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/of_device.h>
32 #include <linux/platform_data/ntc_thermistor.h>
34 #include <linux/iio/iio.h>
35 #include <linux/iio/machine.h>
36 #include <linux/iio/driver.h>
37 #include <linux/iio/consumer.h>
39 #include <linux/hwmon.h>
40 #include <linux/hwmon-sysfs.h>
42 struct ntc_compensation {
47 /* Order matters, ntc_match references the entries by index */
48 static const struct platform_device_id ntc_thermistor_id[] = {
49 { "ncp15wb473", TYPE_NCPXXWB473 },
50 { "ncp18wb473", TYPE_NCPXXWB473 },
51 { "ncp21wb473", TYPE_NCPXXWB473 },
52 { "ncp03wb473", TYPE_NCPXXWB473 },
53 { "ncp15wl333", TYPE_NCPXXWL333 },
58 * A compensation table should be sorted by the values of .ohm
59 * in descending order.
60 * The following compensation tables are from the specification of Murata NTC
61 * Thermistors Datasheet
63 static const struct ntc_compensation ncpXXwb473[] = {
64 { .temp_c = -40, .ohm = 1747920 },
65 { .temp_c = -35, .ohm = 1245428 },
66 { .temp_c = -30, .ohm = 898485 },
67 { .temp_c = -25, .ohm = 655802 },
68 { .temp_c = -20, .ohm = 483954 },
69 { .temp_c = -15, .ohm = 360850 },
70 { .temp_c = -10, .ohm = 271697 },
71 { .temp_c = -5, .ohm = 206463 },
72 { .temp_c = 0, .ohm = 158214 },
73 { .temp_c = 5, .ohm = 122259 },
74 { .temp_c = 10, .ohm = 95227 },
75 { .temp_c = 15, .ohm = 74730 },
76 { .temp_c = 20, .ohm = 59065 },
77 { .temp_c = 25, .ohm = 47000 },
78 { .temp_c = 30, .ohm = 37643 },
79 { .temp_c = 35, .ohm = 30334 },
80 { .temp_c = 40, .ohm = 24591 },
81 { .temp_c = 45, .ohm = 20048 },
82 { .temp_c = 50, .ohm = 16433 },
83 { .temp_c = 55, .ohm = 13539 },
84 { .temp_c = 60, .ohm = 11209 },
85 { .temp_c = 65, .ohm = 9328 },
86 { .temp_c = 70, .ohm = 7798 },
87 { .temp_c = 75, .ohm = 6544 },
88 { .temp_c = 80, .ohm = 5518 },
89 { .temp_c = 85, .ohm = 4674 },
90 { .temp_c = 90, .ohm = 3972 },
91 { .temp_c = 95, .ohm = 3388 },
92 { .temp_c = 100, .ohm = 2902 },
93 { .temp_c = 105, .ohm = 2494 },
94 { .temp_c = 110, .ohm = 2150 },
95 { .temp_c = 115, .ohm = 1860 },
96 { .temp_c = 120, .ohm = 1615 },
97 { .temp_c = 125, .ohm = 1406 },
99 static const struct ntc_compensation ncpXXwl333[] = {
100 { .temp_c = -40, .ohm = 1610154 },
101 { .temp_c = -35, .ohm = 1130850 },
102 { .temp_c = -30, .ohm = 802609 },
103 { .temp_c = -25, .ohm = 575385 },
104 { .temp_c = -20, .ohm = 416464 },
105 { .temp_c = -15, .ohm = 304219 },
106 { .temp_c = -10, .ohm = 224193 },
107 { .temp_c = -5, .ohm = 166623 },
108 { .temp_c = 0, .ohm = 124850 },
109 { .temp_c = 5, .ohm = 94287 },
110 { .temp_c = 10, .ohm = 71747 },
111 { .temp_c = 15, .ohm = 54996 },
112 { .temp_c = 20, .ohm = 42455 },
113 { .temp_c = 25, .ohm = 33000 },
114 { .temp_c = 30, .ohm = 25822 },
115 { .temp_c = 35, .ohm = 20335 },
116 { .temp_c = 40, .ohm = 16115 },
117 { .temp_c = 45, .ohm = 12849 },
118 { .temp_c = 50, .ohm = 10306 },
119 { .temp_c = 55, .ohm = 8314 },
120 { .temp_c = 60, .ohm = 6746 },
121 { .temp_c = 65, .ohm = 5503 },
122 { .temp_c = 70, .ohm = 4513 },
123 { .temp_c = 75, .ohm = 3721 },
124 { .temp_c = 80, .ohm = 3084 },
125 { .temp_c = 85, .ohm = 2569 },
126 { .temp_c = 90, .ohm = 2151 },
127 { .temp_c = 95, .ohm = 1809 },
128 { .temp_c = 100, .ohm = 1529 },
129 { .temp_c = 105, .ohm = 1299 },
130 { .temp_c = 110, .ohm = 1108 },
131 { .temp_c = 115, .ohm = 949 },
132 { .temp_c = 120, .ohm = 817 },
133 { .temp_c = 125, .ohm = 707 },
137 struct device *hwmon_dev;
138 struct ntc_thermistor_platform_data *pdata;
139 const struct ntc_compensation *comp;
142 char name[PLATFORM_NAME_SIZE];
145 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO)
146 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
148 struct iio_channel *channel = pdata->chan;
152 ret = iio_read_channel_raw(channel, &val);
154 pr_err("read channel() error: %d\n", ret);
159 result = pdata->pullup_uv * (s64) val;
165 static const struct of_device_id ntc_match[] = {
166 { .compatible = "ntc,ncp15wb473",
167 .data = &ntc_thermistor_id[0] },
168 { .compatible = "ntc,ncp18wb473",
169 .data = &ntc_thermistor_id[1] },
170 { .compatible = "ntc,ncp21wb473",
171 .data = &ntc_thermistor_id[2] },
172 { .compatible = "ntc,ncp03wb473",
173 .data = &ntc_thermistor_id[3] },
174 { .compatible = "ntc,ncp15wl333",
175 .data = &ntc_thermistor_id[4] },
178 MODULE_DEVICE_TABLE(of, ntc_match);
180 static struct ntc_thermistor_platform_data *
181 ntc_thermistor_parse_dt(struct platform_device *pdev)
183 struct iio_channel *chan;
184 struct device_node *np = pdev->dev.of_node;
185 struct ntc_thermistor_platform_data *pdata;
190 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
192 return ERR_PTR(-ENOMEM);
194 chan = iio_channel_get(&pdev->dev, NULL);
196 return ERR_CAST(chan);
198 if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv))
199 return ERR_PTR(-ENODEV);
200 if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
201 return ERR_PTR(-ENODEV);
202 if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
203 return ERR_PTR(-ENODEV);
205 if (of_find_property(np, "connected-positive", NULL))
206 pdata->connect = NTC_CONNECTED_POSITIVE;
207 else /* status change should be possible if not always on. */
208 pdata->connect = NTC_CONNECTED_GROUND;
211 pdata->read_uv = ntc_adc_iio_read;
215 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
218 iio_channel_release(pdata->chan);
221 static struct ntc_thermistor_platform_data *
222 ntc_thermistor_parse_dt(struct platform_device *pdev)
227 #define ntc_match NULL
229 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
233 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
235 if (divisor == 0 && dividend == 0)
239 return div64_u64(dividend, divisor);
242 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
244 struct ntc_thermistor_platform_data *pdata = data->pdata;
246 u64 pmv = pdata->pullup_uv / 1000;
248 puo = pdata->pullup_ohm;
249 pdo = pdata->pulldown_ohm;
252 if (pdata->connect == NTC_CONNECTED_POSITIVE)
257 return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
260 if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0)
261 n = div64_u64_safe(pdo * (pmv - mv), mv);
262 else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0)
263 n = div64_u64_safe(puo * mv, pmv - mv);
264 else if (pdata->connect == NTC_CONNECTED_POSITIVE)
265 n = div64_u64_safe(pdo * puo * (pmv - mv),
266 puo * mv - pdo * (pmv - mv));
268 n = div64_u64_safe(pdo * puo * mv, pdo * (pmv - mv) - puo * mv);
275 static void lookup_comp(struct ntc_data *data, unsigned int ohm,
276 int *i_low, int *i_high)
281 * Handle special cases: Resistance is higher than or equal to
282 * resistance in first table entry, or resistance is lower or equal
283 * to resistance in last table entry.
284 * In these cases, return i_low == i_high, either pointing to the
285 * beginning or to the end of the table depending on the condition.
287 if (ohm >= data->comp[0].ohm) {
292 if (ohm <= data->comp[data->n_comp - 1].ohm) {
293 *i_low = data->n_comp - 1;
294 *i_high = data->n_comp - 1;
298 /* Do a binary search on compensation table */
301 while (start < end) {
302 mid = start + (end - start) / 2;
305 * data->comp[start].ohm > ohm >= data->comp[end].ohm
307 * We could check for "ohm == data->comp[mid].ohm" here, but
308 * that is a quite unlikely condition, and we would have to
309 * check again after updating start. Check it at the end instead
312 if (ohm >= data->comp[mid].ohm) {
317 * ohm >= data->comp[start].ohm might be true here,
318 * since we set start to mid + 1. In that case, we are
319 * done. We could keep going, but the condition is quite
320 * likely to occur, so it is worth checking for it.
322 if (ohm >= data->comp[start].ohm)
327 * data->comp[start].ohm >= ohm >= data->comp[end].ohm
332 * ohm >= data->comp[end].ohm
335 if (ohm == data->comp[end].ohm)
341 static int get_temp_mc(struct ntc_data *data, unsigned int ohm)
346 lookup_comp(data, ohm, &low, &high);
348 /* Unable to use linear approximation */
349 temp = data->comp[low].temp_c * 1000;
351 temp = data->comp[low].temp_c * 1000 +
352 ((data->comp[high].temp_c - data->comp[low].temp_c) *
353 1000 * ((int)ohm - (int)data->comp[low].ohm)) /
354 ((int)data->comp[high].ohm - (int)data->comp[low].ohm);
359 static int ntc_thermistor_get_ohm(struct ntc_data *data)
363 if (data->pdata->read_ohm)
364 return data->pdata->read_ohm();
366 if (data->pdata->read_uv) {
367 read_uv = data->pdata->read_uv(data->pdata);
370 return get_ohm_of_thermistor(data, read_uv);
375 static ssize_t ntc_show_name(struct device *dev,
376 struct device_attribute *attr, char *buf)
378 struct ntc_data *data = dev_get_drvdata(dev);
380 return sprintf(buf, "%s\n", data->name);
383 static ssize_t ntc_show_type(struct device *dev,
384 struct device_attribute *attr, char *buf)
386 return sprintf(buf, "4\n");
389 static ssize_t ntc_show_temp(struct device *dev,
390 struct device_attribute *attr, char *buf)
392 struct ntc_data *data = dev_get_drvdata(dev);
395 ohm = ntc_thermistor_get_ohm(data);
399 return sprintf(buf, "%d\n", get_temp_mc(data, ohm));
402 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
403 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
404 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);
406 static struct attribute *ntc_attributes[] = {
408 &sensor_dev_attr_temp1_type.dev_attr.attr,
409 &sensor_dev_attr_temp1_input.dev_attr.attr,
413 static const struct attribute_group ntc_attr_group = {
414 .attrs = ntc_attributes,
417 static int ntc_thermistor_probe(struct platform_device *pdev)
419 const struct of_device_id *of_id =
420 of_match_device(of_match_ptr(ntc_match), &pdev->dev);
421 const struct platform_device_id *pdev_id;
422 struct ntc_thermistor_platform_data *pdata;
423 struct ntc_data *data;
426 pdata = ntc_thermistor_parse_dt(pdev);
428 return PTR_ERR(pdata);
429 else if (pdata == NULL)
430 pdata = pdev->dev.platform_data;
433 dev_err(&pdev->dev, "No platform init data supplied.\n");
437 /* Either one of the two is required. */
438 if (!pdata->read_uv && !pdata->read_ohm) {
440 "Both read_uv and read_ohm missing. Need either one of the two.\n");
444 if (pdata->read_uv && pdata->read_ohm) {
446 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n");
447 pdata->read_uv = NULL;
450 if (pdata->read_uv && (pdata->pullup_uv == 0 ||
451 (pdata->pullup_ohm == 0 && pdata->connect ==
452 NTC_CONNECTED_GROUND) ||
453 (pdata->pulldown_ohm == 0 && pdata->connect ==
454 NTC_CONNECTED_POSITIVE) ||
455 (pdata->connect != NTC_CONNECTED_POSITIVE &&
456 pdata->connect != NTC_CONNECTED_GROUND))) {
458 "Required data to use read_uv not supplied.\n");
462 data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
466 pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);
468 data->dev = &pdev->dev;
470 strlcpy(data->name, pdev_id->name, sizeof(data->name));
472 switch (pdev_id->driver_data) {
473 case TYPE_NCPXXWB473:
474 data->comp = ncpXXwb473;
475 data->n_comp = ARRAY_SIZE(ncpXXwb473);
477 case TYPE_NCPXXWL333:
478 data->comp = ncpXXwl333;
479 data->n_comp = ARRAY_SIZE(ncpXXwl333);
482 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
483 pdev_id->driver_data, pdev_id->name);
487 platform_set_drvdata(pdev, data);
489 ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
491 dev_err(data->dev, "unable to create sysfs files\n");
495 data->hwmon_dev = hwmon_device_register(data->dev);
496 if (IS_ERR(data->hwmon_dev)) {
497 dev_err(data->dev, "unable to register as hwmon device.\n");
498 ret = PTR_ERR(data->hwmon_dev);
499 goto err_after_sysfs;
502 dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
507 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
508 ntc_iio_channel_release(pdata);
512 static int ntc_thermistor_remove(struct platform_device *pdev)
514 struct ntc_data *data = platform_get_drvdata(pdev);
515 struct ntc_thermistor_platform_data *pdata = data->pdata;
517 hwmon_device_unregister(data->hwmon_dev);
518 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
519 ntc_iio_channel_release(pdata);
520 platform_set_drvdata(pdev, NULL);
525 static struct platform_driver ntc_thermistor_driver = {
527 .name = "ntc-thermistor",
528 .owner = THIS_MODULE,
529 .of_match_table = of_match_ptr(ntc_match),
531 .probe = ntc_thermistor_probe,
532 .remove = ntc_thermistor_remove,
533 .id_table = ntc_thermistor_id,
536 module_platform_driver(ntc_thermistor_driver);
538 MODULE_DESCRIPTION("NTC Thermistor Driver");
539 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
540 MODULE_LICENSE("GPL");
541 MODULE_ALIAS("platform:ntc-thermistor");