xref: /openbmc/linux/drivers/hwmon/lm75.c (revision 8c749ce9) 
1 /*
2  * lm75.c - Part of lm_sensors, Linux kernel modules for hardware
3  *	 monitoring
4  * Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 #include <linux/module.h>
22 #include <linux/init.h>
23 #include <linux/slab.h>
24 #include <linux/jiffies.h>
25 #include <linux/i2c.h>
26 #include <linux/hwmon.h>
27 #include <linux/hwmon-sysfs.h>
28 #include <linux/err.h>
29 #include <linux/mutex.h>
30 #include <linux/of.h>
31 #include <linux/thermal.h>
32 #include "lm75.h"
33 
34 
35 /*
36  * This driver handles the LM75 and compatible digital temperature sensors.
37  */
38 
39 enum lm75_type {		/* keep sorted in alphabetical order */
40 	adt75,
41 	ds1775,
42 	ds75,
43 	ds7505,
44 	g751,
45 	lm75,
46 	lm75a,
47 	lm75b,
48 	max6625,
49 	max6626,
50 	mcp980x,
51 	stds75,
52 	tcn75,
53 	tmp100,
54 	tmp101,
55 	tmp105,
56 	tmp112,
57 	tmp175,
58 	tmp275,
59 	tmp75,
60 	tmp75c,
61 };
62 
63 /* Addresses scanned */
64 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
65 					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
66 
67 
68 /* The LM75 registers */
69 #define LM75_REG_CONF		0x01
70 static const u8 LM75_REG_TEMP[3] = {
71 	0x00,		/* input */
72 	0x03,		/* max */
73 	0x02,		/* hyst */
74 };
75 
76 /* Each client has this additional data */
77 struct lm75_data {
78 	struct i2c_client	*client;
79 	struct device		*hwmon_dev;
80 	struct thermal_zone_device	*tz;
81 	struct mutex		update_lock;
82 	u8			orig_conf;
83 	u8			resolution;	/* In bits, between 9 and 12 */
84 	u8			resolution_limits;
85 	char			valid;		/* !=0 if registers are valid */
86 	unsigned long		last_updated;	/* In jiffies */
87 	unsigned long		sample_time;	/* In jiffies */
88 	s16			temp[3];	/* Register values,
89 						   0 = input
90 						   1 = max
91 						   2 = hyst */
92 };
93 
94 static int lm75_read_value(struct i2c_client *client, u8 reg);
95 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
96 static struct lm75_data *lm75_update_device(struct device *dev);
97 
98 
99 /*-----------------------------------------------------------------------*/
100 
101 static inline long lm75_reg_to_mc(s16 temp, u8 resolution)
102 {
103 	return ((temp >> (16 - resolution)) * 1000) >> (resolution - 8);
104 }
105 
106 /* sysfs attributes for hwmon */
107 
108 static int lm75_read_temp(void *dev, int *temp)
109 {
110 	struct lm75_data *data = lm75_update_device(dev);
111 
112 	if (IS_ERR(data))
113 		return PTR_ERR(data);
114 
115 	*temp = lm75_reg_to_mc(data->temp[0], data->resolution);
116 
117 	return 0;
118 }
119 
120 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
121 			 char *buf)
122 {
123 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
124 	struct lm75_data *data = lm75_update_device(dev);
125 
126 	if (IS_ERR(data))
127 		return PTR_ERR(data);
128 
129 	return sprintf(buf, "%ld\n", lm75_reg_to_mc(data->temp[attr->index],
130 						    data->resolution));
131 }
132 
133 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
134 			const char *buf, size_t count)
135 {
136 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
137 	struct lm75_data *data = dev_get_drvdata(dev);
138 	struct i2c_client *client = data->client;
139 	int nr = attr->index;
140 	long temp;
141 	int error;
142 	u8 resolution;
143 
144 	error = kstrtol(buf, 10, &temp);
145 	if (error)
146 		return error;
147 
148 	/*
149 	 * Resolution of limit registers is assumed to be the same as the
150 	 * temperature input register resolution unless given explicitly.
151 	 */
152 	if (attr->index && data->resolution_limits)
153 		resolution = data->resolution_limits;
154 	else
155 		resolution = data->resolution;
156 
157 	mutex_lock(&data->update_lock);
158 	temp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
159 	data->temp[nr] = DIV_ROUND_CLOSEST(temp  << (resolution - 8),
160 					   1000) << (16 - resolution);
161 	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
162 	mutex_unlock(&data->update_lock);
163 	return count;
164 }
165 
166 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
167 			show_temp, set_temp, 1);
168 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
169 			show_temp, set_temp, 2);
170 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
171 
172 static struct attribute *lm75_attrs[] = {
173 	&sensor_dev_attr_temp1_input.dev_attr.attr,
174 	&sensor_dev_attr_temp1_max.dev_attr.attr,
175 	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
176 
177 	NULL
178 };
179 ATTRIBUTE_GROUPS(lm75);
180 
181 static const struct thermal_zone_of_device_ops lm75_of_thermal_ops = {
182 	.get_temp = lm75_read_temp,
183 };
184 
185 /*-----------------------------------------------------------------------*/
186 
187 /* device probe and removal */
188 
189 static int
190 lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
191 {
192 	struct device *dev = &client->dev;
193 	struct lm75_data *data;
194 	int status;
195 	u8 set_mask, clr_mask;
196 	int new;
197 	enum lm75_type kind = id->driver_data;
198 
199 	if (!i2c_check_functionality(client->adapter,
200 			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
201 		return -EIO;
202 
203 	data = devm_kzalloc(dev, sizeof(struct lm75_data), GFP_KERNEL);
204 	if (!data)
205 		return -ENOMEM;
206 
207 	data->client = client;
208 	i2c_set_clientdata(client, data);
209 	mutex_init(&data->update_lock);
210 
211 	/* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
212 	 * Then tweak to be more precise when appropriate.
213 	 */
214 	set_mask = 0;
215 	clr_mask = LM75_SHUTDOWN;		/* continuous conversions */
216 
217 	switch (kind) {
218 	case adt75:
219 		clr_mask |= 1 << 5;		/* not one-shot mode */
220 		data->resolution = 12;
221 		data->sample_time = HZ / 8;
222 		break;
223 	case ds1775:
224 	case ds75:
225 	case stds75:
226 		clr_mask |= 3 << 5;
227 		set_mask |= 2 << 5;		/* 11-bit mode */
228 		data->resolution = 11;
229 		data->sample_time = HZ;
230 		break;
231 	case ds7505:
232 		set_mask |= 3 << 5;		/* 12-bit mode */
233 		data->resolution = 12;
234 		data->sample_time = HZ / 4;
235 		break;
236 	case g751:
237 	case lm75:
238 	case lm75a:
239 		data->resolution = 9;
240 		data->sample_time = HZ / 2;
241 		break;
242 	case lm75b:
243 		data->resolution = 11;
244 		data->sample_time = HZ / 4;
245 		break;
246 	case max6625:
247 		data->resolution = 9;
248 		data->sample_time = HZ / 4;
249 		break;
250 	case max6626:
251 		data->resolution = 12;
252 		data->resolution_limits = 9;
253 		data->sample_time = HZ / 4;
254 		break;
255 	case tcn75:
256 		data->resolution = 9;
257 		data->sample_time = HZ / 8;
258 		break;
259 	case mcp980x:
260 		data->resolution_limits = 9;
261 		/* fall through */
262 	case tmp100:
263 	case tmp101:
264 		set_mask |= 3 << 5;		/* 12-bit mode */
265 		data->resolution = 12;
266 		data->sample_time = HZ;
267 		clr_mask |= 1 << 7;		/* not one-shot mode */
268 		break;
269 	case tmp112:
270 		set_mask |= 3 << 5;		/* 12-bit mode */
271 		clr_mask |= 1 << 7;		/* not one-shot mode */
272 		data->resolution = 12;
273 		data->sample_time = HZ / 4;
274 		break;
275 	case tmp105:
276 	case tmp175:
277 	case tmp275:
278 	case tmp75:
279 		set_mask |= 3 << 5;		/* 12-bit mode */
280 		clr_mask |= 1 << 7;		/* not one-shot mode */
281 		data->resolution = 12;
282 		data->sample_time = HZ / 2;
283 		break;
284 	case tmp75c:
285 		clr_mask |= 1 << 5;		/* not one-shot mode */
286 		data->resolution = 12;
287 		data->sample_time = HZ / 4;
288 		break;
289 	}
290 
291 	/* configure as specified */
292 	status = lm75_read_value(client, LM75_REG_CONF);
293 	if (status < 0) {
294 		dev_dbg(dev, "Can't read config? %d\n", status);
295 		return status;
296 	}
297 	data->orig_conf = status;
298 	new = status & ~clr_mask;
299 	new |= set_mask;
300 	if (status != new)
301 		lm75_write_value(client, LM75_REG_CONF, new);
302 	dev_dbg(dev, "Config %02x\n", new);
303 
304 	data->hwmon_dev = hwmon_device_register_with_groups(dev, client->name,
305 							    data, lm75_groups);
306 	if (IS_ERR(data->hwmon_dev))
307 		return PTR_ERR(data->hwmon_dev);
308 
309 	data->tz = thermal_zone_of_sensor_register(data->hwmon_dev, 0,
310 						   data->hwmon_dev,
311 						   &lm75_of_thermal_ops);
312 	if (IS_ERR(data->tz))
313 		data->tz = NULL;
314 
315 	dev_info(dev, "%s: sensor '%s'\n",
316 		 dev_name(data->hwmon_dev), client->name);
317 
318 	return 0;
319 }
320 
321 static int lm75_remove(struct i2c_client *client)
322 {
323 	struct lm75_data *data = i2c_get_clientdata(client);
324 
325 	thermal_zone_of_sensor_unregister(data->hwmon_dev, data->tz);
326 	hwmon_device_unregister(data->hwmon_dev);
327 	lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
328 	return 0;
329 }
330 
331 static const struct i2c_device_id lm75_ids[] = {
332 	{ "adt75", adt75, },
333 	{ "ds1775", ds1775, },
334 	{ "ds75", ds75, },
335 	{ "ds7505", ds7505, },
336 	{ "g751", g751, },
337 	{ "lm75", lm75, },
338 	{ "lm75a", lm75a, },
339 	{ "lm75b", lm75b, },
340 	{ "max6625", max6625, },
341 	{ "max6626", max6626, },
342 	{ "mcp980x", mcp980x, },
343 	{ "stds75", stds75, },
344 	{ "tcn75", tcn75, },
345 	{ "tmp100", tmp100, },
346 	{ "tmp101", tmp101, },
347 	{ "tmp105", tmp105, },
348 	{ "tmp112", tmp112, },
349 	{ "tmp175", tmp175, },
350 	{ "tmp275", tmp275, },
351 	{ "tmp75", tmp75, },
352 	{ "tmp75c", tmp75c, },
353 	{ /* LIST END */ }
354 };
355 MODULE_DEVICE_TABLE(i2c, lm75_ids);
356 
357 #define LM75A_ID 0xA1
358 
359 /* Return 0 if detection is successful, -ENODEV otherwise */
360 static int lm75_detect(struct i2c_client *new_client,
361 		       struct i2c_board_info *info)
362 {
363 	struct i2c_adapter *adapter = new_client->adapter;
364 	int i;
365 	int conf, hyst, os;
366 	bool is_lm75a = 0;
367 
368 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
369 				     I2C_FUNC_SMBUS_WORD_DATA))
370 		return -ENODEV;
371 
372 	/*
373 	 * Now, we do the remaining detection. There is no identification-
374 	 * dedicated register so we have to rely on several tricks:
375 	 * unused bits, registers cycling over 8-address boundaries,
376 	 * addresses 0x04-0x07 returning the last read value.
377 	 * The cycling+unused addresses combination is not tested,
378 	 * since it would significantly slow the detection down and would
379 	 * hardly add any value.
380 	 *
381 	 * The National Semiconductor LM75A is different than earlier
382 	 * LM75s.  It has an ID byte of 0xaX (where X is the chip
383 	 * revision, with 1 being the only revision in existence) in
384 	 * register 7, and unused registers return 0xff rather than the
385 	 * last read value.
386 	 *
387 	 * Note that this function only detects the original National
388 	 * Semiconductor LM75 and the LM75A. Clones from other vendors
389 	 * aren't detected, on purpose, because they are typically never
390 	 * found on PC hardware. They are found on embedded designs where
391 	 * they can be instantiated explicitly so detection is not needed.
392 	 * The absence of identification registers on all these clones
393 	 * would make their exhaustive detection very difficult and weak,
394 	 * and odds are that the driver would bind to unsupported devices.
395 	 */
396 
397 	/* Unused bits */
398 	conf = i2c_smbus_read_byte_data(new_client, 1);
399 	if (conf & 0xe0)
400 		return -ENODEV;
401 
402 	/* First check for LM75A */
403 	if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
404 		/* LM75A returns 0xff on unused registers so
405 		   just to be sure we check for that too. */
406 		if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
407 		 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
408 		 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
409 			return -ENODEV;
410 		is_lm75a = 1;
411 		hyst = i2c_smbus_read_byte_data(new_client, 2);
412 		os = i2c_smbus_read_byte_data(new_client, 3);
413 	} else { /* Traditional style LM75 detection */
414 		/* Unused addresses */
415 		hyst = i2c_smbus_read_byte_data(new_client, 2);
416 		if (i2c_smbus_read_byte_data(new_client, 4) != hyst
417 		 || i2c_smbus_read_byte_data(new_client, 5) != hyst
418 		 || i2c_smbus_read_byte_data(new_client, 6) != hyst
419 		 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
420 			return -ENODEV;
421 		os = i2c_smbus_read_byte_data(new_client, 3);
422 		if (i2c_smbus_read_byte_data(new_client, 4) != os
423 		 || i2c_smbus_read_byte_data(new_client, 5) != os
424 		 || i2c_smbus_read_byte_data(new_client, 6) != os
425 		 || i2c_smbus_read_byte_data(new_client, 7) != os)
426 			return -ENODEV;
427 	}
428 	/*
429 	 * It is very unlikely that this is a LM75 if both
430 	 * hysteresis and temperature limit registers are 0.
431 	 */
432 	if (hyst == 0 && os == 0)
433 		return -ENODEV;
434 
435 	/* Addresses cycling */
436 	for (i = 8; i <= 248; i += 40) {
437 		if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
438 		 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
439 		 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
440 			return -ENODEV;
441 		if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
442 				!= LM75A_ID)
443 			return -ENODEV;
444 	}
445 
446 	strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);
447 
448 	return 0;
449 }
450 
451 #ifdef CONFIG_PM
452 static int lm75_suspend(struct device *dev)
453 {
454 	int status;
455 	struct i2c_client *client = to_i2c_client(dev);
456 	status = lm75_read_value(client, LM75_REG_CONF);
457 	if (status < 0) {
458 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
459 		return status;
460 	}
461 	status = status | LM75_SHUTDOWN;
462 	lm75_write_value(client, LM75_REG_CONF, status);
463 	return 0;
464 }
465 
466 static int lm75_resume(struct device *dev)
467 {
468 	int status;
469 	struct i2c_client *client = to_i2c_client(dev);
470 	status = lm75_read_value(client, LM75_REG_CONF);
471 	if (status < 0) {
472 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
473 		return status;
474 	}
475 	status = status & ~LM75_SHUTDOWN;
476 	lm75_write_value(client, LM75_REG_CONF, status);
477 	return 0;
478 }
479 
480 static const struct dev_pm_ops lm75_dev_pm_ops = {
481 	.suspend	= lm75_suspend,
482 	.resume		= lm75_resume,
483 };
484 #define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
485 #else
486 #define LM75_DEV_PM_OPS NULL
487 #endif /* CONFIG_PM */
488 
489 static struct i2c_driver lm75_driver = {
490 	.class		= I2C_CLASS_HWMON,
491 	.driver = {
492 		.name	= "lm75",
493 		.pm	= LM75_DEV_PM_OPS,
494 	},
495 	.probe		= lm75_probe,
496 	.remove		= lm75_remove,
497 	.id_table	= lm75_ids,
498 	.detect		= lm75_detect,
499 	.address_list	= normal_i2c,
500 };
501 
502 /*-----------------------------------------------------------------------*/
503 
504 /* register access */
505 
506 /*
507  * All registers are word-sized, except for the configuration register.
508  * LM75 uses a high-byte first convention, which is exactly opposite to
509  * the SMBus standard.
510  */
511 static int lm75_read_value(struct i2c_client *client, u8 reg)
512 {
513 	if (reg == LM75_REG_CONF)
514 		return i2c_smbus_read_byte_data(client, reg);
515 	else
516 		return i2c_smbus_read_word_swapped(client, reg);
517 }
518 
519 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
520 {
521 	if (reg == LM75_REG_CONF)
522 		return i2c_smbus_write_byte_data(client, reg, value);
523 	else
524 		return i2c_smbus_write_word_swapped(client, reg, value);
525 }
526 
527 static struct lm75_data *lm75_update_device(struct device *dev)
528 {
529 	struct lm75_data *data = dev_get_drvdata(dev);
530 	struct i2c_client *client = data->client;
531 	struct lm75_data *ret = data;
532 
533 	mutex_lock(&data->update_lock);
534 
535 	if (time_after(jiffies, data->last_updated + data->sample_time)
536 	    || !data->valid) {
537 		int i;
538 		dev_dbg(&client->dev, "Starting lm75 update\n");
539 
540 		for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
541 			int status;
542 
543 			status = lm75_read_value(client, LM75_REG_TEMP[i]);
544 			if (unlikely(status < 0)) {
545 				dev_dbg(dev,
546 					"LM75: Failed to read value: reg %d, error %d\n",
547 					LM75_REG_TEMP[i], status);
548 				ret = ERR_PTR(status);
549 				data->valid = 0;
550 				goto abort;
551 			}
552 			data->temp[i] = status;
553 		}
554 		data->last_updated = jiffies;
555 		data->valid = 1;
556 	}
557 
558 abort:
559 	mutex_unlock(&data->update_lock);
560 	return ret;
561 }
562 
563 module_i2c_driver(lm75_driver);
564 
565 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
566 MODULE_DESCRIPTION("LM75 driver");
567 MODULE_LICENSE("GPL");
568