1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * BU27034 ROHM Ambient Light Sensor
4 *
5 * Copyright (c) 2023, ROHM Semiconductor.
6 * https://fscdn.rohm.com/en/products/databook/datasheet/ic/sensor/light/bu27034nuc-e.pdf
7 */
8
9 #include <linux/bitfield.h>
10 #include <linux/bits.h>
11 #include <linux/device.h>
12 #include <linux/i2c.h>
13 #include <linux/module.h>
14 #include <linux/property.h>
15 #include <linux/regmap.h>
16 #include <linux/regulator/consumer.h>
17 #include <linux/units.h>
18
19 #include <linux/iio/buffer.h>
20 #include <linux/iio/iio.h>
21 #include <linux/iio/iio-gts-helper.h>
22 #include <linux/iio/kfifo_buf.h>
23
24 #define BU27034_REG_SYSTEM_CONTROL 0x40
25 #define BU27034_MASK_SW_RESET BIT(7)
26 #define BU27034_MASK_PART_ID GENMASK(5, 0)
27 #define BU27034_ID 0x19
28 #define BU27034_REG_MODE_CONTROL1 0x41
29 #define BU27034_MASK_MEAS_MODE GENMASK(2, 0)
30
31 #define BU27034_REG_MODE_CONTROL2 0x42
32 #define BU27034_MASK_D01_GAIN GENMASK(7, 3)
33 #define BU27034_MASK_D2_GAIN_HI GENMASK(7, 6)
34 #define BU27034_MASK_D2_GAIN_LO GENMASK(2, 0)
35
36 #define BU27034_REG_MODE_CONTROL3 0x43
37 #define BU27034_REG_MODE_CONTROL4 0x44
38 #define BU27034_MASK_MEAS_EN BIT(0)
39 #define BU27034_MASK_VALID BIT(7)
40 #define BU27034_REG_DATA0_LO 0x50
41 #define BU27034_REG_DATA1_LO 0x52
42 #define BU27034_REG_DATA2_LO 0x54
43 #define BU27034_REG_DATA2_HI 0x55
44 #define BU27034_REG_MANUFACTURER_ID 0x92
45 #define BU27034_REG_MAX BU27034_REG_MANUFACTURER_ID
46
47 /*
48 * The BU27034 does not have interrupt to trigger the data read when a
49 * measurement has finished. Hence we poll the VALID bit in a thread. We will
50 * try to wake the thread BU27034_MEAS_WAIT_PREMATURE_MS milliseconds before
51 * the expected sampling time to prevent the drifting.
52 *
53 * If we constantly wake up a bit too late we would eventually skip a sample.
54 * And because the sleep can't wake up _exactly_ at given time this would be
55 * inevitable even if the sensor clock would be perfectly phase-locked to CPU
56 * clock - which we can't say is the case.
57 *
58 * This is still fragile. No matter how big advance do we have, we will still
59 * risk of losing a sample because things can in a rainy-day scenario be
60 * delayed a lot. Yet, more we reserve the time for polling, more we also lose
61 * the performance by spending cycles polling the register. So, selecting this
62 * value is a balancing dance between severity of wasting CPU time and severity
63 * of losing samples.
64 *
65 * In most cases losing the samples is not _that_ crucial because light levels
66 * tend to change slowly.
67 *
68 * Other option that was pointed to me would be always sleeping 1/2 of the
69 * measurement time, checking the VALID bit and just sleeping again if the bit
70 * was not set. That should be pretty tolerant against missing samples due to
71 * the scheduling delays while also not wasting much of cycles for polling.
72 * Downside is that the time-stamps would be very inaccurate as the wake-up
73 * would not really be tied to the sensor toggling the valid bit. This would also
74 * result 'jumps' in the time-stamps when the delay drifted so that wake-up was
75 * performed during the consecutive wake-ups (Or, when sensor and CPU clocks
76 * were very different and scheduling the wake-ups was very close to given
77 * timeout - and when the time-outs were very close to the actual sensor
78 * sampling, Eg. once in a blue moon, two consecutive time-outs would occur
79 * without having a sample ready).
80 */
81 #define BU27034_MEAS_WAIT_PREMATURE_MS 5
82 #define BU27034_DATA_WAIT_TIME_US 1000
83 #define BU27034_TOTAL_DATA_WAIT_TIME_US (BU27034_MEAS_WAIT_PREMATURE_MS * 1000)
84
85 #define BU27034_RETRY_LIMIT 18
86
87 enum {
88 BU27034_CHAN_ALS,
89 BU27034_CHAN_DATA0,
90 BU27034_CHAN_DATA1,
91 BU27034_CHAN_DATA2,
92 BU27034_NUM_CHANS
93 };
94
95 static const unsigned long bu27034_scan_masks[] = {
96 GENMASK(BU27034_CHAN_DATA2, BU27034_CHAN_ALS), 0
97 };
98
99 /*
100 * Available scales with gain 1x - 4096x, timings 55, 100, 200, 400 mS
101 * Time impacts to gain: 1x, 2x, 4x, 8x.
102 *
103 * => Max total gain is HWGAIN * gain by integration time (8 * 4096) = 32768
104 *
105 * Using NANO precision for scale we must use scale 64x corresponding gain 1x
106 * to avoid precision loss. (32x would result scale 976 562.5(nanos).
107 */
108 #define BU27034_SCALE_1X 64
109
110 /* See the data sheet for the "Gain Setting" table */
111 #define BU27034_GSEL_1X 0x00 /* 00000 */
112 #define BU27034_GSEL_4X 0x08 /* 01000 */
113 #define BU27034_GSEL_16X 0x0a /* 01010 */
114 #define BU27034_GSEL_32X 0x0b /* 01011 */
115 #define BU27034_GSEL_64X 0x0c /* 01100 */
116 #define BU27034_GSEL_256X 0x18 /* 11000 */
117 #define BU27034_GSEL_512X 0x19 /* 11001 */
118 #define BU27034_GSEL_1024X 0x1a /* 11010 */
119 #define BU27034_GSEL_2048X 0x1b /* 11011 */
120 #define BU27034_GSEL_4096X 0x1c /* 11100 */
121
122 /* Available gain settings */
123 static const struct iio_gain_sel_pair bu27034_gains[] = {
124 GAIN_SCALE_GAIN(1, BU27034_GSEL_1X),
125 GAIN_SCALE_GAIN(4, BU27034_GSEL_4X),
126 GAIN_SCALE_GAIN(16, BU27034_GSEL_16X),
127 GAIN_SCALE_GAIN(32, BU27034_GSEL_32X),
128 GAIN_SCALE_GAIN(64, BU27034_GSEL_64X),
129 GAIN_SCALE_GAIN(256, BU27034_GSEL_256X),
130 GAIN_SCALE_GAIN(512, BU27034_GSEL_512X),
131 GAIN_SCALE_GAIN(1024, BU27034_GSEL_1024X),
132 GAIN_SCALE_GAIN(2048, BU27034_GSEL_2048X),
133 GAIN_SCALE_GAIN(4096, BU27034_GSEL_4096X),
134 };
135
136 /*
137 * The IC has 5 modes for sampling time. 5 mS mode is exceptional as it limits
138 * the data collection to data0-channel only and cuts the supported range to
139 * 10 bit. It is not supported by the driver.
140 *
141 * "normal" modes are 55, 100, 200 and 400 mS modes - which do have direct
142 * multiplying impact to the register values (similar to gain).
143 *
144 * This means that if meas-mode is changed for example from 400 => 200,
145 * the scale is doubled. Eg, time impact to total gain is x1, x2, x4, x8.
146 */
147 #define BU27034_MEAS_MODE_100MS 0
148 #define BU27034_MEAS_MODE_55MS 1
149 #define BU27034_MEAS_MODE_200MS 2
150 #define BU27034_MEAS_MODE_400MS 4
151
152 static const struct iio_itime_sel_mul bu27034_itimes[] = {
153 GAIN_SCALE_ITIME_US(400000, BU27034_MEAS_MODE_400MS, 8),
154 GAIN_SCALE_ITIME_US(200000, BU27034_MEAS_MODE_200MS, 4),
155 GAIN_SCALE_ITIME_US(100000, BU27034_MEAS_MODE_100MS, 2),
156 GAIN_SCALE_ITIME_US(55000, BU27034_MEAS_MODE_55MS, 1),
157 };
158
159 #define BU27034_CHAN_DATA(_name, _ch2) \
160 { \
161 .type = IIO_INTENSITY, \
162 .channel = BU27034_CHAN_##_name, \
163 .channel2 = (_ch2), \
164 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
165 BIT(IIO_CHAN_INFO_SCALE), \
166 .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), \
167 .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME), \
168 .info_mask_shared_by_all_available = \
169 BIT(IIO_CHAN_INFO_INT_TIME), \
170 .address = BU27034_REG_##_name##_LO, \
171 .scan_index = BU27034_CHAN_##_name, \
172 .scan_type = { \
173 .sign = 'u', \
174 .realbits = 16, \
175 .storagebits = 16, \
176 .endianness = IIO_LE, \
177 }, \
178 .indexed = 1, \
179 }
180
181 static const struct iio_chan_spec bu27034_channels[] = {
182 {
183 .type = IIO_LIGHT,
184 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
185 BIT(IIO_CHAN_INFO_SCALE),
186 .channel = BU27034_CHAN_ALS,
187 .scan_index = BU27034_CHAN_ALS,
188 .scan_type = {
189 .sign = 'u',
190 .realbits = 32,
191 .storagebits = 32,
192 .endianness = IIO_CPU,
193 },
194 },
195 /*
196 * The BU27034 DATA0 and DATA1 channels are both on the visible light
197 * area (mostly). The data0 sensitivity peaks at 500nm, DATA1 at 600nm.
198 * These wave lengths are pretty much on the border of colours making
199 * these a poor candidates for R/G/B standardization. Hence they're both
200 * marked as clear channels
201 */
202 BU27034_CHAN_DATA(DATA0, IIO_MOD_LIGHT_CLEAR),
203 BU27034_CHAN_DATA(DATA1, IIO_MOD_LIGHT_CLEAR),
204 BU27034_CHAN_DATA(DATA2, IIO_MOD_LIGHT_IR),
205 IIO_CHAN_SOFT_TIMESTAMP(4),
206 };
207
208 struct bu27034_data {
209 struct regmap *regmap;
210 struct device *dev;
211 /*
212 * Protect gain and time during scale adjustment and data reading.
213 * Protect measurement enabling/disabling.
214 */
215 struct mutex mutex;
216 struct iio_gts gts;
217 struct task_struct *task;
218 __le16 raw[3];
219 struct {
220 u32 mlux;
221 __le16 channels[3];
222 s64 ts __aligned(8);
223 } scan;
224 };
225
226 struct bu27034_result {
227 u16 ch0;
228 u16 ch1;
229 u16 ch2;
230 };
231
232 static const struct regmap_range bu27034_volatile_ranges[] = {
233 {
234 .range_min = BU27034_REG_SYSTEM_CONTROL,
235 .range_max = BU27034_REG_SYSTEM_CONTROL,
236 }, {
237 .range_min = BU27034_REG_MODE_CONTROL4,
238 .range_max = BU27034_REG_MODE_CONTROL4,
239 }, {
240 .range_min = BU27034_REG_DATA0_LO,
241 .range_max = BU27034_REG_DATA2_HI,
242 },
243 };
244
245 static const struct regmap_access_table bu27034_volatile_regs = {
246 .yes_ranges = &bu27034_volatile_ranges[0],
247 .n_yes_ranges = ARRAY_SIZE(bu27034_volatile_ranges),
248 };
249
250 static const struct regmap_range bu27034_read_only_ranges[] = {
251 {
252 .range_min = BU27034_REG_DATA0_LO,
253 .range_max = BU27034_REG_DATA2_HI,
254 }, {
255 .range_min = BU27034_REG_MANUFACTURER_ID,
256 .range_max = BU27034_REG_MANUFACTURER_ID,
257 }
258 };
259
260 static const struct regmap_access_table bu27034_ro_regs = {
261 .no_ranges = &bu27034_read_only_ranges[0],
262 .n_no_ranges = ARRAY_SIZE(bu27034_read_only_ranges),
263 };
264
265 static const struct regmap_config bu27034_regmap = {
266 .reg_bits = 8,
267 .val_bits = 8,
268 .max_register = BU27034_REG_MAX,
269 .cache_type = REGCACHE_RBTREE,
270 .volatile_table = &bu27034_volatile_regs,
271 .wr_table = &bu27034_ro_regs,
272 };
273
274 struct bu27034_gain_check {
275 int old_gain;
276 int new_gain;
277 int chan;
278 };
279
bu27034_get_gain_sel(struct bu27034_data * data,int chan)280 static int bu27034_get_gain_sel(struct bu27034_data *data, int chan)
281 {
282 int ret, val;
283
284 switch (chan) {
285 case BU27034_CHAN_DATA0:
286 case BU27034_CHAN_DATA1:
287 {
288 int reg[] = {
289 [BU27034_CHAN_DATA0] = BU27034_REG_MODE_CONTROL2,
290 [BU27034_CHAN_DATA1] = BU27034_REG_MODE_CONTROL3,
291 };
292 ret = regmap_read(data->regmap, reg[chan], &val);
293 if (ret)
294 return ret;
295
296 return FIELD_GET(BU27034_MASK_D01_GAIN, val);
297 }
298 case BU27034_CHAN_DATA2:
299 {
300 int d2_lo_bits = fls(BU27034_MASK_D2_GAIN_LO);
301
302 ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL2, &val);
303 if (ret)
304 return ret;
305
306 /*
307 * The data2 channel gain is composed by 5 non continuous bits
308 * [7:6], [2:0]. Thus when we combine the 5-bit 'selector'
309 * from register value we must right shift the high bits by 3.
310 */
311 return FIELD_GET(BU27034_MASK_D2_GAIN_HI, val) << d2_lo_bits |
312 FIELD_GET(BU27034_MASK_D2_GAIN_LO, val);
313 }
314 default:
315 return -EINVAL;
316 }
317 }
318
bu27034_get_gain(struct bu27034_data * data,int chan,int * gain)319 static int bu27034_get_gain(struct bu27034_data *data, int chan, int *gain)
320 {
321 int ret, sel;
322
323 ret = bu27034_get_gain_sel(data, chan);
324 if (ret < 0)
325 return ret;
326
327 sel = ret;
328
329 ret = iio_gts_find_gain_by_sel(&data->gts, sel);
330 if (ret < 0) {
331 dev_err(data->dev, "chan %u: unknown gain value 0x%x\n", chan,
332 sel);
333
334 return ret;
335 }
336
337 *gain = ret;
338
339 return 0;
340 }
341
bu27034_get_int_time(struct bu27034_data * data)342 static int bu27034_get_int_time(struct bu27034_data *data)
343 {
344 int ret, sel;
345
346 ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &sel);
347 if (ret)
348 return ret;
349
350 return iio_gts_find_int_time_by_sel(&data->gts,
351 sel & BU27034_MASK_MEAS_MODE);
352 }
353
_bu27034_get_scale(struct bu27034_data * data,int channel,int * val,int * val2)354 static int _bu27034_get_scale(struct bu27034_data *data, int channel, int *val,
355 int *val2)
356 {
357 int gain, ret;
358
359 ret = bu27034_get_gain(data, channel, &gain);
360 if (ret)
361 return ret;
362
363 ret = bu27034_get_int_time(data);
364 if (ret < 0)
365 return ret;
366
367 return iio_gts_get_scale(&data->gts, gain, ret, val, val2);
368 }
369
bu27034_get_scale(struct bu27034_data * data,int channel,int * val,int * val2)370 static int bu27034_get_scale(struct bu27034_data *data, int channel, int *val,
371 int *val2)
372 {
373 int ret;
374
375 if (channel == BU27034_CHAN_ALS) {
376 *val = 0;
377 *val2 = 1000;
378 return IIO_VAL_INT_PLUS_MICRO;
379 }
380
381 mutex_lock(&data->mutex);
382 ret = _bu27034_get_scale(data, channel, val, val2);
383 mutex_unlock(&data->mutex);
384 if (ret)
385 return ret;
386
387 return IIO_VAL_INT_PLUS_NANO;
388 }
389
390 /* Caller should hold the lock to protect lux reading */
bu27034_write_gain_sel(struct bu27034_data * data,int chan,int sel)391 static int bu27034_write_gain_sel(struct bu27034_data *data, int chan, int sel)
392 {
393 static const int reg[] = {
394 [BU27034_CHAN_DATA0] = BU27034_REG_MODE_CONTROL2,
395 [BU27034_CHAN_DATA1] = BU27034_REG_MODE_CONTROL3,
396 };
397 int mask, val;
398
399 if (chan != BU27034_CHAN_DATA0 && chan != BU27034_CHAN_DATA1)
400 return -EINVAL;
401
402 val = FIELD_PREP(BU27034_MASK_D01_GAIN, sel);
403
404 mask = BU27034_MASK_D01_GAIN;
405
406 if (chan == BU27034_CHAN_DATA0) {
407 /*
408 * We keep the same gain for channel 2 as we set for channel 0
409 * We can't allow them to be individually controlled because
410 * setting one will impact also the other. Also, if we don't
411 * always update both gains we may result unsupported bit
412 * combinations.
413 *
414 * This is not nice but this is yet another place where the
415 * user space must be prepared to surprizes. Namely, see chan 2
416 * gain changed when chan 0 gain is changed.
417 *
418 * This is not fatal for most users though. I don't expect the
419 * channel 2 to be used in any generic cases - the intensity
420 * values provided by the sensor for IR area are not openly
421 * documented. Also, channel 2 is not used for visible light.
422 *
423 * So, if there is application which is written to utilize the
424 * channel 2 - then it is probably specifically targeted to this
425 * sensor and knows how to utilize those values. It is safe to
426 * hope such user can also cope with the gain changes.
427 */
428 mask |= BU27034_MASK_D2_GAIN_LO;
429
430 /*
431 * The D2 gain bits are directly the lowest bits of selector.
432 * Just do add those bits to the value
433 */
434 val |= sel & BU27034_MASK_D2_GAIN_LO;
435 }
436
437 return regmap_update_bits(data->regmap, reg[chan], mask, val);
438 }
439
bu27034_set_gain(struct bu27034_data * data,int chan,int gain)440 static int bu27034_set_gain(struct bu27034_data *data, int chan, int gain)
441 {
442 int ret;
443
444 /*
445 * We don't allow setting channel 2 gain as it messes up the
446 * gain for channel 0 - which shares the high bits
447 */
448 if (chan != BU27034_CHAN_DATA0 && chan != BU27034_CHAN_DATA1)
449 return -EINVAL;
450
451 ret = iio_gts_find_sel_by_gain(&data->gts, gain);
452 if (ret < 0)
453 return ret;
454
455 return bu27034_write_gain_sel(data, chan, ret);
456 }
457
458 /* Caller should hold the lock to protect data->int_time */
bu27034_set_int_time(struct bu27034_data * data,int time)459 static int bu27034_set_int_time(struct bu27034_data *data, int time)
460 {
461 int ret;
462
463 ret = iio_gts_find_sel_by_int_time(&data->gts, time);
464 if (ret < 0)
465 return ret;
466
467 return regmap_update_bits(data->regmap, BU27034_REG_MODE_CONTROL1,
468 BU27034_MASK_MEAS_MODE, ret);
469 }
470
471 /*
472 * We try to change the time in such way that the scale is maintained for
473 * given channels by adjusting gain so that it compensates the time change.
474 */
bu27034_try_set_int_time(struct bu27034_data * data,int time_us)475 static int bu27034_try_set_int_time(struct bu27034_data *data, int time_us)
476 {
477 struct bu27034_gain_check gains[] = {
478 { .chan = BU27034_CHAN_DATA0 },
479 { .chan = BU27034_CHAN_DATA1 },
480 };
481 int numg = ARRAY_SIZE(gains);
482 int ret, int_time_old, i;
483
484 mutex_lock(&data->mutex);
485 ret = bu27034_get_int_time(data);
486 if (ret < 0)
487 goto unlock_out;
488
489 int_time_old = ret;
490
491 if (!iio_gts_valid_time(&data->gts, time_us)) {
492 dev_err(data->dev, "Unsupported integration time %u\n",
493 time_us);
494 ret = -EINVAL;
495
496 goto unlock_out;
497 }
498
499 if (time_us == int_time_old) {
500 ret = 0;
501 goto unlock_out;
502 }
503
504 for (i = 0; i < numg; i++) {
505 ret = bu27034_get_gain(data, gains[i].chan, &gains[i].old_gain);
506 if (ret)
507 goto unlock_out;
508
509 ret = iio_gts_find_new_gain_by_old_gain_time(&data->gts,
510 gains[i].old_gain,
511 int_time_old, time_us,
512 &gains[i].new_gain);
513 if (ret) {
514 int scale1, scale2;
515 bool ok;
516
517 _bu27034_get_scale(data, gains[i].chan, &scale1, &scale2);
518 dev_dbg(data->dev,
519 "chan %u, can't support time %u with scale %u %u\n",
520 gains[i].chan, time_us, scale1, scale2);
521
522 if (gains[i].new_gain < 0)
523 goto unlock_out;
524
525 /*
526 * If caller requests for integration time change and we
527 * can't support the scale - then the caller should be
528 * prepared to 'pick up the pieces and deal with the
529 * fact that the scale changed'.
530 */
531 ret = iio_find_closest_gain_low(&data->gts,
532 gains[i].new_gain, &ok);
533
534 if (!ok)
535 dev_dbg(data->dev,
536 "optimal gain out of range for chan %u\n",
537 gains[i].chan);
538
539 if (ret < 0) {
540 dev_dbg(data->dev,
541 "Total gain increase. Risk of saturation");
542 ret = iio_gts_get_min_gain(&data->gts);
543 if (ret < 0)
544 goto unlock_out;
545 }
546 dev_dbg(data->dev, "chan %u scale changed\n",
547 gains[i].chan);
548 gains[i].new_gain = ret;
549 dev_dbg(data->dev, "chan %u new gain %u\n",
550 gains[i].chan, gains[i].new_gain);
551 }
552 }
553
554 for (i = 0; i < numg; i++) {
555 ret = bu27034_set_gain(data, gains[i].chan, gains[i].new_gain);
556 if (ret)
557 goto unlock_out;
558 }
559
560 ret = bu27034_set_int_time(data, time_us);
561
562 unlock_out:
563 mutex_unlock(&data->mutex);
564
565 return ret;
566 }
567
bu27034_set_scale(struct bu27034_data * data,int chan,int val,int val2)568 static int bu27034_set_scale(struct bu27034_data *data, int chan,
569 int val, int val2)
570 {
571 int ret, time_sel, gain_sel, i;
572 bool found = false;
573
574 if (chan == BU27034_CHAN_DATA2)
575 return -EINVAL;
576
577 if (chan == BU27034_CHAN_ALS) {
578 if (val == 0 && val2 == 1000000)
579 return 0;
580
581 return -EINVAL;
582 }
583
584 mutex_lock(&data->mutex);
585 ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &time_sel);
586 if (ret)
587 goto unlock_out;
588
589 ret = iio_gts_find_gain_sel_for_scale_using_time(&data->gts, time_sel,
590 val, val2, &gain_sel);
591 if (ret) {
592 /*
593 * Could not support scale with given time. Need to change time.
594 * We still want to maintain the scale for all channels
595 */
596 struct bu27034_gain_check gain;
597 int new_time_sel;
598
599 /*
600 * Populate information for the other channel which should also
601 * maintain the scale. (Due to the HW limitations the chan2
602 * gets the same gain as chan0, so we only need to explicitly
603 * set the chan 0 and 1).
604 */
605 if (chan == BU27034_CHAN_DATA0)
606 gain.chan = BU27034_CHAN_DATA1;
607 else if (chan == BU27034_CHAN_DATA1)
608 gain.chan = BU27034_CHAN_DATA0;
609
610 ret = bu27034_get_gain(data, gain.chan, &gain.old_gain);
611 if (ret)
612 goto unlock_out;
613
614 /*
615 * Iterate through all the times to see if we find one which
616 * can support requested scale for requested channel, while
617 * maintaining the scale for other channels
618 */
619 for (i = 0; i < data->gts.num_itime; i++) {
620 new_time_sel = data->gts.itime_table[i].sel;
621
622 if (new_time_sel == time_sel)
623 continue;
624
625 /* Can we provide requested scale with this time? */
626 ret = iio_gts_find_gain_sel_for_scale_using_time(
627 &data->gts, new_time_sel, val, val2,
628 &gain_sel);
629 if (ret)
630 continue;
631
632 /* Can the other channel(s) maintain scale? */
633 ret = iio_gts_find_new_gain_sel_by_old_gain_time(
634 &data->gts, gain.old_gain, time_sel,
635 new_time_sel, &gain.new_gain);
636 if (!ret) {
637 /* Yes - we found suitable time */
638 found = true;
639 break;
640 }
641 }
642 if (!found) {
643 dev_dbg(data->dev,
644 "Can't set scale maintaining other channels\n");
645 ret = -EINVAL;
646
647 goto unlock_out;
648 }
649
650 ret = bu27034_set_gain(data, gain.chan, gain.new_gain);
651 if (ret)
652 goto unlock_out;
653
654 ret = regmap_update_bits(data->regmap, BU27034_REG_MODE_CONTROL1,
655 BU27034_MASK_MEAS_MODE, new_time_sel);
656 if (ret)
657 goto unlock_out;
658 }
659
660 ret = bu27034_write_gain_sel(data, chan, gain_sel);
661 unlock_out:
662 mutex_unlock(&data->mutex);
663
664 return ret;
665 }
666
667 /*
668 * for (D1/D0 < 0.87):
669 * lx = 0.004521097 * D1 - 0.002663996 * D0 +
670 * 0.00012213 * D1 * D1 / D0
671 *
672 * => 115.7400832 * ch1 / gain1 / mt -
673 * 68.1982976 * ch0 / gain0 / mt +
674 * 0.00012213 * 25600 * (ch1 / gain1 / mt) * 25600 *
675 * (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)
676 *
677 * A = 0.00012213 * 25600 * (ch1 /gain1 / mt) * 25600 *
678 * (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt)
679 * => 0.00012213 * 25600 * (ch1 /gain1 / mt) *
680 * (ch1 /gain1 / mt) / (ch0 / gain0 / mt)
681 * => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) /
682 * (ch0 / gain0)
683 * => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) *
684 * gain0 / ch0
685 * => 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /ch0
686 *
687 * lx = (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /
688 * mt + A
689 * => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) /
690 * mt + 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /
691 * ch0
692 *
693 * => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0 +
694 * 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0) /
695 * mt
696 *
697 * For (0.87 <= D1/D0 < 1.00)
698 * lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 0.87) * (0.385) + 1)
699 * => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *
700 * 100 * ch1 / gain1 / mt) * ((D1/D0 - 0.87) * (0.385) + 1)
701 * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
702 * ((D1/D0 - 0.87) * (0.385) + 1)
703 * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
704 * (0.385 * D1/D0 - 0.66505)
705 * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
706 * (0.385 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) - 0.66505)
707 * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
708 * (9856 * ch1 / gain1 / mt / (25600 * ch0 / gain0 / mt) + 0.66505)
709 * => 13.118336 * ch1 / (gain1 * mt)
710 * + 22.66064768 * ch0 / (gain0 * mt)
711 * + 8931.90144 * ch1 * ch1 * gain0 /
712 * (25600 * ch0 * gain1 * gain1 * mt)
713 * + 0.602694912 * ch1 / (gain1 * mt)
714 *
715 * => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1)
716 * + 22.66064768 * ch0 / gain0
717 * + 13.721030912 * ch1 / gain1
718 * ] / mt
719 *
720 * For (D1/D0 >= 1.00)
721 *
722 * lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 2.0) * (-0.05) + 1)
723 * => (0.001331* D0 + 0.0000354 * D1) * (-0.05D1/D0 + 1.1)
724 * => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 *
725 * 100 * ch1 / gain1 / mt) * (-0.05D1/D0 + 1.1)
726 * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
727 * (-0.05 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) + 1.1)
728 * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) *
729 * (-1280 * ch1 / (gain1 * mt * 25600 * ch0 / gain0 / mt) + 1.1)
730 * => (34.0736 * ch0 * -1280 * ch1 * gain0 * mt /( gain0 * mt * gain1 * mt * 25600 * ch0)
731 * + 34.0736 * 1.1 * ch0 / (gain0 * mt)
732 * + 0.90624 * ch1 * -1280 * ch1 *gain0 * mt / (gain1 * mt *gain1 * mt * 25600 * ch0)
733 * + 1.1 * 0.90624 * ch1 / (gain1 * mt)
734 * => -43614.208 * ch1 / (gain1 * mt * 25600)
735 * + 37.48096 ch0 / (gain0 * mt)
736 * - 1159.9872 * ch1 * ch1 * gain0 / (gain1 * gain1 * mt * 25600 * ch0)
737 * + 0.996864 ch1 / (gain1 * mt)
738 * => [
739 * - 0.045312 * ch1 * ch1 * gain0 / (gain1 * gain1 * ch0)
740 * - 0.706816 * ch1 / gain1
741 * + 37.48096 ch0 /gain0
742 * ] * mt
743 *
744 *
745 * So, the first case (D1/D0 < 0.87) can be computed to a form:
746 *
747 * lx = (3.126528 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
748 * 115.7400832 * ch1 / gain1 +
749 * -68.1982976 * ch0 / gain0
750 * / mt
751 *
752 * Second case (0.87 <= D1/D0 < 1.00) goes to form:
753 *
754 * => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
755 * 13.721030912 * ch1 / gain1 +
756 * 22.66064768 * ch0 / gain0
757 * ] / mt
758 *
759 * Third case (D1/D0 >= 1.00) goes to form:
760 * => [-0.045312 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
761 * -0.706816 * ch1 / gain1 +
762 * 37.48096 ch0 /(gain0
763 * ] / mt
764 *
765 * This can be unified to format:
766 * lx = [
767 * A * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) +
768 * B * ch1 / gain1 +
769 * C * ch0 / gain0
770 * ] / mt
771 *
772 * For case 1:
773 * A = 3.126528,
774 * B = 115.7400832
775 * C = -68.1982976
776 *
777 * For case 2:
778 * A = 0.3489024
779 * B = 13.721030912
780 * C = 22.66064768
781 *
782 * For case 3:
783 * A = -0.045312
784 * B = -0.706816
785 * C = 37.48096
786 */
787
788 struct bu27034_lx_coeff {
789 unsigned int A;
790 unsigned int B;
791 unsigned int C;
792 /* Indicate which of the coefficients above are negative */
793 bool is_neg[3];
794 };
795
gain_mul_div_helper(u64 val,unsigned int gain,unsigned int div)796 static inline u64 gain_mul_div_helper(u64 val, unsigned int gain,
797 unsigned int div)
798 {
799 /*
800 * Max gain for a channel is 4096. The max u64 (0xffffffffffffffffULL)
801 * divided by 4096 is 0xFFFFFFFFFFFFF (GENMASK_ULL(51, 0)) (floored).
802 * Thus, the 0xFFFFFFFFFFFFF is the largest value we can safely multiply
803 * with the gain, no matter what gain is set.
804 *
805 * So, multiplication with max gain may overflow if val is greater than
806 * 0xFFFFFFFFFFFFF (52 bits set)..
807 *
808 * If this is the case we divide first.
809 */
810 if (val < GENMASK_ULL(51, 0)) {
811 val *= gain;
812 do_div(val, div);
813 } else {
814 do_div(val, div);
815 val *= gain;
816 }
817
818 return val;
819 }
820
bu27034_fixp_calc_t1_64bit(unsigned int coeff,unsigned int ch0,unsigned int ch1,unsigned int gain0,unsigned int gain1)821 static u64 bu27034_fixp_calc_t1_64bit(unsigned int coeff, unsigned int ch0,
822 unsigned int ch1, unsigned int gain0,
823 unsigned int gain1)
824 {
825 unsigned int helper;
826 u64 helper64;
827
828 helper64 = (u64)coeff * (u64)ch1 * (u64)ch1;
829
830 helper = gain1 * gain1;
831 if (helper > ch0) {
832 do_div(helper64, helper);
833
834 return gain_mul_div_helper(helper64, gain0, ch0);
835 }
836
837 do_div(helper64, ch0);
838
839 return gain_mul_div_helper(helper64, gain0, helper);
840
841 }
842
bu27034_fixp_calc_t1(unsigned int coeff,unsigned int ch0,unsigned int ch1,unsigned int gain0,unsigned int gain1)843 static u64 bu27034_fixp_calc_t1(unsigned int coeff, unsigned int ch0,
844 unsigned int ch1, unsigned int gain0,
845 unsigned int gain1)
846 {
847 unsigned int helper, tmp;
848
849 /*
850 * Here we could overflow even the 64bit value. Hence we
851 * multiply with gain0 only after the divisions - even though
852 * it may result loss of accuracy
853 */
854 helper = coeff * ch1 * ch1;
855 tmp = helper * gain0;
856
857 helper = ch1 * ch1;
858
859 if (check_mul_overflow(helper, coeff, &helper))
860 return bu27034_fixp_calc_t1_64bit(coeff, ch0, ch1, gain0, gain1);
861
862 if (check_mul_overflow(helper, gain0, &tmp))
863 return bu27034_fixp_calc_t1_64bit(coeff, ch0, ch1, gain0, gain1);
864
865 return tmp / (gain1 * gain1) / ch0;
866
867 }
868
bu27034_fixp_calc_t23(unsigned int coeff,unsigned int ch,unsigned int gain)869 static u64 bu27034_fixp_calc_t23(unsigned int coeff, unsigned int ch,
870 unsigned int gain)
871 {
872 unsigned int helper;
873 u64 helper64;
874
875 if (!check_mul_overflow(coeff, ch, &helper))
876 return helper / gain;
877
878 helper64 = (u64)coeff * (u64)ch;
879 do_div(helper64, gain);
880
881 return helper64;
882 }
883
bu27034_fixp_calc_lx(unsigned int ch0,unsigned int ch1,unsigned int gain0,unsigned int gain1,unsigned int meastime,int coeff_idx)884 static int bu27034_fixp_calc_lx(unsigned int ch0, unsigned int ch1,
885 unsigned int gain0, unsigned int gain1,
886 unsigned int meastime, int coeff_idx)
887 {
888 static const struct bu27034_lx_coeff coeff[] = {
889 {
890 .A = 31265280, /* 3.126528 */
891 .B = 1157400832, /*115.7400832 */
892 .C = 681982976, /* -68.1982976 */
893 .is_neg = {false, false, true},
894 }, {
895 .A = 3489024, /* 0.3489024 */
896 .B = 137210309, /* 13.721030912 */
897 .C = 226606476, /* 22.66064768 */
898 /* All terms positive */
899 }, {
900 .A = 453120, /* -0.045312 */
901 .B = 7068160, /* -0.706816 */
902 .C = 374809600, /* 37.48096 */
903 .is_neg = {true, true, false},
904 }
905 };
906 const struct bu27034_lx_coeff *c = &coeff[coeff_idx];
907 u64 res = 0, terms[3];
908 int i;
909
910 if (coeff_idx >= ARRAY_SIZE(coeff))
911 return -EINVAL;
912
913 terms[0] = bu27034_fixp_calc_t1(c->A, ch0, ch1, gain0, gain1);
914 terms[1] = bu27034_fixp_calc_t23(c->B, ch1, gain1);
915 terms[2] = bu27034_fixp_calc_t23(c->C, ch0, gain0);
916
917 /* First, add positive terms */
918 for (i = 0; i < 3; i++)
919 if (!c->is_neg[i])
920 res += terms[i];
921
922 /* No positive term => zero lux */
923 if (!res)
924 return 0;
925
926 /* Then, subtract negative terms (if any) */
927 for (i = 0; i < 3; i++)
928 if (c->is_neg[i]) {
929 /*
930 * If the negative term is greater than positive - then
931 * the darkness has taken over and we are all doomed! Eh,
932 * I mean, then we can just return 0 lx and go out
933 */
934 if (terms[i] >= res)
935 return 0;
936
937 res -= terms[i];
938 }
939
940 meastime *= 10;
941 do_div(res, meastime);
942
943 return (int) res;
944 }
945
bu27034_has_valid_sample(struct bu27034_data * data)946 static bool bu27034_has_valid_sample(struct bu27034_data *data)
947 {
948 int ret, val;
949
950 ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL4, &val);
951 if (ret) {
952 dev_err(data->dev, "Read failed %d\n", ret);
953
954 return false;
955 }
956
957 return val & BU27034_MASK_VALID;
958 }
959
960 /*
961 * Reading the register where VALID bit is clears this bit. (So does changing
962 * any gain / integration time configuration registers) The bit gets
963 * set when we have acquired new data. We use this bit to indicate data
964 * validity.
965 */
bu27034_invalidate_read_data(struct bu27034_data * data)966 static void bu27034_invalidate_read_data(struct bu27034_data *data)
967 {
968 bu27034_has_valid_sample(data);
969 }
970
bu27034_read_result(struct bu27034_data * data,int chan,int * res)971 static int bu27034_read_result(struct bu27034_data *data, int chan, int *res)
972 {
973 int reg[] = {
974 [BU27034_CHAN_DATA0] = BU27034_REG_DATA0_LO,
975 [BU27034_CHAN_DATA1] = BU27034_REG_DATA1_LO,
976 [BU27034_CHAN_DATA2] = BU27034_REG_DATA2_LO,
977 };
978 int valid, ret;
979 __le16 val;
980
981 ret = regmap_read_poll_timeout(data->regmap, BU27034_REG_MODE_CONTROL4,
982 valid, (valid & BU27034_MASK_VALID),
983 BU27034_DATA_WAIT_TIME_US, 0);
984 if (ret)
985 return ret;
986
987 ret = regmap_bulk_read(data->regmap, reg[chan], &val, sizeof(val));
988 if (ret)
989 return ret;
990
991 *res = le16_to_cpu(val);
992
993 return 0;
994 }
995
bu27034_get_result_unlocked(struct bu27034_data * data,__le16 * res,int size)996 static int bu27034_get_result_unlocked(struct bu27034_data *data, __le16 *res,
997 int size)
998 {
999 int ret = 0, retry_cnt = 0;
1000
1001 retry:
1002 /* Get new value from sensor if data is ready */
1003 if (bu27034_has_valid_sample(data)) {
1004 ret = regmap_bulk_read(data->regmap, BU27034_REG_DATA0_LO,
1005 res, size);
1006 if (ret)
1007 return ret;
1008
1009 bu27034_invalidate_read_data(data);
1010 } else {
1011 /* No new data in sensor. Wait and retry */
1012 retry_cnt++;
1013
1014 if (retry_cnt > BU27034_RETRY_LIMIT) {
1015 dev_err(data->dev, "No data from sensor\n");
1016
1017 return -ETIMEDOUT;
1018 }
1019
1020 msleep(25);
1021
1022 goto retry;
1023 }
1024
1025 return ret;
1026 }
1027
bu27034_meas_set(struct bu27034_data * data,bool en)1028 static int bu27034_meas_set(struct bu27034_data *data, bool en)
1029 {
1030 if (en)
1031 return regmap_set_bits(data->regmap, BU27034_REG_MODE_CONTROL4,
1032 BU27034_MASK_MEAS_EN);
1033
1034 return regmap_clear_bits(data->regmap, BU27034_REG_MODE_CONTROL4,
1035 BU27034_MASK_MEAS_EN);
1036 }
1037
bu27034_get_single_result(struct bu27034_data * data,int chan,int * val)1038 static int bu27034_get_single_result(struct bu27034_data *data, int chan,
1039 int *val)
1040 {
1041 int ret;
1042
1043 if (chan < BU27034_CHAN_DATA0 || chan > BU27034_CHAN_DATA2)
1044 return -EINVAL;
1045
1046 ret = bu27034_meas_set(data, true);
1047 if (ret)
1048 return ret;
1049
1050 ret = bu27034_get_int_time(data);
1051 if (ret < 0)
1052 return ret;
1053
1054 msleep(ret / 1000);
1055
1056 return bu27034_read_result(data, chan, val);
1057 }
1058
1059 /*
1060 * The formula given by vendor for computing luxes out of data0 and data1
1061 * (in open air) is as follows:
1062 *
1063 * Let's mark:
1064 * D0 = data0/ch0_gain/meas_time_ms * 25600
1065 * D1 = data1/ch1_gain/meas_time_ms * 25600
1066 *
1067 * Then:
1068 * if (D1/D0 < 0.87)
1069 * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 3.45 + 1)
1070 * else if (D1/D0 < 1)
1071 * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 0.385 + 1)
1072 * else
1073 * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 2) * -0.05 + 1)
1074 *
1075 * We use it here. Users who have for example some colored lens
1076 * need to modify the calculation but I hope this gives a starting point for
1077 * those working with such devices.
1078 */
1079
bu27034_calc_mlux(struct bu27034_data * data,__le16 * res,int * val)1080 static int bu27034_calc_mlux(struct bu27034_data *data, __le16 *res, int *val)
1081 {
1082 unsigned int gain0, gain1, meastime;
1083 unsigned int d1_d0_ratio_scaled;
1084 u16 ch0, ch1;
1085 u64 helper64;
1086 int ret;
1087
1088 /*
1089 * We return 0 lux if calculation fails. This should be reasonably
1090 * easy to spot from the buffers especially if raw-data channels show
1091 * valid values
1092 */
1093 *val = 0;
1094
1095 ch0 = max_t(u16, 1, le16_to_cpu(res[0]));
1096 ch1 = max_t(u16, 1, le16_to_cpu(res[1]));
1097
1098 ret = bu27034_get_gain(data, BU27034_CHAN_DATA0, &gain0);
1099 if (ret)
1100 return ret;
1101
1102 ret = bu27034_get_gain(data, BU27034_CHAN_DATA1, &gain1);
1103 if (ret)
1104 return ret;
1105
1106 ret = bu27034_get_int_time(data);
1107 if (ret < 0)
1108 return ret;
1109
1110 meastime = ret;
1111
1112 d1_d0_ratio_scaled = (unsigned int)ch1 * (unsigned int)gain0 * 100;
1113 helper64 = (u64)ch1 * (u64)gain0 * 100LLU;
1114
1115 if (helper64 != d1_d0_ratio_scaled) {
1116 unsigned int div = (unsigned int)ch0 * gain1;
1117
1118 do_div(helper64, div);
1119 d1_d0_ratio_scaled = helper64;
1120 } else {
1121 d1_d0_ratio_scaled /= ch0 * gain1;
1122 }
1123
1124 if (d1_d0_ratio_scaled < 87)
1125 ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 0);
1126 else if (d1_d0_ratio_scaled < 100)
1127 ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 1);
1128 else
1129 ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 2);
1130
1131 if (ret < 0)
1132 return ret;
1133
1134 *val = ret;
1135
1136 return 0;
1137
1138 }
1139
bu27034_get_mlux(struct bu27034_data * data,int chan,int * val)1140 static int bu27034_get_mlux(struct bu27034_data *data, int chan, int *val)
1141 {
1142 __le16 res[3];
1143 int ret;
1144
1145 ret = bu27034_meas_set(data, true);
1146 if (ret)
1147 return ret;
1148
1149 ret = bu27034_get_result_unlocked(data, &res[0], sizeof(res));
1150 if (ret)
1151 return ret;
1152
1153 ret = bu27034_calc_mlux(data, res, val);
1154 if (ret)
1155 return ret;
1156
1157 ret = bu27034_meas_set(data, false);
1158 if (ret)
1159 dev_err(data->dev, "failed to disable measurement\n");
1160
1161 return 0;
1162 }
1163
bu27034_read_raw(struct iio_dev * idev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)1164 static int bu27034_read_raw(struct iio_dev *idev,
1165 struct iio_chan_spec const *chan,
1166 int *val, int *val2, long mask)
1167 {
1168 struct bu27034_data *data = iio_priv(idev);
1169 int ret;
1170
1171 switch (mask) {
1172 case IIO_CHAN_INFO_INT_TIME:
1173 *val = 0;
1174 *val2 = bu27034_get_int_time(data);
1175 if (*val2 < 0)
1176 return *val2;
1177
1178 return IIO_VAL_INT_PLUS_MICRO;
1179
1180 case IIO_CHAN_INFO_SCALE:
1181 return bu27034_get_scale(data, chan->channel, val, val2);
1182
1183 case IIO_CHAN_INFO_RAW:
1184 {
1185 int (*result_get)(struct bu27034_data *data, int chan, int *val);
1186
1187 if (chan->type == IIO_INTENSITY)
1188 result_get = bu27034_get_single_result;
1189 else if (chan->type == IIO_LIGHT)
1190 result_get = bu27034_get_mlux;
1191 else
1192 return -EINVAL;
1193
1194 /* Don't mess with measurement enabling while buffering */
1195 ret = iio_device_claim_direct_mode(idev);
1196 if (ret)
1197 return ret;
1198
1199 mutex_lock(&data->mutex);
1200 /*
1201 * Reading one channel at a time is inefficient but we
1202 * don't care here. Buffered version should be used if
1203 * performance is an issue.
1204 */
1205 ret = result_get(data, chan->channel, val);
1206
1207 mutex_unlock(&data->mutex);
1208 iio_device_release_direct_mode(idev);
1209
1210 if (ret)
1211 return ret;
1212
1213 return IIO_VAL_INT;
1214 }
1215 default:
1216 return -EINVAL;
1217 }
1218 }
1219
bu27034_write_raw_get_fmt(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,long mask)1220 static int bu27034_write_raw_get_fmt(struct iio_dev *indio_dev,
1221 struct iio_chan_spec const *chan,
1222 long mask)
1223 {
1224
1225 switch (mask) {
1226 case IIO_CHAN_INFO_SCALE:
1227 return IIO_VAL_INT_PLUS_NANO;
1228 case IIO_CHAN_INFO_INT_TIME:
1229 return IIO_VAL_INT_PLUS_MICRO;
1230 default:
1231 return -EINVAL;
1232 }
1233 }
1234
bu27034_write_raw(struct iio_dev * idev,struct iio_chan_spec const * chan,int val,int val2,long mask)1235 static int bu27034_write_raw(struct iio_dev *idev,
1236 struct iio_chan_spec const *chan,
1237 int val, int val2, long mask)
1238 {
1239 struct bu27034_data *data = iio_priv(idev);
1240 int ret;
1241
1242 ret = iio_device_claim_direct_mode(idev);
1243 if (ret)
1244 return ret;
1245
1246 switch (mask) {
1247 case IIO_CHAN_INFO_SCALE:
1248 ret = bu27034_set_scale(data, chan->channel, val, val2);
1249 break;
1250 case IIO_CHAN_INFO_INT_TIME:
1251 if (!val)
1252 ret = bu27034_try_set_int_time(data, val2);
1253 else
1254 ret = -EINVAL;
1255 break;
1256 default:
1257 ret = -EINVAL;
1258 break;
1259 }
1260
1261 iio_device_release_direct_mode(idev);
1262
1263 return ret;
1264 }
1265
bu27034_read_avail(struct iio_dev * idev,struct iio_chan_spec const * chan,const int ** vals,int * type,int * length,long mask)1266 static int bu27034_read_avail(struct iio_dev *idev,
1267 struct iio_chan_spec const *chan, const int **vals,
1268 int *type, int *length, long mask)
1269 {
1270 struct bu27034_data *data = iio_priv(idev);
1271
1272 switch (mask) {
1273 case IIO_CHAN_INFO_INT_TIME:
1274 return iio_gts_avail_times(&data->gts, vals, type, length);
1275 case IIO_CHAN_INFO_SCALE:
1276 return iio_gts_all_avail_scales(&data->gts, vals, type, length);
1277 default:
1278 return -EINVAL;
1279 }
1280 }
1281
1282 static const struct iio_info bu27034_info = {
1283 .read_raw = &bu27034_read_raw,
1284 .write_raw = &bu27034_write_raw,
1285 .write_raw_get_fmt = &bu27034_write_raw_get_fmt,
1286 .read_avail = &bu27034_read_avail,
1287 };
1288
bu27034_chip_init(struct bu27034_data * data)1289 static int bu27034_chip_init(struct bu27034_data *data)
1290 {
1291 int ret, sel;
1292
1293 /* Reset */
1294 ret = regmap_write_bits(data->regmap, BU27034_REG_SYSTEM_CONTROL,
1295 BU27034_MASK_SW_RESET, BU27034_MASK_SW_RESET);
1296 if (ret)
1297 return dev_err_probe(data->dev, ret, "Sensor reset failed\n");
1298
1299 msleep(1);
1300
1301 ret = regmap_reinit_cache(data->regmap, &bu27034_regmap);
1302 if (ret) {
1303 dev_err(data->dev, "Failed to reinit reg cache\n");
1304 return ret;
1305 }
1306
1307 /*
1308 * Read integration time here to ensure it is in regmap cache. We do
1309 * this to speed-up the int-time acquisition in the start of the buffer
1310 * handling thread where longer delays could make it more likely we end
1311 * up skipping a sample, and where the longer delays make timestamps
1312 * less accurate.
1313 */
1314 ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &sel);
1315 if (ret)
1316 dev_err(data->dev, "reading integration time failed\n");
1317
1318 return 0;
1319 }
1320
bu27034_wait_for_data(struct bu27034_data * data)1321 static int bu27034_wait_for_data(struct bu27034_data *data)
1322 {
1323 int ret, val;
1324
1325 ret = regmap_read_poll_timeout(data->regmap, BU27034_REG_MODE_CONTROL4,
1326 val, val & BU27034_MASK_VALID,
1327 BU27034_DATA_WAIT_TIME_US,
1328 BU27034_TOTAL_DATA_WAIT_TIME_US);
1329 if (ret) {
1330 dev_err(data->dev, "data polling %s\n",
1331 !(val & BU27034_MASK_VALID) ? "timeout" : "fail");
1332
1333 return ret;
1334 }
1335
1336 ret = regmap_bulk_read(data->regmap, BU27034_REG_DATA0_LO,
1337 &data->scan.channels[0],
1338 sizeof(data->scan.channels));
1339 if (ret)
1340 return ret;
1341
1342 bu27034_invalidate_read_data(data);
1343
1344 return 0;
1345 }
1346
bu27034_buffer_thread(void * arg)1347 static int bu27034_buffer_thread(void *arg)
1348 {
1349 struct iio_dev *idev = arg;
1350 struct bu27034_data *data;
1351 int wait_ms;
1352
1353 data = iio_priv(idev);
1354
1355 wait_ms = bu27034_get_int_time(data);
1356 wait_ms /= 1000;
1357
1358 wait_ms -= BU27034_MEAS_WAIT_PREMATURE_MS;
1359
1360 while (!kthread_should_stop()) {
1361 int ret;
1362 int64_t tstamp;
1363
1364 msleep(wait_ms);
1365 ret = bu27034_wait_for_data(data);
1366 if (ret)
1367 continue;
1368
1369 tstamp = iio_get_time_ns(idev);
1370
1371 if (test_bit(BU27034_CHAN_ALS, idev->active_scan_mask)) {
1372 int mlux;
1373
1374 ret = bu27034_calc_mlux(data, &data->scan.channels[0],
1375 &mlux);
1376 if (ret)
1377 dev_err(data->dev, "failed to calculate lux\n");
1378
1379 /*
1380 * The maximum Milli lux value we get with gain 1x time
1381 * 55mS data ch0 = 0xffff ch1 = 0xffff fits in 26 bits
1382 * so there should be no problem returning int from
1383 * computations and casting it to u32
1384 */
1385 data->scan.mlux = (u32)mlux;
1386 }
1387 iio_push_to_buffers_with_timestamp(idev, &data->scan, tstamp);
1388 }
1389
1390 return 0;
1391 }
1392
bu27034_buffer_enable(struct iio_dev * idev)1393 static int bu27034_buffer_enable(struct iio_dev *idev)
1394 {
1395 struct bu27034_data *data = iio_priv(idev);
1396 struct task_struct *task;
1397 int ret;
1398
1399 mutex_lock(&data->mutex);
1400 ret = bu27034_meas_set(data, true);
1401 if (ret)
1402 goto unlock_out;
1403
1404 task = kthread_run(bu27034_buffer_thread, idev,
1405 "bu27034-buffering-%u",
1406 iio_device_id(idev));
1407 if (IS_ERR(task)) {
1408 ret = PTR_ERR(task);
1409 goto unlock_out;
1410 }
1411
1412 data->task = task;
1413
1414 unlock_out:
1415 mutex_unlock(&data->mutex);
1416
1417 return ret;
1418 }
1419
bu27034_buffer_disable(struct iio_dev * idev)1420 static int bu27034_buffer_disable(struct iio_dev *idev)
1421 {
1422 struct bu27034_data *data = iio_priv(idev);
1423 int ret;
1424
1425 mutex_lock(&data->mutex);
1426 if (data->task) {
1427 kthread_stop(data->task);
1428 data->task = NULL;
1429 }
1430
1431 ret = bu27034_meas_set(data, false);
1432 mutex_unlock(&data->mutex);
1433
1434 return ret;
1435 }
1436
1437 static const struct iio_buffer_setup_ops bu27034_buffer_ops = {
1438 .postenable = &bu27034_buffer_enable,
1439 .predisable = &bu27034_buffer_disable,
1440 };
1441
bu27034_probe(struct i2c_client * i2c)1442 static int bu27034_probe(struct i2c_client *i2c)
1443 {
1444 struct device *dev = &i2c->dev;
1445 struct bu27034_data *data;
1446 struct regmap *regmap;
1447 struct iio_dev *idev;
1448 unsigned int part_id, reg;
1449 int ret;
1450
1451 regmap = devm_regmap_init_i2c(i2c, &bu27034_regmap);
1452 if (IS_ERR(regmap))
1453 return dev_err_probe(dev, PTR_ERR(regmap),
1454 "Failed to initialize Regmap\n");
1455
1456 idev = devm_iio_device_alloc(dev, sizeof(*data));
1457 if (!idev)
1458 return -ENOMEM;
1459
1460 ret = devm_regulator_get_enable(dev, "vdd");
1461 if (ret)
1462 return dev_err_probe(dev, ret, "Failed to get regulator\n");
1463
1464 data = iio_priv(idev);
1465
1466 ret = regmap_read(regmap, BU27034_REG_SYSTEM_CONTROL, ®);
1467 if (ret)
1468 return dev_err_probe(dev, ret, "Failed to access sensor\n");
1469
1470 part_id = FIELD_GET(BU27034_MASK_PART_ID, reg);
1471
1472 if (part_id != BU27034_ID)
1473 dev_warn(dev, "unknown device 0x%x\n", part_id);
1474
1475 ret = devm_iio_init_iio_gts(dev, BU27034_SCALE_1X, 0, bu27034_gains,
1476 ARRAY_SIZE(bu27034_gains), bu27034_itimes,
1477 ARRAY_SIZE(bu27034_itimes), &data->gts);
1478 if (ret)
1479 return ret;
1480
1481 mutex_init(&data->mutex);
1482 data->regmap = regmap;
1483 data->dev = dev;
1484
1485 idev->channels = bu27034_channels;
1486 idev->num_channels = ARRAY_SIZE(bu27034_channels);
1487 idev->name = "bu27034";
1488 idev->info = &bu27034_info;
1489
1490 idev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
1491 idev->available_scan_masks = bu27034_scan_masks;
1492
1493 ret = bu27034_chip_init(data);
1494 if (ret)
1495 return ret;
1496
1497 ret = devm_iio_kfifo_buffer_setup(dev, idev, &bu27034_buffer_ops);
1498 if (ret)
1499 return dev_err_probe(dev, ret, "buffer setup failed\n");
1500
1501 ret = devm_iio_device_register(dev, idev);
1502 if (ret < 0)
1503 return dev_err_probe(dev, ret,
1504 "Unable to register iio device\n");
1505
1506 return ret;
1507 }
1508
1509 static const struct of_device_id bu27034_of_match[] = {
1510 { .compatible = "rohm,bu27034" },
1511 { }
1512 };
1513 MODULE_DEVICE_TABLE(of, bu27034_of_match);
1514
1515 static struct i2c_driver bu27034_i2c_driver = {
1516 .driver = {
1517 .name = "bu27034-als",
1518 .of_match_table = bu27034_of_match,
1519 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
1520 },
1521 .probe = bu27034_probe,
1522 };
1523 module_i2c_driver(bu27034_i2c_driver);
1524
1525 MODULE_LICENSE("GPL");
1526 MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
1527 MODULE_DESCRIPTION("ROHM BU27034 ambient light sensor driver");
1528 MODULE_IMPORT_NS(IIO_GTS_HELPER);
1529