xref: /openbmc/linux/drivers/hwmon/lm75.c (revision e23feb16) 
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 "lm75.h"
31 
32 
33 /*
34  * This driver handles the LM75 and compatible digital temperature sensors.
35  */
36 
37 enum lm75_type {		/* keep sorted in alphabetical order */
38 	adt75,
39 	ds1775,
40 	ds75,
41 	ds7505,
42 	lm75,
43 	lm75a,
44 	max6625,
45 	max6626,
46 	mcp980x,
47 	stds75,
48 	tcn75,
49 	tmp100,
50 	tmp101,
51 	tmp105,
52 	tmp175,
53 	tmp275,
54 	tmp75,
55 };
56 
57 /* Addresses scanned */
58 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
59 					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
60 
61 
62 /* The LM75 registers */
63 #define LM75_REG_CONF		0x01
64 static const u8 LM75_REG_TEMP[3] = {
65 	0x00,		/* input */
66 	0x03,		/* max */
67 	0x02,		/* hyst */
68 };
69 
70 /* Each client has this additional data */
71 struct lm75_data {
72 	struct device		*hwmon_dev;
73 	struct mutex		update_lock;
74 	u8			orig_conf;
75 	u8			resolution;	/* In bits, between 9 and 12 */
76 	u8			resolution_limits;
77 	char			valid;		/* !=0 if registers are valid */
78 	unsigned long		last_updated;	/* In jiffies */
79 	unsigned long		sample_time;	/* In jiffies */
80 	s16			temp[3];	/* Register values,
81 						   0 = input
82 						   1 = max
83 						   2 = hyst */
84 };
85 
86 static int lm75_read_value(struct i2c_client *client, u8 reg);
87 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
88 static struct lm75_data *lm75_update_device(struct device *dev);
89 
90 
91 /*-----------------------------------------------------------------------*/
92 
93 /* sysfs attributes for hwmon */
94 
95 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
96 			 char *buf)
97 {
98 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
99 	struct lm75_data *data = lm75_update_device(dev);
100 	long temp;
101 
102 	if (IS_ERR(data))
103 		return PTR_ERR(data);
104 
105 	temp = ((data->temp[attr->index] >> (16 - data->resolution)) * 1000)
106 	       >> (data->resolution - 8);
107 
108 	return sprintf(buf, "%ld\n", temp);
109 }
110 
111 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
112 			const char *buf, size_t count)
113 {
114 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
115 	struct i2c_client *client = to_i2c_client(dev);
116 	struct lm75_data *data = i2c_get_clientdata(client);
117 	int nr = attr->index;
118 	long temp;
119 	int error;
120 	u8 resolution;
121 
122 	error = kstrtol(buf, 10, &temp);
123 	if (error)
124 		return error;
125 
126 	/*
127 	 * Resolution of limit registers is assumed to be the same as the
128 	 * temperature input register resolution unless given explicitly.
129 	 */
130 	if (attr->index && data->resolution_limits)
131 		resolution = data->resolution_limits;
132 	else
133 		resolution = data->resolution;
134 
135 	mutex_lock(&data->update_lock);
136 	temp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
137 	data->temp[nr] = DIV_ROUND_CLOSEST(temp  << (resolution - 8),
138 					   1000) << (16 - resolution);
139 	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
140 	mutex_unlock(&data->update_lock);
141 	return count;
142 }
143 
144 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
145 			show_temp, set_temp, 1);
146 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
147 			show_temp, set_temp, 2);
148 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
149 
150 static struct attribute *lm75_attributes[] = {
151 	&sensor_dev_attr_temp1_input.dev_attr.attr,
152 	&sensor_dev_attr_temp1_max.dev_attr.attr,
153 	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
154 
155 	NULL
156 };
157 
158 static const struct attribute_group lm75_group = {
159 	.attrs = lm75_attributes,
160 };
161 
162 /*-----------------------------------------------------------------------*/
163 
164 /* device probe and removal */
165 
166 static int
167 lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
168 {
169 	struct lm75_data *data;
170 	int status;
171 	u8 set_mask, clr_mask;
172 	int new;
173 	enum lm75_type kind = id->driver_data;
174 
175 	if (!i2c_check_functionality(client->adapter,
176 			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
177 		return -EIO;
178 
179 	data = devm_kzalloc(&client->dev, sizeof(struct lm75_data), GFP_KERNEL);
180 	if (!data)
181 		return -ENOMEM;
182 
183 	i2c_set_clientdata(client, data);
184 	mutex_init(&data->update_lock);
185 
186 	/* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
187 	 * Then tweak to be more precise when appropriate.
188 	 */
189 	set_mask = 0;
190 	clr_mask = LM75_SHUTDOWN;		/* continuous conversions */
191 
192 	switch (kind) {
193 	case adt75:
194 		clr_mask |= 1 << 5;		/* not one-shot mode */
195 		data->resolution = 12;
196 		data->sample_time = HZ / 8;
197 		break;
198 	case ds1775:
199 	case ds75:
200 	case stds75:
201 		clr_mask |= 3 << 5;
202 		set_mask |= 2 << 5;		/* 11-bit mode */
203 		data->resolution = 11;
204 		data->sample_time = HZ;
205 		break;
206 	case ds7505:
207 		set_mask |= 3 << 5;		/* 12-bit mode */
208 		data->resolution = 12;
209 		data->sample_time = HZ / 4;
210 		break;
211 	case lm75:
212 	case lm75a:
213 		data->resolution = 9;
214 		data->sample_time = HZ / 2;
215 		break;
216 	case max6625:
217 		data->resolution = 9;
218 		data->sample_time = HZ / 4;
219 		break;
220 	case max6626:
221 		data->resolution = 12;
222 		data->resolution_limits = 9;
223 		data->sample_time = HZ / 4;
224 		break;
225 	case tcn75:
226 		data->resolution = 9;
227 		data->sample_time = HZ / 8;
228 		break;
229 	case mcp980x:
230 		data->resolution_limits = 9;
231 		/* fall through */
232 	case tmp100:
233 	case tmp101:
234 		set_mask |= 3 << 5;		/* 12-bit mode */
235 		data->resolution = 12;
236 		data->sample_time = HZ;
237 		clr_mask |= 1 << 7;		/* not one-shot mode */
238 		break;
239 	case tmp105:
240 	case tmp175:
241 	case tmp275:
242 	case tmp75:
243 		set_mask |= 3 << 5;		/* 12-bit mode */
244 		clr_mask |= 1 << 7;		/* not one-shot mode */
245 		data->resolution = 12;
246 		data->sample_time = HZ / 2;
247 		break;
248 	}
249 
250 	/* configure as specified */
251 	status = lm75_read_value(client, LM75_REG_CONF);
252 	if (status < 0) {
253 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
254 		return status;
255 	}
256 	data->orig_conf = status;
257 	new = status & ~clr_mask;
258 	new |= set_mask;
259 	if (status != new)
260 		lm75_write_value(client, LM75_REG_CONF, new);
261 	dev_dbg(&client->dev, "Config %02x\n", new);
262 
263 	/* Register sysfs hooks */
264 	status = sysfs_create_group(&client->dev.kobj, &lm75_group);
265 	if (status)
266 		return status;
267 
268 	data->hwmon_dev = hwmon_device_register(&client->dev);
269 	if (IS_ERR(data->hwmon_dev)) {
270 		status = PTR_ERR(data->hwmon_dev);
271 		goto exit_remove;
272 	}
273 
274 	dev_info(&client->dev, "%s: sensor '%s'\n",
275 		 dev_name(data->hwmon_dev), client->name);
276 
277 	return 0;
278 
279 exit_remove:
280 	sysfs_remove_group(&client->dev.kobj, &lm75_group);
281 	return status;
282 }
283 
284 static int lm75_remove(struct i2c_client *client)
285 {
286 	struct lm75_data *data = i2c_get_clientdata(client);
287 
288 	hwmon_device_unregister(data->hwmon_dev);
289 	sysfs_remove_group(&client->dev.kobj, &lm75_group);
290 	lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
291 	return 0;
292 }
293 
294 static const struct i2c_device_id lm75_ids[] = {
295 	{ "adt75", adt75, },
296 	{ "ds1775", ds1775, },
297 	{ "ds75", ds75, },
298 	{ "ds7505", ds7505, },
299 	{ "lm75", lm75, },
300 	{ "lm75a", lm75a, },
301 	{ "max6625", max6625, },
302 	{ "max6626", max6626, },
303 	{ "mcp980x", mcp980x, },
304 	{ "stds75", stds75, },
305 	{ "tcn75", tcn75, },
306 	{ "tmp100", tmp100, },
307 	{ "tmp101", tmp101, },
308 	{ "tmp105", tmp105, },
309 	{ "tmp175", tmp175, },
310 	{ "tmp275", tmp275, },
311 	{ "tmp75", tmp75, },
312 	{ /* LIST END */ }
313 };
314 MODULE_DEVICE_TABLE(i2c, lm75_ids);
315 
316 #define LM75A_ID 0xA1
317 
318 /* Return 0 if detection is successful, -ENODEV otherwise */
319 static int lm75_detect(struct i2c_client *new_client,
320 		       struct i2c_board_info *info)
321 {
322 	struct i2c_adapter *adapter = new_client->adapter;
323 	int i;
324 	int conf, hyst, os;
325 	bool is_lm75a = 0;
326 
327 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
328 				     I2C_FUNC_SMBUS_WORD_DATA))
329 		return -ENODEV;
330 
331 	/*
332 	 * Now, we do the remaining detection. There is no identification-
333 	 * dedicated register so we have to rely on several tricks:
334 	 * unused bits, registers cycling over 8-address boundaries,
335 	 * addresses 0x04-0x07 returning the last read value.
336 	 * The cycling+unused addresses combination is not tested,
337 	 * since it would significantly slow the detection down and would
338 	 * hardly add any value.
339 	 *
340 	 * The National Semiconductor LM75A is different than earlier
341 	 * LM75s.  It has an ID byte of 0xaX (where X is the chip
342 	 * revision, with 1 being the only revision in existence) in
343 	 * register 7, and unused registers return 0xff rather than the
344 	 * last read value.
345 	 *
346 	 * Note that this function only detects the original National
347 	 * Semiconductor LM75 and the LM75A. Clones from other vendors
348 	 * aren't detected, on purpose, because they are typically never
349 	 * found on PC hardware. They are found on embedded designs where
350 	 * they can be instantiated explicitly so detection is not needed.
351 	 * The absence of identification registers on all these clones
352 	 * would make their exhaustive detection very difficult and weak,
353 	 * and odds are that the driver would bind to unsupported devices.
354 	 */
355 
356 	/* Unused bits */
357 	conf = i2c_smbus_read_byte_data(new_client, 1);
358 	if (conf & 0xe0)
359 		return -ENODEV;
360 
361 	/* First check for LM75A */
362 	if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
363 		/* LM75A returns 0xff on unused registers so
364 		   just to be sure we check for that too. */
365 		if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
366 		 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
367 		 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
368 			return -ENODEV;
369 		is_lm75a = 1;
370 		hyst = i2c_smbus_read_byte_data(new_client, 2);
371 		os = i2c_smbus_read_byte_data(new_client, 3);
372 	} else { /* Traditional style LM75 detection */
373 		/* Unused addresses */
374 		hyst = i2c_smbus_read_byte_data(new_client, 2);
375 		if (i2c_smbus_read_byte_data(new_client, 4) != hyst
376 		 || i2c_smbus_read_byte_data(new_client, 5) != hyst
377 		 || i2c_smbus_read_byte_data(new_client, 6) != hyst
378 		 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
379 			return -ENODEV;
380 		os = i2c_smbus_read_byte_data(new_client, 3);
381 		if (i2c_smbus_read_byte_data(new_client, 4) != os
382 		 || i2c_smbus_read_byte_data(new_client, 5) != os
383 		 || i2c_smbus_read_byte_data(new_client, 6) != os
384 		 || i2c_smbus_read_byte_data(new_client, 7) != os)
385 			return -ENODEV;
386 	}
387 
388 	/* Addresses cycling */
389 	for (i = 8; i <= 248; i += 40) {
390 		if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
391 		 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
392 		 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
393 			return -ENODEV;
394 		if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
395 				!= LM75A_ID)
396 			return -ENODEV;
397 	}
398 
399 	strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);
400 
401 	return 0;
402 }
403 
404 #ifdef CONFIG_PM
405 static int lm75_suspend(struct device *dev)
406 {
407 	int status;
408 	struct i2c_client *client = to_i2c_client(dev);
409 	status = lm75_read_value(client, LM75_REG_CONF);
410 	if (status < 0) {
411 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
412 		return status;
413 	}
414 	status = status | LM75_SHUTDOWN;
415 	lm75_write_value(client, LM75_REG_CONF, status);
416 	return 0;
417 }
418 
419 static int lm75_resume(struct device *dev)
420 {
421 	int status;
422 	struct i2c_client *client = to_i2c_client(dev);
423 	status = lm75_read_value(client, LM75_REG_CONF);
424 	if (status < 0) {
425 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
426 		return status;
427 	}
428 	status = status & ~LM75_SHUTDOWN;
429 	lm75_write_value(client, LM75_REG_CONF, status);
430 	return 0;
431 }
432 
433 static const struct dev_pm_ops lm75_dev_pm_ops = {
434 	.suspend	= lm75_suspend,
435 	.resume		= lm75_resume,
436 };
437 #define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
438 #else
439 #define LM75_DEV_PM_OPS NULL
440 #endif /* CONFIG_PM */
441 
442 static struct i2c_driver lm75_driver = {
443 	.class		= I2C_CLASS_HWMON,
444 	.driver = {
445 		.name	= "lm75",
446 		.pm	= LM75_DEV_PM_OPS,
447 	},
448 	.probe		= lm75_probe,
449 	.remove		= lm75_remove,
450 	.id_table	= lm75_ids,
451 	.detect		= lm75_detect,
452 	.address_list	= normal_i2c,
453 };
454 
455 /*-----------------------------------------------------------------------*/
456 
457 /* register access */
458 
459 /*
460  * All registers are word-sized, except for the configuration register.
461  * LM75 uses a high-byte first convention, which is exactly opposite to
462  * the SMBus standard.
463  */
464 static int lm75_read_value(struct i2c_client *client, u8 reg)
465 {
466 	if (reg == LM75_REG_CONF)
467 		return i2c_smbus_read_byte_data(client, reg);
468 	else
469 		return i2c_smbus_read_word_swapped(client, reg);
470 }
471 
472 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
473 {
474 	if (reg == LM75_REG_CONF)
475 		return i2c_smbus_write_byte_data(client, reg, value);
476 	else
477 		return i2c_smbus_write_word_swapped(client, reg, value);
478 }
479 
480 static struct lm75_data *lm75_update_device(struct device *dev)
481 {
482 	struct i2c_client *client = to_i2c_client(dev);
483 	struct lm75_data *data = i2c_get_clientdata(client);
484 	struct lm75_data *ret = data;
485 
486 	mutex_lock(&data->update_lock);
487 
488 	if (time_after(jiffies, data->last_updated + data->sample_time)
489 	    || !data->valid) {
490 		int i;
491 		dev_dbg(&client->dev, "Starting lm75 update\n");
492 
493 		for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
494 			int status;
495 
496 			status = lm75_read_value(client, LM75_REG_TEMP[i]);
497 			if (unlikely(status < 0)) {
498 				dev_dbg(dev,
499 					"LM75: Failed to read value: reg %d, error %d\n",
500 					LM75_REG_TEMP[i], status);
501 				ret = ERR_PTR(status);
502 				data->valid = 0;
503 				goto abort;
504 			}
505 			data->temp[i] = status;
506 		}
507 		data->last_updated = jiffies;
508 		data->valid = 1;
509 	}
510 
511 abort:
512 	mutex_unlock(&data->update_lock);
513 	return ret;
514 }
515 
516 module_i2c_driver(lm75_driver);
517 
518 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
519 MODULE_DESCRIPTION("LM75 driver");
520 MODULE_LICENSE("GPL");
521