2 * lm75.c - Part of lm_sensors, Linux kernel modules for hardware
4 * Copyright (c) 1998, 1999 Frodo Looijaard <frodol@dds.nl>
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.
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.
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.
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>
34 * This driver handles the LM75 and compatible digital temperature sensors.
37 enum lm75_type { /* keep sorted in alphabetical order */
56 /* Addresses scanned */
57 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
58 0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
61 /* The LM75 registers */
62 #define LM75_REG_CONF 0x01
63 static const u8 LM75_REG_TEMP[3] = {
69 /* Each client has this additional data */
71 struct device *hwmon_dev;
72 struct mutex update_lock;
74 char valid; /* !=0 if registers are valid */
75 unsigned long last_updated; /* In jiffies */
76 u16 temp[3]; /* Register values,
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);
87 /*-----------------------------------------------------------------------*/
89 /* sysfs attributes for hwmon */
91 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
94 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
95 struct lm75_data *data = lm75_update_device(dev);
96 return sprintf(buf, "%d\n",
97 LM75_TEMP_FROM_REG(data->temp[attr->index]));
100 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
101 const char *buf, size_t count)
103 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
104 struct i2c_client *client = to_i2c_client(dev);
105 struct lm75_data *data = i2c_get_clientdata(client);
106 int nr = attr->index;
110 error = strict_strtol(buf, 10, &temp);
114 mutex_lock(&data->update_lock);
115 data->temp[nr] = LM75_TEMP_TO_REG(temp);
116 lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
117 mutex_unlock(&data->update_lock);
121 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
122 show_temp, set_temp, 1);
123 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
124 show_temp, set_temp, 2);
125 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
127 static struct attribute *lm75_attributes[] = {
128 &sensor_dev_attr_temp1_input.dev_attr.attr,
129 &sensor_dev_attr_temp1_max.dev_attr.attr,
130 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
135 static const struct attribute_group lm75_group = {
136 .attrs = lm75_attributes,
139 /*-----------------------------------------------------------------------*/
141 /* device probe and removal */
144 lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
146 struct lm75_data *data;
148 u8 set_mask, clr_mask;
151 if (!i2c_check_functionality(client->adapter,
152 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
155 data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL);
159 i2c_set_clientdata(client, data);
160 mutex_init(&data->update_lock);
162 /* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
163 * Then tweak to be more precise when appropriate.
166 clr_mask = (1 << 0) /* continuous conversions */
167 | (1 << 6) | (1 << 5); /* 9-bit mode */
169 /* configure as specified */
170 status = lm75_read_value(client, LM75_REG_CONF);
172 dev_dbg(&client->dev, "Can't read config? %d\n", status);
175 data->orig_conf = status;
176 new = status & ~clr_mask;
179 lm75_write_value(client, LM75_REG_CONF, new);
180 dev_dbg(&client->dev, "Config %02x\n", new);
182 /* Register sysfs hooks */
183 status = sysfs_create_group(&client->dev.kobj, &lm75_group);
187 data->hwmon_dev = hwmon_device_register(&client->dev);
188 if (IS_ERR(data->hwmon_dev)) {
189 status = PTR_ERR(data->hwmon_dev);
193 dev_info(&client->dev, "%s: sensor '%s'\n",
194 dev_name(data->hwmon_dev), client->name);
199 sysfs_remove_group(&client->dev.kobj, &lm75_group);
205 static int lm75_remove(struct i2c_client *client)
207 struct lm75_data *data = i2c_get_clientdata(client);
209 hwmon_device_unregister(data->hwmon_dev);
210 sysfs_remove_group(&client->dev.kobj, &lm75_group);
211 lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
216 static const struct i2c_device_id lm75_ids[] = {
218 { "ds1775", ds1775, },
222 { "max6625", max6625, },
223 { "max6626", max6626, },
224 { "mcp980x", mcp980x, },
225 { "stds75", stds75, },
227 { "tmp100", tmp100, },
228 { "tmp101", tmp101, },
229 { "tmp105", tmp105, },
230 { "tmp175", tmp175, },
231 { "tmp275", tmp275, },
235 MODULE_DEVICE_TABLE(i2c, lm75_ids);
237 #define LM75A_ID 0xA1
239 /* Return 0 if detection is successful, -ENODEV otherwise */
240 static int lm75_detect(struct i2c_client *new_client,
241 struct i2c_board_info *info)
243 struct i2c_adapter *adapter = new_client->adapter;
248 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
249 I2C_FUNC_SMBUS_WORD_DATA))
253 * Now, we do the remaining detection. There is no identification-
254 * dedicated register so we have to rely on several tricks:
255 * unused bits, registers cycling over 8-address boundaries,
256 * addresses 0x04-0x07 returning the last read value.
257 * The cycling+unused addresses combination is not tested,
258 * since it would significantly slow the detection down and would
259 * hardly add any value.
261 * The National Semiconductor LM75A is different than earlier
262 * LM75s. It has an ID byte of 0xaX (where X is the chip
263 * revision, with 1 being the only revision in existence) in
264 * register 7, and unused registers return 0xff rather than the
267 * Note that this function only detects the original National
268 * Semiconductor LM75 and the LM75A. Clones from other vendors
269 * aren't detected, on purpose, because they are typically never
270 * found on PC hardware. They are found on embedded designs where
271 * they can be instantiated explicitly so detection is not needed.
272 * The absence of identification registers on all these clones
273 * would make their exhaustive detection very difficult and weak,
274 * and odds are that the driver would bind to unsupported devices.
278 conf = i2c_smbus_read_byte_data(new_client, 1);
282 /* First check for LM75A */
283 if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
284 /* LM75A returns 0xff on unused registers so
285 just to be sure we check for that too. */
286 if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
287 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
288 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
291 hyst = i2c_smbus_read_byte_data(new_client, 2);
292 os = i2c_smbus_read_byte_data(new_client, 3);
293 } else { /* Traditional style LM75 detection */
294 /* Unused addresses */
295 hyst = i2c_smbus_read_byte_data(new_client, 2);
296 if (i2c_smbus_read_byte_data(new_client, 4) != hyst
297 || i2c_smbus_read_byte_data(new_client, 5) != hyst
298 || i2c_smbus_read_byte_data(new_client, 6) != hyst
299 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
301 os = i2c_smbus_read_byte_data(new_client, 3);
302 if (i2c_smbus_read_byte_data(new_client, 4) != os
303 || i2c_smbus_read_byte_data(new_client, 5) != os
304 || i2c_smbus_read_byte_data(new_client, 6) != os
305 || i2c_smbus_read_byte_data(new_client, 7) != os)
309 /* Addresses cycling */
310 for (i = 8; i <= 248; i += 40) {
311 if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
312 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
313 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
315 if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
320 strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);
326 static int lm75_suspend(struct device *dev)
329 struct i2c_client *client = to_i2c_client(dev);
330 status = lm75_read_value(client, LM75_REG_CONF);
332 dev_dbg(&client->dev, "Can't read config? %d\n", status);
335 status = status | LM75_SHUTDOWN;
336 lm75_write_value(client, LM75_REG_CONF, status);
340 static int lm75_resume(struct device *dev)
343 struct i2c_client *client = to_i2c_client(dev);
344 status = lm75_read_value(client, LM75_REG_CONF);
346 dev_dbg(&client->dev, "Can't read config? %d\n", status);
349 status = status & ~LM75_SHUTDOWN;
350 lm75_write_value(client, LM75_REG_CONF, status);
354 static const struct dev_pm_ops lm75_dev_pm_ops = {
355 .suspend = lm75_suspend,
356 .resume = lm75_resume,
358 #define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
360 #define LM75_DEV_PM_OPS NULL
361 #endif /* CONFIG_PM */
363 static struct i2c_driver lm75_driver = {
364 .class = I2C_CLASS_HWMON,
367 .pm = LM75_DEV_PM_OPS,
370 .remove = lm75_remove,
371 .id_table = lm75_ids,
372 .detect = lm75_detect,
373 .address_list = normal_i2c,
376 /*-----------------------------------------------------------------------*/
378 /* register access */
381 * All registers are word-sized, except for the configuration register.
382 * LM75 uses a high-byte first convention, which is exactly opposite to
383 * the SMBus standard.
385 static int lm75_read_value(struct i2c_client *client, u8 reg)
387 if (reg == LM75_REG_CONF)
388 return i2c_smbus_read_byte_data(client, reg);
390 return i2c_smbus_read_word_swapped(client, reg);
393 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
395 if (reg == LM75_REG_CONF)
396 return i2c_smbus_write_byte_data(client, reg, value);
398 return i2c_smbus_write_word_swapped(client, reg, value);
401 static struct lm75_data *lm75_update_device(struct device *dev)
403 struct i2c_client *client = to_i2c_client(dev);
404 struct lm75_data *data = i2c_get_clientdata(client);
406 mutex_lock(&data->update_lock);
408 if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
411 dev_dbg(&client->dev, "Starting lm75 update\n");
413 for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
416 status = lm75_read_value(client, LM75_REG_TEMP[i]);
418 dev_dbg(&client->dev, "reg %d, err %d\n",
419 LM75_REG_TEMP[i], status);
421 data->temp[i] = status;
423 data->last_updated = jiffies;
427 mutex_unlock(&data->update_lock);
432 /*-----------------------------------------------------------------------*/
436 static int __init sensors_lm75_init(void)
438 return i2c_add_driver(&lm75_driver);
441 static void __exit sensors_lm75_exit(void)
443 i2c_del_driver(&lm75_driver);
446 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
447 MODULE_DESCRIPTION("LM75 driver");
448 MODULE_LICENSE("GPL");
450 module_init(sensors_lm75_init);
451 module_exit(sensors_lm75_exit);