xref: /openbmc/linux/drivers/hwmon/lm75.c (revision 94cdda6b) 
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 };
61 
62 /* Addresses scanned */
63 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
64 					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
65 
66 
67 /* The LM75 registers */
68 #define LM75_REG_CONF		0x01
69 static const u8 LM75_REG_TEMP[3] = {
70 	0x00,		/* input */
71 	0x03,		/* max */
72 	0x02,		/* hyst */
73 };
74 
75 /* Each client has this additional data */
76 struct lm75_data {
77 	struct i2c_client	*client;
78 	struct device		*hwmon_dev;
79 	struct thermal_zone_device	*tz;
80 	struct mutex		update_lock;
81 	u8			orig_conf;
82 	u8			resolution;	/* In bits, between 9 and 12 */
83 	u8			resolution_limits;
84 	char			valid;		/* !=0 if registers are valid */
85 	unsigned long		last_updated;	/* In jiffies */
86 	unsigned long		sample_time;	/* In jiffies */
87 	s16			temp[3];	/* Register values,
88 						   0 = input
89 						   1 = max
90 						   2 = hyst */
91 };
92 
93 static int lm75_read_value(struct i2c_client *client, u8 reg);
94 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
95 static struct lm75_data *lm75_update_device(struct device *dev);
96 
97 
98 /*-----------------------------------------------------------------------*/
99 
100 static inline long lm75_reg_to_mc(s16 temp, u8 resolution)
101 {
102 	return ((temp >> (16 - resolution)) * 1000) >> (resolution - 8);
103 }
104 
105 /* sysfs attributes for hwmon */
106 
107 static int lm75_read_temp(void *dev, long *temp)
108 {
109 	struct lm75_data *data = lm75_update_device(dev);
110 
111 	if (IS_ERR(data))
112 		return PTR_ERR(data);
113 
114 	*temp = lm75_reg_to_mc(data->temp[0], data->resolution);
115 
116 	return 0;
117 }
118 
119 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
120 			 char *buf)
121 {
122 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
123 	struct lm75_data *data = lm75_update_device(dev);
124 
125 	if (IS_ERR(data))
126 		return PTR_ERR(data);
127 
128 	return sprintf(buf, "%ld\n", lm75_reg_to_mc(data->temp[attr->index],
129 						    data->resolution));
130 }
131 
132 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
133 			const char *buf, size_t count)
134 {
135 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
136 	struct lm75_data *data = dev_get_drvdata(dev);
137 	struct i2c_client *client = data->client;
138 	int nr = attr->index;
139 	long temp;
140 	int error;
141 	u8 resolution;
142 
143 	error = kstrtol(buf, 10, &temp);
144 	if (error)
145 		return error;
146 
147 	/*
148 	 * Resolution of limit registers is assumed to be the same as the
149 	 * temperature input register resolution unless given explicitly.
150 	 */
151 	if (attr->index && data->resolution_limits)
152 		resolution = data->resolution_limits;
153 	else
154 		resolution = data->resolution;
155 
156 	mutex_lock(&data->update_lock);
157 	temp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
158 	data->temp[nr] = DIV_ROUND_CLOSEST(temp  << (resolution - 8),
159 					   1000) << (16 - resolution);
160 	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
161 	mutex_unlock(&data->update_lock);
162 	return count;
163 }
164 
165 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
166 			show_temp, set_temp, 1);
167 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
168 			show_temp, set_temp, 2);
169 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
170 
171 static struct attribute *lm75_attrs[] = {
172 	&sensor_dev_attr_temp1_input.dev_attr.attr,
173 	&sensor_dev_attr_temp1_max.dev_attr.attr,
174 	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
175 
176 	NULL
177 };
178 ATTRIBUTE_GROUPS(lm75);
179 
180 static const struct thermal_zone_of_device_ops lm75_of_thermal_ops = {
181 	.get_temp = lm75_read_temp,
182 };
183 
184 /*-----------------------------------------------------------------------*/
185 
186 /* device probe and removal */
187 
188 static int
189 lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
190 {
191 	struct device *dev = &client->dev;
192 	struct lm75_data *data;
193 	int status;
194 	u8 set_mask, clr_mask;
195 	int new;
196 	enum lm75_type kind = id->driver_data;
197 
198 	if (!i2c_check_functionality(client->adapter,
199 			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
200 		return -EIO;
201 
202 	data = devm_kzalloc(dev, sizeof(struct lm75_data), GFP_KERNEL);
203 	if (!data)
204 		return -ENOMEM;
205 
206 	data->client = client;
207 	i2c_set_clientdata(client, data);
208 	mutex_init(&data->update_lock);
209 
210 	/* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
211 	 * Then tweak to be more precise when appropriate.
212 	 */
213 	set_mask = 0;
214 	clr_mask = LM75_SHUTDOWN;		/* continuous conversions */
215 
216 	switch (kind) {
217 	case adt75:
218 		clr_mask |= 1 << 5;		/* not one-shot mode */
219 		data->resolution = 12;
220 		data->sample_time = HZ / 8;
221 		break;
222 	case ds1775:
223 	case ds75:
224 	case stds75:
225 		clr_mask |= 3 << 5;
226 		set_mask |= 2 << 5;		/* 11-bit mode */
227 		data->resolution = 11;
228 		data->sample_time = HZ;
229 		break;
230 	case ds7505:
231 		set_mask |= 3 << 5;		/* 12-bit mode */
232 		data->resolution = 12;
233 		data->sample_time = HZ / 4;
234 		break;
235 	case g751:
236 	case lm75:
237 	case lm75a:
238 		data->resolution = 9;
239 		data->sample_time = HZ / 2;
240 		break;
241 	case lm75b:
242 		data->resolution = 11;
243 		data->sample_time = HZ / 4;
244 		break;
245 	case max6625:
246 		data->resolution = 9;
247 		data->sample_time = HZ / 4;
248 		break;
249 	case max6626:
250 		data->resolution = 12;
251 		data->resolution_limits = 9;
252 		data->sample_time = HZ / 4;
253 		break;
254 	case tcn75:
255 		data->resolution = 9;
256 		data->sample_time = HZ / 8;
257 		break;
258 	case mcp980x:
259 		data->resolution_limits = 9;
260 		/* fall through */
261 	case tmp100:
262 	case tmp101:
263 		set_mask |= 3 << 5;		/* 12-bit mode */
264 		data->resolution = 12;
265 		data->sample_time = HZ;
266 		clr_mask |= 1 << 7;		/* not one-shot mode */
267 		break;
268 	case tmp112:
269 		set_mask |= 3 << 5;		/* 12-bit mode */
270 		clr_mask |= 1 << 7;		/* not one-shot mode */
271 		data->resolution = 12;
272 		data->sample_time = HZ / 4;
273 		break;
274 	case tmp105:
275 	case tmp175:
276 	case tmp275:
277 	case tmp75:
278 		set_mask |= 3 << 5;		/* 12-bit mode */
279 		clr_mask |= 1 << 7;		/* not one-shot mode */
280 		data->resolution = 12;
281 		data->sample_time = HZ / 2;
282 		break;
283 	}
284 
285 	/* configure as specified */
286 	status = lm75_read_value(client, LM75_REG_CONF);
287 	if (status < 0) {
288 		dev_dbg(dev, "Can't read config? %d\n", status);
289 		return status;
290 	}
291 	data->orig_conf = status;
292 	new = status & ~clr_mask;
293 	new |= set_mask;
294 	if (status != new)
295 		lm75_write_value(client, LM75_REG_CONF, new);
296 	dev_dbg(dev, "Config %02x\n", new);
297 
298 	data->hwmon_dev = hwmon_device_register_with_groups(dev, client->name,
299 							    data, lm75_groups);
300 	if (IS_ERR(data->hwmon_dev))
301 		return PTR_ERR(data->hwmon_dev);
302 
303 	data->tz = thermal_zone_of_sensor_register(data->hwmon_dev, 0,
304 						   data->hwmon_dev,
305 						   &lm75_of_thermal_ops);
306 	if (IS_ERR(data->tz))
307 		data->tz = NULL;
308 
309 	dev_info(dev, "%s: sensor '%s'\n",
310 		 dev_name(data->hwmon_dev), client->name);
311 
312 	return 0;
313 }
314 
315 static int lm75_remove(struct i2c_client *client)
316 {
317 	struct lm75_data *data = i2c_get_clientdata(client);
318 
319 	thermal_zone_of_sensor_unregister(data->hwmon_dev, data->tz);
320 	hwmon_device_unregister(data->hwmon_dev);
321 	lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
322 	return 0;
323 }
324 
325 static const struct i2c_device_id lm75_ids[] = {
326 	{ "adt75", adt75, },
327 	{ "ds1775", ds1775, },
328 	{ "ds75", ds75, },
329 	{ "ds7505", ds7505, },
330 	{ "g751", g751, },
331 	{ "lm75", lm75, },
332 	{ "lm75a", lm75a, },
333 	{ "lm75b", lm75b, },
334 	{ "max6625", max6625, },
335 	{ "max6626", max6626, },
336 	{ "mcp980x", mcp980x, },
337 	{ "stds75", stds75, },
338 	{ "tcn75", tcn75, },
339 	{ "tmp100", tmp100, },
340 	{ "tmp101", tmp101, },
341 	{ "tmp105", tmp105, },
342 	{ "tmp112", tmp112, },
343 	{ "tmp175", tmp175, },
344 	{ "tmp275", tmp275, },
345 	{ "tmp75", tmp75, },
346 	{ /* LIST END */ }
347 };
348 MODULE_DEVICE_TABLE(i2c, lm75_ids);
349 
350 #define LM75A_ID 0xA1
351 
352 /* Return 0 if detection is successful, -ENODEV otherwise */
353 static int lm75_detect(struct i2c_client *new_client,
354 		       struct i2c_board_info *info)
355 {
356 	struct i2c_adapter *adapter = new_client->adapter;
357 	int i;
358 	int conf, hyst, os;
359 	bool is_lm75a = 0;
360 
361 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
362 				     I2C_FUNC_SMBUS_WORD_DATA))
363 		return -ENODEV;
364 
365 	/*
366 	 * Now, we do the remaining detection. There is no identification-
367 	 * dedicated register so we have to rely on several tricks:
368 	 * unused bits, registers cycling over 8-address boundaries,
369 	 * addresses 0x04-0x07 returning the last read value.
370 	 * The cycling+unused addresses combination is not tested,
371 	 * since it would significantly slow the detection down and would
372 	 * hardly add any value.
373 	 *
374 	 * The National Semiconductor LM75A is different than earlier
375 	 * LM75s.  It has an ID byte of 0xaX (where X is the chip
376 	 * revision, with 1 being the only revision in existence) in
377 	 * register 7, and unused registers return 0xff rather than the
378 	 * last read value.
379 	 *
380 	 * Note that this function only detects the original National
381 	 * Semiconductor LM75 and the LM75A. Clones from other vendors
382 	 * aren't detected, on purpose, because they are typically never
383 	 * found on PC hardware. They are found on embedded designs where
384 	 * they can be instantiated explicitly so detection is not needed.
385 	 * The absence of identification registers on all these clones
386 	 * would make their exhaustive detection very difficult and weak,
387 	 * and odds are that the driver would bind to unsupported devices.
388 	 */
389 
390 	/* Unused bits */
391 	conf = i2c_smbus_read_byte_data(new_client, 1);
392 	if (conf & 0xe0)
393 		return -ENODEV;
394 
395 	/* First check for LM75A */
396 	if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
397 		/* LM75A returns 0xff on unused registers so
398 		   just to be sure we check for that too. */
399 		if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
400 		 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
401 		 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
402 			return -ENODEV;
403 		is_lm75a = 1;
404 		hyst = i2c_smbus_read_byte_data(new_client, 2);
405 		os = i2c_smbus_read_byte_data(new_client, 3);
406 	} else { /* Traditional style LM75 detection */
407 		/* Unused addresses */
408 		hyst = i2c_smbus_read_byte_data(new_client, 2);
409 		if (i2c_smbus_read_byte_data(new_client, 4) != hyst
410 		 || i2c_smbus_read_byte_data(new_client, 5) != hyst
411 		 || i2c_smbus_read_byte_data(new_client, 6) != hyst
412 		 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
413 			return -ENODEV;
414 		os = i2c_smbus_read_byte_data(new_client, 3);
415 		if (i2c_smbus_read_byte_data(new_client, 4) != os
416 		 || i2c_smbus_read_byte_data(new_client, 5) != os
417 		 || i2c_smbus_read_byte_data(new_client, 6) != os
418 		 || i2c_smbus_read_byte_data(new_client, 7) != os)
419 			return -ENODEV;
420 	}
421 	/*
422 	 * It is very unlikely that this is a LM75 if both
423 	 * hysteresis and temperature limit registers are 0.
424 	 */
425 	if (hyst == 0 && os == 0)
426 		return -ENODEV;
427 
428 	/* Addresses cycling */
429 	for (i = 8; i <= 248; i += 40) {
430 		if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
431 		 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
432 		 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
433 			return -ENODEV;
434 		if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
435 				!= LM75A_ID)
436 			return -ENODEV;
437 	}
438 
439 	strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);
440 
441 	return 0;
442 }
443 
444 #ifdef CONFIG_PM
445 static int lm75_suspend(struct device *dev)
446 {
447 	int status;
448 	struct i2c_client *client = to_i2c_client(dev);
449 	status = lm75_read_value(client, LM75_REG_CONF);
450 	if (status < 0) {
451 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
452 		return status;
453 	}
454 	status = status | LM75_SHUTDOWN;
455 	lm75_write_value(client, LM75_REG_CONF, status);
456 	return 0;
457 }
458 
459 static int lm75_resume(struct device *dev)
460 {
461 	int status;
462 	struct i2c_client *client = to_i2c_client(dev);
463 	status = lm75_read_value(client, LM75_REG_CONF);
464 	if (status < 0) {
465 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
466 		return status;
467 	}
468 	status = status & ~LM75_SHUTDOWN;
469 	lm75_write_value(client, LM75_REG_CONF, status);
470 	return 0;
471 }
472 
473 static const struct dev_pm_ops lm75_dev_pm_ops = {
474 	.suspend	= lm75_suspend,
475 	.resume		= lm75_resume,
476 };
477 #define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
478 #else
479 #define LM75_DEV_PM_OPS NULL
480 #endif /* CONFIG_PM */
481 
482 static struct i2c_driver lm75_driver = {
483 	.class		= I2C_CLASS_HWMON,
484 	.driver = {
485 		.name	= "lm75",
486 		.pm	= LM75_DEV_PM_OPS,
487 	},
488 	.probe		= lm75_probe,
489 	.remove		= lm75_remove,
490 	.id_table	= lm75_ids,
491 	.detect		= lm75_detect,
492 	.address_list	= normal_i2c,
493 };
494 
495 /*-----------------------------------------------------------------------*/
496 
497 /* register access */
498 
499 /*
500  * All registers are word-sized, except for the configuration register.
501  * LM75 uses a high-byte first convention, which is exactly opposite to
502  * the SMBus standard.
503  */
504 static int lm75_read_value(struct i2c_client *client, u8 reg)
505 {
506 	if (reg == LM75_REG_CONF)
507 		return i2c_smbus_read_byte_data(client, reg);
508 	else
509 		return i2c_smbus_read_word_swapped(client, reg);
510 }
511 
512 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
513 {
514 	if (reg == LM75_REG_CONF)
515 		return i2c_smbus_write_byte_data(client, reg, value);
516 	else
517 		return i2c_smbus_write_word_swapped(client, reg, value);
518 }
519 
520 static struct lm75_data *lm75_update_device(struct device *dev)
521 {
522 	struct lm75_data *data = dev_get_drvdata(dev);
523 	struct i2c_client *client = data->client;
524 	struct lm75_data *ret = data;
525 
526 	mutex_lock(&data->update_lock);
527 
528 	if (time_after(jiffies, data->last_updated + data->sample_time)
529 	    || !data->valid) {
530 		int i;
531 		dev_dbg(&client->dev, "Starting lm75 update\n");
532 
533 		for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
534 			int status;
535 
536 			status = lm75_read_value(client, LM75_REG_TEMP[i]);
537 			if (unlikely(status < 0)) {
538 				dev_dbg(dev,
539 					"LM75: Failed to read value: reg %d, error %d\n",
540 					LM75_REG_TEMP[i], status);
541 				ret = ERR_PTR(status);
542 				data->valid = 0;
543 				goto abort;
544 			}
545 			data->temp[i] = status;
546 		}
547 		data->last_updated = jiffies;
548 		data->valid = 1;
549 	}
550 
551 abort:
552 	mutex_unlock(&data->update_lock);
553 	return ret;
554 }
555 
556 module_i2c_driver(lm75_driver);
557 
558 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
559 MODULE_DESCRIPTION("LM75 driver");
560 MODULE_LICENSE("GPL");
561