xref: /linux/drivers/iio/adc/ad4695.c (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * SPI ADC driver for Analog Devices Inc. AD4695 and similar chips
4  *
5  * https://www.analog.com/en/products/ad4695.html
6  * https://www.analog.com/en/products/ad4696.html
7  * https://www.analog.com/en/products/ad4697.html
8  * https://www.analog.com/en/products/ad4698.html
9  *
10  * Copyright 2024 Analog Devices Inc.
11  * Copyright 2024 BayLibre, SAS
12  */
13 
14 #include <linux/align.h>
15 #include <linux/bitfield.h>
16 #include <linux/bits.h>
17 #include <linux/compiler.h>
18 #include <linux/delay.h>
19 #include <linux/device.h>
20 #include <linux/err.h>
21 #include <linux/gpio/consumer.h>
22 #include <linux/iio/buffer.h>
23 #include <linux/iio/iio.h>
24 #include <linux/iio/triggered_buffer.h>
25 #include <linux/iio/trigger_consumer.h>
26 #include <linux/minmax.h>
27 #include <linux/property.h>
28 #include <linux/regmap.h>
29 #include <linux/regulator/consumer.h>
30 #include <linux/spi/spi.h>
31 #include <linux/units.h>
32 
33 #include <dt-bindings/iio/adi,ad4695.h>
34 
35 /* AD4695 registers */
36 #define AD4695_REG_SPI_CONFIG_A				0x0000
37 #define   AD4695_REG_SPI_CONFIG_A_SW_RST		  (BIT(7) | BIT(0))
38 #define   AD4695_REG_SPI_CONFIG_A_ADDR_DIR		  BIT(5)
39 #define AD4695_REG_SPI_CONFIG_B				0x0001
40 #define   AD4695_REG_SPI_CONFIG_B_INST_MODE		  BIT(7)
41 #define AD4695_REG_DEVICE_TYPE				0x0003
42 #define AD4695_REG_SCRATCH_PAD				0x000A
43 #define AD4695_REG_VENDOR_L				0x000C
44 #define AD4695_REG_VENDOR_H				0x000D
45 #define AD4695_REG_LOOP_MODE				0x000E
46 #define AD4695_REG_SPI_CONFIG_C				0x0010
47 #define   AD4695_REG_SPI_CONFIG_C_MB_STRICT		  BIT(7)
48 #define AD4695_REG_SPI_STATUS				0x0011
49 #define AD4695_REG_STATUS				0x0014
50 #define AD4695_REG_ALERT_STATUS1			0x0015
51 #define AD4695_REG_ALERT_STATUS2			0x0016
52 #define AD4695_REG_CLAMP_STATUS				0x001A
53 #define AD4695_REG_SETUP				0x0020
54 #define   AD4695_REG_SETUP_LDO_EN			  BIT(4)
55 #define   AD4695_REG_SETUP_SPI_MODE			  BIT(2)
56 #define   AD4695_REG_SETUP_SPI_CYC_CTRL			  BIT(1)
57 #define AD4695_REG_REF_CTRL				0x0021
58 #define   AD4695_REG_REF_CTRL_OV_MODE			  BIT(7)
59 #define   AD4695_REG_REF_CTRL_VREF_SET			  GENMASK(4, 2)
60 #define   AD4695_REG_REF_CTRL_REFHIZ_EN			  BIT(1)
61 #define   AD4695_REG_REF_CTRL_REFBUF_EN			  BIT(0)
62 #define AD4695_REG_SEQ_CTRL				0x0022
63 #define   AD4695_REG_SEQ_CTRL_STD_SEQ_EN		  BIT(7)
64 #define   AD4695_REG_SEQ_CTRL_NUM_SLOTS_AS		  GENMASK(6, 0)
65 #define AD4695_REG_AC_CTRL				0x0023
66 #define AD4695_REG_STD_SEQ_CONFIG			0x0024
67 #define AD4695_REG_GPIO_CTRL				0x0026
68 #define AD4695_REG_GP_MODE				0x0027
69 #define AD4695_REG_TEMP_CTRL				0x0029
70 #define   AD4695_REG_TEMP_CTRL_TEMP_EN			  BIT(0)
71 #define AD4695_REG_CONFIG_IN(n)				(0x0030 | (n))
72 #define   AD4695_REG_CONFIG_IN_MODE			  BIT(6)
73 #define   AD4695_REG_CONFIG_IN_PAIR			  GENMASK(5, 4)
74 #define   AD4695_REG_CONFIG_IN_AINHIGHZ_EN		  BIT(3)
75 #define AD4695_REG_UPPER_IN(n)				(0x0040 | (2 * (n)))
76 #define AD4695_REG_LOWER_IN(n)				(0x0060 | (2 * (n)))
77 #define AD4695_REG_HYST_IN(n)				(0x0080 | (2 * (n)))
78 #define AD4695_REG_OFFSET_IN(n)				(0x00A0 | (2 * (n)))
79 #define AD4695_REG_GAIN_IN(n)				(0x00C0 | (2 * (n)))
80 #define AD4695_REG_AS_SLOT(n)				(0x0100 | (n))
81 #define   AD4695_REG_AS_SLOT_INX			  GENMASK(3, 0)
82 
83 /* Conversion mode commands */
84 #define AD4695_CMD_EXIT_CNV_MODE	0x0A
85 #define AD4695_CMD_TEMP_CHAN		0x0F
86 #define AD4695_CMD_VOLTAGE_CHAN(n)	(0x10 | (n))
87 
88 /* timing specs */
89 #define AD4695_T_CONVERT_NS		415
90 #define AD4695_T_WAKEUP_HW_MS		3
91 #define AD4695_T_WAKEUP_SW_MS		3
92 #define AD4695_T_REFBUF_MS		100
93 #define AD4695_T_REGCONFIG_NS		20
94 #define AD4695_REG_ACCESS_SCLK_HZ	(10 * MEGA)
95 
96 /* Max number of voltage input channels. */
97 #define AD4695_MAX_CHANNELS		16
98 /* Max size of 1 raw sample in bytes. */
99 #define AD4695_MAX_CHANNEL_SIZE		2
100 
101 enum ad4695_in_pair {
102 	AD4695_IN_PAIR_REFGND,
103 	AD4695_IN_PAIR_COM,
104 	AD4695_IN_PAIR_EVEN_ODD,
105 };
106 
107 struct ad4695_chip_info {
108 	const char *name;
109 	int max_sample_rate;
110 	u32 t_acq_ns;
111 	u8 num_voltage_inputs;
112 };
113 
114 struct ad4695_channel_config {
115 	unsigned int channel;
116 	bool highz_en;
117 	bool bipolar;
118 	enum ad4695_in_pair pin_pairing;
119 	unsigned int common_mode_mv;
120 };
121 
122 struct ad4695_state {
123 	struct spi_device *spi;
124 	struct regmap *regmap;
125 	struct regmap *regmap16;
126 	struct gpio_desc *reset_gpio;
127 	/* voltages channels plus temperature and timestamp */
128 	struct iio_chan_spec iio_chan[AD4695_MAX_CHANNELS + 2];
129 	struct ad4695_channel_config channels_cfg[AD4695_MAX_CHANNELS];
130 	const struct ad4695_chip_info *chip_info;
131 	/* Reference voltage. */
132 	unsigned int vref_mv;
133 	/* Common mode input pin voltage. */
134 	unsigned int com_mv;
135 	/* 1 per voltage and temperature chan plus 1 xfer to trigger 1st CNV */
136 	struct spi_transfer buf_read_xfer[AD4695_MAX_CHANNELS + 2];
137 	struct spi_message buf_read_msg;
138 	/* Raw conversion data received. */
139 	u8 buf[ALIGN((AD4695_MAX_CHANNELS + 2) * AD4695_MAX_CHANNEL_SIZE,
140 		     sizeof(s64)) + sizeof(s64)] __aligned(IIO_DMA_MINALIGN);
141 	u16 raw_data;
142 	/* Commands to send for single conversion. */
143 	u16 cnv_cmd;
144 	u8 cnv_cmd2;
145 };
146 
147 static const struct regmap_range ad4695_regmap_rd_ranges[] = {
148 	regmap_reg_range(AD4695_REG_SPI_CONFIG_A, AD4695_REG_SPI_CONFIG_B),
149 	regmap_reg_range(AD4695_REG_DEVICE_TYPE, AD4695_REG_DEVICE_TYPE),
150 	regmap_reg_range(AD4695_REG_SCRATCH_PAD, AD4695_REG_SCRATCH_PAD),
151 	regmap_reg_range(AD4695_REG_VENDOR_L, AD4695_REG_LOOP_MODE),
152 	regmap_reg_range(AD4695_REG_SPI_CONFIG_C, AD4695_REG_SPI_STATUS),
153 	regmap_reg_range(AD4695_REG_STATUS, AD4695_REG_ALERT_STATUS2),
154 	regmap_reg_range(AD4695_REG_CLAMP_STATUS, AD4695_REG_CLAMP_STATUS),
155 	regmap_reg_range(AD4695_REG_SETUP, AD4695_REG_AC_CTRL),
156 	regmap_reg_range(AD4695_REG_GPIO_CTRL, AD4695_REG_TEMP_CTRL),
157 	regmap_reg_range(AD4695_REG_CONFIG_IN(0), AD4695_REG_CONFIG_IN(15)),
158 	regmap_reg_range(AD4695_REG_AS_SLOT(0), AD4695_REG_AS_SLOT(127)),
159 };
160 
161 static const struct regmap_access_table ad4695_regmap_rd_table = {
162 	.yes_ranges = ad4695_regmap_rd_ranges,
163 	.n_yes_ranges = ARRAY_SIZE(ad4695_regmap_rd_ranges),
164 };
165 
166 static const struct regmap_range ad4695_regmap_wr_ranges[] = {
167 	regmap_reg_range(AD4695_REG_SPI_CONFIG_A, AD4695_REG_SPI_CONFIG_B),
168 	regmap_reg_range(AD4695_REG_SCRATCH_PAD, AD4695_REG_SCRATCH_PAD),
169 	regmap_reg_range(AD4695_REG_LOOP_MODE, AD4695_REG_LOOP_MODE),
170 	regmap_reg_range(AD4695_REG_SPI_CONFIG_C, AD4695_REG_SPI_STATUS),
171 	regmap_reg_range(AD4695_REG_SETUP, AD4695_REG_AC_CTRL),
172 	regmap_reg_range(AD4695_REG_GPIO_CTRL, AD4695_REG_TEMP_CTRL),
173 	regmap_reg_range(AD4695_REG_CONFIG_IN(0), AD4695_REG_CONFIG_IN(15)),
174 	regmap_reg_range(AD4695_REG_AS_SLOT(0), AD4695_REG_AS_SLOT(127)),
175 };
176 
177 static const struct regmap_access_table ad4695_regmap_wr_table = {
178 	.yes_ranges = ad4695_regmap_wr_ranges,
179 	.n_yes_ranges = ARRAY_SIZE(ad4695_regmap_wr_ranges),
180 };
181 
182 static const struct regmap_config ad4695_regmap_config = {
183 	.name = "ad4695-8",
184 	.reg_bits = 16,
185 	.val_bits = 8,
186 	.max_register = AD4695_REG_AS_SLOT(127),
187 	.rd_table = &ad4695_regmap_rd_table,
188 	.wr_table = &ad4695_regmap_wr_table,
189 	.can_multi_write = true,
190 };
191 
192 static const struct regmap_range ad4695_regmap16_rd_ranges[] = {
193 	regmap_reg_range(AD4695_REG_STD_SEQ_CONFIG, AD4695_REG_STD_SEQ_CONFIG),
194 	regmap_reg_range(AD4695_REG_UPPER_IN(0), AD4695_REG_GAIN_IN(15)),
195 };
196 
197 static const struct regmap_access_table ad4695_regmap16_rd_table = {
198 	.yes_ranges = ad4695_regmap16_rd_ranges,
199 	.n_yes_ranges = ARRAY_SIZE(ad4695_regmap16_rd_ranges),
200 };
201 
202 static const struct regmap_range ad4695_regmap16_wr_ranges[] = {
203 	regmap_reg_range(AD4695_REG_STD_SEQ_CONFIG, AD4695_REG_STD_SEQ_CONFIG),
204 	regmap_reg_range(AD4695_REG_UPPER_IN(0), AD4695_REG_GAIN_IN(15)),
205 };
206 
207 static const struct regmap_access_table ad4695_regmap16_wr_table = {
208 	.yes_ranges = ad4695_regmap16_wr_ranges,
209 	.n_yes_ranges = ARRAY_SIZE(ad4695_regmap16_wr_ranges),
210 };
211 
212 static const struct regmap_config ad4695_regmap16_config = {
213 	.name = "ad4695-16",
214 	.reg_bits = 16,
215 	.reg_stride = 2,
216 	.val_bits = 16,
217 	.val_format_endian = REGMAP_ENDIAN_LITTLE,
218 	.max_register = AD4695_REG_GAIN_IN(15),
219 	.rd_table = &ad4695_regmap16_rd_table,
220 	.wr_table = &ad4695_regmap16_wr_table,
221 	.can_multi_write = true,
222 };
223 
224 static const struct iio_chan_spec ad4695_channel_template = {
225 	.type = IIO_VOLTAGE,
226 	.indexed = 1,
227 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
228 			      BIT(IIO_CHAN_INFO_SCALE) |
229 			      BIT(IIO_CHAN_INFO_OFFSET) |
230 			      BIT(IIO_CHAN_INFO_CALIBSCALE) |
231 			      BIT(IIO_CHAN_INFO_CALIBBIAS),
232 	.info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBSCALE) |
233 					BIT(IIO_CHAN_INFO_CALIBBIAS),
234 	.scan_type = {
235 		.sign = 'u',
236 		.realbits = 16,
237 		.storagebits = 16,
238 	},
239 };
240 
241 static const struct iio_chan_spec ad4695_temp_channel_template = {
242 	.address = AD4695_CMD_TEMP_CHAN,
243 	.type = IIO_TEMP,
244 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
245 			      BIT(IIO_CHAN_INFO_SCALE) |
246 			      BIT(IIO_CHAN_INFO_OFFSET),
247 	.scan_type = {
248 		.sign = 's',
249 		.realbits = 16,
250 		.storagebits = 16,
251 	},
252 };
253 
254 static const struct iio_chan_spec ad4695_soft_timestamp_channel_template =
255 	IIO_CHAN_SOFT_TIMESTAMP(0);
256 
257 static const char * const ad4695_power_supplies[] = {
258 	"avdd", "vio"
259 };
260 
261 static const struct ad4695_chip_info ad4695_chip_info = {
262 	.name = "ad4695",
263 	.max_sample_rate = 500 * KILO,
264 	.t_acq_ns = 1715,
265 	.num_voltage_inputs = 16,
266 };
267 
268 static const struct ad4695_chip_info ad4696_chip_info = {
269 	.name = "ad4696",
270 	.max_sample_rate = 1 * MEGA,
271 	.t_acq_ns = 715,
272 	.num_voltage_inputs = 16,
273 };
274 
275 static const struct ad4695_chip_info ad4697_chip_info = {
276 	.name = "ad4697",
277 	.max_sample_rate = 500 * KILO,
278 	.t_acq_ns = 1715,
279 	.num_voltage_inputs = 8,
280 };
281 
282 static const struct ad4695_chip_info ad4698_chip_info = {
283 	.name = "ad4698",
284 	.max_sample_rate = 1 * MEGA,
285 	.t_acq_ns = 715,
286 	.num_voltage_inputs = 8,
287 };
288 
289 /**
290  * ad4695_set_single_cycle_mode - Set the device in single cycle mode
291  * @st: The AD4695 state
292  * @channel: The first channel to read
293  *
294  * As per the datasheet, to enable single cycle mode, we need to set
295  * STD_SEQ_EN=0, NUM_SLOTS_AS=0 and CYC_CTRL=1 (Table 15). Setting SPI_MODE=1
296  * triggers the first conversion using the channel in AS_SLOT0.
297  *
298  * Context: can sleep, must be called with iio_device_claim_direct held
299  * Return: 0 on success, a negative error code on failure
300  */
301 static int ad4695_set_single_cycle_mode(struct ad4695_state *st,
302 					unsigned int channel)
303 {
304 	int ret;
305 
306 	ret = regmap_clear_bits(st->regmap, AD4695_REG_SEQ_CTRL,
307 				AD4695_REG_SEQ_CTRL_STD_SEQ_EN |
308 				AD4695_REG_SEQ_CTRL_NUM_SLOTS_AS);
309 	if (ret)
310 		return ret;
311 
312 	ret = regmap_write(st->regmap, AD4695_REG_AS_SLOT(0),
313 			   FIELD_PREP(AD4695_REG_AS_SLOT_INX, channel));
314 	if (ret)
315 		return ret;
316 
317 	return regmap_set_bits(st->regmap, AD4695_REG_SETUP,
318 			       AD4695_REG_SETUP_SPI_MODE |
319 			       AD4695_REG_SETUP_SPI_CYC_CTRL);
320 }
321 
322 /**
323  * ad4695_enter_advanced_sequencer_mode - Put the ADC in advanced sequencer mode
324  * @st: The driver state
325  * @n: The number of slots to use - must be >= 2, <= 128
326  *
327  * As per the datasheet, to enable advanced sequencer, we need to set
328  * STD_SEQ_EN=0, NUM_SLOTS_AS=n-1 and CYC_CTRL=0 (Table 15). Setting SPI_MODE=1
329  * triggers the first conversion using the channel in AS_SLOT0.
330  *
331  * Return: 0 on success, a negative error code on failure
332  */
333 static int ad4695_enter_advanced_sequencer_mode(struct ad4695_state *st, u32 n)
334 {
335 	int ret;
336 
337 	ret = regmap_update_bits(st->regmap, AD4695_REG_SEQ_CTRL,
338 		AD4695_REG_SEQ_CTRL_STD_SEQ_EN |
339 		AD4695_REG_SEQ_CTRL_NUM_SLOTS_AS,
340 		FIELD_PREP(AD4695_REG_SEQ_CTRL_STD_SEQ_EN, 0) |
341 		FIELD_PREP(AD4695_REG_SEQ_CTRL_NUM_SLOTS_AS, n - 1));
342 	if (ret)
343 		return ret;
344 
345 	return regmap_update_bits(st->regmap, AD4695_REG_SETUP,
346 		AD4695_REG_SETUP_SPI_MODE | AD4695_REG_SETUP_SPI_CYC_CTRL,
347 		FIELD_PREP(AD4695_REG_SETUP_SPI_MODE, 1) |
348 		FIELD_PREP(AD4695_REG_SETUP_SPI_CYC_CTRL, 0));
349 }
350 
351 /**
352  * ad4695_exit_conversion_mode - Exit conversion mode
353  * @st: The AD4695 state
354  *
355  * Sends SPI command to exit conversion mode.
356  *
357  * Return: 0 on success, a negative error code on failure
358  */
359 static int ad4695_exit_conversion_mode(struct ad4695_state *st)
360 {
361 	struct spi_transfer xfer = {
362 		.tx_buf = &st->cnv_cmd2,
363 		.len = 1,
364 		.delay.value = AD4695_T_REGCONFIG_NS,
365 		.delay.unit = SPI_DELAY_UNIT_NSECS,
366 	};
367 
368 	/*
369 	 * Technically, could do a 5-bit transfer, but shifting to start of
370 	 * 8 bits instead for better SPI controller support.
371 	 */
372 	st->cnv_cmd2 = AD4695_CMD_EXIT_CNV_MODE << 3;
373 
374 	return spi_sync_transfer(st->spi, &xfer, 1);
375 }
376 
377 static int ad4695_set_ref_voltage(struct ad4695_state *st, int vref_mv)
378 {
379 	u8 val;
380 
381 	if (vref_mv >= 2400 && vref_mv <= 2750)
382 		val = 0;
383 	else if (vref_mv > 2750 && vref_mv <= 3250)
384 		val = 1;
385 	else if (vref_mv > 3250 && vref_mv <= 3750)
386 		val = 2;
387 	else if (vref_mv > 3750 && vref_mv <= 4500)
388 		val = 3;
389 	else if (vref_mv > 4500 && vref_mv <= 5100)
390 		val = 4;
391 	else
392 		return -EINVAL;
393 
394 	return regmap_update_bits(st->regmap, AD4695_REG_REF_CTRL,
395 				  AD4695_REG_REF_CTRL_VREF_SET,
396 				  FIELD_PREP(AD4695_REG_REF_CTRL_VREF_SET, val));
397 }
398 
399 static int ad4695_write_chn_cfg(struct ad4695_state *st,
400 				struct ad4695_channel_config *cfg)
401 {
402 	u32 mask, val;
403 
404 	mask = AD4695_REG_CONFIG_IN_MODE;
405 	val = FIELD_PREP(AD4695_REG_CONFIG_IN_MODE, cfg->bipolar ? 1 : 0);
406 
407 	mask |= AD4695_REG_CONFIG_IN_PAIR;
408 	val |= FIELD_PREP(AD4695_REG_CONFIG_IN_PAIR, cfg->pin_pairing);
409 
410 	mask |= AD4695_REG_CONFIG_IN_AINHIGHZ_EN;
411 	val |= FIELD_PREP(AD4695_REG_CONFIG_IN_AINHIGHZ_EN,
412 			  cfg->highz_en ? 1 : 0);
413 
414 	return regmap_update_bits(st->regmap,
415 				  AD4695_REG_CONFIG_IN(cfg->channel),
416 				  mask, val);
417 }
418 
419 static int ad4695_buffer_preenable(struct iio_dev *indio_dev)
420 {
421 	struct ad4695_state *st = iio_priv(indio_dev);
422 	struct spi_transfer *xfer;
423 	u8 temp_chan_bit = st->chip_info->num_voltage_inputs;
424 	u32 bit, num_xfer, num_slots;
425 	u32 temp_en = 0;
426 	int ret;
427 
428 	/*
429 	 * We are using the advanced sequencer since it is the only way to read
430 	 * multiple channels that allows individual configuration of each
431 	 * voltage input channel. Slot 0 in the advanced sequencer is used to
432 	 * account for the gap between trigger polls - we don't read data from
433 	 * this slot. Each enabled voltage channel is assigned a slot starting
434 	 * with slot 1.
435 	 */
436 	num_slots = 1;
437 
438 	memset(st->buf_read_xfer, 0, sizeof(st->buf_read_xfer));
439 
440 	/* First xfer is only to trigger conversion of slot 1, so no rx. */
441 	xfer = &st->buf_read_xfer[0];
442 	xfer->cs_change = 1;
443 	xfer->delay.value = st->chip_info->t_acq_ns;
444 	xfer->delay.unit = SPI_DELAY_UNIT_NSECS;
445 	xfer->cs_change_delay.value = AD4695_T_CONVERT_NS;
446 	xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
447 	num_xfer = 1;
448 
449 	iio_for_each_active_channel(indio_dev, bit) {
450 		xfer = &st->buf_read_xfer[num_xfer];
451 		xfer->bits_per_word = 16;
452 		xfer->rx_buf = &st->buf[(num_xfer - 1) * 2];
453 		xfer->len = 2;
454 		xfer->cs_change = 1;
455 		xfer->cs_change_delay.value = AD4695_T_CONVERT_NS;
456 		xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
457 
458 		if (bit == temp_chan_bit) {
459 			temp_en = 1;
460 		} else {
461 			ret = regmap_write(st->regmap,
462 				AD4695_REG_AS_SLOT(num_slots),
463 				FIELD_PREP(AD4695_REG_AS_SLOT_INX, bit));
464 			if (ret)
465 				return ret;
466 
467 			num_slots++;
468 		}
469 
470 		num_xfer++;
471 	}
472 
473 	/*
474 	 * The advanced sequencer requires that at least 2 slots are enabled.
475 	 * Since slot 0 is always used for other purposes, we need only 1
476 	 * enabled voltage channel to meet this requirement. If the temperature
477 	 * channel is the only enabled channel, we need to add one more slot
478 	 * in the sequence but not read from it.
479 	 */
480 	if (num_slots < 2) {
481 		/* move last xfer so we can insert one more xfer before it */
482 		st->buf_read_xfer[num_xfer] = *xfer;
483 		num_xfer++;
484 
485 		/* modify 2nd to last xfer for extra slot */
486 		memset(xfer, 0, sizeof(*xfer));
487 		xfer->cs_change = 1;
488 		xfer->delay.value = st->chip_info->t_acq_ns;
489 		xfer->delay.unit = SPI_DELAY_UNIT_NSECS;
490 		xfer->cs_change_delay.value = AD4695_T_CONVERT_NS;
491 		xfer->cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
492 		xfer++;
493 
494 		/* and add the extra slot in the sequencer */
495 		ret = regmap_write(st->regmap,
496 				   AD4695_REG_AS_SLOT(num_slots),
497 				   FIELD_PREP(AD4695_REG_AS_SLOT_INX, 0));
498 		if (ret)
499 			return ret;
500 
501 		num_slots++;
502 	}
503 
504 	/*
505 	 * Don't keep CS asserted after last xfer. Also triggers conversion of
506 	 * slot 0.
507 	 */
508 	xfer->cs_change = 0;
509 
510 	/*
511 	 * Temperature channel isn't included in the sequence, but rather
512 	 * controlled by setting a bit in the TEMP_CTRL register.
513 	 */
514 
515 	ret = regmap_update_bits(st->regmap, AD4695_REG_TEMP_CTRL,
516 		AD4695_REG_TEMP_CTRL_TEMP_EN,
517 		FIELD_PREP(AD4695_REG_TEMP_CTRL_TEMP_EN, temp_en));
518 	if (ret)
519 		return ret;
520 
521 	spi_message_init_with_transfers(&st->buf_read_msg, st->buf_read_xfer,
522 					num_xfer);
523 
524 	ret = spi_optimize_message(st->spi, &st->buf_read_msg);
525 	if (ret)
526 		return ret;
527 
528 	/* This triggers conversion of slot 0. */
529 	ret = ad4695_enter_advanced_sequencer_mode(st, num_slots);
530 	if (ret)
531 		spi_unoptimize_message(&st->buf_read_msg);
532 
533 	return ret;
534 }
535 
536 static int ad4695_buffer_postdisable(struct iio_dev *indio_dev)
537 {
538 	struct ad4695_state *st = iio_priv(indio_dev);
539 	int ret;
540 
541 	ret = ad4695_exit_conversion_mode(st);
542 	if (ret)
543 		return ret;
544 
545 	spi_unoptimize_message(&st->buf_read_msg);
546 
547 	return 0;
548 }
549 
550 static const struct iio_buffer_setup_ops ad4695_buffer_setup_ops = {
551 	.preenable = ad4695_buffer_preenable,
552 	.postdisable = ad4695_buffer_postdisable,
553 };
554 
555 static irqreturn_t ad4695_trigger_handler(int irq, void *p)
556 {
557 	struct iio_poll_func *pf = p;
558 	struct iio_dev *indio_dev = pf->indio_dev;
559 	struct ad4695_state *st = iio_priv(indio_dev);
560 	int ret;
561 
562 	ret = spi_sync(st->spi, &st->buf_read_msg);
563 	if (ret)
564 		goto out;
565 
566 	iio_push_to_buffers_with_timestamp(indio_dev, st->buf, pf->timestamp);
567 
568 out:
569 	iio_trigger_notify_done(indio_dev->trig);
570 
571 	return IRQ_HANDLED;
572 }
573 
574 /**
575  * ad4695_read_one_sample - Read a single sample using single-cycle mode
576  * @st: The AD4695 state
577  * @address: The address of the channel to read
578  *
579  * Upon successful return, the sample will be stored in `st->raw_data`.
580  *
581  * Context: can sleep, must be called with iio_device_claim_direct held
582  * Return: 0 on success, a negative error code on failure
583  */
584 static int ad4695_read_one_sample(struct ad4695_state *st, unsigned int address)
585 {
586 	struct spi_transfer xfer[2] = { };
587 	int ret, i = 0;
588 
589 	ret = ad4695_set_single_cycle_mode(st, address);
590 	if (ret)
591 		return ret;
592 
593 	/*
594 	 * Setting the first channel to the temperature channel isn't supported
595 	 * in single-cycle mode, so we have to do an extra xfer to read the
596 	 * temperature.
597 	 */
598 	if (address == AD4695_CMD_TEMP_CHAN) {
599 		/* We aren't reading, so we can make this a short xfer. */
600 		st->cnv_cmd2 = AD4695_CMD_TEMP_CHAN << 3;
601 		xfer[0].tx_buf = &st->cnv_cmd2;
602 		xfer[0].len = 1;
603 		xfer[0].cs_change = 1;
604 		xfer[0].cs_change_delay.value = AD4695_T_CONVERT_NS;
605 		xfer[0].cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
606 
607 		i = 1;
608 	}
609 
610 	/* Then read the result and exit conversion mode. */
611 	st->cnv_cmd = AD4695_CMD_EXIT_CNV_MODE << 11;
612 	xfer[i].bits_per_word = 16;
613 	xfer[i].tx_buf = &st->cnv_cmd;
614 	xfer[i].rx_buf = &st->raw_data;
615 	xfer[i].len = 2;
616 
617 	return spi_sync_transfer(st->spi, xfer, i + 1);
618 }
619 
620 static int ad4695_read_raw(struct iio_dev *indio_dev,
621 			   struct iio_chan_spec const *chan,
622 			   int *val, int *val2, long mask)
623 {
624 	struct ad4695_state *st = iio_priv(indio_dev);
625 	struct ad4695_channel_config *cfg = &st->channels_cfg[chan->scan_index];
626 	u8 realbits = chan->scan_type.realbits;
627 	unsigned int reg_val;
628 	int ret, tmp;
629 
630 	switch (mask) {
631 	case IIO_CHAN_INFO_RAW:
632 		iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
633 			ret = ad4695_read_one_sample(st, chan->address);
634 			if (ret)
635 				return ret;
636 
637 			if (chan->scan_type.sign == 's')
638 				*val = sign_extend32(st->raw_data, realbits - 1);
639 			else
640 				*val = st->raw_data;
641 
642 			return IIO_VAL_INT;
643 		}
644 		unreachable();
645 	case IIO_CHAN_INFO_SCALE:
646 		switch (chan->type) {
647 		case IIO_VOLTAGE:
648 			*val = st->vref_mv;
649 			*val2 = chan->scan_type.realbits;
650 			return IIO_VAL_FRACTIONAL_LOG2;
651 		case IIO_TEMP:
652 			/* T_scale (°C) = raw * V_REF (mV) / (-1.8 mV/°C * 2^16) */
653 			*val = st->vref_mv * -556;
654 			*val2 = 16;
655 			return IIO_VAL_FRACTIONAL_LOG2;
656 		default:
657 			return -EINVAL;
658 		}
659 	case IIO_CHAN_INFO_OFFSET:
660 		switch (chan->type) {
661 		case IIO_VOLTAGE:
662 			if (cfg->pin_pairing == AD4695_IN_PAIR_COM)
663 				*val = st->com_mv * (1 << realbits) / st->vref_mv;
664 			else if (cfg->pin_pairing == AD4695_IN_PAIR_EVEN_ODD)
665 				*val = cfg->common_mode_mv * (1 << realbits) / st->vref_mv;
666 			else
667 				*val = 0;
668 
669 			return IIO_VAL_INT;
670 		case IIO_TEMP:
671 			/* T_offset (°C) = -725 mV / (-1.8 mV/°C) */
672 			/* T_offset (raw) = T_offset (°C) * (-1.8 mV/°C) * 2^16 / V_REF (mV) */
673 			*val = -47513600;
674 			*val2 = st->vref_mv;
675 			return IIO_VAL_FRACTIONAL;
676 		default:
677 			return -EINVAL;
678 		}
679 	case IIO_CHAN_INFO_CALIBSCALE:
680 		switch (chan->type) {
681 		case IIO_VOLTAGE:
682 			iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
683 				ret = regmap_read(st->regmap16,
684 					AD4695_REG_GAIN_IN(chan->scan_index),
685 					&reg_val);
686 				if (ret)
687 					return ret;
688 
689 				*val = reg_val;
690 				*val2 = 15;
691 
692 				return IIO_VAL_FRACTIONAL_LOG2;
693 			}
694 			unreachable();
695 		default:
696 			return -EINVAL;
697 		}
698 	case IIO_CHAN_INFO_CALIBBIAS:
699 		switch (chan->type) {
700 		case IIO_VOLTAGE:
701 			iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
702 				ret = regmap_read(st->regmap16,
703 					AD4695_REG_OFFSET_IN(chan->scan_index),
704 					&reg_val);
705 				if (ret)
706 					return ret;
707 
708 				tmp = sign_extend32(reg_val, 15);
709 
710 				*val = tmp / 4;
711 				*val2 = abs(tmp) % 4 * MICRO / 4;
712 
713 				if (tmp < 0 && *val2) {
714 					*val *= -1;
715 					*val2 *= -1;
716 				}
717 
718 				return IIO_VAL_INT_PLUS_MICRO;
719 			}
720 			unreachable();
721 		default:
722 			return -EINVAL;
723 		}
724 	default:
725 		return -EINVAL;
726 	}
727 }
728 
729 static int ad4695_write_raw(struct iio_dev *indio_dev,
730 			    struct iio_chan_spec const *chan,
731 			    int val, int val2, long mask)
732 {
733 	struct ad4695_state *st = iio_priv(indio_dev);
734 	unsigned int reg_val;
735 
736 	iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
737 		switch (mask) {
738 		case IIO_CHAN_INFO_CALIBSCALE:
739 			switch (chan->type) {
740 			case IIO_VOLTAGE:
741 				if (val < 0 || val2 < 0)
742 					reg_val = 0;
743 				else if (val > 1)
744 					reg_val = U16_MAX;
745 				else
746 					reg_val = (val * (1 << 16) +
747 						   mul_u64_u32_div(val2, 1 << 16,
748 								   MICRO)) / 2;
749 
750 				return regmap_write(st->regmap16,
751 					AD4695_REG_GAIN_IN(chan->scan_index),
752 					reg_val);
753 			default:
754 				return -EINVAL;
755 			}
756 		case IIO_CHAN_INFO_CALIBBIAS:
757 			switch (chan->type) {
758 			case IIO_VOLTAGE:
759 				if (val2 >= 0 && val > S16_MAX / 4)
760 					reg_val = S16_MAX;
761 				else if ((val2 < 0 ? -val : val) < S16_MIN / 4)
762 					reg_val = S16_MIN;
763 				else if (val2 < 0)
764 					reg_val = clamp_t(int,
765 						-(val * 4 + -val2 * 4 / MICRO),
766 						S16_MIN, S16_MAX);
767 				else if (val < 0)
768 					reg_val = clamp_t(int,
769 						val * 4 - val2 * 4 / MICRO,
770 						S16_MIN, S16_MAX);
771 				else
772 					reg_val = clamp_t(int,
773 						val * 4 + val2 * 4 / MICRO,
774 						S16_MIN, S16_MAX);
775 
776 				return regmap_write(st->regmap16,
777 					AD4695_REG_OFFSET_IN(chan->scan_index),
778 					reg_val);
779 			default:
780 				return -EINVAL;
781 			}
782 		default:
783 			return -EINVAL;
784 		}
785 	}
786 	unreachable();
787 }
788 
789 static int ad4695_read_avail(struct iio_dev *indio_dev,
790 			     struct iio_chan_spec const *chan,
791 			     const int **vals, int *type, int *length,
792 			     long mask)
793 {
794 	static const int ad4695_calibscale_available[6] = {
795 		/* Range of 0 (inclusive) to 2 (exclusive) */
796 		0, 15, 1, 15, U16_MAX, 15
797 	};
798 	static const int ad4695_calibbias_available[6] = {
799 		/*
800 		 * Datasheet says FSR/8 which translates to signed/4. The step
801 		 * depends on oversampling ratio which is always 1 for now.
802 		 */
803 		S16_MIN / 4, 0, 0, MICRO / 4, S16_MAX / 4, S16_MAX % 4 * MICRO / 4
804 	};
805 
806 	switch (mask) {
807 	case IIO_CHAN_INFO_CALIBSCALE:
808 		switch (chan->type) {
809 		case IIO_VOLTAGE:
810 			*vals = ad4695_calibscale_available;
811 			*type = IIO_VAL_FRACTIONAL_LOG2;
812 			return IIO_AVAIL_RANGE;
813 		default:
814 			return -EINVAL;
815 		}
816 	case IIO_CHAN_INFO_CALIBBIAS:
817 		switch (chan->type) {
818 		case IIO_VOLTAGE:
819 			*vals = ad4695_calibbias_available;
820 			*type = IIO_VAL_INT_PLUS_MICRO;
821 			return IIO_AVAIL_RANGE;
822 		default:
823 			return -EINVAL;
824 		}
825 	default:
826 		return -EINVAL;
827 	}
828 }
829 
830 static int ad4695_debugfs_reg_access(struct iio_dev *indio_dev,
831 				     unsigned int reg,
832 				     unsigned int writeval,
833 				     unsigned int *readval)
834 {
835 	struct ad4695_state *st = iio_priv(indio_dev);
836 
837 	iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
838 		if (readval) {
839 			if (regmap_check_range_table(st->regmap, reg,
840 						     &ad4695_regmap_rd_table))
841 				return regmap_read(st->regmap, reg, readval);
842 			if (regmap_check_range_table(st->regmap16, reg,
843 						     &ad4695_regmap16_rd_table))
844 				return regmap_read(st->regmap16, reg, readval);
845 		} else {
846 			if (regmap_check_range_table(st->regmap, reg,
847 						     &ad4695_regmap_wr_table))
848 				return regmap_write(st->regmap, reg, writeval);
849 			if (regmap_check_range_table(st->regmap16, reg,
850 						     &ad4695_regmap16_wr_table))
851 				return regmap_write(st->regmap16, reg, writeval);
852 		}
853 	}
854 
855 	return -EINVAL;
856 }
857 
858 static const struct iio_info ad4695_info = {
859 	.read_raw = &ad4695_read_raw,
860 	.write_raw = &ad4695_write_raw,
861 	.read_avail = &ad4695_read_avail,
862 	.debugfs_reg_access = &ad4695_debugfs_reg_access,
863 };
864 
865 static int ad4695_parse_channel_cfg(struct ad4695_state *st)
866 {
867 	struct device *dev = &st->spi->dev;
868 	struct ad4695_channel_config *chan_cfg;
869 	struct iio_chan_spec *iio_chan;
870 	int ret, i;
871 
872 	/* populate defaults */
873 	for (i = 0; i < st->chip_info->num_voltage_inputs; i++) {
874 		chan_cfg = &st->channels_cfg[i];
875 		iio_chan = &st->iio_chan[i];
876 
877 		chan_cfg->highz_en = true;
878 		chan_cfg->channel = i;
879 
880 		*iio_chan = ad4695_channel_template;
881 		iio_chan->channel = i;
882 		iio_chan->scan_index = i;
883 		iio_chan->address = AD4695_CMD_VOLTAGE_CHAN(i);
884 	}
885 
886 	/* modify based on firmware description */
887 	device_for_each_child_node_scoped(dev, child) {
888 		u32 reg, val;
889 
890 		ret = fwnode_property_read_u32(child, "reg", &reg);
891 		if (ret)
892 			return dev_err_probe(dev, ret,
893 				"failed to read reg property (%s)\n",
894 				fwnode_get_name(child));
895 
896 		if (reg >= st->chip_info->num_voltage_inputs)
897 			return dev_err_probe(dev, -EINVAL,
898 				"reg out of range (%s)\n",
899 				fwnode_get_name(child));
900 
901 		iio_chan = &st->iio_chan[reg];
902 		chan_cfg = &st->channels_cfg[reg];
903 
904 		chan_cfg->highz_en =
905 			!fwnode_property_read_bool(child, "adi,no-high-z");
906 		chan_cfg->bipolar = fwnode_property_read_bool(child, "bipolar");
907 
908 		ret = fwnode_property_read_u32(child, "common-mode-channel",
909 					       &val);
910 		if (ret && ret != -EINVAL)
911 			return dev_err_probe(dev, ret,
912 				"failed to read common-mode-channel (%s)\n",
913 				fwnode_get_name(child));
914 
915 		if (ret == -EINVAL || val == AD4695_COMMON_MODE_REFGND)
916 			chan_cfg->pin_pairing = AD4695_IN_PAIR_REFGND;
917 		else if (val == AD4695_COMMON_MODE_COM)
918 			chan_cfg->pin_pairing = AD4695_IN_PAIR_COM;
919 		else
920 			chan_cfg->pin_pairing = AD4695_IN_PAIR_EVEN_ODD;
921 
922 		if (chan_cfg->pin_pairing == AD4695_IN_PAIR_EVEN_ODD &&
923 		    val % 2 == 0)
924 			return dev_err_probe(dev, -EINVAL,
925 				"common-mode-channel must be odd number (%s)\n",
926 				fwnode_get_name(child));
927 
928 		if (chan_cfg->pin_pairing == AD4695_IN_PAIR_EVEN_ODD &&
929 		    val != reg + 1)
930 			return dev_err_probe(dev, -EINVAL,
931 				"common-mode-channel must be next consecutive channel (%s)\n",
932 				fwnode_get_name(child));
933 
934 		if (chan_cfg->pin_pairing == AD4695_IN_PAIR_EVEN_ODD) {
935 			char name[5];
936 
937 			snprintf(name, sizeof(name), "in%d", reg + 1);
938 
939 			ret = devm_regulator_get_enable_read_voltage(dev, name);
940 			if (ret < 0)
941 				return dev_err_probe(dev, ret,
942 					"failed to get %s voltage (%s)\n",
943 					name, fwnode_get_name(child));
944 
945 			chan_cfg->common_mode_mv = ret / 1000;
946 		}
947 
948 		if (chan_cfg->bipolar &&
949 		    chan_cfg->pin_pairing == AD4695_IN_PAIR_REFGND)
950 			return dev_err_probe(dev, -EINVAL,
951 				"bipolar mode is not available for inputs paired with REFGND (%s).\n",
952 				fwnode_get_name(child));
953 
954 		if (chan_cfg->bipolar)
955 			iio_chan->scan_type.sign = 's';
956 
957 		ret = ad4695_write_chn_cfg(st, chan_cfg);
958 		if (ret)
959 			return ret;
960 	}
961 
962 	/* Temperature channel must be next scan index after voltage channels. */
963 	st->iio_chan[i] = ad4695_temp_channel_template;
964 	st->iio_chan[i].scan_index = i;
965 	i++;
966 
967 	st->iio_chan[i] = ad4695_soft_timestamp_channel_template;
968 	st->iio_chan[i].scan_index = i;
969 
970 	return 0;
971 }
972 
973 static int ad4695_probe(struct spi_device *spi)
974 {
975 	struct device *dev = &spi->dev;
976 	struct ad4695_state *st;
977 	struct iio_dev *indio_dev;
978 	struct gpio_desc *cnv_gpio;
979 	bool use_internal_ldo_supply;
980 	bool use_internal_ref_buffer;
981 	int ret;
982 
983 	cnv_gpio = devm_gpiod_get_optional(dev, "cnv", GPIOD_OUT_LOW);
984 	if (IS_ERR(cnv_gpio))
985 		return dev_err_probe(dev, PTR_ERR(cnv_gpio),
986 				     "Failed to get CNV GPIO\n");
987 
988 	/* Driver currently requires CNV pin to be connected to SPI CS */
989 	if (cnv_gpio)
990 		return dev_err_probe(dev, -ENODEV,
991 				     "CNV GPIO is not supported\n");
992 
993 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
994 	if (!indio_dev)
995 		return -ENOMEM;
996 
997 	st = iio_priv(indio_dev);
998 	st->spi = spi;
999 
1000 	st->chip_info = spi_get_device_match_data(spi);
1001 	if (!st->chip_info)
1002 		return -EINVAL;
1003 
1004 	/* Registers cannot be read at the max allowable speed */
1005 	spi->max_speed_hz = AD4695_REG_ACCESS_SCLK_HZ;
1006 
1007 	st->regmap = devm_regmap_init_spi(spi, &ad4695_regmap_config);
1008 	if (IS_ERR(st->regmap))
1009 		return dev_err_probe(dev, PTR_ERR(st->regmap),
1010 				     "Failed to initialize regmap\n");
1011 
1012 	st->regmap16 = devm_regmap_init_spi(spi, &ad4695_regmap16_config);
1013 	if (IS_ERR(st->regmap16))
1014 		return dev_err_probe(dev, PTR_ERR(st->regmap16),
1015 				     "Failed to initialize regmap16\n");
1016 
1017 	ret = devm_regulator_bulk_get_enable(dev,
1018 					     ARRAY_SIZE(ad4695_power_supplies),
1019 					     ad4695_power_supplies);
1020 	if (ret)
1021 		return dev_err_probe(dev, ret,
1022 				     "Failed to enable power supplies\n");
1023 
1024 	/* If LDO_IN supply is present, then we are using internal LDO. */
1025 	ret = devm_regulator_get_enable_optional(dev, "ldo-in");
1026 	if (ret < 0 && ret != -ENODEV)
1027 		return dev_err_probe(dev, ret,
1028 				     "Failed to enable LDO_IN supply\n");
1029 
1030 	use_internal_ldo_supply = ret == 0;
1031 
1032 	if (!use_internal_ldo_supply) {
1033 		/* Otherwise we need an external VDD supply. */
1034 		ret = devm_regulator_get_enable(dev, "vdd");
1035 		if (ret < 0)
1036 			return dev_err_probe(dev, ret,
1037 					     "Failed to enable VDD supply\n");
1038 	}
1039 
1040 	/* If REFIN supply is given, then we are using internal buffer */
1041 	ret = devm_regulator_get_enable_read_voltage(dev, "refin");
1042 	if (ret < 0 && ret != -ENODEV)
1043 		return dev_err_probe(dev, ret, "Failed to get REFIN voltage\n");
1044 
1045 	if (ret != -ENODEV) {
1046 		st->vref_mv = ret / 1000;
1047 		use_internal_ref_buffer = true;
1048 	} else {
1049 		/* Otherwise, we need an external reference. */
1050 		ret = devm_regulator_get_enable_read_voltage(dev, "ref");
1051 		if (ret < 0)
1052 			return dev_err_probe(dev, ret,
1053 					     "Failed to get REF voltage\n");
1054 
1055 		st->vref_mv = ret / 1000;
1056 		use_internal_ref_buffer = false;
1057 	}
1058 
1059 	ret = devm_regulator_get_enable_read_voltage(dev, "com");
1060 	if (ret < 0 && ret != -ENODEV)
1061 		return dev_err_probe(dev, ret, "Failed to get COM voltage\n");
1062 
1063 	st->com_mv = ret == -ENODEV ? 0 : ret / 1000;
1064 
1065 	/*
1066 	 * Reset the device using hardware reset if available or fall back to
1067 	 * software reset.
1068 	 */
1069 
1070 	st->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
1071 	if (IS_ERR(st->reset_gpio))
1072 		return PTR_ERR(st->reset_gpio);
1073 
1074 	if (st->reset_gpio) {
1075 		gpiod_set_value(st->reset_gpio, 0);
1076 		msleep(AD4695_T_WAKEUP_HW_MS);
1077 	} else {
1078 		ret = regmap_write(st->regmap, AD4695_REG_SPI_CONFIG_A,
1079 				   AD4695_REG_SPI_CONFIG_A_SW_RST);
1080 		if (ret)
1081 			return ret;
1082 
1083 		msleep(AD4695_T_WAKEUP_SW_MS);
1084 	}
1085 
1086 	/* Needed for regmap16 to be able to work correctly. */
1087 	ret = regmap_set_bits(st->regmap, AD4695_REG_SPI_CONFIG_A,
1088 			      AD4695_REG_SPI_CONFIG_A_ADDR_DIR);
1089 	if (ret)
1090 		return ret;
1091 
1092 	/* Disable internal LDO if it isn't needed. */
1093 	ret = regmap_update_bits(st->regmap, AD4695_REG_SETUP,
1094 				 AD4695_REG_SETUP_LDO_EN,
1095 				 FIELD_PREP(AD4695_REG_SETUP_LDO_EN,
1096 					    use_internal_ldo_supply ? 1 : 0));
1097 	if (ret)
1098 		return ret;
1099 
1100 	/* configure reference supply */
1101 
1102 	if (device_property_present(dev, "adi,no-ref-current-limit")) {
1103 		ret = regmap_set_bits(st->regmap, AD4695_REG_REF_CTRL,
1104 				      AD4695_REG_REF_CTRL_OV_MODE);
1105 		if (ret)
1106 			return ret;
1107 	}
1108 
1109 	if (device_property_present(dev, "adi,no-ref-high-z")) {
1110 		if (use_internal_ref_buffer)
1111 			return dev_err_probe(dev, -EINVAL,
1112 				"Cannot disable high-Z mode for internal reference buffer\n");
1113 
1114 		ret = regmap_clear_bits(st->regmap, AD4695_REG_REF_CTRL,
1115 					AD4695_REG_REF_CTRL_REFHIZ_EN);
1116 		if (ret)
1117 			return ret;
1118 	}
1119 
1120 	ret = ad4695_set_ref_voltage(st, st->vref_mv);
1121 	if (ret)
1122 		return ret;
1123 
1124 	if (use_internal_ref_buffer) {
1125 		ret = regmap_set_bits(st->regmap, AD4695_REG_REF_CTRL,
1126 				      AD4695_REG_REF_CTRL_REFBUF_EN);
1127 		if (ret)
1128 			return ret;
1129 
1130 		/* Give the capacitor some time to charge up. */
1131 		msleep(AD4695_T_REFBUF_MS);
1132 	}
1133 
1134 	ret = ad4695_parse_channel_cfg(st);
1135 	if (ret)
1136 		return ret;
1137 
1138 	indio_dev->name = st->chip_info->name;
1139 	indio_dev->info = &ad4695_info;
1140 	indio_dev->modes = INDIO_DIRECT_MODE;
1141 	indio_dev->channels = st->iio_chan;
1142 	indio_dev->num_channels = st->chip_info->num_voltage_inputs + 2;
1143 
1144 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
1145 					      iio_pollfunc_store_time,
1146 					      ad4695_trigger_handler,
1147 					      &ad4695_buffer_setup_ops);
1148 	if (ret)
1149 		return ret;
1150 
1151 	return devm_iio_device_register(dev, indio_dev);
1152 }
1153 
1154 static const struct spi_device_id ad4695_spi_id_table[] = {
1155 	{ .name = "ad4695", .driver_data = (kernel_ulong_t)&ad4695_chip_info },
1156 	{ .name = "ad4696", .driver_data = (kernel_ulong_t)&ad4696_chip_info },
1157 	{ .name = "ad4697", .driver_data = (kernel_ulong_t)&ad4697_chip_info },
1158 	{ .name = "ad4698", .driver_data = (kernel_ulong_t)&ad4698_chip_info },
1159 	{ }
1160 };
1161 MODULE_DEVICE_TABLE(spi, ad4695_spi_id_table);
1162 
1163 static const struct of_device_id ad4695_of_match_table[] = {
1164 	{ .compatible = "adi,ad4695", .data = &ad4695_chip_info, },
1165 	{ .compatible = "adi,ad4696", .data = &ad4696_chip_info, },
1166 	{ .compatible = "adi,ad4697", .data = &ad4697_chip_info, },
1167 	{ .compatible = "adi,ad4698", .data = &ad4698_chip_info, },
1168 	{ }
1169 };
1170 MODULE_DEVICE_TABLE(of, ad4695_of_match_table);
1171 
1172 static struct spi_driver ad4695_driver = {
1173 	.driver = {
1174 		.name = "ad4695",
1175 		.of_match_table = ad4695_of_match_table,
1176 	},
1177 	.probe = ad4695_probe,
1178 	.id_table = ad4695_spi_id_table,
1179 };
1180 module_spi_driver(ad4695_driver);
1181 
1182 MODULE_AUTHOR("Ramona Gradinariu <ramona.gradinariu@analog.com>");
1183 MODULE_AUTHOR("David Lechner <dlechner@baylibre.com>");
1184 MODULE_DESCRIPTION("Analog Devices AD4695 ADC driver");
1185 MODULE_LICENSE("GPL");
1186