xref: /openbmc/linux/drivers/hwmon/lm92.c (revision 12eb4683)
1 /*
2  * lm92 - Hardware monitoring driver
3  * Copyright (C) 2005-2008  Jean Delvare <khali@linux-fr.org>
4  *
5  * Based on the lm90 driver, with some ideas taken from the lm_sensors
6  * lm92 driver as well.
7  *
8  * The LM92 is a sensor chip made by National Semiconductor. It reports
9  * its own temperature with a 0.0625 deg resolution and a 0.33 deg
10  * accuracy. Complete datasheet can be obtained from National's website
11  * at:
12  *   http://www.national.com/pf/LM/LM92.html
13  *
14  * This driver also supports the MAX6635 sensor chip made by Maxim.
15  * This chip is compatible with the LM92, but has a lesser accuracy
16  * (1.0 deg). Complete datasheet can be obtained from Maxim's website
17  * at:
18  *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3074
19  *
20  * Since the LM92 was the first chipset supported by this driver, most
21  * comments will refer to this chipset, but are actually general and
22  * concern all supported chipsets, unless mentioned otherwise.
23  *
24  * Support could easily be added for the National Semiconductor LM76
25  * and Maxim MAX6633 and MAX6634 chips, which are mostly compatible
26  * with the LM92.
27  *
28  * This program is free software; you can redistribute it and/or modify
29  * it under the terms of the GNU General Public License as published by
30  * the Free Software Foundation; either version 2 of the License, or
31  * (at your option) any later version.
32  *
33  * This program is distributed in the hope that it will be useful,
34  * but WITHOUT ANY WARRANTY; without even the implied warranty of
35  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
36  * GNU General Public License for more details.
37  *
38  * You should have received a copy of the GNU General Public License
39  * along with this program; if not, write to the Free Software
40  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
41  */
42 
43 #include <linux/module.h>
44 #include <linux/init.h>
45 #include <linux/slab.h>
46 #include <linux/i2c.h>
47 #include <linux/hwmon.h>
48 #include <linux/hwmon-sysfs.h>
49 #include <linux/err.h>
50 #include <linux/mutex.h>
51 #include <linux/jiffies.h>
52 
53 /*
54  * The LM92 and MAX6635 have 2 two-state pins for address selection,
55  * resulting in 4 possible addresses.
56  */
57 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
58 						I2C_CLIENT_END };
59 
60 /* The LM92 registers */
61 #define LM92_REG_CONFIG			0x01 /* 8-bit, RW */
62 #define LM92_REG_TEMP			0x00 /* 16-bit, RO */
63 #define LM92_REG_TEMP_HYST		0x02 /* 16-bit, RW */
64 #define LM92_REG_TEMP_CRIT		0x03 /* 16-bit, RW */
65 #define LM92_REG_TEMP_LOW		0x04 /* 16-bit, RW */
66 #define LM92_REG_TEMP_HIGH		0x05 /* 16-bit, RW */
67 #define LM92_REG_MAN_ID			0x07 /* 16-bit, RO, LM92 only */
68 
69 /*
70  * The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius,
71  * left-justified in 16-bit registers. No rounding is done, with such
72  * a resolution it's just not worth it. Note that the MAX6635 doesn't
73  * make use of the 4 lower bits for limits (i.e. effective resolution
74  * for limits is 1 degree Celsius).
75  */
76 static inline int TEMP_FROM_REG(s16 reg)
77 {
78 	return reg / 8 * 625 / 10;
79 }
80 
81 static inline s16 TEMP_TO_REG(int val)
82 {
83 	if (val <= -60000)
84 		return -60000 * 10 / 625 * 8;
85 	if (val >= 160000)
86 		return 160000 * 10 / 625 * 8;
87 	return val * 10 / 625 * 8;
88 }
89 
90 /* Alarm flags are stored in the 3 LSB of the temperature register */
91 static inline u8 ALARMS_FROM_REG(s16 reg)
92 {
93 	return reg & 0x0007;
94 }
95 
96 /* Driver data (common to all clients) */
97 static struct i2c_driver lm92_driver;
98 
99 /* Client data (each client gets its own) */
100 struct lm92_data {
101 	struct device *hwmon_dev;
102 	struct mutex update_lock;
103 	char valid; /* zero until following fields are valid */
104 	unsigned long last_updated; /* in jiffies */
105 
106 	/* registers values */
107 	s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst;
108 };
109 
110 
111 /*
112  * Sysfs attributes and callback functions
113  */
114 
115 static struct lm92_data *lm92_update_device(struct device *dev)
116 {
117 	struct i2c_client *client = to_i2c_client(dev);
118 	struct lm92_data *data = i2c_get_clientdata(client);
119 
120 	mutex_lock(&data->update_lock);
121 
122 	if (time_after(jiffies, data->last_updated + HZ)
123 	 || !data->valid) {
124 		dev_dbg(&client->dev, "Updating lm92 data\n");
125 		data->temp1_input = i2c_smbus_read_word_swapped(client,
126 				    LM92_REG_TEMP);
127 		data->temp1_hyst = i2c_smbus_read_word_swapped(client,
128 				    LM92_REG_TEMP_HYST);
129 		data->temp1_crit = i2c_smbus_read_word_swapped(client,
130 				    LM92_REG_TEMP_CRIT);
131 		data->temp1_min = i2c_smbus_read_word_swapped(client,
132 				    LM92_REG_TEMP_LOW);
133 		data->temp1_max = i2c_smbus_read_word_swapped(client,
134 				    LM92_REG_TEMP_HIGH);
135 
136 		data->last_updated = jiffies;
137 		data->valid = 1;
138 	}
139 
140 	mutex_unlock(&data->update_lock);
141 
142 	return data;
143 }
144 
145 #define show_temp(value) \
146 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, \
147 			    char *buf) \
148 { \
149 	struct lm92_data *data = lm92_update_device(dev); \
150 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \
151 }
152 show_temp(temp1_input);
153 show_temp(temp1_crit);
154 show_temp(temp1_min);
155 show_temp(temp1_max);
156 
157 #define set_temp(value, reg) \
158 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, \
159 			   const char *buf, \
160 	size_t count) \
161 { \
162 	struct i2c_client *client = to_i2c_client(dev); \
163 	struct lm92_data *data = i2c_get_clientdata(client); \
164 	long val; \
165 	int err = kstrtol(buf, 10, &val); \
166 	if (err) \
167 		return err; \
168 \
169 	mutex_lock(&data->update_lock); \
170 	data->value = TEMP_TO_REG(val); \
171 	i2c_smbus_write_word_swapped(client, reg, data->value); \
172 	mutex_unlock(&data->update_lock); \
173 	return count; \
174 }
175 set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
176 set_temp(temp1_min, LM92_REG_TEMP_LOW);
177 set_temp(temp1_max, LM92_REG_TEMP_HIGH);
178 
179 static ssize_t show_temp1_crit_hyst(struct device *dev,
180 				    struct device_attribute *attr, char *buf)
181 {
182 	struct lm92_data *data = lm92_update_device(dev);
183 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit)
184 		       - TEMP_FROM_REG(data->temp1_hyst));
185 }
186 static ssize_t show_temp1_max_hyst(struct device *dev,
187 				   struct device_attribute *attr, char *buf)
188 {
189 	struct lm92_data *data = lm92_update_device(dev);
190 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max)
191 		       - TEMP_FROM_REG(data->temp1_hyst));
192 }
193 static ssize_t show_temp1_min_hyst(struct device *dev,
194 				   struct device_attribute *attr, char *buf)
195 {
196 	struct lm92_data *data = lm92_update_device(dev);
197 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min)
198 		       + TEMP_FROM_REG(data->temp1_hyst));
199 }
200 
201 static ssize_t set_temp1_crit_hyst(struct device *dev,
202 				   struct device_attribute *attr,
203 				   const char *buf, size_t count)
204 {
205 	struct i2c_client *client = to_i2c_client(dev);
206 	struct lm92_data *data = i2c_get_clientdata(client);
207 	long val;
208 	int err;
209 
210 	err = kstrtol(buf, 10, &val);
211 	if (err)
212 		return err;
213 
214 	mutex_lock(&data->update_lock);
215 	data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val;
216 	i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
217 				     TEMP_TO_REG(data->temp1_hyst));
218 	mutex_unlock(&data->update_lock);
219 	return count;
220 }
221 
222 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr,
223 			   char *buf)
224 {
225 	struct lm92_data *data = lm92_update_device(dev);
226 	return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input));
227 }
228 
229 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
230 			  char *buf)
231 {
232 	int bitnr = to_sensor_dev_attr(attr)->index;
233 	struct lm92_data *data = lm92_update_device(dev);
234 	return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1);
235 }
236 
237 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
238 static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit,
239 	set_temp1_crit);
240 static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst,
241 	set_temp1_crit_hyst);
242 static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min,
243 	set_temp1_min);
244 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
245 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max,
246 	set_temp1_max);
247 static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
248 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
249 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
250 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
251 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
252 
253 
254 /*
255  * Detection and registration
256  */
257 
258 static void lm92_init_client(struct i2c_client *client)
259 {
260 	u8 config;
261 
262 	/* Start the conversions if needed */
263 	config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
264 	if (config & 0x01)
265 		i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
266 					  config & 0xFE);
267 }
268 
269 /*
270  * The MAX6635 has no identification register, so we have to use tricks
271  * to identify it reliably. This is somewhat slow.
272  * Note that we do NOT rely on the 2 MSB of the configuration register
273  * always reading 0, as suggested by the datasheet, because it was once
274  * reported not to be true.
275  */
276 static int max6635_check(struct i2c_client *client)
277 {
278 	u16 temp_low, temp_high, temp_hyst, temp_crit;
279 	u8 conf;
280 	int i;
281 
282 	/*
283 	 * No manufacturer ID register, so a read from this address will
284 	 * always return the last read value.
285 	 */
286 	temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
287 	if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
288 		return 0;
289 	temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
290 	if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
291 		return 0;
292 
293 	/* Limits are stored as integer values (signed, 9-bit). */
294 	if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
295 		return 0;
296 	temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
297 	temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
298 	if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
299 		return 0;
300 
301 	/*
302 	 * Registers addresses were found to cycle over 16-byte boundaries.
303 	 * We don't test all registers with all offsets so as to save some
304 	 * reads and time, but this should still be sufficient to dismiss
305 	 * non-MAX6635 chips.
306 	 */
307 	conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
308 	for (i = 16; i < 96; i *= 2) {
309 		if (temp_hyst != i2c_smbus_read_word_data(client,
310 				 LM92_REG_TEMP_HYST + i - 16)
311 		 || temp_crit != i2c_smbus_read_word_data(client,
312 				 LM92_REG_TEMP_CRIT + i)
313 		 || temp_low != i2c_smbus_read_word_data(client,
314 				LM92_REG_TEMP_LOW + i + 16)
315 		 || temp_high != i2c_smbus_read_word_data(client,
316 				 LM92_REG_TEMP_HIGH + i + 32)
317 		 || conf != i2c_smbus_read_byte_data(client,
318 			    LM92_REG_CONFIG + i))
319 			return 0;
320 	}
321 
322 	return 1;
323 }
324 
325 static struct attribute *lm92_attributes[] = {
326 	&dev_attr_temp1_input.attr,
327 	&dev_attr_temp1_crit.attr,
328 	&dev_attr_temp1_crit_hyst.attr,
329 	&dev_attr_temp1_min.attr,
330 	&dev_attr_temp1_min_hyst.attr,
331 	&dev_attr_temp1_max.attr,
332 	&dev_attr_temp1_max_hyst.attr,
333 	&dev_attr_alarms.attr,
334 	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
335 	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
336 	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
337 	NULL
338 };
339 
340 static const struct attribute_group lm92_group = {
341 	.attrs = lm92_attributes,
342 };
343 
344 /* Return 0 if detection is successful, -ENODEV otherwise */
345 static int lm92_detect(struct i2c_client *new_client,
346 		       struct i2c_board_info *info)
347 {
348 	struct i2c_adapter *adapter = new_client->adapter;
349 	u8 config;
350 	u16 man_id;
351 
352 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
353 					    | I2C_FUNC_SMBUS_WORD_DATA))
354 		return -ENODEV;
355 
356 	config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
357 	man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);
358 
359 	if ((config & 0xe0) == 0x00 && man_id == 0x0180)
360 		pr_info("lm92: Found National Semiconductor LM92 chip\n");
361 	else if (max6635_check(new_client))
362 		pr_info("lm92: Found Maxim MAX6635 chip\n");
363 	else
364 		return -ENODEV;
365 
366 	strlcpy(info->type, "lm92", I2C_NAME_SIZE);
367 
368 	return 0;
369 }
370 
371 static int lm92_probe(struct i2c_client *new_client,
372 		      const struct i2c_device_id *id)
373 {
374 	struct lm92_data *data;
375 	int err;
376 
377 	data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data),
378 			    GFP_KERNEL);
379 	if (!data)
380 		return -ENOMEM;
381 
382 	i2c_set_clientdata(new_client, data);
383 	data->valid = 0;
384 	mutex_init(&data->update_lock);
385 
386 	/* Initialize the chipset */
387 	lm92_init_client(new_client);
388 
389 	/* Register sysfs hooks */
390 	err = sysfs_create_group(&new_client->dev.kobj, &lm92_group);
391 	if (err)
392 		return err;
393 
394 	data->hwmon_dev = hwmon_device_register(&new_client->dev);
395 	if (IS_ERR(data->hwmon_dev)) {
396 		err = PTR_ERR(data->hwmon_dev);
397 		goto exit_remove;
398 	}
399 
400 	return 0;
401 
402 exit_remove:
403 	sysfs_remove_group(&new_client->dev.kobj, &lm92_group);
404 	return err;
405 }
406 
407 static int lm92_remove(struct i2c_client *client)
408 {
409 	struct lm92_data *data = i2c_get_clientdata(client);
410 
411 	hwmon_device_unregister(data->hwmon_dev);
412 	sysfs_remove_group(&client->dev.kobj, &lm92_group);
413 
414 	return 0;
415 }
416 
417 
418 /*
419  * Module and driver stuff
420  */
421 
422 static const struct i2c_device_id lm92_id[] = {
423 	{ "lm92", 0 },
424 	/* max6635 could be added here */
425 	{ }
426 };
427 MODULE_DEVICE_TABLE(i2c, lm92_id);
428 
429 static struct i2c_driver lm92_driver = {
430 	.class		= I2C_CLASS_HWMON,
431 	.driver = {
432 		.name	= "lm92",
433 	},
434 	.probe		= lm92_probe,
435 	.remove		= lm92_remove,
436 	.id_table	= lm92_id,
437 	.detect		= lm92_detect,
438 	.address_list	= normal_i2c,
439 };
440 
441 module_i2c_driver(lm92_driver);
442 
443 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
444 MODULE_DESCRIPTION("LM92/MAX6635 driver");
445 MODULE_LICENSE("GPL");
446