65, .ohm = 5503 },
105 { .temp_C = 70, .ohm = 4513 },
106 { .temp_C = 75, .ohm = 3721 },
107 { .temp_C = 80, .ohm = 3084 },
108 { .temp_C = 85, .ohm = 2569 },
109 { .temp_C = 90, .ohm = 2151 },
110 { .temp_C = 95, .ohm = 1809 },
111 { .temp_C = 100, .ohm = 1529 },
112 { .temp_C = 105, .ohm = 1299 },
113 { .temp_C = 110, .ohm = 1108 },
114 { .temp_C = 115, .ohm = 949 },
115 { .temp_C = 120, .ohm = 817 },
116 { .temp_C = 125, .ohm = 707 },
120 struct device *hwmon_dev;
121 struct ntc_thermistor_platform_data *pdata;
122 const struct ntc_compensation *comp;
125 char name[PLATFORM_NAME_SIZE];
128 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
130 if (divisor == 0 && dividend == 0)
134 return div64_u64(dividend, divisor);
137 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uV)
139 struct ntc_thermistor_platform_data *pdata = data->pdata;
141 u64 pmV = pdata->pullup_uV / 1000;
143 puO = pdata->pullup_ohm;
144 pdO = pdata->pulldown_ohm;
147 if (pdata->connect == NTC_CONNECTED_POSITIVE)
152 return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
155 if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0)
156 N = div64_u64_safe(pdO * (pmV - mV), mV);
157 else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0)
158 N = div64_u64_safe(puO * mV, pmV - mV);
159 else if (pdata->connect == NTC_CONNECTED_POSITIVE)
160 N = div64_u64_safe(pdO * puO * (pmV - mV),
161 puO * mV - pdO * (pmV - mV));
163 N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV);
170 static void lookup_comp(struct ntc_data *data, unsigned int ohm,
171 int *i_low, int *i_high)
176 * Handle special cases: Resistance is higher than or equal to
177 * resistance in first table entry, or resistance is lower or equal
178 * to resistance in last table entry.
179 * In these cases, return i_low == i_high, either pointing to the
180 * beginning or to the end of the table depending on the condition.
182 if (ohm >= data->comp[0].ohm) {
187 if (ohm <= data->comp[data->n_comp - 1].ohm) {
188 *i_low = data->n_comp - 1;
189 *i_high = data->n_comp - 1;
193 /* Do a binary search on compensation table */
196 while (start < end) {
197 mid = start + (end - start) / 2;
200 * data->comp[start].ohm > ohm >= data->comp[end].ohm
202 * We could check for "ohm == data->comp[mid].ohm" here, but
203 * that is a quite unlikely condition, and we would have to
204 * check again after updating start. Check it at the end instead
207 if (ohm >= data->comp[mid].ohm) {
212 * ohm >= data->comp[start].ohm might be true here,
213 * since we set start to mid + 1. In that case, we are
214 * done. We could keep going, but the condition is quite
215 * likely to occur, so it is worth checking for it.
217 if (ohm >= data->comp[start].ohm)
222 * data->comp[start].ohm >= ohm >= data->comp[end].ohm
227 * ohm >= data->comp[end].ohm
230 if (ohm == data->comp[end].ohm)
236 static int get_temp_mC(struct ntc_data *data, unsigned int ohm)
241 lookup_comp(data, ohm, &low, &high);
243 /* Unable to use linear approximation */
244 temp = data->comp[low].temp_C * 1000;
246 temp = data->comp[low].temp_C * 1000 +
247 ((data->comp[high].temp_C - data->comp[low].temp_C) *
248 1000 * ((int)ohm - (int)data->comp[low].ohm)) /
249 ((int)data->comp[high].ohm - (int)data->comp[low].ohm);
254 static int ntc_thermistor_get_ohm(struct ntc_data *data)
258 if (data->pdata->read_ohm)
259 return data->pdata->read_ohm();
261 if (data->pdata->read_uV) {
262 read_uV = data->pdata->read_uV();
265 return get_ohm_of_thermistor(data, read_uV);
270 static ssize_t ntc_show_name(struct device *dev,
271 struct device_attribute *attr, char *buf)
273 struct ntc_data *data = dev_get_drvdata(dev);
275 return sprintf(buf, "%s\n", data->name);
278 static ssize_t ntc_show_type(struct device *dev,
279 struct device_attribute *attr, char *buf)
281 return sprintf(buf, "4\n");
284 static ssize_t ntc_show_temp(struct device *dev,
285 struct device_attribute *attr, char *buf)
287 struct ntc_data *data = dev_get_drvdata(dev);
290 ohm = ntc_thermistor_get_ohm(data);
294 return sprintf(buf, "%d\n", get_temp_mC(data, ohm));
297 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
298 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
299 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);
301 static struct attribute *ntc_attributes[] = {
303 &sensor_dev_attr_temp1_type.dev_attr.attr,
304 &sensor_dev_attr_temp1_input.dev_attr.attr,
308 static const struct attribute_group ntc_attr_group = {
309 .attrs = ntc_attributes,
312 static int __devinit ntc_thermistor_probe(struct platform_device *pdev)
314 struct ntc_data *data;
315 struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
319 dev_err(&pdev->dev, "No platform init data supplied.\n");
323 /* Either one of the two is required. */
324 if (!pdata->read_uV && !pdata->read_ohm) {
326 "Both read_uV and read_ohm missing. Need either one of the two.\n");
330 if (pdata->read_uV && pdata->read_ohm) {
332 "Only one of read_uV and read_ohm is needed; ignoring read_uV.\n");
333 pdata->read_uV = NULL;
336 if (pdata->read_uV && (pdata->pullup_uV == 0 ||
337 (pdata->pullup_ohm == 0 && pdata->connect ==
338 NTC_CONNECTED_GROUND) ||
339 (pdata->pulldown_ohm == 0 && pdata->connect ==
340 NTC_CONNECTED_POSITIVE) ||
341 (pdata->connect != NTC_CONNECTED_POSITIVE &&
342 pdata->connect != NTC_CONNECTED_GROUND))) {
344 "Required data to use read_uV not supplied.\n");
348 data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
352 data->dev = &pdev->dev;
354 strlcpy(data->name, pdev->id_entry->name, sizeof(data->name));
356 switch (pdev->id_entry->driver_data) {
357 case TYPE_NCPXXWB473:
358 data->comp = ncpXXwb473;
359 data->n_comp = ARRAY_SIZE(ncpXXwb473);
361 case TYPE_NCPXXWL333:
362 data->comp = ncpXXwl333;
363 data->n_comp = ARRAY_SIZE(ncpXXwl333);
366 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
367 pdev->id_entry->driver_data,
368 pdev->id_entry->name);
372 platform_set_drvdata(pdev, data);
374 ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
376 dev_err(data->dev, "unable to create sysfs files\n");
380 data->hwmon_dev = hwmon_device_register(data->dev);
381 if (IS_ERR(data->hwmon_dev)) {
382 dev_err(data->dev, "unable to register as hwmon device.\n");
383 ret = PTR_ERR(data->hwmon_dev);
384 goto err_after_sysfs;
387 dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
388 pdev->name, pdev->id, pdev->id_entry->name,
389 pdev->id_entry->driver_data);
392 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
396 static int __devexit ntc_thermistor_remove(struct platform_device *pdev)
398 struct ntc_data *data = platform_get_drvdata(pdev);
400 hwmon_device_unregister(data->hwmon_dev);
401 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
402 platform_set_drvdata(pdev, NULL);
407 static const struct platform_device_id ntc_thermistor_id[] = {
408 { "ncp15wb473", TYPE_NCPXXWB473 },
409 { "ncp18wb473", TYPE_NCPXXWB473 },
410 { "ncp21wb473", TYPE_NCPXXWB473 },
411 { "ncp03wb473", TYPE_NCPXXWB473 },
412 { "ncp15wl333", TYPE_NCPXXWL333 },
416 static struct platform_driver ntc_thermistor_driver = {
418 .name = "ntc-thermistor",
419 .owner = THIS_MODULE,
421 .probe = ntc_thermistor_probe,
422 .remove = __devexit_p(ntc_thermistor_remove),
423 .id_table = ntc_thermistor_id,
426 module_platform_driver(ntc_thermistor_driver);
428 MODULE_DESCRIPTION("NTC Thermistor Driver");
429 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
430 MODULE_LICENSE("GPL");
431 MODULE_ALIAS("platform:ntc-thermistor");