xref: /linux/drivers/iio/adc/ad7944.c (revision 2697b79a469b68e3ad3640f55284359c1396278d)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Analog Devices AD7944/85/86 PulSAR ADC family driver.
4  *
5  * Copyright 2024 Analog Devices, Inc.
6  * Copyright 2024 BayLibre, SAS
7  */
8 
9 #include <linux/align.h>
10 #include <linux/bitfield.h>
11 #include <linux/bitops.h>
12 #include <linux/delay.h>
13 #include <linux/device.h>
14 #include <linux/err.h>
15 #include <linux/gpio/consumer.h>
16 #include <linux/module.h>
17 #include <linux/property.h>
18 #include <linux/regulator/consumer.h>
19 #include <linux/spi/spi.h>
20 #include <linux/string_helpers.h>
21 
22 #include <linux/iio/iio.h>
23 #include <linux/iio/sysfs.h>
24 #include <linux/iio/trigger_consumer.h>
25 #include <linux/iio/triggered_buffer.h>
26 
27 #define AD7944_INTERNAL_REF_MV		4096
28 
29 struct ad7944_timing_spec {
30 	/* Normal mode max conversion time (t_{CONV}). */
31 	unsigned int conv_ns;
32 	/* TURBO mode max conversion time (t_{CONV}). */
33 	unsigned int turbo_conv_ns;
34 };
35 
36 enum ad7944_spi_mode {
37 	/* datasheet calls this "4-wire mode" */
38 	AD7944_SPI_MODE_DEFAULT,
39 	/* datasheet calls this "3-wire mode" (not related to SPI_3WIRE!) */
40 	AD7944_SPI_MODE_SINGLE,
41 	/* datasheet calls this "chain mode" */
42 	AD7944_SPI_MODE_CHAIN,
43 };
44 
45 /* maps adi,spi-mode property value to enum */
46 static const char * const ad7944_spi_modes[] = {
47 	[AD7944_SPI_MODE_DEFAULT] = "",
48 	[AD7944_SPI_MODE_SINGLE] = "single",
49 	[AD7944_SPI_MODE_CHAIN] = "chain",
50 };
51 
52 struct ad7944_adc {
53 	struct spi_device *spi;
54 	enum ad7944_spi_mode spi_mode;
55 	struct spi_transfer xfers[3];
56 	struct spi_message msg;
57 	void *chain_mode_buf;
58 	/* Chip-specific timing specifications. */
59 	const struct ad7944_timing_spec *timing_spec;
60 	/* GPIO connected to CNV pin. */
61 	struct gpio_desc *cnv;
62 	/* Optional GPIO to enable turbo mode. */
63 	struct gpio_desc *turbo;
64 	/* Indicates TURBO is hard-wired to be always enabled. */
65 	bool always_turbo;
66 	/* Reference voltage (millivolts). */
67 	unsigned int ref_mv;
68 
69 	/*
70 	 * DMA (thus cache coherency maintenance) requires the
71 	 * transfer buffers to live in their own cache lines.
72 	 */
73 	struct {
74 		union {
75 			u16 u16;
76 			u32 u32;
77 		} raw;
78 		u64 timestamp __aligned(8);
79 	 } sample __aligned(IIO_DMA_MINALIGN);
80 };
81 
82 /* quite time before CNV rising edge */
83 #define T_QUIET_NS	20
84 
85 static const struct ad7944_timing_spec ad7944_timing_spec = {
86 	.conv_ns = 420,
87 	.turbo_conv_ns = 320,
88 };
89 
90 static const struct ad7944_timing_spec ad7986_timing_spec = {
91 	.conv_ns = 500,
92 	.turbo_conv_ns = 400,
93 };
94 
95 struct ad7944_chip_info {
96 	const char *name;
97 	const struct ad7944_timing_spec *timing_spec;
98 	const struct iio_chan_spec channels[2];
99 };
100 
101 /*
102  * AD7944_DEFINE_CHIP_INFO - Define a chip info structure for a specific chip
103  * @_name: The name of the chip
104  * @_ts: The timing specification for the chip
105  * @_bits: The number of bits in the conversion result
106  * @_diff: Whether the chip is true differential or not
107  */
108 #define AD7944_DEFINE_CHIP_INFO(_name, _ts, _bits, _diff)		\
109 static const struct ad7944_chip_info _name##_chip_info = {		\
110 	.name = #_name,							\
111 	.timing_spec = &_ts##_timing_spec,				\
112 	.channels = {							\
113 		{							\
114 			.type = IIO_VOLTAGE,				\
115 			.indexed = 1,					\
116 			.differential = _diff,				\
117 			.channel = 0,					\
118 			.channel2 = _diff ? 1 : 0,			\
119 			.scan_index = 0,				\
120 			.scan_type.sign = _diff ? 's' : 'u',		\
121 			.scan_type.realbits = _bits,			\
122 			.scan_type.storagebits = _bits > 16 ? 32 : 16,	\
123 			.scan_type.endianness = IIO_CPU,		\
124 			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)	\
125 					| BIT(IIO_CHAN_INFO_SCALE),	\
126 		},							\
127 		IIO_CHAN_SOFT_TIMESTAMP(1),				\
128 	},								\
129 }
130 
131 /* pseudo-differential with ground sense */
132 AD7944_DEFINE_CHIP_INFO(ad7944, ad7944, 14, 0);
133 AD7944_DEFINE_CHIP_INFO(ad7985, ad7944, 16, 0);
134 /* fully differential */
135 AD7944_DEFINE_CHIP_INFO(ad7986, ad7986, 18, 1);
136 
137 static void ad7944_unoptimize_msg(void *msg)
138 {
139 	spi_unoptimize_message(msg);
140 }
141 
142 static int ad7944_3wire_cs_mode_init_msg(struct device *dev, struct ad7944_adc *adc,
143 					 const struct iio_chan_spec *chan)
144 {
145 	unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns
146 						   : adc->timing_spec->conv_ns;
147 	struct spi_transfer *xfers = adc->xfers;
148 	int ret;
149 
150 	/*
151 	 * NB: can get better performance from some SPI controllers if we use
152 	 * the same bits_per_word in every transfer.
153 	 */
154 	xfers[0].bits_per_word = chan->scan_type.realbits;
155 	/*
156 	 * CS is tied to CNV and we need a low to high transition to start the
157 	 * conversion, so place CNV low for t_QUIET to prepare for this.
158 	 */
159 	xfers[0].delay.value = T_QUIET_NS;
160 	xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS;
161 
162 	/*
163 	 * CS has to be high for full conversion time to avoid triggering the
164 	 * busy indication.
165 	 */
166 	xfers[1].cs_off = 1;
167 	xfers[1].delay.value = t_conv_ns;
168 	xfers[1].delay.unit = SPI_DELAY_UNIT_NSECS;
169 	xfers[1].bits_per_word = chan->scan_type.realbits;
170 
171 	/* Then we can read the data during the acquisition phase */
172 	xfers[2].rx_buf = &adc->sample.raw;
173 	xfers[2].len = BITS_TO_BYTES(chan->scan_type.storagebits);
174 	xfers[2].bits_per_word = chan->scan_type.realbits;
175 
176 	spi_message_init_with_transfers(&adc->msg, xfers, 3);
177 
178 	ret = spi_optimize_message(adc->spi, &adc->msg);
179 	if (ret)
180 		return ret;
181 
182 	return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg);
183 }
184 
185 static int ad7944_4wire_mode_init_msg(struct device *dev, struct ad7944_adc *adc,
186 				      const struct iio_chan_spec *chan)
187 {
188 	unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns
189 						   : adc->timing_spec->conv_ns;
190 	struct spi_transfer *xfers = adc->xfers;
191 	int ret;
192 
193 	/*
194 	 * NB: can get better performance from some SPI controllers if we use
195 	 * the same bits_per_word in every transfer.
196 	 */
197 	xfers[0].bits_per_word = chan->scan_type.realbits;
198 	/*
199 	 * CS has to be high for full conversion time to avoid triggering the
200 	 * busy indication.
201 	 */
202 	xfers[0].cs_off = 1;
203 	xfers[0].delay.value = t_conv_ns;
204 	xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS;
205 
206 	xfers[1].rx_buf = &adc->sample.raw;
207 	xfers[1].len = BITS_TO_BYTES(chan->scan_type.storagebits);
208 	xfers[1].bits_per_word = chan->scan_type.realbits;
209 
210 	spi_message_init_with_transfers(&adc->msg, xfers, 2);
211 
212 	ret = spi_optimize_message(adc->spi, &adc->msg);
213 	if (ret)
214 		return ret;
215 
216 	return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg);
217 }
218 
219 static int ad7944_chain_mode_init_msg(struct device *dev, struct ad7944_adc *adc,
220 				      const struct iio_chan_spec *chan,
221 				      u32 n_chain_dev)
222 {
223 	struct spi_transfer *xfers = adc->xfers;
224 	int ret;
225 
226 	/*
227 	 * NB: SCLK has to be low before we toggle CS to avoid triggering the
228 	 * busy indication.
229 	 */
230 	if (adc->spi->mode & SPI_CPOL)
231 		return dev_err_probe(dev, -EINVAL,
232 				     "chain mode requires ~SPI_CPOL\n");
233 
234 	/*
235 	 * We only support CNV connected to CS in chain mode and we need CNV
236 	 * to be high during the transfer to trigger the conversion.
237 	 */
238 	if (!(adc->spi->mode & SPI_CS_HIGH))
239 		return dev_err_probe(dev, -EINVAL,
240 				     "chain mode requires SPI_CS_HIGH\n");
241 
242 	/* CNV has to be high for full conversion time before reading data. */
243 	xfers[0].delay.value = adc->timing_spec->conv_ns;
244 	xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS;
245 
246 	xfers[1].rx_buf = adc->chain_mode_buf;
247 	xfers[1].len = BITS_TO_BYTES(chan->scan_type.storagebits) * n_chain_dev;
248 	xfers[1].bits_per_word = chan->scan_type.realbits;
249 
250 	spi_message_init_with_transfers(&adc->msg, xfers, 2);
251 
252 	ret = spi_optimize_message(adc->spi, &adc->msg);
253 	if (ret)
254 		return ret;
255 
256 	return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg);
257 }
258 
259 /**
260  * ad7944_convert_and_acquire - Perform a single conversion and acquisition
261  * @adc: The ADC device structure
262  * @chan: The channel specification
263  * Return: 0 on success, a negative error code on failure
264  *
265  * Perform a conversion and acquisition of a single sample using the
266  * pre-optimized adc->msg.
267  *
268  * Upon successful return adc->sample.raw will contain the conversion result
269  * (or adc->chain_mode_buf if the device is using chain mode).
270  */
271 static int ad7944_convert_and_acquire(struct ad7944_adc *adc,
272 				      const struct iio_chan_spec *chan)
273 {
274 	int ret;
275 
276 	/*
277 	 * In 4-wire mode, the CNV line is held high for the entire conversion
278 	 * and acquisition process. In other modes adc->cnv is NULL and is
279 	 * ignored (CS is wired to CNV in those cases).
280 	 */
281 	gpiod_set_value_cansleep(adc->cnv, 1);
282 	ret = spi_sync(adc->spi, &adc->msg);
283 	gpiod_set_value_cansleep(adc->cnv, 0);
284 
285 	return ret;
286 }
287 
288 static int ad7944_single_conversion(struct ad7944_adc *adc,
289 				    const struct iio_chan_spec *chan,
290 				    int *val)
291 {
292 	int ret;
293 
294 	ret = ad7944_convert_and_acquire(adc, chan);
295 	if (ret)
296 		return ret;
297 
298 	if (adc->spi_mode == AD7944_SPI_MODE_CHAIN) {
299 		if (chan->scan_type.storagebits > 16)
300 			*val = ((u32 *)adc->chain_mode_buf)[chan->scan_index];
301 		else
302 			*val = ((u16 *)adc->chain_mode_buf)[chan->scan_index];
303 	} else {
304 		if (chan->scan_type.storagebits > 16)
305 			*val = adc->sample.raw.u32;
306 		else
307 			*val = adc->sample.raw.u16;
308 	}
309 
310 	if (chan->scan_type.sign == 's')
311 		*val = sign_extend32(*val, chan->scan_type.realbits - 1);
312 
313 	return IIO_VAL_INT;
314 }
315 
316 static int ad7944_read_raw(struct iio_dev *indio_dev,
317 			   const struct iio_chan_spec *chan,
318 			   int *val, int *val2, long info)
319 {
320 	struct ad7944_adc *adc = iio_priv(indio_dev);
321 	int ret;
322 
323 	switch (info) {
324 	case IIO_CHAN_INFO_RAW:
325 		ret = iio_device_claim_direct_mode(indio_dev);
326 		if (ret)
327 			return ret;
328 
329 		ret = ad7944_single_conversion(adc, chan, val);
330 		iio_device_release_direct_mode(indio_dev);
331 		return ret;
332 
333 	case IIO_CHAN_INFO_SCALE:
334 		switch (chan->type) {
335 		case IIO_VOLTAGE:
336 			*val = adc->ref_mv;
337 
338 			if (chan->scan_type.sign == 's')
339 				*val2 = chan->scan_type.realbits - 1;
340 			else
341 				*val2 = chan->scan_type.realbits;
342 
343 			return IIO_VAL_FRACTIONAL_LOG2;
344 		default:
345 			return -EINVAL;
346 		}
347 
348 	default:
349 		return -EINVAL;
350 	}
351 }
352 
353 static const struct iio_info ad7944_iio_info = {
354 	.read_raw = &ad7944_read_raw,
355 };
356 
357 static irqreturn_t ad7944_trigger_handler(int irq, void *p)
358 {
359 	struct iio_poll_func *pf = p;
360 	struct iio_dev *indio_dev = pf->indio_dev;
361 	struct ad7944_adc *adc = iio_priv(indio_dev);
362 	int ret;
363 
364 	ret = ad7944_convert_and_acquire(adc, &indio_dev->channels[0]);
365 	if (ret)
366 		goto out;
367 
368 	if (adc->spi_mode == AD7944_SPI_MODE_CHAIN)
369 		iio_push_to_buffers_with_timestamp(indio_dev, adc->chain_mode_buf,
370 						   pf->timestamp);
371 	else
372 		iio_push_to_buffers_with_timestamp(indio_dev, &adc->sample.raw,
373 						   pf->timestamp);
374 
375 out:
376 	iio_trigger_notify_done(indio_dev->trig);
377 
378 	return IRQ_HANDLED;
379 }
380 
381 /**
382  * ad7944_chain_mode_alloc - allocate and initialize channel specs and buffers
383  *                           for daisy-chained devices
384  * @dev: The device for devm_ functions
385  * @chan_template: The channel template for the devices (array of 2 channels
386  *                 voltage and timestamp)
387  * @n_chain_dev: The number of devices in the chain
388  * @chain_chan: Pointer to receive the allocated channel specs
389  * @chain_mode_buf: Pointer to receive the allocated rx buffer
390  * @chain_scan_masks: Pointer to receive the allocated scan masks
391  * Return: 0 on success, a negative error code on failure
392  */
393 static int ad7944_chain_mode_alloc(struct device *dev,
394 				   const struct iio_chan_spec *chan_template,
395 				   u32 n_chain_dev,
396 				   struct iio_chan_spec **chain_chan,
397 				   void **chain_mode_buf,
398 				   unsigned long **chain_scan_masks)
399 {
400 	struct iio_chan_spec *chan;
401 	size_t chain_mode_buf_size;
402 	unsigned long *scan_masks;
403 	void *buf;
404 	int i;
405 
406 	/* 1 channel for each device in chain plus 1 for soft timestamp */
407 
408 	chan = devm_kcalloc(dev, n_chain_dev + 1, sizeof(*chan), GFP_KERNEL);
409 	if (!chan)
410 		return -ENOMEM;
411 
412 	for (i = 0; i < n_chain_dev; i++) {
413 		chan[i] = chan_template[0];
414 
415 		if (chan_template[0].differential) {
416 			chan[i].channel = 2 * i;
417 			chan[i].channel2 = 2 * i + 1;
418 		} else {
419 			chan[i].channel = i;
420 		}
421 
422 		chan[i].scan_index = i;
423 	}
424 
425 	/* soft timestamp */
426 	chan[i] = chan_template[1];
427 	chan[i].scan_index = i;
428 
429 	*chain_chan = chan;
430 
431 	/* 1 word for each voltage channel + aligned u64 for timestamp */
432 
433 	chain_mode_buf_size = ALIGN(n_chain_dev *
434 		BITS_TO_BYTES(chan[0].scan_type.storagebits), sizeof(u64))
435 		+ sizeof(u64);
436 	buf = devm_kzalloc(dev, chain_mode_buf_size, GFP_KERNEL);
437 	if (!buf)
438 		return -ENOMEM;
439 
440 	*chain_mode_buf = buf;
441 
442 	/*
443 	 * Have to limit n_chain_dev due to current implementation of
444 	 * available_scan_masks.
445 	 */
446 	if (n_chain_dev > BITS_PER_LONG)
447 		return dev_err_probe(dev, -EINVAL,
448 				     "chain is limited to 32 devices\n");
449 
450 	scan_masks = devm_kcalloc(dev, 2, sizeof(*scan_masks), GFP_KERNEL);
451 	if (!scan_masks)
452 		return -ENOMEM;
453 
454 	/*
455 	 * Scan mask is needed since we always have to read all devices in the
456 	 * chain in one SPI transfer.
457 	 */
458 	scan_masks[0] = GENMASK(n_chain_dev - 1, 0);
459 
460 	*chain_scan_masks = scan_masks;
461 
462 	return 0;
463 }
464 
465 static const char * const ad7944_power_supplies[] = {
466 	"avdd",	"dvdd",	"bvdd", "vio"
467 };
468 
469 static void ad7944_ref_disable(void *ref)
470 {
471 	regulator_disable(ref);
472 }
473 
474 static int ad7944_probe(struct spi_device *spi)
475 {
476 	const struct ad7944_chip_info *chip_info;
477 	struct device *dev = &spi->dev;
478 	struct iio_dev *indio_dev;
479 	struct ad7944_adc *adc;
480 	bool have_refin = false;
481 	struct regulator *ref;
482 	struct iio_chan_spec *chain_chan;
483 	unsigned long *chain_scan_masks;
484 	u32 n_chain_dev;
485 	int ret;
486 
487 	indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
488 	if (!indio_dev)
489 		return -ENOMEM;
490 
491 	adc = iio_priv(indio_dev);
492 	adc->spi = spi;
493 
494 	chip_info = spi_get_device_match_data(spi);
495 	if (!chip_info)
496 		return dev_err_probe(dev, -EINVAL, "no chip info\n");
497 
498 	adc->timing_spec = chip_info->timing_spec;
499 
500 	ret = device_property_match_property_string(dev, "adi,spi-mode",
501 						    ad7944_spi_modes,
502 						    ARRAY_SIZE(ad7944_spi_modes));
503 	/* absence of adi,spi-mode property means default mode */
504 	if (ret == -EINVAL)
505 		adc->spi_mode = AD7944_SPI_MODE_DEFAULT;
506 	else if (ret < 0)
507 		return dev_err_probe(dev, ret,
508 				     "getting adi,spi-mode property failed\n");
509 	else
510 		adc->spi_mode = ret;
511 
512 	/*
513 	 * Some chips use unusual word sizes, so check now instead of waiting
514 	 * for the first xfer.
515 	 */
516 	if (!spi_is_bpw_supported(spi, chip_info->channels[0].scan_type.realbits))
517 		return dev_err_probe(dev, -EINVAL,
518 				"SPI host does not support %d bits per word\n",
519 				chip_info->channels[0].scan_type.realbits);
520 
521 	ret = devm_regulator_bulk_get_enable(dev,
522 					     ARRAY_SIZE(ad7944_power_supplies),
523 					     ad7944_power_supplies);
524 	if (ret)
525 		return dev_err_probe(dev, ret,
526 				     "failed to get and enable supplies\n");
527 
528 	/*
529 	 * Sort out what is being used for the reference voltage. Options are:
530 	 * - internal reference: neither REF or REFIN is connected
531 	 * - internal reference with external buffer: REF not connected, REFIN
532 	 *   is connected
533 	 * - external reference: REF is connected, REFIN is not connected
534 	 */
535 
536 	ref = devm_regulator_get_optional(dev, "ref");
537 	if (IS_ERR(ref)) {
538 		if (PTR_ERR(ref) != -ENODEV)
539 			return dev_err_probe(dev, PTR_ERR(ref),
540 					     "failed to get REF supply\n");
541 
542 		ref = NULL;
543 	}
544 
545 	ret = devm_regulator_get_enable_optional(dev, "refin");
546 	if (ret == 0)
547 		have_refin = true;
548 	else if (ret != -ENODEV)
549 		return dev_err_probe(dev, ret,
550 				     "failed to get and enable REFIN supply\n");
551 
552 	if (have_refin && ref)
553 		return dev_err_probe(dev, -EINVAL,
554 				     "cannot have both refin and ref supplies\n");
555 
556 	if (ref) {
557 		ret = regulator_enable(ref);
558 		if (ret)
559 			return dev_err_probe(dev, ret,
560 					     "failed to enable REF supply\n");
561 
562 		ret = devm_add_action_or_reset(dev, ad7944_ref_disable, ref);
563 		if (ret)
564 			return ret;
565 
566 		ret = regulator_get_voltage(ref);
567 		if (ret < 0)
568 			return dev_err_probe(dev, ret,
569 					     "failed to get REF voltage\n");
570 
571 		/* external reference */
572 		adc->ref_mv = ret / 1000;
573 	} else {
574 		/* internal reference */
575 		adc->ref_mv = AD7944_INTERNAL_REF_MV;
576 	}
577 
578 	adc->cnv = devm_gpiod_get_optional(dev, "cnv", GPIOD_OUT_LOW);
579 	if (IS_ERR(adc->cnv))
580 		return dev_err_probe(dev, PTR_ERR(adc->cnv),
581 				     "failed to get CNV GPIO\n");
582 
583 	if (!adc->cnv && adc->spi_mode == AD7944_SPI_MODE_DEFAULT)
584 		return dev_err_probe(&spi->dev, -EINVAL, "CNV GPIO is required\n");
585 	if (adc->cnv && adc->spi_mode != AD7944_SPI_MODE_DEFAULT)
586 		return dev_err_probe(&spi->dev, -EINVAL,
587 				     "CNV GPIO in single and chain mode is not currently supported\n");
588 
589 	adc->turbo = devm_gpiod_get_optional(dev, "turbo", GPIOD_OUT_LOW);
590 	if (IS_ERR(adc->turbo))
591 		return dev_err_probe(dev, PTR_ERR(adc->turbo),
592 				     "failed to get TURBO GPIO\n");
593 
594 	adc->always_turbo = device_property_present(dev, "adi,always-turbo");
595 
596 	if (adc->turbo && adc->always_turbo)
597 		return dev_err_probe(dev, -EINVAL,
598 			"cannot have both turbo-gpios and adi,always-turbo\n");
599 
600 	if (adc->spi_mode == AD7944_SPI_MODE_CHAIN && adc->always_turbo)
601 		return dev_err_probe(dev, -EINVAL,
602 			"cannot have both chain mode and always turbo\n");
603 
604 	switch (adc->spi_mode) {
605 	case AD7944_SPI_MODE_DEFAULT:
606 		ret = ad7944_4wire_mode_init_msg(dev, adc, &chip_info->channels[0]);
607 		if (ret)
608 			return ret;
609 
610 		break;
611 	case AD7944_SPI_MODE_SINGLE:
612 		ret = ad7944_3wire_cs_mode_init_msg(dev, adc, &chip_info->channels[0]);
613 		if (ret)
614 			return ret;
615 
616 		break;
617 	case AD7944_SPI_MODE_CHAIN:
618 		ret = device_property_read_u32(dev, "#daisy-chained-devices",
619 					       &n_chain_dev);
620 		if (ret)
621 			return dev_err_probe(dev, ret,
622 					"failed to get #daisy-chained-devices\n");
623 
624 		ret = ad7944_chain_mode_alloc(dev, chip_info->channels,
625 					      n_chain_dev, &chain_chan,
626 					      &adc->chain_mode_buf,
627 					      &chain_scan_masks);
628 		if (ret)
629 			return ret;
630 
631 		ret = ad7944_chain_mode_init_msg(dev, adc, &chain_chan[0],
632 						 n_chain_dev);
633 		if (ret)
634 			return ret;
635 
636 		break;
637 	}
638 
639 	indio_dev->name = chip_info->name;
640 	indio_dev->modes = INDIO_DIRECT_MODE;
641 	indio_dev->info = &ad7944_iio_info;
642 
643 	if (adc->spi_mode == AD7944_SPI_MODE_CHAIN) {
644 		indio_dev->available_scan_masks = chain_scan_masks;
645 		indio_dev->channels = chain_chan;
646 		indio_dev->num_channels = n_chain_dev + 1;
647 	} else {
648 		indio_dev->channels = chip_info->channels;
649 		indio_dev->num_channels = ARRAY_SIZE(chip_info->channels);
650 	}
651 
652 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
653 					      iio_pollfunc_store_time,
654 					      ad7944_trigger_handler, NULL);
655 	if (ret)
656 		return ret;
657 
658 	return devm_iio_device_register(dev, indio_dev);
659 }
660 
661 static const struct of_device_id ad7944_of_match[] = {
662 	{ .compatible = "adi,ad7944", .data = &ad7944_chip_info },
663 	{ .compatible = "adi,ad7985", .data = &ad7985_chip_info },
664 	{ .compatible = "adi,ad7986", .data = &ad7986_chip_info },
665 	{ }
666 };
667 MODULE_DEVICE_TABLE(of, ad7944_of_match);
668 
669 static const struct spi_device_id ad7944_spi_id[] = {
670 	{ "ad7944", (kernel_ulong_t)&ad7944_chip_info },
671 	{ "ad7985", (kernel_ulong_t)&ad7985_chip_info },
672 	{ "ad7986", (kernel_ulong_t)&ad7986_chip_info },
673 	{ }
674 
675 };
676 MODULE_DEVICE_TABLE(spi, ad7944_spi_id);
677 
678 static struct spi_driver ad7944_driver = {
679 	.driver = {
680 		.name = "ad7944",
681 		.of_match_table = ad7944_of_match,
682 	},
683 	.probe = ad7944_probe,
684 	.id_table = ad7944_spi_id,
685 };
686 module_spi_driver(ad7944_driver);
687 
688 MODULE_AUTHOR("David Lechner <dlechner@baylibre.com>");
689 MODULE_DESCRIPTION("Analog Devices AD7944 PulSAR ADC family driver");
690 MODULE_LICENSE("GPL");
691