1 /*
2  * ntc_thermistor.c - NTC Thermistors
3  *
4  *  Copyright (C) 2010 Samsung Electronics
5  *  MyungJoo Ham <myungjoo.ham@samsung.com>
6  *
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.
11  *
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.
16  *
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
20  *
21  */
22 
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>
29 #include <linux/of.h>
30 #include <linux/of_device.h>
31 
32 #include <linux/platform_data/ntc_thermistor.h>
33 
34 #include <linux/iio/iio.h>
35 #include <linux/iio/machine.h>
36 #include <linux/iio/driver.h>
37 #include <linux/iio/consumer.h>
38 
39 #include <linux/hwmon.h>
40 #include <linux/hwmon-sysfs.h>
41 
42 struct ntc_compensation {
43 	int		temp_c;
44 	unsigned int	ohm;
45 };
46 
47 static const struct platform_device_id ntc_thermistor_id[] = {
48 	{ "ncp15wb473", TYPE_NCPXXWB473 },
49 	{ "ncp18wb473", TYPE_NCPXXWB473 },
50 	{ "ncp21wb473", TYPE_NCPXXWB473 },
51 	{ "ncp03wb473", TYPE_NCPXXWB473 },
52 	{ "ncp15wl333", TYPE_NCPXXWL333 },
53 	{ },
54 };
55 
56 /*
57  * A compensation table should be sorted by the values of .ohm
58  * in descending order.
59  * The following compensation tables are from the specification of Murata NTC
60  * Thermistors Datasheet
61  */
62 static const struct ntc_compensation ncpXXwb473[] = {
63 	{ .temp_c	= -40, .ohm	= 1747920 },
64 	{ .temp_c	= -35, .ohm	= 1245428 },
65 	{ .temp_c	= -30, .ohm	= 898485 },
66 	{ .temp_c	= -25, .ohm	= 655802 },
67 	{ .temp_c	= -20, .ohm	= 483954 },
68 	{ .temp_c	= -15, .ohm	= 360850 },
69 	{ .temp_c	= -10, .ohm	= 271697 },
70 	{ .temp_c	= -5, .ohm	= 206463 },
71 	{ .temp_c	= 0, .ohm	= 158214 },
72 	{ .temp_c	= 5, .ohm	= 122259 },
73 	{ .temp_c	= 10, .ohm	= 95227 },
74 	{ .temp_c	= 15, .ohm	= 74730 },
75 	{ .temp_c	= 20, .ohm	= 59065 },
76 	{ .temp_c	= 25, .ohm	= 47000 },
77 	{ .temp_c	= 30, .ohm	= 37643 },
78 	{ .temp_c	= 35, .ohm	= 30334 },
79 	{ .temp_c	= 40, .ohm	= 24591 },
80 	{ .temp_c	= 45, .ohm	= 20048 },
81 	{ .temp_c	= 50, .ohm	= 16433 },
82 	{ .temp_c	= 55, .ohm	= 13539 },
83 	{ .temp_c	= 60, .ohm	= 11209 },
84 	{ .temp_c	= 65, .ohm	= 9328 },
85 	{ .temp_c	= 70, .ohm	= 7798 },
86 	{ .temp_c	= 75, .ohm	= 6544 },
87 	{ .temp_c	= 80, .ohm	= 5518 },
88 	{ .temp_c	= 85, .ohm	= 4674 },
89 	{ .temp_c	= 90, .ohm	= 3972 },
90 	{ .temp_c	= 95, .ohm	= 3388 },
91 	{ .temp_c	= 100, .ohm	= 2902 },
92 	{ .temp_c	= 105, .ohm	= 2494 },
93 	{ .temp_c	= 110, .ohm	= 2150 },
94 	{ .temp_c	= 115, .ohm	= 1860 },
95 	{ .temp_c	= 120, .ohm	= 1615 },
96 	{ .temp_c	= 125, .ohm	= 1406 },
97 };
98 static const struct ntc_compensation ncpXXwl333[] = {
99 	{ .temp_c	= -40, .ohm	= 1610154 },
100 	{ .temp_c	= -35, .ohm	= 1130850 },
101 	{ .temp_c	= -30, .ohm	= 802609 },
102 	{ .temp_c	= -25, .ohm	= 575385 },
103 	{ .temp_c	= -20, .ohm	= 416464 },
104 	{ .temp_c	= -15, .ohm	= 304219 },
105 	{ .temp_c	= -10, .ohm	= 224193 },
106 	{ .temp_c	= -5, .ohm	= 166623 },
107 	{ .temp_c	= 0, .ohm	= 124850 },
108 	{ .temp_c	= 5, .ohm	= 94287 },
109 	{ .temp_c	= 10, .ohm	= 71747 },
110 	{ .temp_c	= 15, .ohm	= 54996 },
111 	{ .temp_c	= 20, .ohm	= 42455 },
112 	{ .temp_c	= 25, .ohm	= 33000 },
113 	{ .temp_c	= 30, .ohm	= 25822 },
114 	{ .temp_c	= 35, .ohm	= 20335 },
115 	{ .temp_c	= 40, .ohm	= 16115 },
116 	{ .temp_c	= 45, .ohm	= 12849 },
117 	{ .temp_c	= 50, .ohm	= 10306 },
118 	{ .temp_c	= 55, .ohm	= 8314 },
119 	{ .temp_c	= 60, .ohm	= 6746 },
120 	{ .temp_c	= 65, .ohm	= 5503 },
121 	{ .temp_c	= 70, .ohm	= 4513 },
122 	{ .temp_c	= 75, .ohm	= 3721 },
123 	{ .temp_c	= 80, .ohm	= 3084 },
124 	{ .temp_c	= 85, .ohm	= 2569 },
125 	{ .temp_c	= 90, .ohm	= 2151 },
126 	{ .temp_c	= 95, .ohm	= 1809 },
127 	{ .temp_c	= 100, .ohm	= 1529 },
128 	{ .temp_c	= 105, .ohm	= 1299 },
129 	{ .temp_c	= 110, .ohm	= 1108 },
130 	{ .temp_c	= 115, .ohm	= 949 },
131 	{ .temp_c	= 120, .ohm	= 817 },
132 	{ .temp_c	= 125, .ohm	= 707 },
133 };
134 
135 struct ntc_data {
136 	struct device *hwmon_dev;
137 	struct ntc_thermistor_platform_data *pdata;
138 	const struct ntc_compensation *comp;
139 	struct device *dev;
140 	int n_comp;
141 	char name[PLATFORM_NAME_SIZE];
142 };
143 
144 #ifdef CONFIG_OF
145 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
146 {
147 	struct iio_channel *channel = pdata->chan;
148 	unsigned int result;
149 	int val, ret;
150 
151 	ret = iio_read_channel_raw(channel, &val);
152 	if (ret < 0) {
153 		pr_err("read channel() error: %d\n", ret);
154 		return ret;
155 	}
156 
157 	/* unit: mV */
158 	result = pdata->pullup_uv * val;
159 	result >>= 12;
160 
161 	return result;
162 }
163 
164 static const struct of_device_id ntc_match[] = {
165 	{ .compatible = "ntc,ncp15wb473",
166 		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
167 	{ .compatible = "ntc,ncp18wb473",
168 		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
169 	{ .compatible = "ntc,ncp21wb473",
170 		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
171 	{ .compatible = "ntc,ncp03wb473",
172 		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
173 	{ .compatible = "ntc,ncp15wl333",
174 		.data = &ntc_thermistor_id[TYPE_NCPXXWL333] },
175 	{ },
176 };
177 MODULE_DEVICE_TABLE(of, ntc_match);
178 
179 static struct ntc_thermistor_platform_data *
180 ntc_thermistor_parse_dt(struct platform_device *pdev)
181 {
182 	struct iio_channel *chan;
183 	struct device_node *np = pdev->dev.of_node;
184 	struct ntc_thermistor_platform_data *pdata;
185 
186 	if (!np)
187 		return NULL;
188 
189 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
190 	if (!pdata)
191 		return ERR_PTR(-ENOMEM);
192 
193 	chan = iio_channel_get(&pdev->dev, NULL);
194 	if (IS_ERR(chan))
195 		return ERR_CAST(chan);
196 
197 	if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv))
198 		return ERR_PTR(-ENODEV);
199 	if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
200 		return ERR_PTR(-ENODEV);
201 	if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
202 		return ERR_PTR(-ENODEV);
203 
204 	if (of_find_property(np, "connected-positive", NULL))
205 		pdata->connect = NTC_CONNECTED_POSITIVE;
206 	else /* status change should be possible if not always on. */
207 		pdata->connect = NTC_CONNECTED_GROUND;
208 
209 	pdata->chan = chan;
210 	pdata->read_uv = ntc_adc_iio_read;
211 
212 	return pdata;
213 }
214 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
215 {
216 	if (pdata->chan)
217 		iio_channel_release(pdata->chan);
218 }
219 #else
220 static struct ntc_thermistor_platform_data *
221 ntc_thermistor_parse_dt(struct platform_device *pdev)
222 {
223 	return NULL;
224 }
225 
226 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
227 { }
228 #endif
229 
230 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
231 {
232 	if (divisor == 0 && dividend == 0)
233 		return 0;
234 	if (divisor == 0)
235 		return UINT_MAX;
236 	return div64_u64(dividend, divisor);
237 }
238 
239 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
240 {
241 	struct ntc_thermistor_platform_data *pdata = data->pdata;
242 	u64 mv = uv / 1000;
243 	u64 pmv = pdata->pullup_uv / 1000;
244 	u64 n, puo, pdo;
245 	puo = pdata->pullup_ohm;
246 	pdo = pdata->pulldown_ohm;
247 
248 	if (mv == 0) {
249 		if (pdata->connect == NTC_CONNECTED_POSITIVE)
250 			return INT_MAX;
251 		return 0;
252 	}
253 	if (mv >= pmv)
254 		return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
255 			0 : INT_MAX;
256 
257 	if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0)
258 		n = div64_u64_safe(pdo * (pmv - mv), mv);
259 	else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0)
260 		n = div64_u64_safe(puo * mv, pmv - mv);
261 	else if (pdata->connect == NTC_CONNECTED_POSITIVE)
262 		n = div64_u64_safe(pdo * puo * (pmv - mv),
263 				puo * mv - pdo * (pmv - mv));
264 	else
265 		n = div64_u64_safe(pdo * puo * mv, pdo * (pmv - mv) - puo * mv);
266 
267 	if (n > INT_MAX)
268 		n = INT_MAX;
269 	return n;
270 }
271 
272 static void lookup_comp(struct ntc_data *data, unsigned int ohm,
273 			int *i_low, int *i_high)
274 {
275 	int start, end, mid;
276 
277 	/*
278 	 * Handle special cases: Resistance is higher than or equal to
279 	 * resistance in first table entry, or resistance is lower or equal
280 	 * to resistance in last table entry.
281 	 * In these cases, return i_low == i_high, either pointing to the
282 	 * beginning or to the end of the table depending on the condition.
283 	 */
284 	if (ohm >= data->comp[0].ohm) {
285 		*i_low = 0;
286 		*i_high = 0;
287 		return;
288 	}
289 	if (ohm <= data->comp[data->n_comp - 1].ohm) {
290 		*i_low = data->n_comp - 1;
291 		*i_high = data->n_comp - 1;
292 		return;
293 	}
294 
295 	/* Do a binary search on compensation table */
296 	start = 0;
297 	end = data->n_comp;
298 	while (start < end) {
299 		mid = start + (end - start) / 2;
300 		/*
301 		 * start <= mid < end
302 		 * data->comp[start].ohm > ohm >= data->comp[end].ohm
303 		 *
304 		 * We could check for "ohm == data->comp[mid].ohm" here, but
305 		 * that is a quite unlikely condition, and we would have to
306 		 * check again after updating start. Check it at the end instead
307 		 * for simplicity.
308 		 */
309 		if (ohm >= data->comp[mid].ohm) {
310 			end = mid;
311 		} else {
312 			start = mid + 1;
313 			/*
314 			 * ohm >= data->comp[start].ohm might be true here,
315 			 * since we set start to mid + 1. In that case, we are
316 			 * done. We could keep going, but the condition is quite
317 			 * likely to occur, so it is worth checking for it.
318 			 */
319 			if (ohm >= data->comp[start].ohm)
320 				end = start;
321 		}
322 		/*
323 		 * start <= end
324 		 * data->comp[start].ohm >= ohm >= data->comp[end].ohm
325 		 */
326 	}
327 	/*
328 	 * start == end
329 	 * ohm >= data->comp[end].ohm
330 	 */
331 	*i_low = end;
332 	if (ohm == data->comp[end].ohm)
333 		*i_high = end;
334 	else
335 		*i_high = end - 1;
336 }
337 
338 static int get_temp_mc(struct ntc_data *data, unsigned int ohm)
339 {
340 	int low, high;
341 	int temp;
342 
343 	lookup_comp(data, ohm, &low, &high);
344 	if (low == high) {
345 		/* Unable to use linear approximation */
346 		temp = data->comp[low].temp_c * 1000;
347 	} else {
348 		temp = data->comp[low].temp_c * 1000 +
349 			((data->comp[high].temp_c - data->comp[low].temp_c) *
350 			 1000 * ((int)ohm - (int)data->comp[low].ohm)) /
351 			((int)data->comp[high].ohm - (int)data->comp[low].ohm);
352 	}
353 	return temp;
354 }
355 
356 static int ntc_thermistor_get_ohm(struct ntc_data *data)
357 {
358 	int read_uv;
359 
360 	if (data->pdata->read_ohm)
361 		return data->pdata->read_ohm();
362 
363 	if (data->pdata->read_uv) {
364 		read_uv = data->pdata->read_uv(data->pdata);
365 		if (read_uv < 0)
366 			return read_uv;
367 		return get_ohm_of_thermistor(data, read_uv);
368 	}
369 	return -EINVAL;
370 }
371 
372 static ssize_t ntc_show_name(struct device *dev,
373 		struct device_attribute *attr, char *buf)
374 {
375 	struct ntc_data *data = dev_get_drvdata(dev);
376 
377 	return sprintf(buf, "%s\n", data->name);
378 }
379 
380 static ssize_t ntc_show_type(struct device *dev,
381 		struct device_attribute *attr, char *buf)
382 {
383 	return sprintf(buf, "4\n");
384 }
385 
386 static ssize_t ntc_show_temp(struct device *dev,
387 		struct device_attribute *attr, char *buf)
388 {
389 	struct ntc_data *data = dev_get_drvdata(dev);
390 	int ohm;
391 
392 	ohm = ntc_thermistor_get_ohm(data);
393 	if (ohm < 0)
394 		return ohm;
395 
396 	return sprintf(buf, "%d\n", get_temp_mc(data, ohm));
397 }
398 
399 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
400 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
401 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);
402 
403 static struct attribute *ntc_attributes[] = {
404 	&dev_attr_name.attr,
405 	&sensor_dev_attr_temp1_type.dev_attr.attr,
406 	&sensor_dev_attr_temp1_input.dev_attr.attr,
407 	NULL,
408 };
409 
410 static const struct attribute_group ntc_attr_group = {
411 	.attrs = ntc_attributes,
412 };
413 
414 static int ntc_thermistor_probe(struct platform_device *pdev)
415 {
416 	const struct of_device_id *of_id =
417 			of_match_device(of_match_ptr(ntc_match), &pdev->dev);
418 	const struct platform_device_id *pdev_id;
419 	struct ntc_thermistor_platform_data *pdata;
420 	struct ntc_data *data;
421 	int ret;
422 
423 	pdata = ntc_thermistor_parse_dt(pdev);
424 	if (IS_ERR(pdata))
425 		return PTR_ERR(pdata);
426 	else if (pdata == NULL)
427 		pdata = dev_get_platdata(&pdev->dev);
428 
429 	if (!pdata) {
430 		dev_err(&pdev->dev, "No platform init data supplied.\n");
431 		return -ENODEV;
432 	}
433 
434 	/* Either one of the two is required. */
435 	if (!pdata->read_uv && !pdata->read_ohm) {
436 		dev_err(&pdev->dev,
437 			"Both read_uv and read_ohm missing. Need either one of the two.\n");
438 		return -EINVAL;
439 	}
440 
441 	if (pdata->read_uv && pdata->read_ohm) {
442 		dev_warn(&pdev->dev,
443 			 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n");
444 		pdata->read_uv = NULL;
445 	}
446 
447 	if (pdata->read_uv && (pdata->pullup_uv == 0 ||
448 				(pdata->pullup_ohm == 0 && pdata->connect ==
449 				 NTC_CONNECTED_GROUND) ||
450 				(pdata->pulldown_ohm == 0 && pdata->connect ==
451 				 NTC_CONNECTED_POSITIVE) ||
452 				(pdata->connect != NTC_CONNECTED_POSITIVE &&
453 				 pdata->connect != NTC_CONNECTED_GROUND))) {
454 		dev_err(&pdev->dev,
455 			"Required data to use read_uv not supplied.\n");
456 		return -EINVAL;
457 	}
458 
459 	data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
460 	if (!data)
461 		return -ENOMEM;
462 
463 	pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);
464 
465 	data->dev = &pdev->dev;
466 	data->pdata = pdata;
467 	strlcpy(data->name, pdev_id->name, sizeof(data->name));
468 
469 	switch (pdev_id->driver_data) {
470 	case TYPE_NCPXXWB473:
471 		data->comp = ncpXXwb473;
472 		data->n_comp = ARRAY_SIZE(ncpXXwb473);
473 		break;
474 	case TYPE_NCPXXWL333:
475 		data->comp = ncpXXwl333;
476 		data->n_comp = ARRAY_SIZE(ncpXXwl333);
477 		break;
478 	default:
479 		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
480 				pdev_id->driver_data, pdev_id->name);
481 		return -EINVAL;
482 	}
483 
484 	platform_set_drvdata(pdev, data);
485 
486 	ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
487 	if (ret) {
488 		dev_err(data->dev, "unable to create sysfs files\n");
489 		return ret;
490 	}
491 
492 	data->hwmon_dev = hwmon_device_register(data->dev);
493 	if (IS_ERR(data->hwmon_dev)) {
494 		dev_err(data->dev, "unable to register as hwmon device.\n");
495 		ret = PTR_ERR(data->hwmon_dev);
496 		goto err_after_sysfs;
497 	}
498 
499 	dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
500 								pdev->name);
501 
502 	return 0;
503 err_after_sysfs:
504 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
505 	ntc_iio_channel_release(pdata);
506 	return ret;
507 }
508 
509 static int ntc_thermistor_remove(struct platform_device *pdev)
510 {
511 	struct ntc_data *data = platform_get_drvdata(pdev);
512 	struct ntc_thermistor_platform_data *pdata = data->pdata;
513 
514 	hwmon_device_unregister(data->hwmon_dev);
515 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
516 	ntc_iio_channel_release(pdata);
517 
518 	return 0;
519 }
520 
521 static struct platform_driver ntc_thermistor_driver = {
522 	.driver = {
523 		.name = "ntc-thermistor",
524 		.owner = THIS_MODULE,
525 		.of_match_table = of_match_ptr(ntc_match),
526 	},
527 	.probe = ntc_thermistor_probe,
528 	.remove = ntc_thermistor_remove,
529 	.id_table = ntc_thermistor_id,
530 };
531 
532 module_platform_driver(ntc_thermistor_driver);
533 
534 MODULE_DESCRIPTION("NTC Thermistor Driver");
535 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
536 MODULE_LICENSE("GPL");
537 MODULE_ALIAS("platform:ntc-thermistor");
538