2 * lm92 - Hardware monitoring driver
3 * Copyright (C) 2005-2008 Jean Delvare <jdelvare@suse.de>
5 * Based on the lm90 driver, with some ideas taken from the lm_sensors
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
12 * http://www.national.com/pf/LM/LM92.html
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
18 * http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3074
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.
24 * Support could easily be added for the National Semiconductor LM76
25 * and Maxim MAX6633 and MAX6634 chips, which are mostly compatible
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.
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.
39 #include <linux/module.h>
40 #include <linux/init.h>
41 #include <linux/slab.h>
42 #include <linux/i2c.h>
43 #include <linux/hwmon.h>
44 #include <linux/hwmon-sysfs.h>
45 #include <linux/err.h>
46 #include <linux/mutex.h>
47 #include <linux/jiffies.h>
50 * The LM92 and MAX6635 have 2 two-state pins for address selection,
51 * resulting in 4 possible addresses.
53 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
56 /* The LM92 registers */
57 #define LM92_REG_CONFIG 0x01 /* 8-bit, RW */
58 #define LM92_REG_TEMP 0x00 /* 16-bit, RO */
59 #define LM92_REG_TEMP_HYST 0x02 /* 16-bit, RW */
60 #define LM92_REG_TEMP_CRIT 0x03 /* 16-bit, RW */
61 #define LM92_REG_TEMP_LOW 0x04 /* 16-bit, RW */
62 #define LM92_REG_TEMP_HIGH 0x05 /* 16-bit, RW */
63 #define LM92_REG_MAN_ID 0x07 /* 16-bit, RO, LM92 only */
66 * The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius,
67 * left-justified in 16-bit registers. No rounding is done, with such
68 * a resolution it's just not worth it. Note that the MAX6635 doesn't
69 * make use of the 4 lower bits for limits (i.e. effective resolution
70 * for limits is 1 degree Celsius).
72 static inline int TEMP_FROM_REG(s16 reg)
74 return reg / 8 * 625 / 10;
77 static inline s16 TEMP_TO_REG(int val)
80 return -60000 * 10 / 625 * 8;
82 return 160000 * 10 / 625 * 8;
83 return val * 10 / 625 * 8;
86 /* Alarm flags are stored in the 3 LSB of the temperature register */
87 static inline u8 ALARMS_FROM_REG(s16 reg)
101 static const u8 regs[t_num_regs] = {
102 [t_input] = LM92_REG_TEMP,
103 [t_crit] = LM92_REG_TEMP_CRIT,
104 [t_min] = LM92_REG_TEMP_LOW,
105 [t_max] = LM92_REG_TEMP_HIGH,
106 [t_hyst] = LM92_REG_TEMP_HYST,
109 /* Client data (each client gets its own) */
111 struct i2c_client *client;
112 struct mutex update_lock;
113 char valid; /* zero until following fields are valid */
114 unsigned long last_updated; /* in jiffies */
116 /* registers values */
117 s16 temp[t_num_regs]; /* index with enum temp_index */
121 * Sysfs attributes and callback functions
124 static struct lm92_data *lm92_update_device(struct device *dev)
126 struct lm92_data *data = dev_get_drvdata(dev);
127 struct i2c_client *client = data->client;
130 mutex_lock(&data->update_lock);
132 if (time_after(jiffies, data->last_updated + HZ)
134 dev_dbg(&client->dev, "Updating lm92 data\n");
135 for (i = 0; i < t_num_regs; i++) {
137 i2c_smbus_read_word_swapped(client, regs[i]);
139 data->last_updated = jiffies;
143 mutex_unlock(&data->update_lock);
148 static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
151 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
152 struct lm92_data *data = lm92_update_device(dev);
154 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[attr->index]));
157 static ssize_t set_temp(struct device *dev, struct device_attribute *devattr,
158 const char *buf, size_t count)
160 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
161 struct lm92_data *data = dev_get_drvdata(dev);
162 struct i2c_client *client = data->client;
163 int nr = attr->index;
167 err = kstrtol(buf, 10, &val);
171 mutex_lock(&data->update_lock);
172 data->temp[nr] = TEMP_TO_REG(val);
173 i2c_smbus_write_word_swapped(client, regs[nr], data->temp[nr]);
174 mutex_unlock(&data->update_lock);
178 static ssize_t show_temp_hyst(struct device *dev,
179 struct device_attribute *devattr, char *buf)
181 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
182 struct lm92_data *data = lm92_update_device(dev);
183 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[attr->index])
184 - TEMP_FROM_REG(data->temp[t_hyst]));
187 static ssize_t show_temp_min_hyst(struct device *dev,
188 struct device_attribute *attr, char *buf)
190 struct lm92_data *data = lm92_update_device(dev);
191 return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp[t_min])
192 + TEMP_FROM_REG(data->temp[t_hyst]));
195 static ssize_t set_temp_hyst(struct device *dev,
196 struct device_attribute *devattr,
197 const char *buf, size_t count)
199 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
200 struct lm92_data *data = dev_get_drvdata(dev);
201 struct i2c_client *client = data->client;
205 err = kstrtol(buf, 10, &val);
209 mutex_lock(&data->update_lock);
210 data->temp[t_hyst] = TEMP_FROM_REG(data->temp[attr->index]) - val;
211 i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
212 TEMP_TO_REG(data->temp[t_hyst]));
213 mutex_unlock(&data->update_lock);
217 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr,
220 struct lm92_data *data = lm92_update_device(dev);
221 return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp[t_input]));
224 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
227 int bitnr = to_sensor_dev_attr(attr)->index;
228 struct lm92_data *data = lm92_update_device(dev);
229 return sprintf(buf, "%d\n", (data->temp[t_input] >> bitnr) & 1);
232 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input);
233 static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp,
235 static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst,
236 set_temp_hyst, t_crit);
237 static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp,
239 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp_min_hyst, NULL);
240 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp,
242 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max);
243 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
244 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
245 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
246 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
249 * Detection and registration
252 static void lm92_init_client(struct i2c_client *client)
256 /* Start the conversions if needed */
257 config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
259 i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
264 * The MAX6635 has no identification register, so we have to use tricks
265 * to identify it reliably. This is somewhat slow.
266 * Note that we do NOT rely on the 2 MSB of the configuration register
267 * always reading 0, as suggested by the datasheet, because it was once
268 * reported not to be true.
270 static int max6635_check(struct i2c_client *client)
272 u16 temp_low, temp_high, temp_hyst, temp_crit;
277 * No manufacturer ID register, so a read from this address will
278 * always return the last read value.
280 temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
281 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
283 temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
284 if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
287 /* Limits are stored as integer values (signed, 9-bit). */
288 if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
290 temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
291 temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
292 if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
296 * Registers addresses were found to cycle over 16-byte boundaries.
297 * We don't test all registers with all offsets so as to save some
298 * reads and time, but this should still be sufficient to dismiss
301 conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
302 for (i = 16; i < 96; i *= 2) {
303 if (temp_hyst != i2c_smbus_read_word_data(client,
304 LM92_REG_TEMP_HYST + i - 16)
305 || temp_crit != i2c_smbus_read_word_data(client,
306 LM92_REG_TEMP_CRIT + i)
307 || temp_low != i2c_smbus_read_word_data(client,
308 LM92_REG_TEMP_LOW + i + 16)
309 || temp_high != i2c_smbus_read_word_data(client,
310 LM92_REG_TEMP_HIGH + i + 32)
311 || conf != i2c_smbus_read_byte_data(client,
312 LM92_REG_CONFIG + i))
319 static struct attribute *lm92_attrs[] = {
320 &sensor_dev_attr_temp1_input.dev_attr.attr,
321 &sensor_dev_attr_temp1_crit.dev_attr.attr,
322 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
323 &sensor_dev_attr_temp1_min.dev_attr.attr,
324 &dev_attr_temp1_min_hyst.attr,
325 &sensor_dev_attr_temp1_max.dev_attr.attr,
326 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
327 &dev_attr_alarms.attr,
328 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
329 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
330 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
333 ATTRIBUTE_GROUPS(lm92);
335 /* Return 0 if detection is successful, -ENODEV otherwise */
336 static int lm92_detect(struct i2c_client *new_client,
337 struct i2c_board_info *info)
339 struct i2c_adapter *adapter = new_client->adapter;
343 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
344 | I2C_FUNC_SMBUS_WORD_DATA))
347 config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
348 man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);
350 if ((config & 0xe0) == 0x00 && man_id == 0x0180)
351 pr_info("lm92: Found National Semiconductor LM92 chip\n");
352 else if (max6635_check(new_client))
353 pr_info("lm92: Found Maxim MAX6635 chip\n");
357 strlcpy(info->type, "lm92", I2C_NAME_SIZE);
362 static int lm92_probe(struct i2c_client *new_client,
363 const struct i2c_device_id *id)
365 struct device *hwmon_dev;
366 struct lm92_data *data;
368 data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data),
373 data->client = new_client;
374 mutex_init(&data->update_lock);
376 /* Initialize the chipset */
377 lm92_init_client(new_client);
379 hwmon_dev = devm_hwmon_device_register_with_groups(&new_client->dev,
382 return PTR_ERR_OR_ZERO(hwmon_dev);
387 * Module and driver stuff
390 static const struct i2c_device_id lm92_id[] = {
392 /* max6635 could be added here */
395 MODULE_DEVICE_TABLE(i2c, lm92_id);
397 static struct i2c_driver lm92_driver = {
398 .class = I2C_CLASS_HWMON,
404 .detect = lm92_detect,
405 .address_list = normal_i2c,
408 module_i2c_driver(lm92_driver);
410 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
411 MODULE_DESCRIPTION("LM92/MAX6635 driver");
412 MODULE_LICENSE("GPL");