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 u8 resolution; /* In bits, between 9 and 12 */
76 char valid; /* !=0 if registers are valid */
77 unsigned long last_updated; /* In jiffies */
78 unsigned long sample_time; /* In jiffies */
79 s16 temp[3]; /* Register values,
85 static int lm75_read_value(struct i2c_client *client, u8 reg);
86 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
87 static struct lm75_data *lm75_update_device(struct device *dev);
90 /*-----------------------------------------------------------------------*/
92 /* sysfs attributes for hwmon */
94 static ssize_t show_temp(struct device *dev, struct device_attribute *da,
97 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
98 struct lm75_data *data = lm75_update_device(dev);
102 return PTR_ERR(data);
104 temp = ((data->temp[attr->index] >> (16 - data->resolution)) * 1000)
105 >> (data->resolution - 8);
107 return sprintf(buf, "%ld\n", temp);
110 static ssize_t set_temp(struct device *dev, struct device_attribute *da,
111 const char *buf, size_t count)
113 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
114 struct i2c_client *client = to_i2c_client(dev);
115 struct lm75_data *data = i2c_get_clientdata(client);
116 int nr = attr->index;
121 error = kstrtol(buf, 10, &temp);
126 * Resolution of limit registers is assumed to be the same as the
127 * temperature input register resolution unless given explicitly.
129 if (attr->index && data->resolution_limits)
130 resolution = data->resolution_limits;
132 resolution = data->resolution;
134 mutex_lock(&data->update_lock);
135 temp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
136 data->temp[nr] = DIV_ROUND_CLOSEST(temp << (resolution - 8),
137 1000) << (16 - resolution);
138 lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
139 mutex_unlock(&data->update_lock);
143 static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
144 show_temp, set_temp, 1);
145 static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
146 show_temp, set_temp, 2);
147 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
149 static struct attribute *lm75_attributes[] = {
150 &sensor_dev_attr_temp1_input.dev_attr.attr,
151 &sensor_dev_attr_temp1_max.dev_attr.attr,
152 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
157 static const struct attribute_group lm75_group = {
158 .attrs = lm75_attributes,
161 /*-----------------------------------------------------------------------*/
163 /* device probe and removal */
166 lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
168 struct lm75_data *data;
170 u8 set_mask, clr_mask;
172 enum lm75_type kind = id->driver_data;
174 if (!i2c_check_functionality(client->adapter,
175 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
178 data = devm_kzalloc(&client->dev, sizeof(struct lm75_data), GFP_KERNEL);
182 i2c_set_clientdata(client, data);
183 mutex_init(&data->update_lock);
185 /* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
186 * Then tweak to be more precise when appropriate.
189 clr_mask = LM75_SHUTDOWN; /* continuous conversions */
193 clr_mask |= 1 << 5; /* not one-shot mode */
194 data->resolution = 12;
195 data->sample_time = HZ / 8;
201 set_mask |= 2 << 5; /* 11-bit mode */
202 data->resolution = 11;
203 data->sample_time = HZ;
207 data->resolution = 9;
208 data->sample_time = HZ / 2;
211 data->resolution = 9;
212 data->sample_time = HZ / 4;
215 data->resolution = 12;
216 data->resolution_limits = 9;
217 data->sample_time = HZ / 4;
220 data->resolution = 9;
221 data->sample_time = HZ / 8;
224 data->resolution_limits = 9;
228 set_mask |= 3 << 5; /* 12-bit mode */
229 data->resolution = 12;
230 data->sample_time = HZ;
231 clr_mask |= 1 << 7; /* not one-shot mode */
237 set_mask |= 3 << 5; /* 12-bit mode */
238 clr_mask |= 1 << 7; /* not one-shot mode */
239 data->resolution = 12;
240 data->sample_time = HZ / 2;
244 /* configure as specified */
245 status = lm75_read_value(client, LM75_REG_CONF);
247 dev_dbg(&client->dev, "Can't read config? %d\n", status);
250 data->orig_conf = status;
251 new = status & ~clr_mask;
254 lm75_write_value(client, LM75_REG_CONF, new);
255 dev_dbg(&client->dev, "Config %02x\n", new);
257 /* Register sysfs hooks */
258 status = sysfs_create_group(&client->dev.kobj, &lm75_group);
262 data->hwmon_dev = hwmon_device_register(&client->dev);
263 if (IS_ERR(data->hwmon_dev)) {
264 status = PTR_ERR(data->hwmon_dev);
268 dev_info(&client->dev, "%s: sensor '%s'\n",
269 dev_name(data->hwmon_dev), client->name);
274 sysfs_remove_group(&client->dev.kobj, &lm75_group);
278 static int lm75_remove(struct i2c_client *client)
280 struct lm75_data *data = i2c_get_clientdata(client);
282 hwmon_device_unregister(data->hwmon_dev);
283 sysfs_remove_group(&client->dev.kobj, &lm75_group);
284 lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
288 static const struct i2c_device_id lm75_ids[] = {
290 { "ds1775", ds1775, },
294 { "max6625", max6625, },
295 { "max6626", max6626, },
296 { "mcp980x", mcp980x, },
297 { "stds75", stds75, },
299 { "tmp100", tmp100, },
300 { "tmp101", tmp101, },
301 { "tmp105", tmp105, },
302 { "tmp175", tmp175, },
303 { "tmp275", tmp275, },
307 MODULE_DEVICE_TABLE(i2c, lm75_ids);
309 #define LM75A_ID 0xA1
311 /* Return 0 if detection is successful, -ENODEV otherwise */
312 static int lm75_detect(struct i2c_client *new_client,
313 struct i2c_board_info *info)
315 struct i2c_adapter *adapter = new_client->adapter;
320 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
321 I2C_FUNC_SMBUS_WORD_DATA))
325 * Now, we do the remaining detection. There is no identification-
326 * dedicated register so we have to rely on several tricks:
327 * unused bits, registers cycling over 8-address boundaries,
328 * addresses 0x04-0x07 returning the last read value.
329 * The cycling+unused addresses combination is not tested,
330 * since it would significantly slow the detection down and would
331 * hardly add any value.
333 * The National Semiconductor LM75A is different than earlier
334 * LM75s. It has an ID byte of 0xaX (where X is the chip
335 * revision, with 1 being the only revision in existence) in
336 * register 7, and unused registers return 0xff rather than the
339 * Note that this function only detects the original National
340 * Semiconductor LM75 and the LM75A. Clones from other vendors
341 * aren't detected, on purpose, because they are typically never
342 * found on PC hardware. They are found on embedded designs where
343 * they can be instantiated explicitly so detection is not needed.
344 * The absence of identification registers on all these clones
345 * would make their exhaustive detection very difficult and weak,
346 * and odds are that the driver would bind to unsupported devices.
350 conf = i2c_smbus_read_byte_data(new_client, 1);
354 /* First check for LM75A */
355 if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
356 /* LM75A returns 0xff on unused registers so
357 just to be sure we check for that too. */
358 if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
359 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
360 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
363 hyst = i2c_smbus_read_byte_data(new_client, 2);
364 os = i2c_smbus_read_byte_data(new_client, 3);
365 } else { /* Traditional style LM75 detection */
366 /* Unused addresses */
367 hyst = i2c_smbus_read_byte_data(new_client, 2);
368 if (i2c_smbus_read_byte_data(new_client, 4) != hyst
369 || i2c_smbus_read_byte_data(new_client, 5) != hyst
370 || i2c_smbus_read_byte_data(new_client, 6) != hyst
371 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
373 os = i2c_smbus_read_byte_data(new_client, 3);
374 if (i2c_smbus_read_byte_data(new_client, 4) != os
375 || i2c_smbus_read_byte_data(new_client, 5) != os
376 || i2c_smbus_read_byte_data(new_client, 6) != os
377 || i2c_smbus_read_byte_data(new_client, 7) != os)
381 /* Addresses cycling */
382 for (i = 8; i <= 248; i += 40) {
383 if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
384 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
385 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
387 if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
392 strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);
398 static int lm75_suspend(struct device *dev)
401 struct i2c_client *client = to_i2c_client(dev);
402 status = lm75_read_value(client, LM75_REG_CONF);
404 dev_dbg(&client->dev, "Can't read config? %d\n", status);
407 status = status | LM75_SHUTDOWN;
408 lm75_write_value(client, LM75_REG_CONF, status);
412 static int lm75_resume(struct device *dev)
415 struct i2c_client *client = to_i2c_client(dev);
416 status = lm75_read_value(client, LM75_REG_CONF);
418 dev_dbg(&client->dev, "Can't read config? %d\n", status);
421 status = status & ~LM75_SHUTDOWN;
422 lm75_write_value(client, LM75_REG_CONF, status);
426 static const struct dev_pm_ops lm75_dev_pm_ops = {
427 .suspend = lm75_suspend,
428 .resume = lm75_resume,
430 #define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
432 #define LM75_DEV_PM_OPS NULL
433 #endif /* CONFIG_PM */
435 static struct i2c_driver lm75_driver = {
436 .class = I2C_CLASS_HWMON,
439 .pm = LM75_DEV_PM_OPS,
442 .remove = lm75_remove,
443 .id_table = lm75_ids,
444 .detect = lm75_detect,
445 .address_list = normal_i2c,
448 /*-----------------------------------------------------------------------*/
450 /* register access */
453 * All registers are word-sized, except for the configuration register.
454 * LM75 uses a high-byte first convention, which is exactly opposite to
455 * the SMBus standard.
457 static int lm75_read_value(struct i2c_client *client, u8 reg)
459 if (reg == LM75_REG_CONF)
460 return i2c_smbus_read_byte_data(client, reg);
462 return i2c_smbus_read_word_swapped(client, reg);
465 static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
467 if (reg == LM75_REG_CONF)
468 return i2c_smbus_write_byte_data(client, reg, value);
470 return i2c_smbus_write_word_swapped(client, reg, value);
473 static struct lm75_data *lm75_update_device(struct device *dev)
475 struct i2c_client *client = to_i2c_client(dev);
476 struct lm75_data *data = i2c_get_clientdata(client);
477 struct lm75_data *ret = data;
479 mutex_lock(&data->update_lock);
481 if (time_after(jiffies, data->last_updated + data->sample_time)
484 dev_dbg(&client->dev, "Starting lm75 update\n");
486 for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
489 status = lm75_read_value(client, LM75_REG_TEMP[i]);
490 if (unlikely(status < 0)) {
492 "LM75: Failed to read value: reg %d, error %d\n",
493 LM75_REG_TEMP[i], status);
494 ret = ERR_PTR(status);
498 data->temp[i] = status;
500 data->last_updated = jiffies;
505 mutex_unlock(&data->update_lock);
509 module_i2c_driver(lm75_driver);
511 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
512 MODULE_DESCRIPTION("LM75 driver");
513 MODULE_LICENSE("GPL");