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5bf1d290 | 1 | /* Copyright (c) 2010 Christoph Mair <christoph.mair@gmail.com> |
e939ca0a EA |
2 | * Copyright (c) 2012 Bosch Sensortec GmbH |
3 | * Copyright (c) 2012 Unixphere AB | |
4 | * | |
985087db EA |
5 | * This driver supports the bmp085 and bmp18x digital barometric pressure |
6 | * and temperature sensors from Bosch Sensortec. The datasheets | |
7 | * are available from their website: | |
e939ca0a | 8 | * http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP085-DS000-05.pdf |
985087db | 9 | * http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP180-DS000-07.pdf |
e939ca0a EA |
10 | * |
11 | * A pressure measurement is issued by reading from pressure0_input. | |
12 | * The return value ranges from 30000 to 110000 pascal with a resulution | |
13 | * of 1 pascal (0.01 millibar) which enables measurements from 9000m above | |
14 | * to 500m below sea level. | |
15 | * | |
16 | * The temperature can be read from temp0_input. Values range from | |
17 | * -400 to 850 representing the ambient temperature in degree celsius | |
18 | * multiplied by 10.The resolution is 0.1 celsius. | |
19 | * | |
20 | * Because ambient pressure is temperature dependent, a temperature | |
21 | * measurement will be executed automatically even if the user is reading | |
22 | * from pressure0_input. This happens if the last temperature measurement | |
23 | * has been executed more then one second ago. | |
24 | * | |
25 | * To decrease RMS noise from pressure measurements, the bmp085 can | |
26 | * autonomously calculate the average of up to eight samples. This is | |
27 | * set up by writing to the oversampling sysfs file. Accepted values | |
28 | * are 0, 1, 2 and 3. 2^x when x is the value written to this file | |
29 | * specifies the number of samples used to calculate the ambient pressure. | |
30 | * RMS noise is specified with six pascal (without averaging) and decreases | |
31 | * down to 3 pascal when using an oversampling setting of 3. | |
32 | * | |
33 | * This program is free software; you can redistribute it and/or modify | |
34 | * it under the terms of the GNU General Public License as published by | |
35 | * the Free Software Foundation; either version 2 of the License, or | |
36 | * (at your option) any later version. | |
37 | * | |
38 | * This program is distributed in the hope that it will be useful, | |
39 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
40 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
41 | * GNU General Public License for more details. | |
42 | * | |
43 | * You should have received a copy of the GNU General Public License | |
44 | * along with this program; if not, write to the Free Software | |
45 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
46 | */ | |
5bf1d290 CM |
47 | |
48 | #include <linux/module.h> | |
e939ca0a | 49 | #include <linux/device.h> |
5bf1d290 | 50 | #include <linux/init.h> |
5bf1d290 CM |
51 | #include <linux/slab.h> |
52 | #include <linux/delay.h> | |
c5a86ab6 | 53 | #include <linux/of.h> |
985087db | 54 | #include "bmp085.h" |
5bf1d290 | 55 | |
5bf1d290 | 56 | #define BMP085_CHIP_ID 0x55 |
5bf1d290 CM |
57 | #define BMP085_CALIBRATION_DATA_START 0xAA |
58 | #define BMP085_CALIBRATION_DATA_LENGTH 11 /* 16 bit values */ | |
59 | #define BMP085_CHIP_ID_REG 0xD0 | |
5bf1d290 CM |
60 | #define BMP085_CTRL_REG 0xF4 |
61 | #define BMP085_TEMP_MEASUREMENT 0x2E | |
62 | #define BMP085_PRESSURE_MEASUREMENT 0x34 | |
63 | #define BMP085_CONVERSION_REGISTER_MSB 0xF6 | |
64 | #define BMP085_CONVERSION_REGISTER_LSB 0xF7 | |
65 | #define BMP085_CONVERSION_REGISTER_XLSB 0xF8 | |
66 | #define BMP085_TEMP_CONVERSION_TIME 5 | |
67 | ||
5bf1d290 CM |
68 | struct bmp085_calibration_data { |
69 | s16 AC1, AC2, AC3; | |
70 | u16 AC4, AC5, AC6; | |
71 | s16 B1, B2; | |
72 | s16 MB, MC, MD; | |
73 | }; | |
74 | ||
5bf1d290 | 75 | struct bmp085_data { |
985087db EA |
76 | struct device *dev; |
77 | struct regmap *regmap; | |
e939ca0a EA |
78 | struct mutex lock; |
79 | struct bmp085_calibration_data calibration; | |
80 | u8 oversampling_setting; | |
81 | u32 raw_temperature; | |
82 | u32 raw_pressure; | |
83 | u32 temp_measurement_period; | |
b222258a | 84 | unsigned long last_temp_measurement; |
c5a86ab6 | 85 | u8 chip_id; |
e939ca0a | 86 | s32 b6; /* calculated temperature correction coefficient */ |
5bf1d290 CM |
87 | }; |
88 | ||
985087db | 89 | static s32 bmp085_read_calibration_data(struct bmp085_data *data) |
5bf1d290 CM |
90 | { |
91 | u16 tmp[BMP085_CALIBRATION_DATA_LENGTH]; | |
5bf1d290 | 92 | struct bmp085_calibration_data *cali = &(data->calibration); |
985087db EA |
93 | s32 status = regmap_bulk_read(data->regmap, |
94 | BMP085_CALIBRATION_DATA_START, (u8 *)tmp, | |
95 | (BMP085_CALIBRATION_DATA_LENGTH << 1)); | |
5bf1d290 CM |
96 | if (status < 0) |
97 | return status; | |
98 | ||
5bf1d290 CM |
99 | cali->AC1 = be16_to_cpu(tmp[0]); |
100 | cali->AC2 = be16_to_cpu(tmp[1]); | |
101 | cali->AC3 = be16_to_cpu(tmp[2]); | |
102 | cali->AC4 = be16_to_cpu(tmp[3]); | |
103 | cali->AC5 = be16_to_cpu(tmp[4]); | |
104 | cali->AC6 = be16_to_cpu(tmp[5]); | |
105 | cali->B1 = be16_to_cpu(tmp[6]); | |
106 | cali->B2 = be16_to_cpu(tmp[7]); | |
107 | cali->MB = be16_to_cpu(tmp[8]); | |
108 | cali->MC = be16_to_cpu(tmp[9]); | |
109 | cali->MD = be16_to_cpu(tmp[10]); | |
110 | return 0; | |
111 | } | |
112 | ||
5bf1d290 CM |
113 | static s32 bmp085_update_raw_temperature(struct bmp085_data *data) |
114 | { | |
115 | u16 tmp; | |
116 | s32 status; | |
117 | ||
118 | mutex_lock(&data->lock); | |
985087db EA |
119 | status = regmap_write(data->regmap, BMP085_CTRL_REG, |
120 | BMP085_TEMP_MEASUREMENT); | |
e939ca0a | 121 | if (status < 0) { |
985087db | 122 | dev_err(data->dev, |
5bf1d290 CM |
123 | "Error while requesting temperature measurement.\n"); |
124 | goto exit; | |
125 | } | |
126 | msleep(BMP085_TEMP_CONVERSION_TIME); | |
127 | ||
985087db EA |
128 | status = regmap_bulk_read(data->regmap, BMP085_CONVERSION_REGISTER_MSB, |
129 | &tmp, sizeof(tmp)); | |
130 | if (status < 0) { | |
131 | dev_err(data->dev, | |
5bf1d290 | 132 | "Error while reading temperature measurement result\n"); |
5bf1d290 CM |
133 | goto exit; |
134 | } | |
135 | data->raw_temperature = be16_to_cpu(tmp); | |
136 | data->last_temp_measurement = jiffies; | |
137 | status = 0; /* everything ok, return 0 */ | |
138 | ||
139 | exit: | |
140 | mutex_unlock(&data->lock); | |
141 | return status; | |
142 | } | |
143 | ||
144 | static s32 bmp085_update_raw_pressure(struct bmp085_data *data) | |
145 | { | |
146 | u32 tmp = 0; | |
147 | s32 status; | |
148 | ||
149 | mutex_lock(&data->lock); | |
985087db | 150 | status = regmap_write(data->regmap, BMP085_CTRL_REG, |
e939ca0a EA |
151 | BMP085_PRESSURE_MEASUREMENT + |
152 | (data->oversampling_setting << 6)); | |
153 | if (status < 0) { | |
985087db | 154 | dev_err(data->dev, |
5bf1d290 CM |
155 | "Error while requesting pressure measurement.\n"); |
156 | goto exit; | |
157 | } | |
158 | ||
159 | /* wait for the end of conversion */ | |
160 | msleep(2+(3 << data->oversampling_setting)); | |
161 | ||
162 | /* copy data into a u32 (4 bytes), but skip the first byte. */ | |
985087db EA |
163 | status = regmap_bulk_read(data->regmap, BMP085_CONVERSION_REGISTER_MSB, |
164 | ((u8 *)&tmp)+1, 3); | |
165 | if (status < 0) { | |
166 | dev_err(data->dev, | |
5bf1d290 | 167 | "Error while reading pressure measurement results\n"); |
5bf1d290 CM |
168 | goto exit; |
169 | } | |
170 | data->raw_pressure = be32_to_cpu((tmp)); | |
171 | data->raw_pressure >>= (8-data->oversampling_setting); | |
172 | status = 0; /* everything ok, return 0 */ | |
173 | ||
174 | exit: | |
175 | mutex_unlock(&data->lock); | |
176 | return status; | |
177 | } | |
178 | ||
5bf1d290 CM |
179 | /* |
180 | * This function starts the temperature measurement and returns the value | |
181 | * in tenth of a degree celsius. | |
182 | */ | |
183 | static s32 bmp085_get_temperature(struct bmp085_data *data, int *temperature) | |
184 | { | |
185 | struct bmp085_calibration_data *cali = &data->calibration; | |
186 | long x1, x2; | |
187 | int status; | |
188 | ||
189 | status = bmp085_update_raw_temperature(data); | |
e939ca0a | 190 | if (status < 0) |
5bf1d290 CM |
191 | goto exit; |
192 | ||
193 | x1 = ((data->raw_temperature - cali->AC6) * cali->AC5) >> 15; | |
194 | x2 = (cali->MC << 11) / (x1 + cali->MD); | |
195 | data->b6 = x1 + x2 - 4000; | |
196 | /* if NULL just update b6. Used for pressure only measurements */ | |
197 | if (temperature != NULL) | |
198 | *temperature = (x1+x2+8) >> 4; | |
199 | ||
200 | exit: | |
f80ea668 | 201 | return status; |
5bf1d290 CM |
202 | } |
203 | ||
204 | /* | |
205 | * This function starts the pressure measurement and returns the value | |
206 | * in millibar. Since the pressure depends on the ambient temperature, | |
e939ca0a EA |
207 | * a temperature measurement is executed according to the given temperature |
208 | * measurement period (default is 1 sec boundary). This period could vary | |
209 | * and needs to be adjusted according to the sensor environment, i.e. if big | |
210 | * temperature variations then the temperature needs to be read out often. | |
5bf1d290 CM |
211 | */ |
212 | static s32 bmp085_get_pressure(struct bmp085_data *data, int *pressure) | |
213 | { | |
214 | struct bmp085_calibration_data *cali = &data->calibration; | |
215 | s32 x1, x2, x3, b3; | |
216 | u32 b4, b7; | |
217 | s32 p; | |
218 | int status; | |
219 | ||
220 | /* alt least every second force an update of the ambient temperature */ | |
e939ca0a EA |
221 | if ((data->last_temp_measurement == 0) || |
222 | time_is_before_jiffies(data->last_temp_measurement + 1*HZ)) { | |
5bf1d290 | 223 | status = bmp085_get_temperature(data, NULL); |
e939ca0a EA |
224 | if (status < 0) |
225 | return status; | |
5bf1d290 CM |
226 | } |
227 | ||
228 | status = bmp085_update_raw_pressure(data); | |
e939ca0a EA |
229 | if (status < 0) |
230 | return status; | |
5bf1d290 CM |
231 | |
232 | x1 = (data->b6 * data->b6) >> 12; | |
233 | x1 *= cali->B2; | |
234 | x1 >>= 11; | |
235 | ||
236 | x2 = cali->AC2 * data->b6; | |
237 | x2 >>= 11; | |
238 | ||
239 | x3 = x1 + x2; | |
240 | ||
241 | b3 = (((((s32)cali->AC1) * 4 + x3) << data->oversampling_setting) + 2); | |
242 | b3 >>= 2; | |
243 | ||
244 | x1 = (cali->AC3 * data->b6) >> 13; | |
245 | x2 = (cali->B1 * ((data->b6 * data->b6) >> 12)) >> 16; | |
246 | x3 = (x1 + x2 + 2) >> 2; | |
247 | b4 = (cali->AC4 * (u32)(x3 + 32768)) >> 15; | |
248 | ||
249 | b7 = ((u32)data->raw_pressure - b3) * | |
250 | (50000 >> data->oversampling_setting); | |
251 | p = ((b7 < 0x80000000) ? ((b7 << 1) / b4) : ((b7 / b4) * 2)); | |
252 | ||
253 | x1 = p >> 8; | |
254 | x1 *= x1; | |
255 | x1 = (x1 * 3038) >> 16; | |
256 | x2 = (-7357 * p) >> 16; | |
257 | p += (x1 + x2 + 3791) >> 4; | |
258 | ||
259 | *pressure = p; | |
260 | ||
e939ca0a | 261 | return 0; |
5bf1d290 CM |
262 | } |
263 | ||
264 | /* | |
265 | * This function sets the chip-internal oversampling. Valid values are 0..3. | |
266 | * The chip will use 2^oversampling samples for internal averaging. | |
267 | * This influences the measurement time and the accuracy; larger values | |
e939ca0a | 268 | * increase both. The datasheet gives an overview on how measurement time, |
5bf1d290 CM |
269 | * accuracy and noise correlate. |
270 | */ | |
271 | static void bmp085_set_oversampling(struct bmp085_data *data, | |
272 | unsigned char oversampling) | |
273 | { | |
274 | if (oversampling > 3) | |
275 | oversampling = 3; | |
276 | data->oversampling_setting = oversampling; | |
277 | } | |
278 | ||
279 | /* | |
280 | * Returns the currently selected oversampling. Range: 0..3 | |
281 | */ | |
282 | static unsigned char bmp085_get_oversampling(struct bmp085_data *data) | |
283 | { | |
284 | return data->oversampling_setting; | |
285 | } | |
286 | ||
287 | /* sysfs callbacks */ | |
288 | static ssize_t set_oversampling(struct device *dev, | |
289 | struct device_attribute *attr, | |
290 | const char *buf, size_t count) | |
291 | { | |
985087db | 292 | struct bmp085_data *data = dev_get_drvdata(dev); |
5bf1d290 | 293 | unsigned long oversampling; |
e939ca0a EA |
294 | int err = kstrtoul(buf, 10, &oversampling); |
295 | ||
296 | if (err == 0) { | |
297 | mutex_lock(&data->lock); | |
5bf1d290 | 298 | bmp085_set_oversampling(data, oversampling); |
e939ca0a | 299 | mutex_unlock(&data->lock); |
5bf1d290 CM |
300 | return count; |
301 | } | |
e939ca0a EA |
302 | |
303 | return err; | |
5bf1d290 CM |
304 | } |
305 | ||
306 | static ssize_t show_oversampling(struct device *dev, | |
307 | struct device_attribute *attr, char *buf) | |
308 | { | |
985087db | 309 | struct bmp085_data *data = dev_get_drvdata(dev); |
e939ca0a | 310 | |
5bf1d290 CM |
311 | return sprintf(buf, "%u\n", bmp085_get_oversampling(data)); |
312 | } | |
313 | static DEVICE_ATTR(oversampling, S_IWUSR | S_IRUGO, | |
314 | show_oversampling, set_oversampling); | |
315 | ||
316 | ||
317 | static ssize_t show_temperature(struct device *dev, | |
318 | struct device_attribute *attr, char *buf) | |
319 | { | |
320 | int temperature; | |
321 | int status; | |
985087db | 322 | struct bmp085_data *data = dev_get_drvdata(dev); |
5bf1d290 CM |
323 | |
324 | status = bmp085_get_temperature(data, &temperature); | |
e939ca0a | 325 | if (status < 0) |
5bf1d290 CM |
326 | return status; |
327 | else | |
328 | return sprintf(buf, "%d\n", temperature); | |
329 | } | |
330 | static DEVICE_ATTR(temp0_input, S_IRUGO, show_temperature, NULL); | |
331 | ||
332 | ||
333 | static ssize_t show_pressure(struct device *dev, | |
334 | struct device_attribute *attr, char *buf) | |
335 | { | |
336 | int pressure; | |
337 | int status; | |
985087db | 338 | struct bmp085_data *data = dev_get_drvdata(dev); |
5bf1d290 CM |
339 | |
340 | status = bmp085_get_pressure(data, &pressure); | |
e939ca0a | 341 | if (status < 0) |
5bf1d290 CM |
342 | return status; |
343 | else | |
344 | return sprintf(buf, "%d\n", pressure); | |
345 | } | |
346 | static DEVICE_ATTR(pressure0_input, S_IRUGO, show_pressure, NULL); | |
347 | ||
348 | ||
349 | static struct attribute *bmp085_attributes[] = { | |
350 | &dev_attr_temp0_input.attr, | |
351 | &dev_attr_pressure0_input.attr, | |
352 | &dev_attr_oversampling.attr, | |
353 | NULL | |
354 | }; | |
355 | ||
356 | static const struct attribute_group bmp085_attr_group = { | |
357 | .attrs = bmp085_attributes, | |
358 | }; | |
359 | ||
985087db | 360 | int bmp085_detect(struct device *dev) |
5bf1d290 | 361 | { |
985087db EA |
362 | struct bmp085_data *data = dev_get_drvdata(dev); |
363 | unsigned int id; | |
364 | int ret; | |
365 | ||
366 | ret = regmap_read(data->regmap, BMP085_CHIP_ID_REG, &id); | |
367 | if (ret < 0) | |
368 | return ret; | |
5bf1d290 | 369 | |
985087db | 370 | if (id != data->chip_id) |
5bf1d290 CM |
371 | return -ENODEV; |
372 | ||
373 | return 0; | |
374 | } | |
985087db | 375 | EXPORT_SYMBOL_GPL(bmp085_detect); |
5bf1d290 | 376 | |
985087db | 377 | static void __init bmp085_get_of_properties(struct bmp085_data *data) |
c5a86ab6 EA |
378 | { |
379 | #ifdef CONFIG_OF | |
985087db | 380 | struct device_node *np = data->dev->of_node; |
c5a86ab6 EA |
381 | u32 prop; |
382 | ||
383 | if (!np) | |
384 | return; | |
385 | ||
386 | if (!of_property_read_u32(np, "chip-id", &prop)) | |
387 | data->chip_id = prop & 0xff; | |
388 | ||
389 | if (!of_property_read_u32(np, "temp-measurement-period", &prop)) | |
390 | data->temp_measurement_period = (prop/100)*HZ; | |
391 | ||
392 | if (!of_property_read_u32(np, "default-oversampling", &prop)) | |
393 | data->oversampling_setting = prop & 0xff; | |
394 | #endif | |
395 | } | |
396 | ||
985087db | 397 | static int bmp085_init_client(struct bmp085_data *data) |
5bf1d290 | 398 | { |
985087db | 399 | int status = bmp085_read_calibration_data(data); |
e939ca0a EA |
400 | |
401 | if (status < 0) | |
402 | return status; | |
403 | ||
c5a86ab6 | 404 | /* default settings */ |
c5a86ab6 | 405 | data->chip_id = BMP085_CHIP_ID; |
5bf1d290 | 406 | data->last_temp_measurement = 0; |
e939ca0a | 407 | data->temp_measurement_period = 1*HZ; |
5bf1d290 | 408 | data->oversampling_setting = 3; |
c5a86ab6 | 409 | |
985087db | 410 | bmp085_get_of_properties(data); |
c5a86ab6 | 411 | |
5bf1d290 | 412 | mutex_init(&data->lock); |
e939ca0a EA |
413 | |
414 | return 0; | |
5bf1d290 CM |
415 | } |
416 | ||
985087db EA |
417 | struct regmap_config bmp085_regmap_config = { |
418 | .reg_bits = 8, | |
419 | .val_bits = 8 | |
420 | }; | |
421 | EXPORT_SYMBOL_GPL(bmp085_regmap_config); | |
422 | ||
80c8ae28 | 423 | int bmp085_probe(struct device *dev, struct regmap *regmap) |
5bf1d290 CM |
424 | { |
425 | struct bmp085_data *data; | |
426 | int err = 0; | |
427 | ||
428 | data = kzalloc(sizeof(struct bmp085_data), GFP_KERNEL); | |
429 | if (!data) { | |
430 | err = -ENOMEM; | |
431 | goto exit; | |
432 | } | |
433 | ||
985087db EA |
434 | dev_set_drvdata(dev, data); |
435 | data->dev = dev; | |
436 | data->regmap = regmap; | |
5bf1d290 CM |
437 | |
438 | /* Initialize the BMP085 chip */ | |
985087db | 439 | err = bmp085_init_client(data); |
e939ca0a | 440 | if (err < 0) |
5bf1d290 CM |
441 | goto exit_free; |
442 | ||
985087db EA |
443 | err = bmp085_detect(dev); |
444 | if (err < 0) { | |
445 | dev_err(dev, "%s: chip_id failed!\n", BMP085_NAME); | |
446 | goto exit_free; | |
447 | } | |
448 | ||
5bf1d290 | 449 | /* Register sysfs hooks */ |
985087db | 450 | err = sysfs_create_group(&dev->kobj, &bmp085_attr_group); |
5bf1d290 CM |
451 | if (err) |
452 | goto exit_free; | |
453 | ||
985087db | 454 | dev_info(dev, "Successfully initialized %s!\n", BMP085_NAME); |
e939ca0a EA |
455 | |
456 | return 0; | |
5bf1d290 CM |
457 | |
458 | exit_free: | |
459 | kfree(data); | |
460 | exit: | |
461 | return err; | |
462 | } | |
985087db | 463 | EXPORT_SYMBOL_GPL(bmp085_probe); |
5bf1d290 | 464 | |
985087db | 465 | int bmp085_remove(struct device *dev) |
5bf1d290 | 466 | { |
985087db | 467 | struct bmp085_data *data = dev_get_drvdata(dev); |
e939ca0a | 468 | |
985087db | 469 | sysfs_remove_group(&data->dev->kobj, &bmp085_attr_group); |
e939ca0a EA |
470 | kfree(data); |
471 | ||
5bf1d290 CM |
472 | return 0; |
473 | } | |
985087db | 474 | EXPORT_SYMBOL_GPL(bmp085_remove); |
5bf1d290 | 475 | |
e939ca0a | 476 | MODULE_AUTHOR("Christoph Mair <christoph.mair@gmail.com>"); |
5bf1d290 CM |
477 | MODULE_DESCRIPTION("BMP085 driver"); |
478 | MODULE_LICENSE("GPL"); |