1 /*
2  * STMicroelectronics st_lsm6dsx FIFO buffer library driver
3  *
4  * LSM6DS3/LSM6DS3H/LSM6DSL/LSM6DSM/ISM330DLC: The FIFO buffer can be
5  * configured to store data from gyroscope and accelerometer. Samples are
6  * queued without any tag according to a specific pattern based on
7  * 'FIFO data sets' (6 bytes each):
8  *  - 1st data set is reserved for gyroscope data
9  *  - 2nd data set is reserved for accelerometer data
10  * The FIFO pattern changes depending on the ODRs and decimation factors
11  * assigned to the FIFO data sets. The first sequence of data stored in FIFO
12  * buffer contains the data of all the enabled FIFO data sets
13  * (e.g. Gx, Gy, Gz, Ax, Ay, Az), then data are repeated depending on the
14  * value of the decimation factor and ODR set for each FIFO data set.
15  *
16  * LSM6DSO: The FIFO buffer can be configured to store data from gyroscope and
17  * accelerometer. Each sample is queued with a tag (1B) indicating data source
18  * (gyroscope, accelerometer, hw timer).
19  *
20  * FIFO supported modes:
21  *  - BYPASS: FIFO disabled
22  *  - CONTINUOUS: FIFO enabled. When the buffer is full, the FIFO index
23  *    restarts from the beginning and the oldest sample is overwritten
24  *
25  * Copyright 2016 STMicroelectronics Inc.
26  *
27  * Lorenzo Bianconi <lorenzo.bianconi@st.com>
28  * Denis Ciocca <denis.ciocca@st.com>
29  *
30  * Licensed under the GPL-2.
31  */
32 #include <linux/module.h>
33 #include <linux/interrupt.h>
34 #include <linux/irq.h>
35 #include <linux/iio/kfifo_buf.h>
36 #include <linux/iio/iio.h>
37 #include <linux/iio/buffer.h>
38 #include <linux/regmap.h>
39 #include <linux/bitfield.h>
40 
41 #include <linux/platform_data/st_sensors_pdata.h>
42 
43 #include "st_lsm6dsx.h"
44 
45 #define ST_LSM6DSX_REG_HLACTIVE_ADDR		0x12
46 #define ST_LSM6DSX_REG_HLACTIVE_MASK		BIT(5)
47 #define ST_LSM6DSX_REG_PP_OD_ADDR		0x12
48 #define ST_LSM6DSX_REG_PP_OD_MASK		BIT(4)
49 #define ST_LSM6DSX_REG_FIFO_MODE_ADDR		0x0a
50 #define ST_LSM6DSX_FIFO_MODE_MASK		GENMASK(2, 0)
51 #define ST_LSM6DSX_FIFO_ODR_MASK		GENMASK(6, 3)
52 #define ST_LSM6DSX_FIFO_EMPTY_MASK		BIT(12)
53 #define ST_LSM6DSX_REG_FIFO_OUTL_ADDR		0x3e
54 #define ST_LSM6DSX_REG_FIFO_OUT_TAG_ADDR	0x78
55 #define ST_LSM6DSX_REG_TS_RESET_ADDR		0x42
56 
57 #define ST_LSM6DSX_MAX_FIFO_ODR_VAL		0x08
58 
59 #define ST_LSM6DSX_TS_SENSITIVITY		25000UL /* 25us */
60 #define ST_LSM6DSX_TS_RESET_VAL			0xaa
61 
62 struct st_lsm6dsx_decimator_entry {
63 	u8 decimator;
64 	u8 val;
65 };
66 
67 enum st_lsm6dsx_fifo_tag {
68 	ST_LSM6DSX_GYRO_TAG = 0x01,
69 	ST_LSM6DSX_ACC_TAG = 0x02,
70 	ST_LSM6DSX_TS_TAG = 0x04,
71 	ST_LSM6DSX_EXT0_TAG = 0x0f,
72 	ST_LSM6DSX_EXT1_TAG = 0x10,
73 	ST_LSM6DSX_EXT2_TAG = 0x11,
74 };
75 
76 static const
77 struct st_lsm6dsx_decimator_entry st_lsm6dsx_decimator_table[] = {
78 	{  0, 0x0 },
79 	{  1, 0x1 },
80 	{  2, 0x2 },
81 	{  3, 0x3 },
82 	{  4, 0x4 },
83 	{  8, 0x5 },
84 	{ 16, 0x6 },
85 	{ 32, 0x7 },
86 };
87 
88 static int st_lsm6dsx_get_decimator_val(u8 val)
89 {
90 	const int max_size = ARRAY_SIZE(st_lsm6dsx_decimator_table);
91 	int i;
92 
93 	for (i = 0; i < max_size; i++)
94 		if (st_lsm6dsx_decimator_table[i].decimator == val)
95 			break;
96 
97 	return i == max_size ? 0 : st_lsm6dsx_decimator_table[i].val;
98 }
99 
100 static void st_lsm6dsx_get_max_min_odr(struct st_lsm6dsx_hw *hw,
101 				       u16 *max_odr, u16 *min_odr)
102 {
103 	struct st_lsm6dsx_sensor *sensor;
104 	int i;
105 
106 	*max_odr = 0, *min_odr = ~0;
107 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
108 		if (!hw->iio_devs[i])
109 			continue;
110 
111 		sensor = iio_priv(hw->iio_devs[i]);
112 
113 		if (!(hw->enable_mask & BIT(sensor->id)))
114 			continue;
115 
116 		*max_odr = max_t(u16, *max_odr, sensor->odr);
117 		*min_odr = min_t(u16, *min_odr, sensor->odr);
118 	}
119 }
120 
121 static int st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw *hw)
122 {
123 	u16 max_odr, min_odr, sip = 0, ts_sip = 0;
124 	const struct st_lsm6dsx_reg *ts_dec_reg;
125 	struct st_lsm6dsx_sensor *sensor;
126 	int err = 0, i;
127 	u8 data;
128 
129 	st_lsm6dsx_get_max_min_odr(hw, &max_odr, &min_odr);
130 
131 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
132 		const struct st_lsm6dsx_reg *dec_reg;
133 
134 		if (!hw->iio_devs[i])
135 			continue;
136 
137 		sensor = iio_priv(hw->iio_devs[i]);
138 		/* update fifo decimators and sample in pattern */
139 		if (hw->enable_mask & BIT(sensor->id)) {
140 			sensor->sip = sensor->odr / min_odr;
141 			sensor->decimator = max_odr / sensor->odr;
142 			data = st_lsm6dsx_get_decimator_val(sensor->decimator);
143 		} else {
144 			sensor->sip = 0;
145 			sensor->decimator = 0;
146 			data = 0;
147 		}
148 		ts_sip = max_t(u16, ts_sip, sensor->sip);
149 
150 		dec_reg = &hw->settings->decimator[sensor->id];
151 		if (dec_reg->addr) {
152 			int val = ST_LSM6DSX_SHIFT_VAL(data, dec_reg->mask);
153 
154 			err = st_lsm6dsx_update_bits_locked(hw, dec_reg->addr,
155 							    dec_reg->mask,
156 							    val);
157 			if (err < 0)
158 				return err;
159 		}
160 		sip += sensor->sip;
161 	}
162 	hw->sip = sip + ts_sip;
163 	hw->ts_sip = ts_sip;
164 
165 	/*
166 	 * update hw ts decimator if necessary. Decimator for hw timestamp
167 	 * is always 1 or 0 in order to have a ts sample for each data
168 	 * sample in FIFO
169 	 */
170 	ts_dec_reg = &hw->settings->ts_settings.decimator;
171 	if (ts_dec_reg->addr) {
172 		int val, ts_dec = !!hw->ts_sip;
173 
174 		val = ST_LSM6DSX_SHIFT_VAL(ts_dec, ts_dec_reg->mask);
175 		err = st_lsm6dsx_update_bits_locked(hw, ts_dec_reg->addr,
176 						    ts_dec_reg->mask, val);
177 	}
178 	return err;
179 }
180 
181 int st_lsm6dsx_set_fifo_mode(struct st_lsm6dsx_hw *hw,
182 			     enum st_lsm6dsx_fifo_mode fifo_mode)
183 {
184 	unsigned int data;
185 	int err;
186 
187 	data = FIELD_PREP(ST_LSM6DSX_FIFO_MODE_MASK, fifo_mode);
188 	err = st_lsm6dsx_update_bits_locked(hw, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
189 					    ST_LSM6DSX_FIFO_MODE_MASK, data);
190 	if (err < 0)
191 		return err;
192 
193 	hw->fifo_mode = fifo_mode;
194 
195 	return 0;
196 }
197 
198 static int st_lsm6dsx_set_fifo_odr(struct st_lsm6dsx_sensor *sensor,
199 				   bool enable)
200 {
201 	struct st_lsm6dsx_hw *hw = sensor->hw;
202 	const struct st_lsm6dsx_reg *batch_reg;
203 	u8 data;
204 
205 	batch_reg = &hw->settings->batch[sensor->id];
206 	if (batch_reg->addr) {
207 		int val;
208 
209 		if (enable) {
210 			int err;
211 
212 			err = st_lsm6dsx_check_odr(sensor, sensor->odr,
213 						   &data);
214 			if (err < 0)
215 				return err;
216 		} else {
217 			data = 0;
218 		}
219 		val = ST_LSM6DSX_SHIFT_VAL(data, batch_reg->mask);
220 		return st_lsm6dsx_update_bits_locked(hw, batch_reg->addr,
221 						     batch_reg->mask, val);
222 	} else {
223 		data = hw->enable_mask ? ST_LSM6DSX_MAX_FIFO_ODR_VAL : 0;
224 		return st_lsm6dsx_update_bits_locked(hw,
225 					ST_LSM6DSX_REG_FIFO_MODE_ADDR,
226 					ST_LSM6DSX_FIFO_ODR_MASK,
227 					FIELD_PREP(ST_LSM6DSX_FIFO_ODR_MASK,
228 						   data));
229 	}
230 }
231 
232 int st_lsm6dsx_update_watermark(struct st_lsm6dsx_sensor *sensor, u16 watermark)
233 {
234 	u16 fifo_watermark = ~0, cur_watermark, fifo_th_mask;
235 	struct st_lsm6dsx_hw *hw = sensor->hw;
236 	struct st_lsm6dsx_sensor *cur_sensor;
237 	int i, err, data;
238 	__le16 wdata;
239 
240 	if (!hw->sip)
241 		return 0;
242 
243 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
244 		if (!hw->iio_devs[i])
245 			continue;
246 
247 		cur_sensor = iio_priv(hw->iio_devs[i]);
248 
249 		if (!(hw->enable_mask & BIT(cur_sensor->id)))
250 			continue;
251 
252 		cur_watermark = (cur_sensor == sensor) ? watermark
253 						       : cur_sensor->watermark;
254 
255 		fifo_watermark = min_t(u16, fifo_watermark, cur_watermark);
256 	}
257 
258 	fifo_watermark = max_t(u16, fifo_watermark, hw->sip);
259 	fifo_watermark = (fifo_watermark / hw->sip) * hw->sip;
260 	fifo_watermark = fifo_watermark * hw->settings->fifo_ops.th_wl;
261 
262 	mutex_lock(&hw->page_lock);
263 	err = regmap_read(hw->regmap, hw->settings->fifo_ops.fifo_th.addr + 1,
264 			  &data);
265 	if (err < 0)
266 		goto out;
267 
268 	fifo_th_mask = hw->settings->fifo_ops.fifo_th.mask;
269 	fifo_watermark = ((data << 8) & ~fifo_th_mask) |
270 			 (fifo_watermark & fifo_th_mask);
271 
272 	wdata = cpu_to_le16(fifo_watermark);
273 	err = regmap_bulk_write(hw->regmap,
274 				hw->settings->fifo_ops.fifo_th.addr,
275 				&wdata, sizeof(wdata));
276 out:
277 	mutex_unlock(&hw->page_lock);
278 	return err;
279 }
280 
281 static int st_lsm6dsx_reset_hw_ts(struct st_lsm6dsx_hw *hw)
282 {
283 	struct st_lsm6dsx_sensor *sensor;
284 	int i, err;
285 
286 	/* reset hw ts counter */
287 	err = st_lsm6dsx_write_locked(hw, ST_LSM6DSX_REG_TS_RESET_ADDR,
288 				      ST_LSM6DSX_TS_RESET_VAL);
289 	if (err < 0)
290 		return err;
291 
292 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
293 		if (!hw->iio_devs[i])
294 			continue;
295 
296 		sensor = iio_priv(hw->iio_devs[i]);
297 		/*
298 		 * store enable buffer timestamp as reference for
299 		 * hw timestamp
300 		 */
301 		sensor->ts_ref = iio_get_time_ns(hw->iio_devs[i]);
302 	}
303 	return 0;
304 }
305 
306 /*
307  * Set max bulk read to ST_LSM6DSX_MAX_WORD_LEN/ST_LSM6DSX_MAX_TAGGED_WORD_LEN
308  * in order to avoid a kmalloc for each bus access
309  */
310 static inline int st_lsm6dsx_read_block(struct st_lsm6dsx_hw *hw, u8 addr,
311 					u8 *data, unsigned int data_len,
312 					unsigned int max_word_len)
313 {
314 	unsigned int word_len, read_len = 0;
315 	int err;
316 
317 	while (read_len < data_len) {
318 		word_len = min_t(unsigned int, data_len - read_len,
319 				 max_word_len);
320 		err = st_lsm6dsx_read_locked(hw, addr, data + read_len,
321 					     word_len);
322 		if (err < 0)
323 			return err;
324 		read_len += word_len;
325 	}
326 	return 0;
327 }
328 
329 #define ST_LSM6DSX_IIO_BUFF_SIZE	(ALIGN(ST_LSM6DSX_SAMPLE_SIZE, \
330 					       sizeof(s64)) + sizeof(s64))
331 /**
332  * st_lsm6dsx_read_fifo() - hw FIFO read routine
333  * @hw: Pointer to instance of struct st_lsm6dsx_hw.
334  *
335  * Read samples from the hw FIFO and push them to IIO buffers.
336  *
337  * Return: Number of bytes read from the FIFO
338  */
339 int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
340 {
341 	u16 fifo_len, pattern_len = hw->sip * ST_LSM6DSX_SAMPLE_SIZE;
342 	u16 fifo_diff_mask = hw->settings->fifo_ops.fifo_diff.mask;
343 	int err, acc_sip, gyro_sip, ts_sip, read_len, offset;
344 	struct st_lsm6dsx_sensor *acc_sensor, *gyro_sensor;
345 	u8 gyro_buff[ST_LSM6DSX_IIO_BUFF_SIZE];
346 	u8 acc_buff[ST_LSM6DSX_IIO_BUFF_SIZE];
347 	bool reset_ts = false;
348 	__le16 fifo_status;
349 	s64 ts = 0;
350 
351 	err = st_lsm6dsx_read_locked(hw,
352 				     hw->settings->fifo_ops.fifo_diff.addr,
353 				     &fifo_status, sizeof(fifo_status));
354 	if (err < 0) {
355 		dev_err(hw->dev, "failed to read fifo status (err=%d)\n",
356 			err);
357 		return err;
358 	}
359 
360 	if (fifo_status & cpu_to_le16(ST_LSM6DSX_FIFO_EMPTY_MASK))
361 		return 0;
362 
363 	fifo_len = (le16_to_cpu(fifo_status) & fifo_diff_mask) *
364 		   ST_LSM6DSX_CHAN_SIZE;
365 	fifo_len = (fifo_len / pattern_len) * pattern_len;
366 
367 	acc_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
368 	gyro_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_GYRO]);
369 
370 	for (read_len = 0; read_len < fifo_len; read_len += pattern_len) {
371 		err = st_lsm6dsx_read_block(hw, ST_LSM6DSX_REG_FIFO_OUTL_ADDR,
372 					    hw->buff, pattern_len,
373 					    ST_LSM6DSX_MAX_WORD_LEN);
374 		if (err < 0) {
375 			dev_err(hw->dev,
376 				"failed to read pattern from fifo (err=%d)\n",
377 				err);
378 			return err;
379 		}
380 
381 		/*
382 		 * Data are written to the FIFO with a specific pattern
383 		 * depending on the configured ODRs. The first sequence of data
384 		 * stored in FIFO contains the data of all enabled sensors
385 		 * (e.g. Gx, Gy, Gz, Ax, Ay, Az, Ts), then data are repeated
386 		 * depending on the value of the decimation factor set for each
387 		 * sensor.
388 		 *
389 		 * Supposing the FIFO is storing data from gyroscope and
390 		 * accelerometer at different ODRs:
391 		 *   - gyroscope ODR = 208Hz, accelerometer ODR = 104Hz
392 		 * Since the gyroscope ODR is twice the accelerometer one, the
393 		 * following pattern is repeated every 9 samples:
394 		 *   - Gx, Gy, Gz, Ax, Ay, Az, Ts, Gx, Gy, Gz, Ts, Gx, ..
395 		 */
396 		gyro_sip = gyro_sensor->sip;
397 		acc_sip = acc_sensor->sip;
398 		ts_sip = hw->ts_sip;
399 		offset = 0;
400 
401 		while (acc_sip > 0 || gyro_sip > 0) {
402 			if (gyro_sip > 0) {
403 				memcpy(gyro_buff, &hw->buff[offset],
404 				       ST_LSM6DSX_SAMPLE_SIZE);
405 				offset += ST_LSM6DSX_SAMPLE_SIZE;
406 			}
407 			if (acc_sip > 0) {
408 				memcpy(acc_buff, &hw->buff[offset],
409 				       ST_LSM6DSX_SAMPLE_SIZE);
410 				offset += ST_LSM6DSX_SAMPLE_SIZE;
411 			}
412 
413 			if (ts_sip-- > 0) {
414 				u8 data[ST_LSM6DSX_SAMPLE_SIZE];
415 
416 				memcpy(data, &hw->buff[offset], sizeof(data));
417 				/*
418 				 * hw timestamp is 3B long and it is stored
419 				 * in FIFO using 6B as 4th FIFO data set
420 				 * according to this schema:
421 				 * B0 = ts[15:8], B1 = ts[23:16], B3 = ts[7:0]
422 				 */
423 				ts = data[1] << 16 | data[0] << 8 | data[3];
424 				/*
425 				 * check if hw timestamp engine is going to
426 				 * reset (the sensor generates an interrupt
427 				 * to signal the hw timestamp will reset in
428 				 * 1.638s)
429 				 */
430 				if (!reset_ts && ts >= 0xff0000)
431 					reset_ts = true;
432 				ts *= ST_LSM6DSX_TS_SENSITIVITY;
433 
434 				offset += ST_LSM6DSX_SAMPLE_SIZE;
435 			}
436 
437 			if (gyro_sip-- > 0)
438 				iio_push_to_buffers_with_timestamp(
439 					hw->iio_devs[ST_LSM6DSX_ID_GYRO],
440 					gyro_buff, gyro_sensor->ts_ref + ts);
441 			if (acc_sip-- > 0)
442 				iio_push_to_buffers_with_timestamp(
443 					hw->iio_devs[ST_LSM6DSX_ID_ACC],
444 					acc_buff, acc_sensor->ts_ref + ts);
445 		}
446 	}
447 
448 	if (unlikely(reset_ts)) {
449 		err = st_lsm6dsx_reset_hw_ts(hw);
450 		if (err < 0) {
451 			dev_err(hw->dev, "failed to reset hw ts (err=%d)\n",
452 				err);
453 			return err;
454 		}
455 	}
456 	return read_len;
457 }
458 
459 static int
460 st_lsm6dsx_push_tagged_data(struct st_lsm6dsx_hw *hw, u8 tag,
461 			    u8 *data, s64 ts)
462 {
463 	struct st_lsm6dsx_sensor *sensor;
464 	struct iio_dev *iio_dev;
465 
466 	/*
467 	 * EXT_TAG are managed in FIFO fashion so ST_LSM6DSX_EXT0_TAG
468 	 * corresponds to the first enabled channel, ST_LSM6DSX_EXT1_TAG
469 	 * to the second one and ST_LSM6DSX_EXT2_TAG to the last enabled
470 	 * channel
471 	 */
472 	switch (tag) {
473 	case ST_LSM6DSX_GYRO_TAG:
474 		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_GYRO];
475 		break;
476 	case ST_LSM6DSX_ACC_TAG:
477 		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_ACC];
478 		break;
479 	case ST_LSM6DSX_EXT0_TAG:
480 		if (hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT0))
481 			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT0];
482 		else if (hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT1))
483 			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT1];
484 		else
485 			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT2];
486 		break;
487 	case ST_LSM6DSX_EXT1_TAG:
488 		if ((hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT0)) &&
489 		    (hw->enable_mask & BIT(ST_LSM6DSX_ID_EXT1)))
490 			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT1];
491 		else
492 			iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT2];
493 		break;
494 	case ST_LSM6DSX_EXT2_TAG:
495 		iio_dev = hw->iio_devs[ST_LSM6DSX_ID_EXT2];
496 		break;
497 	default:
498 		return -EINVAL;
499 	}
500 
501 	sensor = iio_priv(iio_dev);
502 	iio_push_to_buffers_with_timestamp(iio_dev, data,
503 					   ts + sensor->ts_ref);
504 
505 	return 0;
506 }
507 
508 /**
509  * st_lsm6dsx_read_tagged_fifo() - LSM6DSO read FIFO routine
510  * @hw: Pointer to instance of struct st_lsm6dsx_hw.
511  *
512  * Read samples from the hw FIFO and push them to IIO buffers.
513  *
514  * Return: Number of bytes read from the FIFO
515  */
516 int st_lsm6dsx_read_tagged_fifo(struct st_lsm6dsx_hw *hw)
517 {
518 	u16 pattern_len = hw->sip * ST_LSM6DSX_TAGGED_SAMPLE_SIZE;
519 	u16 fifo_len, fifo_diff_mask;
520 	struct st_lsm6dsx_sensor *acc_sensor, *gyro_sensor;
521 	u8 iio_buff[ST_LSM6DSX_IIO_BUFF_SIZE], tag;
522 	bool reset_ts = false;
523 	int i, err, read_len;
524 	__le16 fifo_status;
525 	s64 ts = 0;
526 
527 	err = st_lsm6dsx_read_locked(hw,
528 				     hw->settings->fifo_ops.fifo_diff.addr,
529 				     &fifo_status, sizeof(fifo_status));
530 	if (err < 0) {
531 		dev_err(hw->dev, "failed to read fifo status (err=%d)\n",
532 			err);
533 		return err;
534 	}
535 
536 	fifo_diff_mask = hw->settings->fifo_ops.fifo_diff.mask;
537 	fifo_len = (le16_to_cpu(fifo_status) & fifo_diff_mask) *
538 		   ST_LSM6DSX_TAGGED_SAMPLE_SIZE;
539 	if (!fifo_len)
540 		return 0;
541 
542 	acc_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
543 	gyro_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_GYRO]);
544 
545 	for (read_len = 0; read_len < fifo_len; read_len += pattern_len) {
546 		err = st_lsm6dsx_read_block(hw,
547 					    ST_LSM6DSX_REG_FIFO_OUT_TAG_ADDR,
548 					    hw->buff, pattern_len,
549 					    ST_LSM6DSX_MAX_TAGGED_WORD_LEN);
550 		if (err < 0) {
551 			dev_err(hw->dev,
552 				"failed to read pattern from fifo (err=%d)\n",
553 				err);
554 			return err;
555 		}
556 
557 		for (i = 0; i < pattern_len;
558 		     i += ST_LSM6DSX_TAGGED_SAMPLE_SIZE) {
559 			memcpy(iio_buff, &hw->buff[i + ST_LSM6DSX_TAG_SIZE],
560 			       ST_LSM6DSX_SAMPLE_SIZE);
561 
562 			tag = hw->buff[i] >> 3;
563 			if (tag == ST_LSM6DSX_TS_TAG) {
564 				/*
565 				 * hw timestamp is 4B long and it is stored
566 				 * in FIFO according to this schema:
567 				 * B0 = ts[7:0], B1 = ts[15:8], B2 = ts[23:16],
568 				 * B3 = ts[31:24]
569 				 */
570 				ts = le32_to_cpu(*((__le32 *)iio_buff));
571 				/*
572 				 * check if hw timestamp engine is going to
573 				 * reset (the sensor generates an interrupt
574 				 * to signal the hw timestamp will reset in
575 				 * 1.638s)
576 				 */
577 				if (!reset_ts && ts >= 0xffff0000)
578 					reset_ts = true;
579 				ts *= ST_LSM6DSX_TS_SENSITIVITY;
580 			} else {
581 				st_lsm6dsx_push_tagged_data(hw, tag, iio_buff,
582 							    ts);
583 			}
584 		}
585 	}
586 
587 	if (unlikely(reset_ts)) {
588 		err = st_lsm6dsx_reset_hw_ts(hw);
589 		if (err < 0)
590 			return err;
591 	}
592 	return read_len;
593 }
594 
595 int st_lsm6dsx_flush_fifo(struct st_lsm6dsx_hw *hw)
596 {
597 	int err;
598 
599 	mutex_lock(&hw->fifo_lock);
600 
601 	hw->settings->fifo_ops.read_fifo(hw);
602 	err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_BYPASS);
603 
604 	mutex_unlock(&hw->fifo_lock);
605 
606 	return err;
607 }
608 
609 static int st_lsm6dsx_update_fifo(struct iio_dev *iio_dev, bool enable)
610 {
611 	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
612 	struct st_lsm6dsx_hw *hw = sensor->hw;
613 	int err;
614 
615 	mutex_lock(&hw->conf_lock);
616 
617 	if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS) {
618 		err = st_lsm6dsx_flush_fifo(hw);
619 		if (err < 0)
620 			goto out;
621 	}
622 
623 	if (sensor->id == ST_LSM6DSX_ID_EXT0 ||
624 	    sensor->id == ST_LSM6DSX_ID_EXT1 ||
625 	    sensor->id == ST_LSM6DSX_ID_EXT2) {
626 		err = st_lsm6dsx_shub_set_enable(sensor, enable);
627 		if (err < 0)
628 			goto out;
629 	} else {
630 		err = st_lsm6dsx_sensor_set_enable(sensor, enable);
631 		if (err < 0)
632 			goto out;
633 
634 		err = st_lsm6dsx_set_fifo_odr(sensor, enable);
635 		if (err < 0)
636 			goto out;
637 	}
638 
639 	err = st_lsm6dsx_update_decimators(hw);
640 	if (err < 0)
641 		goto out;
642 
643 	err = st_lsm6dsx_update_watermark(sensor, sensor->watermark);
644 	if (err < 0)
645 		goto out;
646 
647 	if (hw->enable_mask) {
648 		/* reset hw ts counter */
649 		err = st_lsm6dsx_reset_hw_ts(hw);
650 		if (err < 0)
651 			goto out;
652 
653 		err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_CONT);
654 	}
655 
656 out:
657 	mutex_unlock(&hw->conf_lock);
658 
659 	return err;
660 }
661 
662 static irqreturn_t st_lsm6dsx_handler_irq(int irq, void *private)
663 {
664 	struct st_lsm6dsx_hw *hw = private;
665 
666 	return hw->sip > 0 ? IRQ_WAKE_THREAD : IRQ_NONE;
667 }
668 
669 static irqreturn_t st_lsm6dsx_handler_thread(int irq, void *private)
670 {
671 	struct st_lsm6dsx_hw *hw = private;
672 	int count;
673 
674 	mutex_lock(&hw->fifo_lock);
675 	count = hw->settings->fifo_ops.read_fifo(hw);
676 	mutex_unlock(&hw->fifo_lock);
677 
678 	return !count ? IRQ_NONE : IRQ_HANDLED;
679 }
680 
681 static int st_lsm6dsx_buffer_preenable(struct iio_dev *iio_dev)
682 {
683 	return st_lsm6dsx_update_fifo(iio_dev, true);
684 }
685 
686 static int st_lsm6dsx_buffer_postdisable(struct iio_dev *iio_dev)
687 {
688 	return st_lsm6dsx_update_fifo(iio_dev, false);
689 }
690 
691 static const struct iio_buffer_setup_ops st_lsm6dsx_buffer_ops = {
692 	.preenable = st_lsm6dsx_buffer_preenable,
693 	.postdisable = st_lsm6dsx_buffer_postdisable,
694 };
695 
696 int st_lsm6dsx_fifo_setup(struct st_lsm6dsx_hw *hw)
697 {
698 	struct device_node *np = hw->dev->of_node;
699 	struct st_sensors_platform_data *pdata;
700 	struct iio_buffer *buffer;
701 	unsigned long irq_type;
702 	bool irq_active_low;
703 	int i, err;
704 
705 	irq_type = irqd_get_trigger_type(irq_get_irq_data(hw->irq));
706 
707 	switch (irq_type) {
708 	case IRQF_TRIGGER_HIGH:
709 	case IRQF_TRIGGER_RISING:
710 		irq_active_low = false;
711 		break;
712 	case IRQF_TRIGGER_LOW:
713 	case IRQF_TRIGGER_FALLING:
714 		irq_active_low = true;
715 		break;
716 	default:
717 		dev_info(hw->dev, "mode %lx unsupported\n", irq_type);
718 		return -EINVAL;
719 	}
720 
721 	err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_HLACTIVE_ADDR,
722 				 ST_LSM6DSX_REG_HLACTIVE_MASK,
723 				 FIELD_PREP(ST_LSM6DSX_REG_HLACTIVE_MASK,
724 					    irq_active_low));
725 	if (err < 0)
726 		return err;
727 
728 	pdata = (struct st_sensors_platform_data *)hw->dev->platform_data;
729 	if ((np && of_property_read_bool(np, "drive-open-drain")) ||
730 	    (pdata && pdata->open_drain)) {
731 		err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_PP_OD_ADDR,
732 					 ST_LSM6DSX_REG_PP_OD_MASK,
733 					 FIELD_PREP(ST_LSM6DSX_REG_PP_OD_MASK,
734 						    1));
735 		if (err < 0)
736 			return err;
737 
738 		irq_type |= IRQF_SHARED;
739 	}
740 
741 	err = devm_request_threaded_irq(hw->dev, hw->irq,
742 					st_lsm6dsx_handler_irq,
743 					st_lsm6dsx_handler_thread,
744 					irq_type | IRQF_ONESHOT,
745 					"lsm6dsx", hw);
746 	if (err) {
747 		dev_err(hw->dev, "failed to request trigger irq %d\n",
748 			hw->irq);
749 		return err;
750 	}
751 
752 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
753 		if (!hw->iio_devs[i])
754 			continue;
755 
756 		buffer = devm_iio_kfifo_allocate(hw->dev);
757 		if (!buffer)
758 			return -ENOMEM;
759 
760 		iio_device_attach_buffer(hw->iio_devs[i], buffer);
761 		hw->iio_devs[i]->modes |= INDIO_BUFFER_SOFTWARE;
762 		hw->iio_devs[i]->setup_ops = &st_lsm6dsx_buffer_ops;
763 	}
764 
765 	return 0;
766 }
767