xref: /linux/drivers/hwmon/lm75.c (revision 26b0d14106954ae46d2f4f7eec3481828a210f7d)
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 	lm75,
42 	lm75a,
43 	max6625,
44 	max6626,
45 	mcp980x,
46 	stds75,
47 	tcn75,
48 	tmp100,
49 	tmp101,
50 	tmp105,
51 	tmp175,
52 	tmp275,
53 	tmp75,
54 };
55 
56 /* Addresses scanned */
57 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
58 					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
59 
60 
61 /* The LM75 registers */
62 #define LM75_REG_CONF		0x01
63 static const u8 LM75_REG_TEMP[3] = {
64 	0x00,		/* input */
65 	0x03,		/* max */
66 	0x02,		/* hyst */
67 };
68 
69 /* Each client has this additional data */
70 struct lm75_data {
71 	struct device		*hwmon_dev;
72 	struct mutex		update_lock;
73 	u8			orig_conf;
74 	char			valid;		/* !=0 if registers are valid */
75 	unsigned long		last_updated;	/* In jiffies */
76 	u16			temp[3];	/* Register values,
77 						   0 = input
78 						   1 = max
79 						   2 = hyst */
80 };
81 
82 static int lm75_read_value(struct i2c_client *client, u8 reg);
83 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
84 static struct lm75_data *lm75_update_device(struct device *dev);
85 
86 
87 /*-----------------------------------------------------------------------*/
88 
89 /* sysfs attributes for hwmon */
90 
91 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
92 			 char *buf)
93 {
94 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
95 	struct lm75_data *data = lm75_update_device(dev);
96 
97 	if (IS_ERR(data))
98 		return PTR_ERR(data);
99 
100 	return sprintf(buf, "%d\n",
101 		       LM75_TEMP_FROM_REG(data->temp[attr->index]));
102 }
103 
104 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
105 			const char *buf, size_t count)
106 {
107 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
108 	struct i2c_client *client = to_i2c_client(dev);
109 	struct lm75_data *data = i2c_get_clientdata(client);
110 	int nr = attr->index;
111 	long temp;
112 	int error;
113 
114 	error = kstrtol(buf, 10, &temp);
115 	if (error)
116 		return error;
117 
118 	mutex_lock(&data->update_lock);
119 	data->temp[nr] = LM75_TEMP_TO_REG(temp);
120 	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
121 	mutex_unlock(&data->update_lock);
122 	return count;
123 }
124 
125 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
126 			show_temp, set_temp, 1);
127 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
128 			show_temp, set_temp, 2);
129 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
130 
131 static struct attribute *lm75_attributes[] = {
132 	&sensor_dev_attr_temp1_input.dev_attr.attr,
133 	&sensor_dev_attr_temp1_max.dev_attr.attr,
134 	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
135 
136 	NULL
137 };
138 
139 static const struct attribute_group lm75_group = {
140 	.attrs = lm75_attributes,
141 };
142 
143 /*-----------------------------------------------------------------------*/
144 
145 /* device probe and removal */
146 
147 static int
148 lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
149 {
150 	struct lm75_data *data;
151 	int status;
152 	u8 set_mask, clr_mask;
153 	int new;
154 
155 	if (!i2c_check_functionality(client->adapter,
156 			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
157 		return -EIO;
158 
159 	data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL);
160 	if (!data)
161 		return -ENOMEM;
162 
163 	i2c_set_clientdata(client, data);
164 	mutex_init(&data->update_lock);
165 
166 	/* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
167 	 * Then tweak to be more precise when appropriate.
168 	 */
169 	set_mask = 0;
170 	clr_mask = (1 << 0)			/* continuous conversions */
171 		| (1 << 6) | (1 << 5);		/* 9-bit mode */
172 
173 	/* configure as specified */
174 	status = lm75_read_value(client, LM75_REG_CONF);
175 	if (status < 0) {
176 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
177 		goto exit_free;
178 	}
179 	data->orig_conf = status;
180 	new = status & ~clr_mask;
181 	new |= set_mask;
182 	if (status != new)
183 		lm75_write_value(client, LM75_REG_CONF, new);
184 	dev_dbg(&client->dev, "Config %02x\n", new);
185 
186 	/* Register sysfs hooks */
187 	status = sysfs_create_group(&client->dev.kobj, &lm75_group);
188 	if (status)
189 		goto exit_free;
190 
191 	data->hwmon_dev = hwmon_device_register(&client->dev);
192 	if (IS_ERR(data->hwmon_dev)) {
193 		status = PTR_ERR(data->hwmon_dev);
194 		goto exit_remove;
195 	}
196 
197 	dev_info(&client->dev, "%s: sensor '%s'\n",
198 		 dev_name(data->hwmon_dev), client->name);
199 
200 	return 0;
201 
202 exit_remove:
203 	sysfs_remove_group(&client->dev.kobj, &lm75_group);
204 exit_free:
205 	kfree(data);
206 	return status;
207 }
208 
209 static int lm75_remove(struct i2c_client *client)
210 {
211 	struct lm75_data *data = i2c_get_clientdata(client);
212 
213 	hwmon_device_unregister(data->hwmon_dev);
214 	sysfs_remove_group(&client->dev.kobj, &lm75_group);
215 	lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
216 	kfree(data);
217 	return 0;
218 }
219 
220 static const struct i2c_device_id lm75_ids[] = {
221 	{ "adt75", adt75, },
222 	{ "ds1775", ds1775, },
223 	{ "ds75", ds75, },
224 	{ "lm75", lm75, },
225 	{ "lm75a", lm75a, },
226 	{ "max6625", max6625, },
227 	{ "max6626", max6626, },
228 	{ "mcp980x", mcp980x, },
229 	{ "stds75", stds75, },
230 	{ "tcn75", tcn75, },
231 	{ "tmp100", tmp100, },
232 	{ "tmp101", tmp101, },
233 	{ "tmp105", tmp105, },
234 	{ "tmp175", tmp175, },
235 	{ "tmp275", tmp275, },
236 	{ "tmp75", tmp75, },
237 	{ /* LIST END */ }
238 };
239 MODULE_DEVICE_TABLE(i2c, lm75_ids);
240 
241 #define LM75A_ID 0xA1
242 
243 /* Return 0 if detection is successful, -ENODEV otherwise */
244 static int lm75_detect(struct i2c_client *new_client,
245 		       struct i2c_board_info *info)
246 {
247 	struct i2c_adapter *adapter = new_client->adapter;
248 	int i;
249 	int conf, hyst, os;
250 	bool is_lm75a = 0;
251 
252 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
253 				     I2C_FUNC_SMBUS_WORD_DATA))
254 		return -ENODEV;
255 
256 	/*
257 	 * Now, we do the remaining detection. There is no identification-
258 	 * dedicated register so we have to rely on several tricks:
259 	 * unused bits, registers cycling over 8-address boundaries,
260 	 * addresses 0x04-0x07 returning the last read value.
261 	 * The cycling+unused addresses combination is not tested,
262 	 * since it would significantly slow the detection down and would
263 	 * hardly add any value.
264 	 *
265 	 * The National Semiconductor LM75A is different than earlier
266 	 * LM75s.  It has an ID byte of 0xaX (where X is the chip
267 	 * revision, with 1 being the only revision in existence) in
268 	 * register 7, and unused registers return 0xff rather than the
269 	 * last read value.
270 	 *
271 	 * Note that this function only detects the original National
272 	 * Semiconductor LM75 and the LM75A. Clones from other vendors
273 	 * aren't detected, on purpose, because they are typically never
274 	 * found on PC hardware. They are found on embedded designs where
275 	 * they can be instantiated explicitly so detection is not needed.
276 	 * The absence of identification registers on all these clones
277 	 * would make their exhaustive detection very difficult and weak,
278 	 * and odds are that the driver would bind to unsupported devices.
279 	 */
280 
281 	/* Unused bits */
282 	conf = i2c_smbus_read_byte_data(new_client, 1);
283 	if (conf & 0xe0)
284 		return -ENODEV;
285 
286 	/* First check for LM75A */
287 	if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
288 		/* LM75A returns 0xff on unused registers so
289 		   just to be sure we check for that too. */
290 		if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
291 		 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
292 		 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
293 			return -ENODEV;
294 		is_lm75a = 1;
295 		hyst = i2c_smbus_read_byte_data(new_client, 2);
296 		os = i2c_smbus_read_byte_data(new_client, 3);
297 	} else { /* Traditional style LM75 detection */
298 		/* Unused addresses */
299 		hyst = i2c_smbus_read_byte_data(new_client, 2);
300 		if (i2c_smbus_read_byte_data(new_client, 4) != hyst
301 		 || i2c_smbus_read_byte_data(new_client, 5) != hyst
302 		 || i2c_smbus_read_byte_data(new_client, 6) != hyst
303 		 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
304 			return -ENODEV;
305 		os = i2c_smbus_read_byte_data(new_client, 3);
306 		if (i2c_smbus_read_byte_data(new_client, 4) != os
307 		 || i2c_smbus_read_byte_data(new_client, 5) != os
308 		 || i2c_smbus_read_byte_data(new_client, 6) != os
309 		 || i2c_smbus_read_byte_data(new_client, 7) != os)
310 			return -ENODEV;
311 	}
312 
313 	/* Addresses cycling */
314 	for (i = 8; i <= 248; i += 40) {
315 		if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
316 		 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
317 		 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
318 			return -ENODEV;
319 		if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
320 				!= LM75A_ID)
321 			return -ENODEV;
322 	}
323 
324 	strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);
325 
326 	return 0;
327 }
328 
329 #ifdef CONFIG_PM
330 static int lm75_suspend(struct device *dev)
331 {
332 	int status;
333 	struct i2c_client *client = to_i2c_client(dev);
334 	status = lm75_read_value(client, LM75_REG_CONF);
335 	if (status < 0) {
336 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
337 		return status;
338 	}
339 	status = status | LM75_SHUTDOWN;
340 	lm75_write_value(client, LM75_REG_CONF, status);
341 	return 0;
342 }
343 
344 static int lm75_resume(struct device *dev)
345 {
346 	int status;
347 	struct i2c_client *client = to_i2c_client(dev);
348 	status = lm75_read_value(client, LM75_REG_CONF);
349 	if (status < 0) {
350 		dev_dbg(&client->dev, "Can't read config? %d\n", status);
351 		return status;
352 	}
353 	status = status & ~LM75_SHUTDOWN;
354 	lm75_write_value(client, LM75_REG_CONF, status);
355 	return 0;
356 }
357 
358 static const struct dev_pm_ops lm75_dev_pm_ops = {
359 	.suspend	= lm75_suspend,
360 	.resume		= lm75_resume,
361 };
362 #define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
363 #else
364 #define LM75_DEV_PM_OPS NULL
365 #endif /* CONFIG_PM */
366 
367 static struct i2c_driver lm75_driver = {
368 	.class		= I2C_CLASS_HWMON,
369 	.driver = {
370 		.name	= "lm75",
371 		.pm	= LM75_DEV_PM_OPS,
372 	},
373 	.probe		= lm75_probe,
374 	.remove		= lm75_remove,
375 	.id_table	= lm75_ids,
376 	.detect		= lm75_detect,
377 	.address_list	= normal_i2c,
378 };
379 
380 /*-----------------------------------------------------------------------*/
381 
382 /* register access */
383 
384 /*
385  * All registers are word-sized, except for the configuration register.
386  * LM75 uses a high-byte first convention, which is exactly opposite to
387  * the SMBus standard.
388  */
389 static int lm75_read_value(struct i2c_client *client, u8 reg)
390 {
391 	if (reg == LM75_REG_CONF)
392 		return i2c_smbus_read_byte_data(client, reg);
393 	else
394 		return i2c_smbus_read_word_swapped(client, reg);
395 }
396 
397 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
398 {
399 	if (reg == LM75_REG_CONF)
400 		return i2c_smbus_write_byte_data(client, reg, value);
401 	else
402 		return i2c_smbus_write_word_swapped(client, reg, value);
403 }
404 
405 static struct lm75_data *lm75_update_device(struct device *dev)
406 {
407 	struct i2c_client *client = to_i2c_client(dev);
408 	struct lm75_data *data = i2c_get_clientdata(client);
409 	struct lm75_data *ret = data;
410 
411 	mutex_lock(&data->update_lock);
412 
413 	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
414 	    || !data->valid) {
415 		int i;
416 		dev_dbg(&client->dev, "Starting lm75 update\n");
417 
418 		for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
419 			int status;
420 
421 			status = lm75_read_value(client, LM75_REG_TEMP[i]);
422 			if (unlikely(status < 0)) {
423 				dev_dbg(dev,
424 					"LM75: Failed to read value: reg %d, error %d\n",
425 					LM75_REG_TEMP[i], status);
426 				ret = ERR_PTR(status);
427 				data->valid = 0;
428 				goto abort;
429 			}
430 			data->temp[i] = status;
431 		}
432 		data->last_updated = jiffies;
433 		data->valid = 1;
434 	}
435 
436 abort:
437 	mutex_unlock(&data->update_lock);
438 	return ret;
439 }
440 
441 module_i2c_driver(lm75_driver);
442 
443 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
444 MODULE_DESCRIPTION("LM75 driver");
445 MODULE_LICENSE("GPL");
446