1 /*
2 * STMicroelectronics st_lsm6dsx FIFO buffer library driver
3 *
4 * LSM6DS3/LSM6DS3H/LSM6DSL/LSM6DSM: The FIFO buffer can be configured
5 * to store data from gyroscope and accelerometer. Samples are queued
6 * without any tag according to a specific pattern based on 'FIFO data sets'
7 * (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 * FIFO supported modes:
16 * - BYPASS: FIFO disabled
17 * - CONTINUOUS: FIFO enabled. When the buffer is full, the FIFO index
18 * restarts from the beginning and the oldest sample is overwritten
19 *
20 * Copyright 2016 STMicroelectronics Inc.
21 *
22 * Lorenzo Bianconi <lorenzo.bianconi@st.com>
23 * Denis Ciocca <denis.ciocca@st.com>
24 *
25 * Licensed under the GPL-2.
26 */
27 #include <linux/module.h>
28 #include <linux/interrupt.h>
29 #include <linux/irq.h>
30 #include <linux/iio/kfifo_buf.h>
31 #include <linux/iio/iio.h>
32 #include <linux/iio/buffer.h>
33
34 #include <linux/platform_data/st_sensors_pdata.h>
35
36 #include "st_lsm6dsx.h"
37
38 #define ST_LSM6DSX_REG_FIFO_THL_ADDR 0x06
39 #define ST_LSM6DSX_REG_FIFO_THH_ADDR 0x07
40 #define ST_LSM6DSX_FIFO_TH_MASK GENMASK(11, 0)
41 #define ST_LSM6DSX_REG_FIFO_DEC_GXL_ADDR 0x08
42 #define ST_LSM6DSX_REG_HLACTIVE_ADDR 0x12
43 #define ST_LSM6DSX_REG_HLACTIVE_MASK BIT(5)
44 #define ST_LSM6DSX_REG_PP_OD_ADDR 0x12
45 #define ST_LSM6DSX_REG_PP_OD_MASK BIT(4)
46 #define ST_LSM6DSX_REG_FIFO_MODE_ADDR 0x0a
47 #define ST_LSM6DSX_FIFO_MODE_MASK GENMASK(2, 0)
48 #define ST_LSM6DSX_FIFO_ODR_MASK GENMASK(6, 3)
49 #define ST_LSM6DSX_REG_FIFO_DIFFL_ADDR 0x3a
50 #define ST_LSM6DSX_FIFO_DIFF_MASK GENMASK(11, 0)
51 #define ST_LSM6DSX_FIFO_EMPTY_MASK BIT(12)
52 #define ST_LSM6DSX_REG_FIFO_OUTL_ADDR 0x3e
53
54 #define ST_LSM6DSX_MAX_FIFO_ODR_VAL 0x08
55
56 struct st_lsm6dsx_decimator_entry {
57 u8 decimator;
58 u8 val;
59 };
60
61 static const
62 struct st_lsm6dsx_decimator_entry st_lsm6dsx_decimator_table[] = {
63 { 0, 0x0 },
64 { 1, 0x1 },
65 { 2, 0x2 },
66 { 3, 0x3 },
67 { 4, 0x4 },
68 { 8, 0x5 },
69 { 16, 0x6 },
70 { 32, 0x7 },
71 };
72
st_lsm6dsx_get_decimator_val(u8 val)73 static int st_lsm6dsx_get_decimator_val(u8 val)
74 {
75 const int max_size = ARRAY_SIZE(st_lsm6dsx_decimator_table);
76 int i;
77
78 for (i = 0; i < max_size; i++)
79 if (st_lsm6dsx_decimator_table[i].decimator == val)
80 break;
81
82 return i == max_size ? 0 : st_lsm6dsx_decimator_table[i].val;
83 }
84
st_lsm6dsx_get_max_min_odr(struct st_lsm6dsx_hw * hw,u16 * max_odr,u16 * min_odr)85 static void st_lsm6dsx_get_max_min_odr(struct st_lsm6dsx_hw *hw,
86 u16 *max_odr, u16 *min_odr)
87 {
88 struct st_lsm6dsx_sensor *sensor;
89 int i;
90
91 *max_odr = 0, *min_odr = ~0;
92 for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
93 sensor = iio_priv(hw->iio_devs[i]);
94
95 if (!(hw->enable_mask & BIT(sensor->id)))
96 continue;
97
98 *max_odr = max_t(u16, *max_odr, sensor->odr);
99 *min_odr = min_t(u16, *min_odr, sensor->odr);
100 }
101 }
102
st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw * hw)103 static int st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw *hw)
104 {
105 struct st_lsm6dsx_sensor *sensor;
106 u16 max_odr, min_odr, sip = 0;
107 int err, i;
108 u8 data;
109
110 st_lsm6dsx_get_max_min_odr(hw, &max_odr, &min_odr);
111
112 for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
113 sensor = iio_priv(hw->iio_devs[i]);
114
115 /* update fifo decimators and sample in pattern */
116 if (hw->enable_mask & BIT(sensor->id)) {
117 sensor->sip = sensor->odr / min_odr;
118 sensor->decimator = max_odr / sensor->odr;
119 data = st_lsm6dsx_get_decimator_val(sensor->decimator);
120 } else {
121 sensor->sip = 0;
122 sensor->decimator = 0;
123 data = 0;
124 }
125
126 err = st_lsm6dsx_write_with_mask(hw,
127 ST_LSM6DSX_REG_FIFO_DEC_GXL_ADDR,
128 sensor->decimator_mask, data);
129 if (err < 0)
130 return err;
131
132 sip += sensor->sip;
133 }
134 hw->sip = sip;
135
136 return 0;
137 }
138
st_lsm6dsx_set_fifo_mode(struct st_lsm6dsx_hw * hw,enum st_lsm6dsx_fifo_mode fifo_mode)139 int st_lsm6dsx_set_fifo_mode(struct st_lsm6dsx_hw *hw,
140 enum st_lsm6dsx_fifo_mode fifo_mode)
141 {
142 u8 data;
143 int err;
144
145 switch (fifo_mode) {
146 case ST_LSM6DSX_FIFO_BYPASS:
147 data = fifo_mode;
148 break;
149 case ST_LSM6DSX_FIFO_CONT:
150 data = (ST_LSM6DSX_MAX_FIFO_ODR_VAL <<
151 __ffs(ST_LSM6DSX_FIFO_ODR_MASK)) | fifo_mode;
152 break;
153 default:
154 return -EINVAL;
155 }
156
157 err = hw->tf->write(hw->dev, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
158 sizeof(data), &data);
159 if (err < 0)
160 return err;
161
162 hw->fifo_mode = fifo_mode;
163
164 return 0;
165 }
166
st_lsm6dsx_update_watermark(struct st_lsm6dsx_sensor * sensor,u16 watermark)167 int st_lsm6dsx_update_watermark(struct st_lsm6dsx_sensor *sensor, u16 watermark)
168 {
169 u16 fifo_watermark = ~0, cur_watermark, sip = 0;
170 struct st_lsm6dsx_hw *hw = sensor->hw;
171 struct st_lsm6dsx_sensor *cur_sensor;
172 __le16 wdata;
173 int i, err;
174 u8 data;
175
176 for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
177 cur_sensor = iio_priv(hw->iio_devs[i]);
178
179 if (!(hw->enable_mask & BIT(cur_sensor->id)))
180 continue;
181
182 cur_watermark = (cur_sensor == sensor) ? watermark
183 : cur_sensor->watermark;
184
185 fifo_watermark = min_t(u16, fifo_watermark, cur_watermark);
186 sip += cur_sensor->sip;
187 }
188
189 if (!sip)
190 return 0;
191
192 fifo_watermark = max_t(u16, fifo_watermark, sip);
193 fifo_watermark = (fifo_watermark / sip) * sip;
194 fifo_watermark = fifo_watermark * ST_LSM6DSX_SAMPLE_DEPTH;
195
196 mutex_lock(&hw->lock);
197
198 err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_THH_ADDR,
199 sizeof(data), &data);
200 if (err < 0)
201 goto out;
202
203 fifo_watermark = ((data << 8) & ~ST_LSM6DSX_FIFO_TH_MASK) |
204 (fifo_watermark & ST_LSM6DSX_FIFO_TH_MASK);
205
206 wdata = cpu_to_le16(fifo_watermark);
207 err = hw->tf->write(hw->dev, ST_LSM6DSX_REG_FIFO_THL_ADDR,
208 sizeof(wdata), (u8 *)&wdata);
209 out:
210 mutex_unlock(&hw->lock);
211
212 return err < 0 ? err : 0;
213 }
214
215 /**
216 * st_lsm6dsx_read_fifo() - LSM6DS3-LSM6DS3H-LSM6DSL-LSM6DSM read FIFO routine
217 * @hw: Pointer to instance of struct st_lsm6dsx_hw.
218 *
219 * Read samples from the hw FIFO and push them to IIO buffers.
220 *
221 * Return: Number of bytes read from the FIFO
222 */
st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw * hw)223 static int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
224 {
225 u16 fifo_len, pattern_len = hw->sip * ST_LSM6DSX_SAMPLE_SIZE;
226 int err, acc_sip, gyro_sip, read_len, samples, offset;
227 struct st_lsm6dsx_sensor *acc_sensor, *gyro_sensor;
228 s64 acc_ts, acc_delta_ts, gyro_ts, gyro_delta_ts;
229 u8 iio_buff[ALIGN(ST_LSM6DSX_SAMPLE_SIZE, sizeof(s64)) + sizeof(s64)];
230 u8 buff[pattern_len];
231 __le16 fifo_status;
232
233 err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_DIFFL_ADDR,
234 sizeof(fifo_status), (u8 *)&fifo_status);
235 if (err < 0)
236 return err;
237
238 if (fifo_status & cpu_to_le16(ST_LSM6DSX_FIFO_EMPTY_MASK))
239 return 0;
240
241 fifo_len = (le16_to_cpu(fifo_status) & ST_LSM6DSX_FIFO_DIFF_MASK) *
242 ST_LSM6DSX_CHAN_SIZE;
243 samples = fifo_len / ST_LSM6DSX_SAMPLE_SIZE;
244 fifo_len = (fifo_len / pattern_len) * pattern_len;
245
246 /*
247 * compute delta timestamp between two consecutive samples
248 * in order to estimate queueing time of data generated
249 * by the sensor
250 */
251 acc_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
252 acc_ts = acc_sensor->ts - acc_sensor->delta_ts;
253 acc_delta_ts = div_s64(acc_sensor->delta_ts * acc_sensor->decimator,
254 samples);
255
256 gyro_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_GYRO]);
257 gyro_ts = gyro_sensor->ts - gyro_sensor->delta_ts;
258 gyro_delta_ts = div_s64(gyro_sensor->delta_ts * gyro_sensor->decimator,
259 samples);
260
261 for (read_len = 0; read_len < fifo_len; read_len += pattern_len) {
262 err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_OUTL_ADDR,
263 sizeof(buff), buff);
264 if (err < 0)
265 return err;
266
267 /*
268 * Data are written to the FIFO with a specific pattern
269 * depending on the configured ODRs. The first sequence of data
270 * stored in FIFO contains the data of all enabled sensors
271 * (e.g. Gx, Gy, Gz, Ax, Ay, Az), then data are repeated
272 * depending on the value of the decimation factor set for each
273 * sensor.
274 *
275 * Supposing the FIFO is storing data from gyroscope and
276 * accelerometer at different ODRs:
277 * - gyroscope ODR = 208Hz, accelerometer ODR = 104Hz
278 * Since the gyroscope ODR is twice the accelerometer one, the
279 * following pattern is repeated every 9 samples:
280 * - Gx, Gy, Gz, Ax, Ay, Az, Gx, Gy, Gz
281 */
282 gyro_sip = gyro_sensor->sip;
283 acc_sip = acc_sensor->sip;
284 offset = 0;
285
286 while (acc_sip > 0 || gyro_sip > 0) {
287 if (gyro_sip-- > 0) {
288 memcpy(iio_buff, &buff[offset],
289 ST_LSM6DSX_SAMPLE_SIZE);
290 iio_push_to_buffers_with_timestamp(
291 hw->iio_devs[ST_LSM6DSX_ID_GYRO],
292 iio_buff, gyro_ts);
293 offset += ST_LSM6DSX_SAMPLE_SIZE;
294 gyro_ts += gyro_delta_ts;
295 }
296
297 if (acc_sip-- > 0) {
298 memcpy(iio_buff, &buff[offset],
299 ST_LSM6DSX_SAMPLE_SIZE);
300 iio_push_to_buffers_with_timestamp(
301 hw->iio_devs[ST_LSM6DSX_ID_ACC],
302 iio_buff, acc_ts);
303 offset += ST_LSM6DSX_SAMPLE_SIZE;
304 acc_ts += acc_delta_ts;
305 }
306 }
307 }
308
309 return read_len;
310 }
311
st_lsm6dsx_flush_fifo(struct st_lsm6dsx_hw * hw)312 int st_lsm6dsx_flush_fifo(struct st_lsm6dsx_hw *hw)
313 {
314 int err;
315
316 mutex_lock(&hw->fifo_lock);
317
318 st_lsm6dsx_read_fifo(hw);
319 err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_BYPASS);
320
321 mutex_unlock(&hw->fifo_lock);
322
323 return err;
324 }
325
st_lsm6dsx_update_fifo(struct iio_dev * iio_dev,bool enable)326 static int st_lsm6dsx_update_fifo(struct iio_dev *iio_dev, bool enable)
327 {
328 struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
329 struct st_lsm6dsx_hw *hw = sensor->hw;
330 int err;
331
332 if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS) {
333 err = st_lsm6dsx_flush_fifo(hw);
334 if (err < 0)
335 return err;
336 }
337
338 if (enable) {
339 err = st_lsm6dsx_sensor_enable(sensor);
340 if (err < 0)
341 return err;
342 } else {
343 err = st_lsm6dsx_sensor_disable(sensor);
344 if (err < 0)
345 return err;
346 }
347
348 err = st_lsm6dsx_update_decimators(hw);
349 if (err < 0)
350 return err;
351
352 err = st_lsm6dsx_update_watermark(sensor, sensor->watermark);
353 if (err < 0)
354 return err;
355
356 if (hw->enable_mask) {
357 err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_CONT);
358 if (err < 0)
359 return err;
360
361 /*
362 * store enable buffer timestamp as reference to compute
363 * first delta timestamp
364 */
365 sensor->ts = iio_get_time_ns(iio_dev);
366 }
367
368 return 0;
369 }
370
st_lsm6dsx_handler_irq(int irq,void * private)371 static irqreturn_t st_lsm6dsx_handler_irq(int irq, void *private)
372 {
373 struct st_lsm6dsx_hw *hw = private;
374 struct st_lsm6dsx_sensor *sensor;
375 int i;
376
377 if (!hw->sip)
378 return IRQ_NONE;
379
380 for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
381 sensor = iio_priv(hw->iio_devs[i]);
382
383 if (sensor->sip > 0) {
384 s64 timestamp;
385
386 timestamp = iio_get_time_ns(hw->iio_devs[i]);
387 sensor->delta_ts = timestamp - sensor->ts;
388 sensor->ts = timestamp;
389 }
390 }
391
392 return IRQ_WAKE_THREAD;
393 }
394
st_lsm6dsx_handler_thread(int irq,void * private)395 static irqreturn_t st_lsm6dsx_handler_thread(int irq, void *private)
396 {
397 struct st_lsm6dsx_hw *hw = private;
398 int count;
399
400 mutex_lock(&hw->fifo_lock);
401 count = st_lsm6dsx_read_fifo(hw);
402 mutex_unlock(&hw->fifo_lock);
403
404 return !count ? IRQ_NONE : IRQ_HANDLED;
405 }
406
st_lsm6dsx_buffer_preenable(struct iio_dev * iio_dev)407 static int st_lsm6dsx_buffer_preenable(struct iio_dev *iio_dev)
408 {
409 return st_lsm6dsx_update_fifo(iio_dev, true);
410 }
411
st_lsm6dsx_buffer_postdisable(struct iio_dev * iio_dev)412 static int st_lsm6dsx_buffer_postdisable(struct iio_dev *iio_dev)
413 {
414 return st_lsm6dsx_update_fifo(iio_dev, false);
415 }
416
417 static const struct iio_buffer_setup_ops st_lsm6dsx_buffer_ops = {
418 .preenable = st_lsm6dsx_buffer_preenable,
419 .postdisable = st_lsm6dsx_buffer_postdisable,
420 };
421
st_lsm6dsx_fifo_setup(struct st_lsm6dsx_hw * hw)422 int st_lsm6dsx_fifo_setup(struct st_lsm6dsx_hw *hw)
423 {
424 struct device_node *np = hw->dev->of_node;
425 struct st_sensors_platform_data *pdata;
426 struct iio_buffer *buffer;
427 unsigned long irq_type;
428 bool irq_active_low;
429 int i, err;
430
431 irq_type = irqd_get_trigger_type(irq_get_irq_data(hw->irq));
432
433 switch (irq_type) {
434 case IRQF_TRIGGER_HIGH:
435 case IRQF_TRIGGER_RISING:
436 irq_active_low = false;
437 break;
438 case IRQF_TRIGGER_LOW:
439 case IRQF_TRIGGER_FALLING:
440 irq_active_low = true;
441 break;
442 default:
443 dev_info(hw->dev, "mode %lx unsupported\n", irq_type);
444 return -EINVAL;
445 }
446
447 err = st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_HLACTIVE_ADDR,
448 ST_LSM6DSX_REG_HLACTIVE_MASK,
449 irq_active_low);
450 if (err < 0)
451 return err;
452
453 pdata = (struct st_sensors_platform_data *)hw->dev->platform_data;
454 if ((np && of_property_read_bool(np, "drive-open-drain")) ||
455 (pdata && pdata->open_drain)) {
456 err = st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_PP_OD_ADDR,
457 ST_LSM6DSX_REG_PP_OD_MASK, 1);
458 if (err < 0)
459 return err;
460
461 irq_type |= IRQF_SHARED;
462 }
463
464 err = devm_request_threaded_irq(hw->dev, hw->irq,
465 st_lsm6dsx_handler_irq,
466 st_lsm6dsx_handler_thread,
467 irq_type | IRQF_ONESHOT,
468 "lsm6dsx", hw);
469 if (err) {
470 dev_err(hw->dev, "failed to request trigger irq %d\n",
471 hw->irq);
472 return err;
473 }
474
475 for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
476 buffer = devm_iio_kfifo_allocate(hw->dev);
477 if (!buffer)
478 return -ENOMEM;
479
480 iio_device_attach_buffer(hw->iio_devs[i], buffer);
481 hw->iio_devs[i]->modes |= INDIO_BUFFER_SOFTWARE;
482 hw->iio_devs[i]->setup_ops = &st_lsm6dsx_buffer_ops;
483 }
484
485 return 0;
486 }
487