1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Analog Devices LTC2983 Multi-Sensor Digital Temperature Measurement System
4  * driver
5  *
6  * Copyright 2019 Analog Devices Inc.
7  */
8 #include <linux/bitfield.h>
9 #include <linux/completion.h>
10 #include <linux/device.h>
11 #include <linux/kernel.h>
12 #include <linux/iio/iio.h>
13 #include <linux/interrupt.h>
14 #include <linux/list.h>
15 #include <linux/module.h>
16 #include <linux/of_gpio.h>
17 #include <linux/regmap.h>
18 #include <linux/spi/spi.h>
19 
20 /* register map */
21 #define LTC2983_STATUS_REG			0x0000
22 #define LTC2983_TEMP_RES_START_REG		0x0010
23 #define LTC2983_TEMP_RES_END_REG		0x005F
24 #define LTC2983_GLOBAL_CONFIG_REG		0x00F0
25 #define LTC2983_MULT_CHANNEL_START_REG		0x00F4
26 #define LTC2983_MULT_CHANNEL_END_REG		0x00F7
27 #define LTC2983_MUX_CONFIG_REG			0x00FF
28 #define LTC2983_CHAN_ASSIGN_START_REG		0x0200
29 #define LTC2983_CHAN_ASSIGN_END_REG		0x024F
30 #define LTC2983_CUST_SENS_TBL_START_REG		0x0250
31 #define LTC2983_CUST_SENS_TBL_END_REG		0x03CF
32 
33 #define LTC2983_DIFFERENTIAL_CHAN_MIN		2
34 #define LTC2983_MAX_CHANNELS_NR			20
35 #define LTC2983_MIN_CHANNELS_NR			1
36 #define LTC2983_SLEEP				0x97
37 #define LTC2983_CUSTOM_STEINHART_SIZE		24
38 #define LTC2983_CUSTOM_SENSOR_ENTRY_SZ		6
39 #define LTC2983_CUSTOM_STEINHART_ENTRY_SZ	4
40 
41 #define LTC2983_CHAN_START_ADDR(chan) \
42 			(((chan - 1) * 4) + LTC2983_CHAN_ASSIGN_START_REG)
43 #define LTC2983_CHAN_RES_ADDR(chan) \
44 			(((chan - 1) * 4) + LTC2983_TEMP_RES_START_REG)
45 #define LTC2983_THERMOCOUPLE_DIFF_MASK		BIT(3)
46 #define LTC2983_THERMOCOUPLE_SGL(x) \
47 				FIELD_PREP(LTC2983_THERMOCOUPLE_DIFF_MASK, x)
48 #define LTC2983_THERMOCOUPLE_OC_CURR_MASK	GENMASK(1, 0)
49 #define LTC2983_THERMOCOUPLE_OC_CURR(x) \
50 				FIELD_PREP(LTC2983_THERMOCOUPLE_OC_CURR_MASK, x)
51 #define LTC2983_THERMOCOUPLE_OC_CHECK_MASK	BIT(2)
52 #define LTC2983_THERMOCOUPLE_OC_CHECK(x) \
53 			FIELD_PREP(LTC2983_THERMOCOUPLE_OC_CHECK_MASK, x)
54 
55 #define LTC2983_THERMISTOR_DIFF_MASK		BIT(2)
56 #define LTC2983_THERMISTOR_SGL(x) \
57 				FIELD_PREP(LTC2983_THERMISTOR_DIFF_MASK, x)
58 #define LTC2983_THERMISTOR_R_SHARE_MASK		BIT(1)
59 #define LTC2983_THERMISTOR_R_SHARE(x) \
60 				FIELD_PREP(LTC2983_THERMISTOR_R_SHARE_MASK, x)
61 #define LTC2983_THERMISTOR_C_ROTATE_MASK	BIT(0)
62 #define LTC2983_THERMISTOR_C_ROTATE(x) \
63 				FIELD_PREP(LTC2983_THERMISTOR_C_ROTATE_MASK, x)
64 
65 #define LTC2983_DIODE_DIFF_MASK			BIT(2)
66 #define LTC2983_DIODE_SGL(x) \
67 			FIELD_PREP(LTC2983_DIODE_DIFF_MASK, x)
68 #define LTC2983_DIODE_3_CONV_CYCLE_MASK		BIT(1)
69 #define LTC2983_DIODE_3_CONV_CYCLE(x) \
70 				FIELD_PREP(LTC2983_DIODE_3_CONV_CYCLE_MASK, x)
71 #define LTC2983_DIODE_AVERAGE_ON_MASK		BIT(0)
72 #define LTC2983_DIODE_AVERAGE_ON(x) \
73 				FIELD_PREP(LTC2983_DIODE_AVERAGE_ON_MASK, x)
74 
75 #define LTC2983_RTD_4_WIRE_MASK			BIT(3)
76 #define LTC2983_RTD_ROTATION_MASK		BIT(1)
77 #define LTC2983_RTD_C_ROTATE(x) \
78 			FIELD_PREP(LTC2983_RTD_ROTATION_MASK, x)
79 #define LTC2983_RTD_KELVIN_R_SENSE_MASK		GENMASK(3, 2)
80 #define LTC2983_RTD_N_WIRES_MASK		GENMASK(3, 2)
81 #define LTC2983_RTD_N_WIRES(x) \
82 			FIELD_PREP(LTC2983_RTD_N_WIRES_MASK, x)
83 #define LTC2983_RTD_R_SHARE_MASK		BIT(0)
84 #define LTC2983_RTD_R_SHARE(x) \
85 			FIELD_PREP(LTC2983_RTD_R_SHARE_MASK, 1)
86 
87 #define LTC2983_COMMON_HARD_FAULT_MASK	GENMASK(31, 30)
88 #define LTC2983_COMMON_SOFT_FAULT_MASK	GENMASK(27, 25)
89 
90 #define	LTC2983_STATUS_START_MASK	BIT(7)
91 #define	LTC2983_STATUS_START(x)		FIELD_PREP(LTC2983_STATUS_START_MASK, x)
92 
93 #define	LTC2983_STATUS_CHAN_SEL_MASK	GENMASK(4, 0)
94 #define	LTC2983_STATUS_CHAN_SEL(x) \
95 				FIELD_PREP(LTC2983_STATUS_CHAN_SEL_MASK, x)
96 
97 #define LTC2983_TEMP_UNITS_MASK		BIT(2)
98 #define LTC2983_TEMP_UNITS(x)		FIELD_PREP(LTC2983_TEMP_UNITS_MASK, x)
99 
100 #define LTC2983_NOTCH_FREQ_MASK		GENMASK(1, 0)
101 #define LTC2983_NOTCH_FREQ(x)		FIELD_PREP(LTC2983_NOTCH_FREQ_MASK, x)
102 
103 #define LTC2983_RES_VALID_MASK		BIT(24)
104 #define LTC2983_DATA_MASK		GENMASK(23, 0)
105 #define LTC2983_DATA_SIGN_BIT		23
106 
107 #define LTC2983_CHAN_TYPE_MASK		GENMASK(31, 27)
108 #define LTC2983_CHAN_TYPE(x)		FIELD_PREP(LTC2983_CHAN_TYPE_MASK, x)
109 
110 /* cold junction for thermocouples and rsense for rtd's and thermistor's */
111 #define LTC2983_CHAN_ASSIGN_MASK	GENMASK(26, 22)
112 #define LTC2983_CHAN_ASSIGN(x)		FIELD_PREP(LTC2983_CHAN_ASSIGN_MASK, x)
113 
114 #define LTC2983_CUSTOM_LEN_MASK		GENMASK(5, 0)
115 #define LTC2983_CUSTOM_LEN(x)		FIELD_PREP(LTC2983_CUSTOM_LEN_MASK, x)
116 
117 #define LTC2983_CUSTOM_ADDR_MASK	GENMASK(11, 6)
118 #define LTC2983_CUSTOM_ADDR(x)		FIELD_PREP(LTC2983_CUSTOM_ADDR_MASK, x)
119 
120 #define LTC2983_THERMOCOUPLE_CFG_MASK	GENMASK(21, 18)
121 #define LTC2983_THERMOCOUPLE_CFG(x) \
122 				FIELD_PREP(LTC2983_THERMOCOUPLE_CFG_MASK, x)
123 #define LTC2983_THERMOCOUPLE_HARD_FAULT_MASK	GENMASK(31, 29)
124 #define LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK	GENMASK(28, 25)
125 
126 #define LTC2983_RTD_CFG_MASK		GENMASK(21, 18)
127 #define LTC2983_RTD_CFG(x)		FIELD_PREP(LTC2983_RTD_CFG_MASK, x)
128 #define LTC2983_RTD_EXC_CURRENT_MASK	GENMASK(17, 14)
129 #define LTC2983_RTD_EXC_CURRENT(x) \
130 				FIELD_PREP(LTC2983_RTD_EXC_CURRENT_MASK, x)
131 #define LTC2983_RTD_CURVE_MASK		GENMASK(13, 12)
132 #define LTC2983_RTD_CURVE(x)		FIELD_PREP(LTC2983_RTD_CURVE_MASK, x)
133 
134 #define LTC2983_THERMISTOR_CFG_MASK	GENMASK(21, 19)
135 #define LTC2983_THERMISTOR_CFG(x) \
136 				FIELD_PREP(LTC2983_THERMISTOR_CFG_MASK, x)
137 #define LTC2983_THERMISTOR_EXC_CURRENT_MASK	GENMASK(18, 15)
138 #define LTC2983_THERMISTOR_EXC_CURRENT(x) \
139 			FIELD_PREP(LTC2983_THERMISTOR_EXC_CURRENT_MASK, x)
140 
141 #define LTC2983_DIODE_CFG_MASK		GENMASK(26, 24)
142 #define LTC2983_DIODE_CFG(x)		FIELD_PREP(LTC2983_DIODE_CFG_MASK, x)
143 #define LTC2983_DIODE_EXC_CURRENT_MASK	GENMASK(23, 22)
144 #define LTC2983_DIODE_EXC_CURRENT(x) \
145 				FIELD_PREP(LTC2983_DIODE_EXC_CURRENT_MASK, x)
146 #define LTC2983_DIODE_IDEAL_FACTOR_MASK	GENMASK(21, 0)
147 #define LTC2983_DIODE_IDEAL_FACTOR(x) \
148 				FIELD_PREP(LTC2983_DIODE_IDEAL_FACTOR_MASK, x)
149 
150 #define LTC2983_R_SENSE_VAL_MASK	GENMASK(26, 0)
151 #define LTC2983_R_SENSE_VAL(x)		FIELD_PREP(LTC2983_R_SENSE_VAL_MASK, x)
152 
153 #define LTC2983_ADC_SINGLE_ENDED_MASK	BIT(26)
154 #define LTC2983_ADC_SINGLE_ENDED(x) \
155 				FIELD_PREP(LTC2983_ADC_SINGLE_ENDED_MASK, x)
156 
157 enum {
158 	LTC2983_SENSOR_THERMOCOUPLE = 1,
159 	LTC2983_SENSOR_THERMOCOUPLE_CUSTOM = 9,
160 	LTC2983_SENSOR_RTD = 10,
161 	LTC2983_SENSOR_RTD_CUSTOM = 18,
162 	LTC2983_SENSOR_THERMISTOR = 19,
163 	LTC2983_SENSOR_THERMISTOR_STEINHART = 26,
164 	LTC2983_SENSOR_THERMISTOR_CUSTOM = 27,
165 	LTC2983_SENSOR_DIODE = 28,
166 	LTC2983_SENSOR_SENSE_RESISTOR = 29,
167 	LTC2983_SENSOR_DIRECT_ADC = 30,
168 };
169 
170 #define to_thermocouple(_sensor) \
171 		container_of(_sensor, struct ltc2983_thermocouple, sensor)
172 
173 #define to_rtd(_sensor) \
174 		container_of(_sensor, struct ltc2983_rtd, sensor)
175 
176 #define to_thermistor(_sensor) \
177 		container_of(_sensor, struct ltc2983_thermistor, sensor)
178 
179 #define to_diode(_sensor) \
180 		container_of(_sensor, struct ltc2983_diode, sensor)
181 
182 #define to_rsense(_sensor) \
183 		container_of(_sensor, struct ltc2983_rsense, sensor)
184 
185 #define to_adc(_sensor) \
186 		container_of(_sensor, struct ltc2983_adc, sensor)
187 
188 struct ltc2983_data {
189 	struct regmap *regmap;
190 	struct spi_device *spi;
191 	struct mutex lock;
192 	struct completion completion;
193 	struct iio_chan_spec *iio_chan;
194 	struct ltc2983_sensor **sensors;
195 	u32 mux_delay_config;
196 	u32 filter_notch_freq;
197 	u16 custom_table_size;
198 	u8 num_channels;
199 	u8 iio_channels;
200 	/*
201 	 * DMA (thus cache coherency maintenance) requires the
202 	 * transfer buffers to live in their own cache lines.
203 	 * Holds the converted temperature
204 	 */
205 	__be32 temp ____cacheline_aligned;
206 };
207 
208 struct ltc2983_sensor {
209 	int (*fault_handler)(const struct ltc2983_data *st, const u32 result);
210 	int (*assign_chan)(struct ltc2983_data *st,
211 			   const struct ltc2983_sensor *sensor);
212 	/* specifies the sensor channel */
213 	u32 chan;
214 	/* sensor type */
215 	u32 type;
216 };
217 
218 struct ltc2983_custom_sensor {
219 	/* raw table sensor data */
220 	u8 *table;
221 	size_t size;
222 	/* address offset */
223 	s8 offset;
224 	bool is_steinhart;
225 };
226 
227 struct ltc2983_thermocouple {
228 	struct ltc2983_sensor sensor;
229 	struct ltc2983_custom_sensor *custom;
230 	u32 sensor_config;
231 	u32 cold_junction_chan;
232 };
233 
234 struct ltc2983_rtd {
235 	struct ltc2983_sensor sensor;
236 	struct ltc2983_custom_sensor *custom;
237 	u32 sensor_config;
238 	u32 r_sense_chan;
239 	u32 excitation_current;
240 	u32 rtd_curve;
241 };
242 
243 struct ltc2983_thermistor {
244 	struct ltc2983_sensor sensor;
245 	struct ltc2983_custom_sensor *custom;
246 	u32 sensor_config;
247 	u32 r_sense_chan;
248 	u32 excitation_current;
249 };
250 
251 struct ltc2983_diode {
252 	struct ltc2983_sensor sensor;
253 	u32 sensor_config;
254 	u32 excitation_current;
255 	u32 ideal_factor_value;
256 };
257 
258 struct ltc2983_rsense {
259 	struct ltc2983_sensor sensor;
260 	u32 r_sense_val;
261 };
262 
263 struct ltc2983_adc {
264 	struct ltc2983_sensor sensor;
265 	bool single_ended;
266 };
267 
268 /*
269  * Convert to Q format numbers. These number's are integers where
270  * the number of integer and fractional bits are specified. The resolution
271  * is given by 1/@resolution and tell us the number of fractional bits. For
272  * instance a resolution of 2^-10 means we have 10 fractional bits.
273  */
274 static u32 __convert_to_raw(const u64 val, const u32 resolution)
275 {
276 	u64 __res = val * resolution;
277 
278 	/* all values are multiplied by 1000000 to remove the fraction */
279 	do_div(__res, 1000000);
280 
281 	return __res;
282 }
283 
284 static u32 __convert_to_raw_sign(const u64 val, const u32 resolution)
285 {
286 	s64 __res = -(s32)val;
287 
288 	__res = __convert_to_raw(__res, resolution);
289 
290 	return (u32)-__res;
291 }
292 
293 static int __ltc2983_fault_handler(const struct ltc2983_data *st,
294 				   const u32 result, const u32 hard_mask,
295 				   const u32 soft_mask)
296 {
297 	const struct device *dev = &st->spi->dev;
298 
299 	if (result & hard_mask) {
300 		dev_err(dev, "Invalid conversion: Sensor HARD fault\n");
301 		return -EIO;
302 	} else if (result & soft_mask) {
303 		/* just print a warning */
304 		dev_warn(dev, "Suspicious conversion: Sensor SOFT fault\n");
305 	}
306 
307 	return 0;
308 }
309 
310 static int __ltc2983_chan_assign_common(const struct ltc2983_data *st,
311 					const struct ltc2983_sensor *sensor,
312 					u32 chan_val)
313 {
314 	u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
315 	__be32 __chan_val;
316 
317 	chan_val |= LTC2983_CHAN_TYPE(sensor->type);
318 	dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
319 		chan_val);
320 	__chan_val = cpu_to_be32(chan_val);
321 	return regmap_bulk_write(st->regmap, reg, &__chan_val,
322 				 sizeof(__chan_val));
323 }
324 
325 static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,
326 					  struct ltc2983_custom_sensor *custom,
327 					  u32 *chan_val)
328 {
329 	u32 reg;
330 	u8 mult = custom->is_steinhart ? LTC2983_CUSTOM_STEINHART_ENTRY_SZ :
331 		LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
332 	const struct device *dev = &st->spi->dev;
333 	/*
334 	 * custom->size holds the raw size of the table. However, when
335 	 * configuring the sensor channel, we must write the number of
336 	 * entries of the table minus 1. For steinhart sensors 0 is written
337 	 * since the size is constant!
338 	 */
339 	const u8 len = custom->is_steinhart ? 0 :
340 		(custom->size / LTC2983_CUSTOM_SENSOR_ENTRY_SZ) - 1;
341 	/*
342 	 * Check if the offset was assigned already. It should be for steinhart
343 	 * sensors. When coming from sleep, it should be assigned for all.
344 	 */
345 	if (custom->offset < 0) {
346 		/*
347 		 * This needs to be done again here because, from the moment
348 		 * when this test was done (successfully) for this custom
349 		 * sensor, a steinhart sensor might have been added changing
350 		 * custom_table_size...
351 		 */
352 		if (st->custom_table_size + custom->size >
353 		    (LTC2983_CUST_SENS_TBL_END_REG -
354 		     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
355 			dev_err(dev,
356 				"Not space left(%d) for new custom sensor(%zu)",
357 				st->custom_table_size,
358 				custom->size);
359 			return -EINVAL;
360 		}
361 
362 		custom->offset = st->custom_table_size /
363 					LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
364 		st->custom_table_size += custom->size;
365 	}
366 
367 	reg = (custom->offset * mult) + LTC2983_CUST_SENS_TBL_START_REG;
368 
369 	*chan_val |= LTC2983_CUSTOM_LEN(len);
370 	*chan_val |= LTC2983_CUSTOM_ADDR(custom->offset);
371 	dev_dbg(dev, "Assign custom sensor, reg:0x%04X, off:%d, sz:%zu",
372 		reg, custom->offset,
373 		custom->size);
374 	/* write custom sensor table */
375 	return regmap_bulk_write(st->regmap, reg, custom->table, custom->size);
376 }
377 
378 static struct ltc2983_custom_sensor *__ltc2983_custom_sensor_new(
379 						struct ltc2983_data *st,
380 						const struct device_node *np,
381 						const char *propname,
382 						const bool is_steinhart,
383 						const u32 resolution,
384 						const bool has_signed)
385 {
386 	struct ltc2983_custom_sensor *new_custom;
387 	u8 index, n_entries, tbl = 0;
388 	struct device *dev = &st->spi->dev;
389 	/*
390 	 * For custom steinhart, the full u32 is taken. For all the others
391 	 * the MSB is discarded.
392 	 */
393 	const u8 n_size = is_steinhart ? 4 : 3;
394 	const u8 e_size = is_steinhart ? sizeof(u32) : sizeof(u64);
395 
396 	n_entries = of_property_count_elems_of_size(np, propname, e_size);
397 	/* n_entries must be an even number */
398 	if (!n_entries || (n_entries % 2) != 0) {
399 		dev_err(dev, "Number of entries either 0 or not even\n");
400 		return ERR_PTR(-EINVAL);
401 	}
402 
403 	new_custom = devm_kzalloc(dev, sizeof(*new_custom), GFP_KERNEL);
404 	if (!new_custom)
405 		return ERR_PTR(-ENOMEM);
406 
407 	new_custom->size = n_entries * n_size;
408 	/* check Steinhart size */
409 	if (is_steinhart && new_custom->size != LTC2983_CUSTOM_STEINHART_SIZE) {
410 		dev_err(dev, "Steinhart sensors size(%zu) must be 24",
411 							new_custom->size);
412 		return ERR_PTR(-EINVAL);
413 	}
414 	/* Check space on the table. */
415 	if (st->custom_table_size + new_custom->size >
416 	    (LTC2983_CUST_SENS_TBL_END_REG -
417 	     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
418 		dev_err(dev, "No space left(%d) for new custom sensor(%zu)",
419 				st->custom_table_size, new_custom->size);
420 		return ERR_PTR(-EINVAL);
421 	}
422 
423 	/* allocate the table */
424 	new_custom->table = devm_kzalloc(dev, new_custom->size, GFP_KERNEL);
425 	if (!new_custom->table)
426 		return ERR_PTR(-ENOMEM);
427 
428 	for (index = 0; index < n_entries; index++) {
429 		u64 temp = 0, j;
430 		/*
431 		 * Steinhart sensors are configured with raw values in the
432 		 * devicetree. For the other sensors we must convert the
433 		 * value to raw. The odd index's correspond to temperarures
434 		 * and always have 1/1024 of resolution. Temperatures also
435 		 * come in kelvin, so signed values is not possible
436 		 */
437 		if (!is_steinhart) {
438 			of_property_read_u64_index(np, propname, index, &temp);
439 
440 			if ((index % 2) != 0)
441 				temp = __convert_to_raw(temp, 1024);
442 			else if (has_signed && (s64)temp < 0)
443 				temp = __convert_to_raw_sign(temp, resolution);
444 			else
445 				temp = __convert_to_raw(temp, resolution);
446 		} else {
447 			u32 t32;
448 
449 			of_property_read_u32_index(np, propname, index, &t32);
450 			temp = t32;
451 		}
452 
453 		for (j = 0; j < n_size; j++)
454 			new_custom->table[tbl++] =
455 				temp >> (8 * (n_size - j - 1));
456 	}
457 
458 	new_custom->is_steinhart = is_steinhart;
459 	/*
460 	 * This is done to first add all the steinhart sensors to the table,
461 	 * in order to maximize the table usage. If we mix adding steinhart
462 	 * with the other sensors, we might have to do some roundup to make
463 	 * sure that sensor_addr - 0x250(start address) is a multiple of 4
464 	 * (for steinhart), and a multiple of 6 for all the other sensors.
465 	 * Since we have const 24 bytes for steinhart sensors and 24 is
466 	 * also a multiple of 6, we guarantee that the first non-steinhart
467 	 * sensor will sit in a correct address without the need of filling
468 	 * addresses.
469 	 */
470 	if (is_steinhart) {
471 		new_custom->offset = st->custom_table_size /
472 					LTC2983_CUSTOM_STEINHART_ENTRY_SZ;
473 		st->custom_table_size += new_custom->size;
474 	} else {
475 		/* mark as unset. This is checked later on the assign phase */
476 		new_custom->offset = -1;
477 	}
478 
479 	return new_custom;
480 }
481 
482 static int ltc2983_thermocouple_fault_handler(const struct ltc2983_data *st,
483 					      const u32 result)
484 {
485 	return __ltc2983_fault_handler(st, result,
486 				       LTC2983_THERMOCOUPLE_HARD_FAULT_MASK,
487 				       LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK);
488 }
489 
490 static int ltc2983_common_fault_handler(const struct ltc2983_data *st,
491 					const u32 result)
492 {
493 	return __ltc2983_fault_handler(st, result,
494 				       LTC2983_COMMON_HARD_FAULT_MASK,
495 				       LTC2983_COMMON_SOFT_FAULT_MASK);
496 }
497 
498 static int ltc2983_thermocouple_assign_chan(struct ltc2983_data *st,
499 				const struct ltc2983_sensor *sensor)
500 {
501 	struct ltc2983_thermocouple *thermo = to_thermocouple(sensor);
502 	u32 chan_val;
503 
504 	chan_val = LTC2983_CHAN_ASSIGN(thermo->cold_junction_chan);
505 	chan_val |= LTC2983_THERMOCOUPLE_CFG(thermo->sensor_config);
506 
507 	if (thermo->custom) {
508 		int ret;
509 
510 		ret = __ltc2983_chan_custom_sensor_assign(st, thermo->custom,
511 							  &chan_val);
512 		if (ret)
513 			return ret;
514 	}
515 	return __ltc2983_chan_assign_common(st, sensor, chan_val);
516 }
517 
518 static int ltc2983_rtd_assign_chan(struct ltc2983_data *st,
519 				   const struct ltc2983_sensor *sensor)
520 {
521 	struct ltc2983_rtd *rtd = to_rtd(sensor);
522 	u32 chan_val;
523 
524 	chan_val = LTC2983_CHAN_ASSIGN(rtd->r_sense_chan);
525 	chan_val |= LTC2983_RTD_CFG(rtd->sensor_config);
526 	chan_val |= LTC2983_RTD_EXC_CURRENT(rtd->excitation_current);
527 	chan_val |= LTC2983_RTD_CURVE(rtd->rtd_curve);
528 
529 	if (rtd->custom) {
530 		int ret;
531 
532 		ret = __ltc2983_chan_custom_sensor_assign(st, rtd->custom,
533 							  &chan_val);
534 		if (ret)
535 			return ret;
536 	}
537 	return __ltc2983_chan_assign_common(st, sensor, chan_val);
538 }
539 
540 static int ltc2983_thermistor_assign_chan(struct ltc2983_data *st,
541 					  const struct ltc2983_sensor *sensor)
542 {
543 	struct ltc2983_thermistor *thermistor = to_thermistor(sensor);
544 	u32 chan_val;
545 
546 	chan_val = LTC2983_CHAN_ASSIGN(thermistor->r_sense_chan);
547 	chan_val |= LTC2983_THERMISTOR_CFG(thermistor->sensor_config);
548 	chan_val |=
549 		LTC2983_THERMISTOR_EXC_CURRENT(thermistor->excitation_current);
550 
551 	if (thermistor->custom) {
552 		int ret;
553 
554 		ret = __ltc2983_chan_custom_sensor_assign(st,
555 							  thermistor->custom,
556 							  &chan_val);
557 		if (ret)
558 			return ret;
559 	}
560 	return __ltc2983_chan_assign_common(st, sensor, chan_val);
561 }
562 
563 static int ltc2983_diode_assign_chan(struct ltc2983_data *st,
564 				     const struct ltc2983_sensor *sensor)
565 {
566 	struct ltc2983_diode *diode = to_diode(sensor);
567 	u32 chan_val;
568 
569 	chan_val = LTC2983_DIODE_CFG(diode->sensor_config);
570 	chan_val |= LTC2983_DIODE_EXC_CURRENT(diode->excitation_current);
571 	chan_val |= LTC2983_DIODE_IDEAL_FACTOR(diode->ideal_factor_value);
572 
573 	return __ltc2983_chan_assign_common(st, sensor, chan_val);
574 }
575 
576 static int ltc2983_r_sense_assign_chan(struct ltc2983_data *st,
577 				       const struct ltc2983_sensor *sensor)
578 {
579 	struct ltc2983_rsense *rsense = to_rsense(sensor);
580 	u32 chan_val;
581 
582 	chan_val = LTC2983_R_SENSE_VAL(rsense->r_sense_val);
583 
584 	return __ltc2983_chan_assign_common(st, sensor, chan_val);
585 }
586 
587 static int ltc2983_adc_assign_chan(struct ltc2983_data *st,
588 				   const struct ltc2983_sensor *sensor)
589 {
590 	struct ltc2983_adc *adc = to_adc(sensor);
591 	u32 chan_val;
592 
593 	chan_val = LTC2983_ADC_SINGLE_ENDED(adc->single_ended);
594 
595 	return __ltc2983_chan_assign_common(st, sensor, chan_val);
596 }
597 
598 static struct ltc2983_sensor *ltc2983_thermocouple_new(
599 					const struct device_node *child,
600 					struct ltc2983_data *st,
601 					const struct ltc2983_sensor *sensor)
602 {
603 	struct ltc2983_thermocouple *thermo;
604 	struct device_node *phandle;
605 	u32 oc_current;
606 	int ret;
607 
608 	thermo = devm_kzalloc(&st->spi->dev, sizeof(*thermo), GFP_KERNEL);
609 	if (!thermo)
610 		return ERR_PTR(-ENOMEM);
611 
612 	if (of_property_read_bool(child, "adi,single-ended"))
613 		thermo->sensor_config = LTC2983_THERMOCOUPLE_SGL(1);
614 
615 	ret = of_property_read_u32(child, "adi,sensor-oc-current-microamp",
616 				   &oc_current);
617 	if (!ret) {
618 		switch (oc_current) {
619 		case 10:
620 			thermo->sensor_config |=
621 					LTC2983_THERMOCOUPLE_OC_CURR(0);
622 			break;
623 		case 100:
624 			thermo->sensor_config |=
625 					LTC2983_THERMOCOUPLE_OC_CURR(1);
626 			break;
627 		case 500:
628 			thermo->sensor_config |=
629 					LTC2983_THERMOCOUPLE_OC_CURR(2);
630 			break;
631 		case 1000:
632 			thermo->sensor_config |=
633 					LTC2983_THERMOCOUPLE_OC_CURR(3);
634 			break;
635 		default:
636 			dev_err(&st->spi->dev,
637 				"Invalid open circuit current:%u", oc_current);
638 			return ERR_PTR(-EINVAL);
639 		}
640 
641 		thermo->sensor_config |= LTC2983_THERMOCOUPLE_OC_CHECK(1);
642 	}
643 	/* validate channel index */
644 	if (!(thermo->sensor_config & LTC2983_THERMOCOUPLE_DIFF_MASK) &&
645 	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
646 		dev_err(&st->spi->dev,
647 			"Invalid chann:%d for differential thermocouple",
648 			sensor->chan);
649 		return ERR_PTR(-EINVAL);
650 	}
651 
652 	phandle = of_parse_phandle(child, "adi,cold-junction-handle", 0);
653 	if (phandle) {
654 		int ret;
655 
656 		ret = of_property_read_u32(phandle, "reg",
657 					   &thermo->cold_junction_chan);
658 		if (ret) {
659 			/*
660 			 * This would be catched later but we can just return
661 			 * the error right away.
662 			 */
663 			dev_err(&st->spi->dev, "Property reg must be given\n");
664 			of_node_put(phandle);
665 			return ERR_PTR(-EINVAL);
666 		}
667 	}
668 
669 	/* check custom sensor */
670 	if (sensor->type == LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
671 		const char *propname = "adi,custom-thermocouple";
672 
673 		thermo->custom = __ltc2983_custom_sensor_new(st, child,
674 							     propname, false,
675 							     16384, true);
676 		if (IS_ERR(thermo->custom)) {
677 			of_node_put(phandle);
678 			return ERR_CAST(thermo->custom);
679 		}
680 	}
681 
682 	/* set common parameters */
683 	thermo->sensor.fault_handler = ltc2983_thermocouple_fault_handler;
684 	thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;
685 
686 	of_node_put(phandle);
687 	return &thermo->sensor;
688 }
689 
690 static struct ltc2983_sensor *ltc2983_rtd_new(const struct device_node *child,
691 					  struct ltc2983_data *st,
692 					  const struct ltc2983_sensor *sensor)
693 {
694 	struct ltc2983_rtd *rtd;
695 	int ret = 0;
696 	struct device *dev = &st->spi->dev;
697 	struct device_node *phandle;
698 	u32 excitation_current = 0, n_wires = 0;
699 
700 	rtd = devm_kzalloc(dev, sizeof(*rtd), GFP_KERNEL);
701 	if (!rtd)
702 		return ERR_PTR(-ENOMEM);
703 
704 	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
705 	if (!phandle) {
706 		dev_err(dev, "Property adi,rsense-handle missing or invalid");
707 		return ERR_PTR(-EINVAL);
708 	}
709 
710 	ret = of_property_read_u32(phandle, "reg", &rtd->r_sense_chan);
711 	if (ret) {
712 		dev_err(dev, "Property reg must be given\n");
713 		goto fail;
714 	}
715 
716 	ret = of_property_read_u32(child, "adi,number-of-wires", &n_wires);
717 	if (!ret) {
718 		switch (n_wires) {
719 		case 2:
720 			rtd->sensor_config = LTC2983_RTD_N_WIRES(0);
721 			break;
722 		case 3:
723 			rtd->sensor_config = LTC2983_RTD_N_WIRES(1);
724 			break;
725 		case 4:
726 			rtd->sensor_config = LTC2983_RTD_N_WIRES(2);
727 			break;
728 		case 5:
729 			/* 4 wires, Kelvin Rsense */
730 			rtd->sensor_config = LTC2983_RTD_N_WIRES(3);
731 			break;
732 		default:
733 			dev_err(dev, "Invalid number of wires:%u\n", n_wires);
734 			ret = -EINVAL;
735 			goto fail;
736 		}
737 	}
738 
739 	if (of_property_read_bool(child, "adi,rsense-share")) {
740 		/* Current rotation is only available with rsense sharing */
741 		if (of_property_read_bool(child, "adi,current-rotate")) {
742 			if (n_wires == 2 || n_wires == 3) {
743 				dev_err(dev,
744 					"Rotation not allowed for 2/3 Wire RTDs");
745 				ret = -EINVAL;
746 				goto fail;
747 			}
748 			rtd->sensor_config |= LTC2983_RTD_C_ROTATE(1);
749 		} else {
750 			rtd->sensor_config |= LTC2983_RTD_R_SHARE(1);
751 		}
752 	}
753 	/*
754 	 * rtd channel indexes are a bit more complicated to validate.
755 	 * For 4wire RTD with rotation, the channel selection cannot be
756 	 * >=19 since the chann + 1 is used in this configuration.
757 	 * For 4wire RTDs with kelvin rsense, the rsense channel cannot be
758 	 * <=1 since chanel - 1 and channel - 2 are used.
759 	 */
760 	if (rtd->sensor_config & LTC2983_RTD_4_WIRE_MASK) {
761 		/* 4-wire */
762 		u8 min = LTC2983_DIFFERENTIAL_CHAN_MIN,
763 			max = LTC2983_MAX_CHANNELS_NR;
764 
765 		if (rtd->sensor_config & LTC2983_RTD_ROTATION_MASK)
766 			max = LTC2983_MAX_CHANNELS_NR - 1;
767 
768 		if (((rtd->sensor_config & LTC2983_RTD_KELVIN_R_SENSE_MASK)
769 		     == LTC2983_RTD_KELVIN_R_SENSE_MASK) &&
770 		    (rtd->r_sense_chan <=  min)) {
771 			/* kelvin rsense*/
772 			dev_err(dev,
773 				"Invalid rsense chann:%d to use in kelvin rsense",
774 				rtd->r_sense_chan);
775 
776 			ret = -EINVAL;
777 			goto fail;
778 		}
779 
780 		if (sensor->chan < min || sensor->chan > max) {
781 			dev_err(dev, "Invalid chann:%d for the rtd config",
782 				sensor->chan);
783 
784 			ret = -EINVAL;
785 			goto fail;
786 		}
787 	} else {
788 		/* same as differential case */
789 		if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
790 			dev_err(&st->spi->dev,
791 				"Invalid chann:%d for RTD", sensor->chan);
792 
793 			ret = -EINVAL;
794 			goto fail;
795 		}
796 	}
797 
798 	/* check custom sensor */
799 	if (sensor->type == LTC2983_SENSOR_RTD_CUSTOM) {
800 		rtd->custom = __ltc2983_custom_sensor_new(st, child,
801 							  "adi,custom-rtd",
802 							  false, 2048, false);
803 		if (IS_ERR(rtd->custom)) {
804 			of_node_put(phandle);
805 			return ERR_CAST(rtd->custom);
806 		}
807 	}
808 
809 	/* set common parameters */
810 	rtd->sensor.fault_handler = ltc2983_common_fault_handler;
811 	rtd->sensor.assign_chan = ltc2983_rtd_assign_chan;
812 
813 	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
814 				   &excitation_current);
815 	if (ret) {
816 		/* default to 5uA */
817 		rtd->excitation_current = 1;
818 	} else {
819 		switch (excitation_current) {
820 		case 5:
821 			rtd->excitation_current = 0x01;
822 			break;
823 		case 10:
824 			rtd->excitation_current = 0x02;
825 			break;
826 		case 25:
827 			rtd->excitation_current = 0x03;
828 			break;
829 		case 50:
830 			rtd->excitation_current = 0x04;
831 			break;
832 		case 100:
833 			rtd->excitation_current = 0x05;
834 			break;
835 		case 250:
836 			rtd->excitation_current = 0x06;
837 			break;
838 		case 500:
839 			rtd->excitation_current = 0x07;
840 			break;
841 		case 1000:
842 			rtd->excitation_current = 0x08;
843 			break;
844 		default:
845 			dev_err(&st->spi->dev,
846 				"Invalid value for excitation current(%u)",
847 				excitation_current);
848 			ret = -EINVAL;
849 			goto fail;
850 		}
851 	}
852 
853 	of_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);
854 
855 	of_node_put(phandle);
856 	return &rtd->sensor;
857 fail:
858 	of_node_put(phandle);
859 	return ERR_PTR(ret);
860 }
861 
862 static struct ltc2983_sensor *ltc2983_thermistor_new(
863 					const struct device_node *child,
864 					struct ltc2983_data *st,
865 					const struct ltc2983_sensor *sensor)
866 {
867 	struct ltc2983_thermistor *thermistor;
868 	struct device *dev = &st->spi->dev;
869 	struct device_node *phandle;
870 	u32 excitation_current = 0;
871 	int ret = 0;
872 
873 	thermistor = devm_kzalloc(dev, sizeof(*thermistor), GFP_KERNEL);
874 	if (!thermistor)
875 		return ERR_PTR(-ENOMEM);
876 
877 	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
878 	if (!phandle) {
879 		dev_err(dev, "Property adi,rsense-handle missing or invalid");
880 		return ERR_PTR(-EINVAL);
881 	}
882 
883 	ret = of_property_read_u32(phandle, "reg", &thermistor->r_sense_chan);
884 	if (ret) {
885 		dev_err(dev, "rsense channel must be configured...\n");
886 		goto fail;
887 	}
888 
889 	if (of_property_read_bool(child, "adi,single-ended")) {
890 		thermistor->sensor_config = LTC2983_THERMISTOR_SGL(1);
891 	} else if (of_property_read_bool(child, "adi,rsense-share")) {
892 		/* rotation is only possible if sharing rsense */
893 		if (of_property_read_bool(child, "adi,current-rotate"))
894 			thermistor->sensor_config =
895 						LTC2983_THERMISTOR_C_ROTATE(1);
896 		else
897 			thermistor->sensor_config =
898 						LTC2983_THERMISTOR_R_SHARE(1);
899 	}
900 	/* validate channel index */
901 	if (!(thermistor->sensor_config & LTC2983_THERMISTOR_DIFF_MASK) &&
902 	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
903 		dev_err(&st->spi->dev,
904 			"Invalid chann:%d for differential thermistor",
905 			sensor->chan);
906 		ret = -EINVAL;
907 		goto fail;
908 	}
909 
910 	/* check custom sensor */
911 	if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART) {
912 		bool steinhart = false;
913 		const char *propname;
914 
915 		if (sensor->type == LTC2983_SENSOR_THERMISTOR_STEINHART) {
916 			steinhart = true;
917 			propname = "adi,custom-steinhart";
918 		} else {
919 			propname = "adi,custom-thermistor";
920 		}
921 
922 		thermistor->custom = __ltc2983_custom_sensor_new(st, child,
923 								 propname,
924 								 steinhart,
925 								 64, false);
926 		if (IS_ERR(thermistor->custom)) {
927 			of_node_put(phandle);
928 			return ERR_CAST(thermistor->custom);
929 		}
930 	}
931 	/* set common parameters */
932 	thermistor->sensor.fault_handler = ltc2983_common_fault_handler;
933 	thermistor->sensor.assign_chan = ltc2983_thermistor_assign_chan;
934 
935 	ret = of_property_read_u32(child, "adi,excitation-current-nanoamp",
936 				   &excitation_current);
937 	if (ret) {
938 		/* Auto range is not allowed for custom sensors */
939 		if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART)
940 			/* default to 1uA */
941 			thermistor->excitation_current = 0x03;
942 		else
943 			/* default to auto-range */
944 			thermistor->excitation_current = 0x0c;
945 	} else {
946 		switch (excitation_current) {
947 		case 0:
948 			/* auto range */
949 			if (sensor->type >=
950 			    LTC2983_SENSOR_THERMISTOR_STEINHART) {
951 				dev_err(&st->spi->dev,
952 					"Auto Range not allowed for custom sensors\n");
953 				ret = -EINVAL;
954 				goto fail;
955 			}
956 			thermistor->excitation_current = 0x0c;
957 			break;
958 		case 250:
959 			thermistor->excitation_current = 0x01;
960 			break;
961 		case 500:
962 			thermistor->excitation_current = 0x02;
963 			break;
964 		case 1000:
965 			thermistor->excitation_current = 0x03;
966 			break;
967 		case 5000:
968 			thermistor->excitation_current = 0x04;
969 			break;
970 		case 10000:
971 			thermistor->excitation_current = 0x05;
972 			break;
973 		case 25000:
974 			thermistor->excitation_current = 0x06;
975 			break;
976 		case 50000:
977 			thermistor->excitation_current = 0x07;
978 			break;
979 		case 100000:
980 			thermistor->excitation_current = 0x08;
981 			break;
982 		case 250000:
983 			thermistor->excitation_current = 0x09;
984 			break;
985 		case 500000:
986 			thermistor->excitation_current = 0x0a;
987 			break;
988 		case 1000000:
989 			thermistor->excitation_current = 0x0b;
990 			break;
991 		default:
992 			dev_err(&st->spi->dev,
993 				"Invalid value for excitation current(%u)",
994 				excitation_current);
995 			ret = -EINVAL;
996 			goto fail;
997 		}
998 	}
999 
1000 	of_node_put(phandle);
1001 	return &thermistor->sensor;
1002 fail:
1003 	of_node_put(phandle);
1004 	return ERR_PTR(ret);
1005 }
1006 
1007 static struct ltc2983_sensor *ltc2983_diode_new(
1008 					const struct device_node *child,
1009 					const struct ltc2983_data *st,
1010 					const struct ltc2983_sensor *sensor)
1011 {
1012 	struct ltc2983_diode *diode;
1013 	u32 temp = 0, excitation_current = 0;
1014 	int ret;
1015 
1016 	diode = devm_kzalloc(&st->spi->dev, sizeof(*diode), GFP_KERNEL);
1017 	if (!diode)
1018 		return ERR_PTR(-ENOMEM);
1019 
1020 	if (of_property_read_bool(child, "adi,single-ended"))
1021 		diode->sensor_config = LTC2983_DIODE_SGL(1);
1022 
1023 	if (of_property_read_bool(child, "adi,three-conversion-cycles"))
1024 		diode->sensor_config |= LTC2983_DIODE_3_CONV_CYCLE(1);
1025 
1026 	if (of_property_read_bool(child, "adi,average-on"))
1027 		diode->sensor_config |= LTC2983_DIODE_AVERAGE_ON(1);
1028 
1029 	/* validate channel index */
1030 	if (!(diode->sensor_config & LTC2983_DIODE_DIFF_MASK) &&
1031 	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
1032 		dev_err(&st->spi->dev,
1033 			"Invalid chann:%d for differential thermistor",
1034 			sensor->chan);
1035 		return ERR_PTR(-EINVAL);
1036 	}
1037 	/* set common parameters */
1038 	diode->sensor.fault_handler = ltc2983_common_fault_handler;
1039 	diode->sensor.assign_chan = ltc2983_diode_assign_chan;
1040 
1041 	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
1042 				   &excitation_current);
1043 	if (!ret) {
1044 		switch (excitation_current) {
1045 		case 10:
1046 			diode->excitation_current = 0x00;
1047 			break;
1048 		case 20:
1049 			diode->excitation_current = 0x01;
1050 			break;
1051 		case 40:
1052 			diode->excitation_current = 0x02;
1053 			break;
1054 		case 80:
1055 			diode->excitation_current = 0x03;
1056 			break;
1057 		default:
1058 			dev_err(&st->spi->dev,
1059 				"Invalid value for excitation current(%u)",
1060 				excitation_current);
1061 			return ERR_PTR(-EINVAL);
1062 		}
1063 	}
1064 
1065 	of_property_read_u32(child, "adi,ideal-factor-value", &temp);
1066 
1067 	/* 2^20 resolution */
1068 	diode->ideal_factor_value = __convert_to_raw(temp, 1048576);
1069 
1070 	return &diode->sensor;
1071 }
1072 
1073 static struct ltc2983_sensor *ltc2983_r_sense_new(struct device_node *child,
1074 					struct ltc2983_data *st,
1075 					const struct ltc2983_sensor *sensor)
1076 {
1077 	struct ltc2983_rsense *rsense;
1078 	int ret;
1079 	u32 temp;
1080 
1081 	rsense = devm_kzalloc(&st->spi->dev, sizeof(*rsense), GFP_KERNEL);
1082 	if (!rsense)
1083 		return ERR_PTR(-ENOMEM);
1084 
1085 	/* validate channel index */
1086 	if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
1087 		dev_err(&st->spi->dev, "Invalid chann:%d for r_sense",
1088 			sensor->chan);
1089 		return ERR_PTR(-EINVAL);
1090 	}
1091 
1092 	ret = of_property_read_u32(child, "adi,rsense-val-milli-ohms", &temp);
1093 	if (ret) {
1094 		dev_err(&st->spi->dev, "Property adi,rsense-val-milli-ohms missing\n");
1095 		return ERR_PTR(-EINVAL);
1096 	}
1097 	/*
1098 	 * Times 1000 because we have milli-ohms and __convert_to_raw
1099 	 * expects scales of 1000000 which are used for all other
1100 	 * properties.
1101 	 * 2^10 resolution
1102 	 */
1103 	rsense->r_sense_val = __convert_to_raw((u64)temp * 1000, 1024);
1104 
1105 	/* set common parameters */
1106 	rsense->sensor.assign_chan = ltc2983_r_sense_assign_chan;
1107 
1108 	return &rsense->sensor;
1109 }
1110 
1111 static struct ltc2983_sensor *ltc2983_adc_new(struct device_node *child,
1112 					 struct ltc2983_data *st,
1113 					 const struct ltc2983_sensor *sensor)
1114 {
1115 	struct ltc2983_adc *adc;
1116 
1117 	adc = devm_kzalloc(&st->spi->dev, sizeof(*adc), GFP_KERNEL);
1118 	if (!adc)
1119 		return ERR_PTR(-ENOMEM);
1120 
1121 	if (of_property_read_bool(child, "adi,single-ended"))
1122 		adc->single_ended = true;
1123 
1124 	if (!adc->single_ended &&
1125 	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
1126 		dev_err(&st->spi->dev, "Invalid chan:%d for differential adc\n",
1127 			sensor->chan);
1128 		return ERR_PTR(-EINVAL);
1129 	}
1130 	/* set common parameters */
1131 	adc->sensor.assign_chan = ltc2983_adc_assign_chan;
1132 	adc->sensor.fault_handler = ltc2983_common_fault_handler;
1133 
1134 	return &adc->sensor;
1135 }
1136 
1137 static int ltc2983_chan_read(struct ltc2983_data *st,
1138 			const struct ltc2983_sensor *sensor, int *val)
1139 {
1140 	u32 start_conversion = 0;
1141 	int ret;
1142 	unsigned long time;
1143 
1144 	start_conversion = LTC2983_STATUS_START(true);
1145 	start_conversion |= LTC2983_STATUS_CHAN_SEL(sensor->chan);
1146 	dev_dbg(&st->spi->dev, "Start conversion on chan:%d, status:%02X\n",
1147 		sensor->chan, start_conversion);
1148 	/* start conversion */
1149 	ret = regmap_write(st->regmap, LTC2983_STATUS_REG, start_conversion);
1150 	if (ret)
1151 		return ret;
1152 
1153 	reinit_completion(&st->completion);
1154 	/*
1155 	 * wait for conversion to complete.
1156 	 * 300 ms should be more than enough to complete the conversion.
1157 	 * Depending on the sensor configuration, there are 2/3 conversions
1158 	 * cycles of 82ms.
1159 	 */
1160 	time = wait_for_completion_timeout(&st->completion,
1161 					   msecs_to_jiffies(300));
1162 	if (!time) {
1163 		dev_warn(&st->spi->dev, "Conversion timed out\n");
1164 		return -ETIMEDOUT;
1165 	}
1166 
1167 	/* read the converted data */
1168 	ret = regmap_bulk_read(st->regmap, LTC2983_CHAN_RES_ADDR(sensor->chan),
1169 			       &st->temp, sizeof(st->temp));
1170 	if (ret)
1171 		return ret;
1172 
1173 	*val = __be32_to_cpu(st->temp);
1174 
1175 	if (!(LTC2983_RES_VALID_MASK & *val)) {
1176 		dev_err(&st->spi->dev, "Invalid conversion detected\n");
1177 		return -EIO;
1178 	}
1179 
1180 	ret = sensor->fault_handler(st, *val);
1181 	if (ret)
1182 		return ret;
1183 
1184 	*val = sign_extend32((*val) & LTC2983_DATA_MASK, LTC2983_DATA_SIGN_BIT);
1185 	return 0;
1186 }
1187 
1188 static int ltc2983_read_raw(struct iio_dev *indio_dev,
1189 			    struct iio_chan_spec const *chan,
1190 			    int *val, int *val2, long mask)
1191 {
1192 	struct ltc2983_data *st = iio_priv(indio_dev);
1193 	int ret;
1194 
1195 	/* sanity check */
1196 	if (chan->address >= st->num_channels) {
1197 		dev_err(&st->spi->dev, "Invalid chan address:%ld",
1198 			chan->address);
1199 		return -EINVAL;
1200 	}
1201 
1202 	switch (mask) {
1203 	case IIO_CHAN_INFO_RAW:
1204 		mutex_lock(&st->lock);
1205 		ret = ltc2983_chan_read(st, st->sensors[chan->address], val);
1206 		mutex_unlock(&st->lock);
1207 		return ret ?: IIO_VAL_INT;
1208 	case IIO_CHAN_INFO_SCALE:
1209 		switch (chan->type) {
1210 		case IIO_TEMP:
1211 			/* value in milli degrees */
1212 			*val = 1000;
1213 			/* 2^10 */
1214 			*val2 = 1024;
1215 			return IIO_VAL_FRACTIONAL;
1216 		case IIO_VOLTAGE:
1217 			/* value in millivolt */
1218 			*val = 1000;
1219 			/* 2^21 */
1220 			*val2 = 2097152;
1221 			return IIO_VAL_FRACTIONAL;
1222 		default:
1223 			return -EINVAL;
1224 		}
1225 	}
1226 
1227 	return -EINVAL;
1228 }
1229 
1230 static int ltc2983_reg_access(struct iio_dev *indio_dev,
1231 			      unsigned int reg,
1232 			      unsigned int writeval,
1233 			      unsigned int *readval)
1234 {
1235 	struct ltc2983_data *st = iio_priv(indio_dev);
1236 
1237 	if (readval)
1238 		return regmap_read(st->regmap, reg, readval);
1239 	else
1240 		return regmap_write(st->regmap, reg, writeval);
1241 }
1242 
1243 static irqreturn_t ltc2983_irq_handler(int irq, void *data)
1244 {
1245 	struct ltc2983_data *st = data;
1246 
1247 	complete(&st->completion);
1248 	return IRQ_HANDLED;
1249 }
1250 
1251 #define LTC2983_CHAN(__type, index, __address) ({ \
1252 	struct iio_chan_spec __chan = { \
1253 		.type = __type, \
1254 		.indexed = 1, \
1255 		.channel = index, \
1256 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
1257 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
1258 		.address = __address, \
1259 	}; \
1260 	__chan; \
1261 })
1262 
1263 static int ltc2983_parse_dt(struct ltc2983_data *st)
1264 {
1265 	struct device_node *child;
1266 	struct device *dev = &st->spi->dev;
1267 	int ret = 0, chan = 0, channel_avail_mask = 0;
1268 
1269 	of_property_read_u32(dev->of_node, "adi,mux-delay-config-us",
1270 			     &st->mux_delay_config);
1271 
1272 	of_property_read_u32(dev->of_node, "adi,filter-notch-freq",
1273 			     &st->filter_notch_freq);
1274 
1275 	st->num_channels = of_get_available_child_count(dev->of_node);
1276 	st->sensors = devm_kcalloc(dev, st->num_channels, sizeof(*st->sensors),
1277 				   GFP_KERNEL);
1278 	if (!st->sensors)
1279 		return -ENOMEM;
1280 
1281 	st->iio_channels = st->num_channels;
1282 	for_each_available_child_of_node(dev->of_node, child) {
1283 		struct ltc2983_sensor sensor;
1284 
1285 		ret = of_property_read_u32(child, "reg", &sensor.chan);
1286 		if (ret) {
1287 			dev_err(dev, "reg property must given for child nodes\n");
1288 			return ret;
1289 		}
1290 
1291 		/* check if we have a valid channel */
1292 		if (sensor.chan < LTC2983_MIN_CHANNELS_NR ||
1293 		    sensor.chan > LTC2983_MAX_CHANNELS_NR) {
1294 			dev_err(dev,
1295 				"chan:%d must be from 1 to 20\n", sensor.chan);
1296 			return -EINVAL;
1297 		} else if (channel_avail_mask & BIT(sensor.chan)) {
1298 			dev_err(dev, "chan:%d already in use\n", sensor.chan);
1299 			return -EINVAL;
1300 		}
1301 
1302 		ret = of_property_read_u32(child, "adi,sensor-type",
1303 					       &sensor.type);
1304 		if (ret) {
1305 			dev_err(dev,
1306 				"adi,sensor-type property must given for child nodes\n");
1307 			return ret;
1308 		}
1309 
1310 		dev_dbg(dev, "Create new sensor, type %u, chann %u",
1311 								sensor.type,
1312 								sensor.chan);
1313 
1314 		if (sensor.type >= LTC2983_SENSOR_THERMOCOUPLE &&
1315 		    sensor.type <= LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
1316 			st->sensors[chan] = ltc2983_thermocouple_new(child, st,
1317 								     &sensor);
1318 		} else if (sensor.type >= LTC2983_SENSOR_RTD &&
1319 			   sensor.type <= LTC2983_SENSOR_RTD_CUSTOM) {
1320 			st->sensors[chan] = ltc2983_rtd_new(child, st, &sensor);
1321 		} else if (sensor.type >= LTC2983_SENSOR_THERMISTOR &&
1322 			   sensor.type <= LTC2983_SENSOR_THERMISTOR_CUSTOM) {
1323 			st->sensors[chan] = ltc2983_thermistor_new(child, st,
1324 								   &sensor);
1325 		} else if (sensor.type == LTC2983_SENSOR_DIODE) {
1326 			st->sensors[chan] = ltc2983_diode_new(child, st,
1327 							      &sensor);
1328 		} else if (sensor.type == LTC2983_SENSOR_SENSE_RESISTOR) {
1329 			st->sensors[chan] = ltc2983_r_sense_new(child, st,
1330 								&sensor);
1331 			/* don't add rsense to iio */
1332 			st->iio_channels--;
1333 		} else if (sensor.type == LTC2983_SENSOR_DIRECT_ADC) {
1334 			st->sensors[chan] = ltc2983_adc_new(child, st, &sensor);
1335 		} else {
1336 			dev_err(dev, "Unknown sensor type %d\n", sensor.type);
1337 			return -EINVAL;
1338 		}
1339 
1340 		if (IS_ERR(st->sensors[chan])) {
1341 			dev_err(dev, "Failed to create sensor %ld",
1342 				PTR_ERR(st->sensors[chan]));
1343 			return PTR_ERR(st->sensors[chan]);
1344 		}
1345 		/* set generic sensor parameters */
1346 		st->sensors[chan]->chan = sensor.chan;
1347 		st->sensors[chan]->type = sensor.type;
1348 
1349 		channel_avail_mask |= BIT(sensor.chan);
1350 		chan++;
1351 	}
1352 
1353 	return 0;
1354 }
1355 
1356 static int ltc2983_setup(struct ltc2983_data *st, bool assign_iio)
1357 {
1358 	u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0;
1359 	int ret;
1360 	unsigned long time;
1361 
1362 	/* make sure the device is up */
1363 	time = wait_for_completion_timeout(&st->completion,
1364 					    msecs_to_jiffies(250));
1365 
1366 	if (!time) {
1367 		dev_err(&st->spi->dev, "Device startup timed out\n");
1368 		return -ETIMEDOUT;
1369 	}
1370 
1371 	st->iio_chan = devm_kzalloc(&st->spi->dev,
1372 				    st->iio_channels * sizeof(*st->iio_chan),
1373 				    GFP_KERNEL);
1374 
1375 	if (!st->iio_chan)
1376 		return -ENOMEM;
1377 
1378 	ret = regmap_update_bits(st->regmap, LTC2983_GLOBAL_CONFIG_REG,
1379 				 LTC2983_NOTCH_FREQ_MASK,
1380 				 LTC2983_NOTCH_FREQ(st->filter_notch_freq));
1381 	if (ret)
1382 		return ret;
1383 
1384 	ret = regmap_write(st->regmap, LTC2983_MUX_CONFIG_REG,
1385 			   st->mux_delay_config);
1386 	if (ret)
1387 		return ret;
1388 
1389 	for (chan = 0; chan < st->num_channels; chan++) {
1390 		u32 chan_type = 0, *iio_chan;
1391 
1392 		ret = st->sensors[chan]->assign_chan(st, st->sensors[chan]);
1393 		if (ret)
1394 			return ret;
1395 		/*
1396 		 * The assign_iio flag is necessary for when the device is
1397 		 * coming out of sleep. In that case, we just need to
1398 		 * re-configure the device channels.
1399 		 * We also don't assign iio channels for rsense.
1400 		 */
1401 		if (st->sensors[chan]->type == LTC2983_SENSOR_SENSE_RESISTOR ||
1402 		    !assign_iio)
1403 			continue;
1404 
1405 		/* assign iio channel */
1406 		if (st->sensors[chan]->type != LTC2983_SENSOR_DIRECT_ADC) {
1407 			chan_type = IIO_TEMP;
1408 			iio_chan = &iio_chan_t;
1409 		} else {
1410 			chan_type = IIO_VOLTAGE;
1411 			iio_chan = &iio_chan_v;
1412 		}
1413 
1414 		/*
1415 		 * add chan as the iio .address so that, we can directly
1416 		 * reference the sensor given the iio_chan_spec
1417 		 */
1418 		st->iio_chan[iio_idx++] = LTC2983_CHAN(chan_type, (*iio_chan)++,
1419 						       chan);
1420 	}
1421 
1422 	return 0;
1423 }
1424 
1425 static const struct regmap_range ltc2983_reg_ranges[] = {
1426 	regmap_reg_range(LTC2983_STATUS_REG, LTC2983_STATUS_REG),
1427 	regmap_reg_range(LTC2983_TEMP_RES_START_REG, LTC2983_TEMP_RES_END_REG),
1428 	regmap_reg_range(LTC2983_GLOBAL_CONFIG_REG, LTC2983_GLOBAL_CONFIG_REG),
1429 	regmap_reg_range(LTC2983_MULT_CHANNEL_START_REG,
1430 			 LTC2983_MULT_CHANNEL_END_REG),
1431 	regmap_reg_range(LTC2983_MUX_CONFIG_REG, LTC2983_MUX_CONFIG_REG),
1432 	regmap_reg_range(LTC2983_CHAN_ASSIGN_START_REG,
1433 			 LTC2983_CHAN_ASSIGN_END_REG),
1434 	regmap_reg_range(LTC2983_CUST_SENS_TBL_START_REG,
1435 			 LTC2983_CUST_SENS_TBL_END_REG),
1436 };
1437 
1438 static const struct regmap_access_table ltc2983_reg_table = {
1439 	.yes_ranges = ltc2983_reg_ranges,
1440 	.n_yes_ranges = ARRAY_SIZE(ltc2983_reg_ranges),
1441 };
1442 
1443 /*
1444  *  The reg_bits are actually 12 but the device needs the first *complete*
1445  *  byte for the command (R/W).
1446  */
1447 static const struct regmap_config ltc2983_regmap_config = {
1448 	.reg_bits = 24,
1449 	.val_bits = 8,
1450 	.wr_table = &ltc2983_reg_table,
1451 	.rd_table = &ltc2983_reg_table,
1452 	.read_flag_mask = GENMASK(1, 0),
1453 	.write_flag_mask = BIT(1),
1454 };
1455 
1456 static const struct  iio_info ltc2983_iio_info = {
1457 	.read_raw = ltc2983_read_raw,
1458 	.debugfs_reg_access = ltc2983_reg_access,
1459 };
1460 
1461 static int ltc2983_probe(struct spi_device *spi)
1462 {
1463 	struct ltc2983_data *st;
1464 	struct iio_dev *indio_dev;
1465 	const char *name = spi_get_device_id(spi)->name;
1466 	int ret;
1467 
1468 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
1469 	if (!indio_dev)
1470 		return -ENOMEM;
1471 
1472 	st = iio_priv(indio_dev);
1473 
1474 	st->regmap = devm_regmap_init_spi(spi, &ltc2983_regmap_config);
1475 	if (IS_ERR(st->regmap)) {
1476 		dev_err(&spi->dev, "Failed to initialize regmap\n");
1477 		return PTR_ERR(st->regmap);
1478 	}
1479 
1480 	mutex_init(&st->lock);
1481 	init_completion(&st->completion);
1482 	st->spi = spi;
1483 	spi_set_drvdata(spi, st);
1484 
1485 	ret = ltc2983_parse_dt(st);
1486 	if (ret)
1487 		return ret;
1488 	/*
1489 	 * let's request the irq now so it is used to sync the device
1490 	 * startup in ltc2983_setup()
1491 	 */
1492 	ret = devm_request_irq(&spi->dev, spi->irq, ltc2983_irq_handler,
1493 			       IRQF_TRIGGER_RISING, name, st);
1494 	if (ret) {
1495 		dev_err(&spi->dev, "failed to request an irq, %d", ret);
1496 		return ret;
1497 	}
1498 
1499 	ret = ltc2983_setup(st, true);
1500 	if (ret)
1501 		return ret;
1502 
1503 	indio_dev->name = name;
1504 	indio_dev->num_channels = st->iio_channels;
1505 	indio_dev->channels = st->iio_chan;
1506 	indio_dev->modes = INDIO_DIRECT_MODE;
1507 	indio_dev->info = &ltc2983_iio_info;
1508 
1509 	return devm_iio_device_register(&spi->dev, indio_dev);
1510 }
1511 
1512 static int __maybe_unused ltc2983_resume(struct device *dev)
1513 {
1514 	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
1515 	int dummy;
1516 
1517 	/* dummy read to bring the device out of sleep */
1518 	regmap_read(st->regmap, LTC2983_STATUS_REG, &dummy);
1519 	/* we need to re-assign the channels */
1520 	return ltc2983_setup(st, false);
1521 }
1522 
1523 static int __maybe_unused ltc2983_suspend(struct device *dev)
1524 {
1525 	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
1526 
1527 	return regmap_write(st->regmap, LTC2983_STATUS_REG, LTC2983_SLEEP);
1528 }
1529 
1530 static SIMPLE_DEV_PM_OPS(ltc2983_pm_ops, ltc2983_suspend, ltc2983_resume);
1531 
1532 static const struct spi_device_id ltc2983_id_table[] = {
1533 	{ "ltc2983" },
1534 	{},
1535 };
1536 MODULE_DEVICE_TABLE(spi, ltc2983_id_table);
1537 
1538 static const struct of_device_id ltc2983_of_match[] = {
1539 	{ .compatible = "adi,ltc2983" },
1540 	{},
1541 };
1542 MODULE_DEVICE_TABLE(of, ltc2983_of_match);
1543 
1544 static struct spi_driver ltc2983_driver = {
1545 	.driver = {
1546 		.name = "ltc2983",
1547 		.of_match_table = ltc2983_of_match,
1548 		.pm = &ltc2983_pm_ops,
1549 	},
1550 	.probe = ltc2983_probe,
1551 	.id_table = ltc2983_id_table,
1552 };
1553 
1554 module_spi_driver(ltc2983_driver);
1555 
1556 MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>");
1557 MODULE_DESCRIPTION("Analog Devices LTC2983 SPI Temperature sensors");
1558 MODULE_LICENSE("GPL");
1559