xref: /linux/drivers/iio/dac/ltc2664.c (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * LTC2664 4 channel, 12-/16-Bit Voltage Output SoftSpan DAC driver
4  * LTC2672 5 channel, 12-/16-Bit Current Output Softspan DAC driver
5  *
6  * Copyright 2024 Analog Devices Inc.
7  */
8 
9 #include <linux/bitfield.h>
10 #include <linux/cleanup.h>
11 #include <linux/device.h>
12 #include <linux/gpio/consumer.h>
13 #include <linux/iio/iio.h>
14 #include <linux/kernel.h>
15 #include <linux/math64.h>
16 #include <linux/module.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/mutex.h>
19 #include <linux/property.h>
20 #include <linux/regmap.h>
21 #include <linux/regulator/consumer.h>
22 #include <linux/spi/spi.h>
23 
24 #define LTC2664_CMD_WRITE_N(n)		(0x00 + (n))
25 #define LTC2664_CMD_UPDATE_N(n)		(0x10 + (n))
26 #define LTC2664_CMD_WRITE_N_UPDATE_ALL	0x20
27 #define LTC2664_CMD_WRITE_N_UPDATE_N(n)	(0x30 + (n))
28 #define LTC2664_CMD_POWER_DOWN_N(n)	(0x40 + (n))
29 #define LTC2664_CMD_POWER_DOWN_ALL	0x50
30 #define LTC2664_CMD_SPAN_N(n)		(0x60 + (n))
31 #define LTC2664_CMD_CONFIG		0x70
32 #define LTC2664_CMD_MUX			0xB0
33 #define LTC2664_CMD_TOGGLE_SEL		0xC0
34 #define LTC2664_CMD_GLOBAL_TOGGLE	0xD0
35 #define LTC2664_CMD_NO_OPERATION	0xF0
36 #define LTC2664_REF_DISABLE		0x0001
37 #define LTC2664_MSPAN_SOFTSPAN		7
38 
39 #define LTC2672_MAX_CHANNEL		5
40 #define LTC2672_MAX_SPAN		7
41 #define LTC2672_SCALE_MULTIPLIER(n)	(50 * BIT(n))
42 
43 enum {
44 	LTC2664_SPAN_RANGE_0V_5V,
45 	LTC2664_SPAN_RANGE_0V_10V,
46 	LTC2664_SPAN_RANGE_M5V_5V,
47 	LTC2664_SPAN_RANGE_M10V_10V,
48 	LTC2664_SPAN_RANGE_M2V5_2V5,
49 };
50 
51 enum {
52 	LTC2664_INPUT_A,
53 	LTC2664_INPUT_B,
54 	LTC2664_INPUT_B_AVAIL,
55 	LTC2664_POWERDOWN,
56 	LTC2664_POWERDOWN_MODE,
57 	LTC2664_TOGGLE_EN,
58 	LTC2664_GLOBAL_TOGGLE,
59 };
60 
61 static const u16 ltc2664_mspan_lut[8][2] = {
62 	{ LTC2664_SPAN_RANGE_M10V_10V, 32768 }, /* MPS2=0, MPS1=0, MSP0=0 (0)*/
63 	{ LTC2664_SPAN_RANGE_M5V_5V, 32768 }, /* MPS2=0, MPS1=0, MSP0=1 (1)*/
64 	{ LTC2664_SPAN_RANGE_M2V5_2V5, 32768 }, /* MPS2=0, MPS1=1, MSP0=0 (2)*/
65 	{ LTC2664_SPAN_RANGE_0V_10V, 0 }, /* MPS2=0, MPS1=1, MSP0=1 (3)*/
66 	{ LTC2664_SPAN_RANGE_0V_10V, 32768 }, /* MPS2=1, MPS1=0, MSP0=0 (4)*/
67 	{ LTC2664_SPAN_RANGE_0V_5V, 0 }, /* MPS2=1, MPS1=0, MSP0=1 (5)*/
68 	{ LTC2664_SPAN_RANGE_0V_5V, 32768 }, /* MPS2=1, MPS1=1, MSP0=0 (6)*/
69 	{ LTC2664_SPAN_RANGE_0V_5V, 0 } /* MPS2=1, MPS1=1, MSP0=1 (7)*/
70 };
71 
72 struct ltc2664_state;
73 
74 struct ltc2664_chip_info {
75 	const char *name;
76 	int (*scale_get)(const struct ltc2664_state *st, int c);
77 	int (*offset_get)(const struct ltc2664_state *st, int c);
78 	int measurement_type;
79 	unsigned int num_channels;
80 	const int (*span_helper)[2];
81 	unsigned int num_span;
82 	unsigned int internal_vref_mv;
83 	bool manual_span_support;
84 	bool rfsadj_support;
85 };
86 
87 struct ltc2664_chan {
88 	/* indicates if the channel should be toggled */
89 	bool toggle_chan;
90 	/* indicates if the channel is in powered down state */
91 	bool powerdown;
92 	/* span code of the channel */
93 	u8 span;
94 	/* raw data of the current state of the chip registers (A/B) */
95 	u16 raw[2];
96 };
97 
98 struct ltc2664_state {
99 	struct spi_device *spi;
100 	struct regmap *regmap;
101 	struct ltc2664_chan channels[LTC2672_MAX_CHANNEL];
102 	/* lock to protect against multiple access to the device and shared data */
103 	struct mutex lock;
104 	const struct ltc2664_chip_info *chip_info;
105 	struct iio_chan_spec *iio_channels;
106 	int vref_mv;
107 	u32 rfsadj_ohms;
108 	u32 toggle_sel;
109 	bool global_toggle;
110 };
111 
112 static const int ltc2664_span_helper[][2] = {
113 	{ 0, 5000 },
114 	{ 0, 10000 },
115 	{ -5000, 5000 },
116 	{ -10000, 10000 },
117 	{ -2500, 2500 },
118 };
119 
120 static const int ltc2672_span_helper[][2] = {
121 	{ 0, 0 },
122 	{ 0, 3125 },
123 	{ 0, 6250 },
124 	{ 0, 12500 },
125 	{ 0, 25000 },
126 	{ 0, 50000 },
127 	{ 0, 100000 },
128 	{ 0, 200000 },
129 	{ 0, 300000 },
130 };
131 
132 static int ltc2664_scale_get(const struct ltc2664_state *st, int c)
133 {
134 	const struct ltc2664_chan *chan = &st->channels[c];
135 	const int (*span_helper)[2] = st->chip_info->span_helper;
136 	int span, fs;
137 
138 	span = chan->span;
139 	if (span < 0)
140 		return span;
141 
142 	fs = span_helper[span][1] - span_helper[span][0];
143 
144 	return fs * st->vref_mv / 2500;
145 }
146 
147 static int ltc2672_scale_get(const struct ltc2664_state *st, int c)
148 {
149 	const struct ltc2664_chan *chan = &st->channels[c];
150 	int span, fs;
151 
152 	span = chan->span - 1;
153 	if (span < 0)
154 		return span;
155 
156 	fs = 1000 * st->vref_mv;
157 
158 	if (span == LTC2672_MAX_SPAN)
159 		return mul_u64_u32_div(4800, fs, st->rfsadj_ohms);
160 
161 	return mul_u64_u32_div(LTC2672_SCALE_MULTIPLIER(span), fs, st->rfsadj_ohms);
162 }
163 
164 static int ltc2664_offset_get(const struct ltc2664_state *st, int c)
165 {
166 	const struct ltc2664_chan *chan = &st->channels[c];
167 	int span;
168 
169 	span = chan->span;
170 	if (span < 0)
171 		return span;
172 
173 	if (st->chip_info->span_helper[span][0] < 0)
174 		return -32768;
175 
176 	return 0;
177 }
178 
179 static int ltc2664_dac_code_write(struct ltc2664_state *st, u32 chan, u32 input,
180 				  u16 code)
181 {
182 	struct ltc2664_chan *c = &st->channels[chan];
183 	int ret, reg;
184 
185 	guard(mutex)(&st->lock);
186 	/* select the correct input register to write to */
187 	if (c->toggle_chan) {
188 		ret = regmap_write(st->regmap, LTC2664_CMD_TOGGLE_SEL,
189 				   input << chan);
190 		if (ret)
191 			return ret;
192 	}
193 	/*
194 	 * If in toggle mode the dac should be updated by an
195 	 * external signal (or sw toggle) and not here.
196 	 */
197 	if (st->toggle_sel & BIT(chan))
198 		reg = LTC2664_CMD_WRITE_N(chan);
199 	else
200 		reg = LTC2664_CMD_WRITE_N_UPDATE_N(chan);
201 
202 	ret = regmap_write(st->regmap, reg, code);
203 	if (ret)
204 		return ret;
205 
206 	c->raw[input] = code;
207 
208 	if (c->toggle_chan) {
209 		ret = regmap_write(st->regmap, LTC2664_CMD_TOGGLE_SEL,
210 				   st->toggle_sel);
211 		if (ret)
212 			return ret;
213 	}
214 
215 	return 0;
216 }
217 
218 static void ltc2664_dac_code_read(struct ltc2664_state *st, u32 chan, u32 input,
219 				  u32 *code)
220 {
221 	guard(mutex)(&st->lock);
222 	*code = st->channels[chan].raw[input];
223 }
224 
225 static const int ltc2664_raw_range[] = { 0, 1, U16_MAX };
226 
227 static int ltc2664_read_avail(struct iio_dev *indio_dev,
228 			      struct iio_chan_spec const *chan,
229 			      const int **vals, int *type, int *length,
230 			      long info)
231 {
232 	switch (info) {
233 	case IIO_CHAN_INFO_RAW:
234 		*vals = ltc2664_raw_range;
235 		*type = IIO_VAL_INT;
236 
237 		return IIO_AVAIL_RANGE;
238 	default:
239 		return -EINVAL;
240 	}
241 }
242 
243 static int ltc2664_read_raw(struct iio_dev *indio_dev,
244 			    struct iio_chan_spec const *chan, int *val,
245 			    int *val2, long info)
246 {
247 	struct ltc2664_state *st = iio_priv(indio_dev);
248 
249 	switch (info) {
250 	case IIO_CHAN_INFO_RAW:
251 		ltc2664_dac_code_read(st, chan->channel, LTC2664_INPUT_A, val);
252 
253 		return IIO_VAL_INT;
254 	case IIO_CHAN_INFO_OFFSET:
255 		*val = st->chip_info->offset_get(st, chan->channel);
256 
257 		return IIO_VAL_INT;
258 	case IIO_CHAN_INFO_SCALE:
259 		*val = st->chip_info->scale_get(st, chan->channel);
260 
261 		*val2 = 16;
262 		return IIO_VAL_FRACTIONAL_LOG2;
263 	default:
264 		return -EINVAL;
265 	}
266 }
267 
268 static int ltc2664_write_raw(struct iio_dev *indio_dev,
269 			     struct iio_chan_spec const *chan, int val,
270 			     int val2, long info)
271 {
272 	struct ltc2664_state *st = iio_priv(indio_dev);
273 
274 	switch (info) {
275 	case IIO_CHAN_INFO_RAW:
276 		if (val > U16_MAX || val < 0)
277 			return -EINVAL;
278 
279 		return ltc2664_dac_code_write(st, chan->channel,
280 					      LTC2664_INPUT_A, val);
281 	default:
282 		return -EINVAL;
283 	}
284 }
285 
286 static ssize_t ltc2664_reg_bool_get(struct iio_dev *indio_dev,
287 				    uintptr_t private,
288 				    const struct iio_chan_spec *chan,
289 				    char *buf)
290 {
291 	struct ltc2664_state *st = iio_priv(indio_dev);
292 	u32 val;
293 
294 	guard(mutex)(&st->lock);
295 	switch (private) {
296 	case LTC2664_POWERDOWN:
297 		val = st->channels[chan->channel].powerdown;
298 
299 		return sysfs_emit(buf, "%u\n", val);
300 	case LTC2664_POWERDOWN_MODE:
301 		return sysfs_emit(buf, "42kohm_to_gnd\n");
302 	case LTC2664_TOGGLE_EN:
303 		val = !!(st->toggle_sel & BIT(chan->channel));
304 
305 		return sysfs_emit(buf, "%u\n", val);
306 	case LTC2664_GLOBAL_TOGGLE:
307 		val = st->global_toggle;
308 
309 		return sysfs_emit(buf, "%u\n", val);
310 	default:
311 		return -EINVAL;
312 	}
313 }
314 
315 static ssize_t ltc2664_reg_bool_set(struct iio_dev *indio_dev,
316 				    uintptr_t private,
317 				    const struct iio_chan_spec *chan,
318 				    const char *buf, size_t len)
319 {
320 	struct ltc2664_state *st = iio_priv(indio_dev);
321 	int ret;
322 	bool en;
323 
324 	ret = kstrtobool(buf, &en);
325 	if (ret)
326 		return ret;
327 
328 	guard(mutex)(&st->lock);
329 	switch (private) {
330 	case LTC2664_POWERDOWN:
331 		ret = regmap_write(st->regmap,
332 				   en ? LTC2664_CMD_POWER_DOWN_N(chan->channel) :
333 				   LTC2664_CMD_UPDATE_N(chan->channel), en);
334 		if (ret)
335 			return ret;
336 
337 		st->channels[chan->channel].powerdown = en;
338 
339 		return len;
340 	case LTC2664_TOGGLE_EN:
341 		if (en)
342 			st->toggle_sel |= BIT(chan->channel);
343 		else
344 			st->toggle_sel &= ~BIT(chan->channel);
345 
346 		ret = regmap_write(st->regmap, LTC2664_CMD_TOGGLE_SEL,
347 				   st->toggle_sel);
348 		if (ret)
349 			return ret;
350 
351 		return len;
352 	case LTC2664_GLOBAL_TOGGLE:
353 		ret = regmap_write(st->regmap, LTC2664_CMD_GLOBAL_TOGGLE, en);
354 		if (ret)
355 			return ret;
356 
357 		st->global_toggle = en;
358 
359 		return len;
360 	default:
361 		return -EINVAL;
362 	}
363 }
364 
365 static ssize_t ltc2664_dac_input_read(struct iio_dev *indio_dev,
366 				      uintptr_t private,
367 				      const struct iio_chan_spec *chan,
368 				      char *buf)
369 {
370 	struct ltc2664_state *st = iio_priv(indio_dev);
371 	u32 val;
372 
373 	if (private == LTC2664_INPUT_B_AVAIL)
374 		return sysfs_emit(buf, "[%u %u %u]\n", ltc2664_raw_range[0],
375 				  ltc2664_raw_range[1],
376 				  ltc2664_raw_range[2] / 4);
377 
378 	ltc2664_dac_code_read(st, chan->channel, private, &val);
379 
380 	return sysfs_emit(buf, "%u\n", val);
381 }
382 
383 static ssize_t ltc2664_dac_input_write(struct iio_dev *indio_dev,
384 				       uintptr_t private,
385 				       const struct iio_chan_spec *chan,
386 				       const char *buf, size_t len)
387 {
388 	struct ltc2664_state *st = iio_priv(indio_dev);
389 	int ret;
390 	u16 val;
391 
392 	if (private == LTC2664_INPUT_B_AVAIL)
393 		return -EINVAL;
394 
395 	ret = kstrtou16(buf, 10, &val);
396 	if (ret)
397 		return ret;
398 
399 	ret = ltc2664_dac_code_write(st, chan->channel, private, val);
400 	if (ret)
401 		return ret;
402 
403 	return len;
404 }
405 
406 static int ltc2664_reg_access(struct iio_dev *indio_dev,
407 			      unsigned int reg,
408 			      unsigned int writeval,
409 			      unsigned int *readval)
410 {
411 	struct ltc2664_state *st = iio_priv(indio_dev);
412 
413 	if (readval)
414 		return -EOPNOTSUPP;
415 
416 	return regmap_write(st->regmap, reg, writeval);
417 }
418 
419 #define LTC2664_CHAN_EXT_INFO(_name, _what, _shared, _read, _write) {	\
420 	.name = _name,							\
421 	.read = (_read),						\
422 	.write = (_write),						\
423 	.private = (_what),						\
424 	.shared = (_shared),						\
425 }
426 
427 /*
428  * For toggle mode we only expose the symbol attr (sw_toggle) in case a TGPx is
429  * not provided in dts.
430  */
431 static const struct iio_chan_spec_ext_info ltc2664_toggle_sym_ext_info[] = {
432 	LTC2664_CHAN_EXT_INFO("raw0", LTC2664_INPUT_A, IIO_SEPARATE,
433 			      ltc2664_dac_input_read, ltc2664_dac_input_write),
434 	LTC2664_CHAN_EXT_INFO("raw1", LTC2664_INPUT_B, IIO_SEPARATE,
435 			      ltc2664_dac_input_read, ltc2664_dac_input_write),
436 	LTC2664_CHAN_EXT_INFO("powerdown", LTC2664_POWERDOWN, IIO_SEPARATE,
437 			      ltc2664_reg_bool_get, ltc2664_reg_bool_set),
438 	LTC2664_CHAN_EXT_INFO("powerdown_mode", LTC2664_POWERDOWN_MODE,
439 			      IIO_SEPARATE, ltc2664_reg_bool_get, NULL),
440 	LTC2664_CHAN_EXT_INFO("symbol", LTC2664_GLOBAL_TOGGLE, IIO_SEPARATE,
441 			      ltc2664_reg_bool_get, ltc2664_reg_bool_set),
442 	LTC2664_CHAN_EXT_INFO("toggle_en", LTC2664_TOGGLE_EN,
443 			      IIO_SEPARATE, ltc2664_reg_bool_get,
444 			      ltc2664_reg_bool_set),
445 	{ }
446 };
447 
448 static const struct iio_chan_spec_ext_info ltc2664_ext_info[] = {
449 	LTC2664_CHAN_EXT_INFO("powerdown", LTC2664_POWERDOWN, IIO_SEPARATE,
450 			      ltc2664_reg_bool_get, ltc2664_reg_bool_set),
451 	LTC2664_CHAN_EXT_INFO("powerdown_mode", LTC2664_POWERDOWN_MODE,
452 			      IIO_SEPARATE, ltc2664_reg_bool_get, NULL),
453 	{ }
454 };
455 
456 static const struct iio_chan_spec ltc2664_channel_template = {
457 	.indexed = 1,
458 	.output = 1,
459 	.info_mask_separate = BIT(IIO_CHAN_INFO_SCALE) |
460 			      BIT(IIO_CHAN_INFO_OFFSET) |
461 			      BIT(IIO_CHAN_INFO_RAW),
462 	.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
463 	.ext_info = ltc2664_ext_info,
464 };
465 
466 static const struct ltc2664_chip_info ltc2664_chip = {
467 	.name = "ltc2664",
468 	.scale_get = ltc2664_scale_get,
469 	.offset_get = ltc2664_offset_get,
470 	.measurement_type = IIO_VOLTAGE,
471 	.num_channels = 4,
472 	.span_helper = ltc2664_span_helper,
473 	.num_span = ARRAY_SIZE(ltc2664_span_helper),
474 	.internal_vref_mv = 2500,
475 	.manual_span_support = true,
476 	.rfsadj_support = false,
477 };
478 
479 static const struct ltc2664_chip_info ltc2672_chip = {
480 	.name = "ltc2672",
481 	.scale_get = ltc2672_scale_get,
482 	.offset_get = ltc2664_offset_get,
483 	.measurement_type = IIO_CURRENT,
484 	.num_channels = 5,
485 	.span_helper = ltc2672_span_helper,
486 	.num_span = ARRAY_SIZE(ltc2672_span_helper),
487 	.internal_vref_mv = 1250,
488 	.manual_span_support = false,
489 	.rfsadj_support = true,
490 };
491 
492 static int ltc2664_set_span(const struct ltc2664_state *st, int min, int max,
493 			    int chan)
494 {
495 	const struct ltc2664_chip_info *chip_info = st->chip_info;
496 	const int (*span_helper)[2] = chip_info->span_helper;
497 	int span, ret;
498 
499 	for (span = 0; span < chip_info->num_span; span++) {
500 		if (min == span_helper[span][0] && max == span_helper[span][1])
501 			break;
502 	}
503 
504 	if (span == chip_info->num_span)
505 		return -EINVAL;
506 
507 	ret = regmap_write(st->regmap, LTC2664_CMD_SPAN_N(chan), span);
508 	if (ret)
509 		return ret;
510 
511 	return span;
512 }
513 
514 static int ltc2664_channel_config(struct ltc2664_state *st)
515 {
516 	const struct ltc2664_chip_info *chip_info = st->chip_info;
517 	struct device *dev = &st->spi->dev;
518 	u32 reg, tmp[2], mspan;
519 	int ret;
520 
521 	mspan = LTC2664_MSPAN_SOFTSPAN;
522 	ret = device_property_read_u32(dev, "adi,manual-span-operation-config",
523 				       &mspan);
524 	if (!ret) {
525 		if (!chip_info->manual_span_support)
526 			return dev_err_probe(dev, -EINVAL,
527 			       "adi,manual-span-operation-config not supported\n");
528 
529 		if (mspan >= ARRAY_SIZE(ltc2664_mspan_lut))
530 			return dev_err_probe(dev, -EINVAL,
531 			       "adi,manual-span-operation-config not in range\n");
532 	}
533 
534 	st->rfsadj_ohms = 20000;
535 	ret = device_property_read_u32(dev, "adi,rfsadj-ohms", &st->rfsadj_ohms);
536 	if (!ret) {
537 		if (!chip_info->rfsadj_support)
538 			return dev_err_probe(dev, -EINVAL,
539 					     "adi,rfsadj-ohms not supported\n");
540 
541 		if (st->rfsadj_ohms < 19000 || st->rfsadj_ohms > 41000)
542 			return dev_err_probe(dev, -EINVAL,
543 					     "adi,rfsadj-ohms not in range\n");
544 	}
545 
546 	device_for_each_child_node_scoped(dev, child) {
547 		struct ltc2664_chan *chan;
548 
549 		ret = fwnode_property_read_u32(child, "reg", &reg);
550 		if (ret)
551 			return dev_err_probe(dev, ret,
552 					     "Failed to get reg property\n");
553 
554 		if (reg >= chip_info->num_channels)
555 			return dev_err_probe(dev, -EINVAL,
556 					     "reg bigger than: %d\n",
557 					     chip_info->num_channels);
558 
559 		chan = &st->channels[reg];
560 
561 		if (fwnode_property_read_bool(child, "adi,toggle-mode")) {
562 			chan->toggle_chan = true;
563 			/* assume sw toggle ABI */
564 			st->iio_channels[reg].ext_info = ltc2664_toggle_sym_ext_info;
565 
566 			/*
567 			 * Clear IIO_CHAN_INFO_RAW bit as toggle channels expose
568 			 * out_voltage/current_raw{0|1} files.
569 			 */
570 			__clear_bit(IIO_CHAN_INFO_RAW,
571 				    &st->iio_channels[reg].info_mask_separate);
572 		}
573 
574 		chan->raw[0] = ltc2664_mspan_lut[mspan][1];
575 		chan->raw[1] = ltc2664_mspan_lut[mspan][1];
576 
577 		chan->span = ltc2664_mspan_lut[mspan][0];
578 
579 		ret = fwnode_property_read_u32_array(child, "output-range-microvolt",
580 						     tmp, ARRAY_SIZE(tmp));
581 		if (!ret && mspan == LTC2664_MSPAN_SOFTSPAN) {
582 			ret = ltc2664_set_span(st, tmp[0] / 1000, tmp[1] / 1000, reg);
583 			if (ret < 0)
584 				return dev_err_probe(dev, ret,
585 						     "Failed to set span\n");
586 			chan->span = ret;
587 		}
588 
589 		ret = fwnode_property_read_u32_array(child, "output-range-microamp",
590 						     tmp, ARRAY_SIZE(tmp));
591 		if (!ret) {
592 			ret = ltc2664_set_span(st, 0, tmp[1] / 1000, reg);
593 			if (ret < 0)
594 				return dev_err_probe(dev, ret,
595 						     "Failed to set span\n");
596 			chan->span = ret;
597 		}
598 	}
599 
600 	return 0;
601 }
602 
603 static int ltc2664_setup(struct ltc2664_state *st)
604 {
605 	const struct ltc2664_chip_info *chip_info = st->chip_info;
606 	struct gpio_desc *gpio;
607 	int ret, i;
608 
609 	/* If we have a clr/reset pin, use that to reset the chip. */
610 	gpio = devm_gpiod_get_optional(&st->spi->dev, "reset", GPIOD_OUT_HIGH);
611 	if (IS_ERR(gpio))
612 		return dev_err_probe(&st->spi->dev, PTR_ERR(gpio),
613 				     "Failed to get reset gpio");
614 	if (gpio) {
615 		fsleep(1000);
616 		gpiod_set_value_cansleep(gpio, 0);
617 	}
618 
619 	/*
620 	 * Duplicate the default channel configuration as it can change during
621 	 * @ltc2664_channel_config()
622 	 */
623 	st->iio_channels = devm_kcalloc(&st->spi->dev,
624 					chip_info->num_channels,
625 					sizeof(struct iio_chan_spec),
626 					GFP_KERNEL);
627 	if (!st->iio_channels)
628 		return -ENOMEM;
629 
630 	for (i = 0; i < chip_info->num_channels; i++) {
631 		st->iio_channels[i] = ltc2664_channel_template;
632 		st->iio_channels[i].type = chip_info->measurement_type;
633 		st->iio_channels[i].channel = i;
634 	}
635 
636 	ret = ltc2664_channel_config(st);
637 	if (ret)
638 		return ret;
639 
640 	return regmap_set_bits(st->regmap, LTC2664_CMD_CONFIG, LTC2664_REF_DISABLE);
641 }
642 
643 static const struct regmap_config ltc2664_regmap_config = {
644 	.reg_bits = 8,
645 	.val_bits = 16,
646 	.max_register = LTC2664_CMD_NO_OPERATION,
647 };
648 
649 static const struct iio_info ltc2664_info = {
650 	.write_raw = ltc2664_write_raw,
651 	.read_raw = ltc2664_read_raw,
652 	.read_avail = ltc2664_read_avail,
653 	.debugfs_reg_access = ltc2664_reg_access,
654 };
655 
656 static int ltc2664_probe(struct spi_device *spi)
657 {
658 	static const char * const regulators[] = { "vcc", "iovcc", "v-neg" };
659 	const struct ltc2664_chip_info *chip_info;
660 	struct device *dev = &spi->dev;
661 	struct iio_dev *indio_dev;
662 	struct ltc2664_state *st;
663 	int ret;
664 
665 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
666 	if (!indio_dev)
667 		return -ENOMEM;
668 
669 	st = iio_priv(indio_dev);
670 	st->spi = spi;
671 
672 	chip_info = spi_get_device_match_data(spi);
673 	if (!chip_info)
674 		return -ENODEV;
675 
676 	st->chip_info = chip_info;
677 
678 	mutex_init(&st->lock);
679 
680 	st->regmap = devm_regmap_init_spi(spi, &ltc2664_regmap_config);
681 	if (IS_ERR(st->regmap))
682 		return dev_err_probe(dev, PTR_ERR(st->regmap),
683 				     "Failed to init regmap");
684 
685 	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(regulators),
686 					     regulators);
687 	if (ret)
688 		return dev_err_probe(dev, ret, "Failed to enable regulators\n");
689 
690 	ret = devm_regulator_get_enable_read_voltage(dev, "ref");
691 	if (ret < 0 && ret != -ENODEV)
692 		return ret;
693 
694 	st->vref_mv = ret > 0 ? ret / 1000 :  chip_info->internal_vref_mv;
695 
696 	ret = ltc2664_setup(st);
697 	if (ret)
698 		return ret;
699 
700 	indio_dev->name = chip_info->name;
701 	indio_dev->info = &ltc2664_info;
702 	indio_dev->modes = INDIO_DIRECT_MODE;
703 	indio_dev->channels = st->iio_channels;
704 	indio_dev->num_channels = chip_info->num_channels;
705 
706 	return devm_iio_device_register(dev, indio_dev);
707 }
708 
709 static const struct spi_device_id ltc2664_id[] = {
710 	{ "ltc2664", (kernel_ulong_t)&ltc2664_chip },
711 	{ "ltc2672", (kernel_ulong_t)&ltc2672_chip },
712 	{ }
713 };
714 MODULE_DEVICE_TABLE(spi, ltc2664_id);
715 
716 static const struct of_device_id ltc2664_of_id[] = {
717 	{ .compatible = "adi,ltc2664", .data = &ltc2664_chip },
718 	{ .compatible = "adi,ltc2672", .data = &ltc2672_chip },
719 	{ }
720 };
721 MODULE_DEVICE_TABLE(of, ltc2664_of_id);
722 
723 static struct spi_driver ltc2664_driver = {
724 	.driver = {
725 		.name = "ltc2664",
726 		.of_match_table = ltc2664_of_id,
727 	},
728 	.probe = ltc2664_probe,
729 	.id_table = ltc2664_id,
730 };
731 module_spi_driver(ltc2664_driver);
732 
733 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
734 MODULE_AUTHOR("Kim Seer Paller <kimseer.paller@analog.com>");
735 MODULE_DESCRIPTION("Analog Devices LTC2664 and LTC2672 DAC");
736 MODULE_LICENSE("GPL");
737