aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/ntc_thermistor.c
blob: 9b382ec2c3bd4de978d98a6d9f24f797684fe534 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
/*
 * 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;
	} else {
		*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,
};

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");