1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Sensirion SPS30 particulate matter sensor driver
4 *
5 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
6 *
7 * I2C slave address: 0x69
8 */
9
10 #include <asm/unaligned.h>
11 #include <linux/crc8.h>
12 #include <linux/delay.h>
13 #include <linux/i2c.h>
14 #include <linux/iio/buffer.h>
15 #include <linux/iio/iio.h>
16 #include <linux/iio/sysfs.h>
17 #include <linux/iio/trigger_consumer.h>
18 #include <linux/iio/triggered_buffer.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21
22 #define SPS30_CRC8_POLYNOMIAL 0x31
23 /* max number of bytes needed to store PM measurements or serial string */
24 #define SPS30_MAX_READ_SIZE 48
25 /* sensor measures reliably up to 3000 ug / m3 */
26 #define SPS30_MAX_PM 3000
27 /* minimum and maximum self cleaning periods in seconds */
28 #define SPS30_AUTO_CLEANING_PERIOD_MIN 0
29 #define SPS30_AUTO_CLEANING_PERIOD_MAX 604800
30
31 /* SPS30 commands */
32 #define SPS30_START_MEAS 0x0010
33 #define SPS30_STOP_MEAS 0x0104
34 #define SPS30_RESET 0xd304
35 #define SPS30_READ_DATA_READY_FLAG 0x0202
36 #define SPS30_READ_DATA 0x0300
37 #define SPS30_READ_SERIAL 0xd033
38 #define SPS30_START_FAN_CLEANING 0x5607
39 #define SPS30_AUTO_CLEANING_PERIOD 0x8004
40 /* not a sensor command per se, used only to distinguish write from read */
41 #define SPS30_READ_AUTO_CLEANING_PERIOD 0x8005
42
43 enum {
44 PM1,
45 PM2P5,
46 PM4,
47 PM10,
48 };
49
50 enum {
51 RESET,
52 MEASURING,
53 };
54
55 struct sps30_state {
56 struct i2c_client *client;
57 /*
58 * Guards against concurrent access to sensor registers.
59 * Must be held whenever sequence of commands is to be executed.
60 */
61 struct mutex lock;
62 int state;
63 };
64
65 DECLARE_CRC8_TABLE(sps30_crc8_table);
66
sps30_write_then_read(struct sps30_state * state,u8 * txbuf,int txsize,u8 * rxbuf,int rxsize)67 static int sps30_write_then_read(struct sps30_state *state, u8 *txbuf,
68 int txsize, u8 *rxbuf, int rxsize)
69 {
70 int ret;
71
72 /*
73 * Sensor does not support repeated start so instead of
74 * sending two i2c messages in a row we just send one by one.
75 */
76 ret = i2c_master_send(state->client, txbuf, txsize);
77 if (ret != txsize)
78 return ret < 0 ? ret : -EIO;
79
80 if (!rxbuf)
81 return 0;
82
83 ret = i2c_master_recv(state->client, rxbuf, rxsize);
84 if (ret != rxsize)
85 return ret < 0 ? ret : -EIO;
86
87 return 0;
88 }
89
sps30_do_cmd(struct sps30_state * state,u16 cmd,u8 * data,int size)90 static int sps30_do_cmd(struct sps30_state *state, u16 cmd, u8 *data, int size)
91 {
92 /*
93 * Internally sensor stores measurements in a following manner:
94 *
95 * PM1: upper two bytes, crc8, lower two bytes, crc8
96 * PM2P5: upper two bytes, crc8, lower two bytes, crc8
97 * PM4: upper two bytes, crc8, lower two bytes, crc8
98 * PM10: upper two bytes, crc8, lower two bytes, crc8
99 *
100 * What follows next are number concentration measurements and
101 * typical particle size measurement which we omit.
102 */
103 u8 buf[SPS30_MAX_READ_SIZE] = { cmd >> 8, cmd };
104 int i, ret = 0;
105
106 switch (cmd) {
107 case SPS30_START_MEAS:
108 buf[2] = 0x03;
109 buf[3] = 0x00;
110 buf[4] = crc8(sps30_crc8_table, &buf[2], 2, CRC8_INIT_VALUE);
111 ret = sps30_write_then_read(state, buf, 5, NULL, 0);
112 break;
113 case SPS30_STOP_MEAS:
114 case SPS30_RESET:
115 case SPS30_START_FAN_CLEANING:
116 ret = sps30_write_then_read(state, buf, 2, NULL, 0);
117 break;
118 case SPS30_READ_AUTO_CLEANING_PERIOD:
119 buf[0] = SPS30_AUTO_CLEANING_PERIOD >> 8;
120 buf[1] = (u8)SPS30_AUTO_CLEANING_PERIOD;
121 /* fall through */
122 case SPS30_READ_DATA_READY_FLAG:
123 case SPS30_READ_DATA:
124 case SPS30_READ_SERIAL:
125 /* every two data bytes are checksummed */
126 size += size / 2;
127 ret = sps30_write_then_read(state, buf, 2, buf, size);
128 break;
129 case SPS30_AUTO_CLEANING_PERIOD:
130 buf[2] = data[0];
131 buf[3] = data[1];
132 buf[4] = crc8(sps30_crc8_table, &buf[2], 2, CRC8_INIT_VALUE);
133 buf[5] = data[2];
134 buf[6] = data[3];
135 buf[7] = crc8(sps30_crc8_table, &buf[5], 2, CRC8_INIT_VALUE);
136 ret = sps30_write_then_read(state, buf, 8, NULL, 0);
137 break;
138 }
139
140 if (ret)
141 return ret;
142
143 /* validate received data and strip off crc bytes */
144 for (i = 0; i < size; i += 3) {
145 u8 crc = crc8(sps30_crc8_table, &buf[i], 2, CRC8_INIT_VALUE);
146
147 if (crc != buf[i + 2]) {
148 dev_err(&state->client->dev,
149 "data integrity check failed\n");
150 return -EIO;
151 }
152
153 *data++ = buf[i];
154 *data++ = buf[i + 1];
155 }
156
157 return 0;
158 }
159
sps30_float_to_int_clamped(const u8 * fp)160 static s32 sps30_float_to_int_clamped(const u8 *fp)
161 {
162 int val = get_unaligned_be32(fp);
163 int mantissa = val & GENMASK(22, 0);
164 /* this is fine since passed float is always non-negative */
165 int exp = val >> 23;
166 int fraction, shift;
167
168 /* special case 0 */
169 if (!exp && !mantissa)
170 return 0;
171
172 exp -= 127;
173 if (exp < 0) {
174 /* return values ranging from 1 to 99 */
175 return ((((1 << 23) + mantissa) * 100) >> 23) >> (-exp);
176 }
177
178 /* return values ranging from 100 to 300000 */
179 shift = 23 - exp;
180 val = (1 << exp) + (mantissa >> shift);
181 if (val >= SPS30_MAX_PM)
182 return SPS30_MAX_PM * 100;
183
184 fraction = mantissa & GENMASK(shift - 1, 0);
185
186 return val * 100 + ((fraction * 100) >> shift);
187 }
188
sps30_do_meas(struct sps30_state * state,s32 * data,int size)189 static int sps30_do_meas(struct sps30_state *state, s32 *data, int size)
190 {
191 int i, ret, tries = 5;
192 u8 tmp[16];
193
194 if (state->state == RESET) {
195 ret = sps30_do_cmd(state, SPS30_START_MEAS, NULL, 0);
196 if (ret)
197 return ret;
198
199 state->state = MEASURING;
200 }
201
202 while (tries--) {
203 ret = sps30_do_cmd(state, SPS30_READ_DATA_READY_FLAG, tmp, 2);
204 if (ret)
205 return -EIO;
206
207 /* new measurements ready to be read */
208 if (tmp[1] == 1)
209 break;
210
211 msleep_interruptible(300);
212 }
213
214 if (tries == -1)
215 return -ETIMEDOUT;
216
217 ret = sps30_do_cmd(state, SPS30_READ_DATA, tmp, sizeof(int) * size);
218 if (ret)
219 return ret;
220
221 for (i = 0; i < size; i++)
222 data[i] = sps30_float_to_int_clamped(&tmp[4 * i]);
223
224 return 0;
225 }
226
sps30_trigger_handler(int irq,void * p)227 static irqreturn_t sps30_trigger_handler(int irq, void *p)
228 {
229 struct iio_poll_func *pf = p;
230 struct iio_dev *indio_dev = pf->indio_dev;
231 struct sps30_state *state = iio_priv(indio_dev);
232 int ret;
233 s32 data[4 + 2]; /* PM1, PM2P5, PM4, PM10, timestamp */
234
235 mutex_lock(&state->lock);
236 ret = sps30_do_meas(state, data, 4);
237 mutex_unlock(&state->lock);
238 if (ret)
239 goto err;
240
241 iio_push_to_buffers_with_timestamp(indio_dev, data,
242 iio_get_time_ns(indio_dev));
243 err:
244 iio_trigger_notify_done(indio_dev->trig);
245
246 return IRQ_HANDLED;
247 }
248
sps30_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)249 static int sps30_read_raw(struct iio_dev *indio_dev,
250 struct iio_chan_spec const *chan,
251 int *val, int *val2, long mask)
252 {
253 struct sps30_state *state = iio_priv(indio_dev);
254 int data[4], ret = -EINVAL;
255
256 switch (mask) {
257 case IIO_CHAN_INFO_PROCESSED:
258 switch (chan->type) {
259 case IIO_MASSCONCENTRATION:
260 mutex_lock(&state->lock);
261 /* read up to the number of bytes actually needed */
262 switch (chan->channel2) {
263 case IIO_MOD_PM1:
264 ret = sps30_do_meas(state, data, 1);
265 break;
266 case IIO_MOD_PM2P5:
267 ret = sps30_do_meas(state, data, 2);
268 break;
269 case IIO_MOD_PM4:
270 ret = sps30_do_meas(state, data, 3);
271 break;
272 case IIO_MOD_PM10:
273 ret = sps30_do_meas(state, data, 4);
274 break;
275 }
276 mutex_unlock(&state->lock);
277 if (ret)
278 return ret;
279
280 *val = data[chan->address] / 100;
281 *val2 = (data[chan->address] % 100) * 10000;
282
283 return IIO_VAL_INT_PLUS_MICRO;
284 default:
285 return -EINVAL;
286 }
287 case IIO_CHAN_INFO_SCALE:
288 switch (chan->type) {
289 case IIO_MASSCONCENTRATION:
290 switch (chan->channel2) {
291 case IIO_MOD_PM1:
292 case IIO_MOD_PM2P5:
293 case IIO_MOD_PM4:
294 case IIO_MOD_PM10:
295 *val = 0;
296 *val2 = 10000;
297
298 return IIO_VAL_INT_PLUS_MICRO;
299 default:
300 return -EINVAL;
301 }
302 default:
303 return -EINVAL;
304 }
305 }
306
307 return -EINVAL;
308 }
309
sps30_do_cmd_reset(struct sps30_state * state)310 static int sps30_do_cmd_reset(struct sps30_state *state)
311 {
312 int ret;
313
314 ret = sps30_do_cmd(state, SPS30_RESET, NULL, 0);
315 msleep(300);
316 /*
317 * Power-on-reset causes sensor to produce some glitch on i2c bus and
318 * some controllers end up in error state. Recover simply by placing
319 * some data on the bus, for example STOP_MEAS command, which
320 * is NOP in this case.
321 */
322 sps30_do_cmd(state, SPS30_STOP_MEAS, NULL, 0);
323 state->state = RESET;
324
325 return ret;
326 }
327
start_cleaning_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)328 static ssize_t start_cleaning_store(struct device *dev,
329 struct device_attribute *attr,
330 const char *buf, size_t len)
331 {
332 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
333 struct sps30_state *state = iio_priv(indio_dev);
334 int val, ret;
335
336 if (kstrtoint(buf, 0, &val) || val != 1)
337 return -EINVAL;
338
339 mutex_lock(&state->lock);
340 ret = sps30_do_cmd(state, SPS30_START_FAN_CLEANING, NULL, 0);
341 mutex_unlock(&state->lock);
342 if (ret)
343 return ret;
344
345 return len;
346 }
347
cleaning_period_show(struct device * dev,struct device_attribute * attr,char * buf)348 static ssize_t cleaning_period_show(struct device *dev,
349 struct device_attribute *attr,
350 char *buf)
351 {
352 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
353 struct sps30_state *state = iio_priv(indio_dev);
354 u8 tmp[4];
355 int ret;
356
357 mutex_lock(&state->lock);
358 ret = sps30_do_cmd(state, SPS30_READ_AUTO_CLEANING_PERIOD, tmp, 4);
359 mutex_unlock(&state->lock);
360 if (ret)
361 return ret;
362
363 return sprintf(buf, "%d\n", get_unaligned_be32(tmp));
364 }
365
cleaning_period_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)366 static ssize_t cleaning_period_store(struct device *dev,
367 struct device_attribute *attr,
368 const char *buf, size_t len)
369 {
370 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
371 struct sps30_state *state = iio_priv(indio_dev);
372 int val, ret;
373 u8 tmp[4];
374
375 if (kstrtoint(buf, 0, &val))
376 return -EINVAL;
377
378 if ((val < SPS30_AUTO_CLEANING_PERIOD_MIN) ||
379 (val > SPS30_AUTO_CLEANING_PERIOD_MAX))
380 return -EINVAL;
381
382 put_unaligned_be32(val, tmp);
383
384 mutex_lock(&state->lock);
385 ret = sps30_do_cmd(state, SPS30_AUTO_CLEANING_PERIOD, tmp, 0);
386 if (ret) {
387 mutex_unlock(&state->lock);
388 return ret;
389 }
390
391 msleep(20);
392
393 /*
394 * sensor requires reset in order to return up to date self cleaning
395 * period
396 */
397 ret = sps30_do_cmd_reset(state);
398 if (ret)
399 dev_warn(dev,
400 "period changed but reads will return the old value\n");
401
402 mutex_unlock(&state->lock);
403
404 return len;
405 }
406
cleaning_period_available_show(struct device * dev,struct device_attribute * attr,char * buf)407 static ssize_t cleaning_period_available_show(struct device *dev,
408 struct device_attribute *attr,
409 char *buf)
410 {
411 return snprintf(buf, PAGE_SIZE, "[%d %d %d]\n",
412 SPS30_AUTO_CLEANING_PERIOD_MIN, 1,
413 SPS30_AUTO_CLEANING_PERIOD_MAX);
414 }
415
416 static IIO_DEVICE_ATTR_WO(start_cleaning, 0);
417 static IIO_DEVICE_ATTR_RW(cleaning_period, 0);
418 static IIO_DEVICE_ATTR_RO(cleaning_period_available, 0);
419
420 static struct attribute *sps30_attrs[] = {
421 &iio_dev_attr_start_cleaning.dev_attr.attr,
422 &iio_dev_attr_cleaning_period.dev_attr.attr,
423 &iio_dev_attr_cleaning_period_available.dev_attr.attr,
424 NULL
425 };
426
427 static const struct attribute_group sps30_attr_group = {
428 .attrs = sps30_attrs,
429 };
430
431 static const struct iio_info sps30_info = {
432 .attrs = &sps30_attr_group,
433 .read_raw = sps30_read_raw,
434 };
435
436 #define SPS30_CHAN(_index, _mod) { \
437 .type = IIO_MASSCONCENTRATION, \
438 .modified = 1, \
439 .channel2 = IIO_MOD_ ## _mod, \
440 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
441 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
442 .address = _mod, \
443 .scan_index = _index, \
444 .scan_type = { \
445 .sign = 'u', \
446 .realbits = 19, \
447 .storagebits = 32, \
448 .endianness = IIO_CPU, \
449 }, \
450 }
451
452 static const struct iio_chan_spec sps30_channels[] = {
453 SPS30_CHAN(0, PM1),
454 SPS30_CHAN(1, PM2P5),
455 SPS30_CHAN(2, PM4),
456 SPS30_CHAN(3, PM10),
457 IIO_CHAN_SOFT_TIMESTAMP(4),
458 };
459
sps30_stop_meas(void * data)460 static void sps30_stop_meas(void *data)
461 {
462 struct sps30_state *state = data;
463
464 sps30_do_cmd(state, SPS30_STOP_MEAS, NULL, 0);
465 }
466
467 static const unsigned long sps30_scan_masks[] = { 0x0f, 0x00 };
468
sps30_probe(struct i2c_client * client)469 static int sps30_probe(struct i2c_client *client)
470 {
471 struct iio_dev *indio_dev;
472 struct sps30_state *state;
473 u8 buf[32];
474 int ret;
475
476 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
477 return -EOPNOTSUPP;
478
479 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*state));
480 if (!indio_dev)
481 return -ENOMEM;
482
483 state = iio_priv(indio_dev);
484 i2c_set_clientdata(client, indio_dev);
485 state->client = client;
486 state->state = RESET;
487 indio_dev->dev.parent = &client->dev;
488 indio_dev->info = &sps30_info;
489 indio_dev->name = client->name;
490 indio_dev->channels = sps30_channels;
491 indio_dev->num_channels = ARRAY_SIZE(sps30_channels);
492 indio_dev->modes = INDIO_DIRECT_MODE;
493 indio_dev->available_scan_masks = sps30_scan_masks;
494
495 mutex_init(&state->lock);
496 crc8_populate_msb(sps30_crc8_table, SPS30_CRC8_POLYNOMIAL);
497
498 ret = sps30_do_cmd_reset(state);
499 if (ret) {
500 dev_err(&client->dev, "failed to reset device\n");
501 return ret;
502 }
503
504 ret = sps30_do_cmd(state, SPS30_READ_SERIAL, buf, sizeof(buf));
505 if (ret) {
506 dev_err(&client->dev, "failed to read serial number\n");
507 return ret;
508 }
509 /* returned serial number is already NUL terminated */
510 dev_info(&client->dev, "serial number: %s\n", buf);
511
512 ret = devm_add_action_or_reset(&client->dev, sps30_stop_meas, state);
513 if (ret)
514 return ret;
515
516 ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev, NULL,
517 sps30_trigger_handler, NULL);
518 if (ret)
519 return ret;
520
521 return devm_iio_device_register(&client->dev, indio_dev);
522 }
523
524 static const struct i2c_device_id sps30_id[] = {
525 { "sps30" },
526 { }
527 };
528 MODULE_DEVICE_TABLE(i2c, sps30_id);
529
530 static const struct of_device_id sps30_of_match[] = {
531 { .compatible = "sensirion,sps30" },
532 { }
533 };
534 MODULE_DEVICE_TABLE(of, sps30_of_match);
535
536 static struct i2c_driver sps30_driver = {
537 .driver = {
538 .name = "sps30",
539 .of_match_table = sps30_of_match,
540 },
541 .id_table = sps30_id,
542 .probe_new = sps30_probe,
543 };
544 module_i2c_driver(sps30_driver);
545
546 MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
547 MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor driver");
548 MODULE_LICENSE("GPL v2");
549
