summaryrefslogtreecommitdiffstats
path: root/drivers/iio/adc/max9611.c
blob: 643a4e66eb80b2e1d0d11148b534536f8ac3f546 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
/*
 * iio/adc/max9611.c
 *
 * Maxim max9611/max9612 high side current sense amplifier with
 * 12-bit ADC interface.
 *
 * Copyright (C) 2017 Jacopo Mondi
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/*
 * This driver supports input common-mode voltage, current-sense
 * amplifier with programmable gains and die temperature reading from
 * Maxim max9611/max9612.
 *
 * Op-amp, analog comparator, and watchdog functionalities are not
 * supported by this driver.
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/module.h>
#include <linux/of_device.h>

#define DRIVER_NAME			"max9611"

/* max9611 register addresses */
#define MAX9611_REG_CSA_DATA		0x00
#define MAX9611_REG_RS_DATA		0x02
#define MAX9611_REG_TEMP_DATA		0x08
#define MAX9611_REG_CTRL1		0x0a
#define MAX9611_REG_CTRL2		0x0b

/* max9611 REG1 mux configuration options */
#define MAX9611_MUX_MASK		GENMASK(3, 0)
#define MAX9611_MUX_SENSE_1x		0x00
#define MAX9611_MUX_SENSE_4x		0x01
#define MAX9611_MUX_SENSE_8x		0x02
#define MAX9611_INPUT_VOLT		0x03
#define MAX9611_MUX_TEMP		0x06

/* max9611 voltage (both csa and input) helper macros */
#define MAX9611_VOLTAGE_SHIFT		0x04
#define MAX9611_VOLTAGE_RAW(_r)		((_r) >> MAX9611_VOLTAGE_SHIFT)

/*
 * max9611 current sense amplifier voltage output:
 * LSB and offset values depends on selected gain (1x, 4x, 8x)
 *
 * GAIN		LSB (nV)	OFFSET (LSB steps)
 * 1x		107500		1
 * 4x		26880		1
 * 8x		13440		3
 *
 * The complete formula to calculate current sense voltage is:
 *     (((adc_read >> 4) - offset) / ((1 / LSB) * 10^-3)
 */
#define MAX9611_CSA_1X_LSB_nV		107500
#define MAX9611_CSA_4X_LSB_nV		26880
#define MAX9611_CSA_8X_LSB_nV		13440

#define MAX9611_CSA_1X_OFFS_RAW		1
#define MAX9611_CSA_4X_OFFS_RAW		1
#define MAX9611_CSA_8X_OFFS_RAW		3

/*
 * max9611 common input mode (CIM): LSB is 14mV, with 14mV offset at 25 C
 *
 * The complete formula to calculate input common voltage is:
 *     (((adc_read >> 4) * 1000) - offset) / (1 / 14 * 1000)
 */
#define MAX9611_CIM_LSB_mV		14
#define MAX9611_CIM_OFFSET_RAW		1

/*
 * max9611 temperature reading: LSB is 480 milli degrees Celsius
 *
 * The complete formula to calculate temperature is:
 *     ((adc_read >> 7) * 1000) / (1 / 480 * 1000)
 */
#define MAX9611_TEMP_MAX_POS		0x7f80
#define MAX9611_TEMP_MAX_NEG		0xff80
#define MAX9611_TEMP_MIN_NEG		0xd980
#define MAX9611_TEMP_MASK		GENMASK(7, 15)
#define MAX9611_TEMP_SHIFT		0x07
#define MAX9611_TEMP_RAW(_r)		((_r) >> MAX9611_TEMP_SHIFT)
#define MAX9611_TEMP_SCALE_NUM		1000000
#define MAX9611_TEMP_SCALE_DIV		2083

struct max9611_dev {
	struct device *dev;
	struct i2c_client *i2c_client;
	struct mutex lock;
	unsigned int shunt_resistor_uohm;
};

enum max9611_conf_ids {
	CONF_SENSE_1x,
	CONF_SENSE_4x,
	CONF_SENSE_8x,
	CONF_IN_VOLT,
	CONF_TEMP,
};

/**
 * max9611_mux_conf - associate ADC mux configuration with register address
 *		      where data shall be read from
 */
static const unsigned int max9611_mux_conf[][2] = {
	/* CONF_SENSE_1x */
	{ MAX9611_MUX_SENSE_1x, MAX9611_REG_CSA_DATA },
	/* CONF_SENSE_4x */
	{ MAX9611_MUX_SENSE_4x, MAX9611_REG_CSA_DATA },
	/* CONF_SENSE_8x */
	{ MAX9611_MUX_SENSE_8x, MAX9611_REG_CSA_DATA },
	/* CONF_IN_VOLT */
	{ MAX9611_INPUT_VOLT, MAX9611_REG_RS_DATA },
	/* CONF_TEMP */
	{ MAX9611_MUX_TEMP, MAX9611_REG_TEMP_DATA },
};

enum max9611_csa_gain {
	CSA_GAIN_1x,
	CSA_GAIN_4x,
	CSA_GAIN_8x,
};

enum max9611_csa_gain_params {
	CSA_GAIN_LSB_nV,
	CSA_GAIN_OFFS_RAW,
};

/**
 * max9611_csa_gain_conf - associate gain multiplier with LSB and
 *			   offset values.
 *
 * Group together parameters associated with configurable gain
 * on current sense amplifier path to ADC interface.
 * Current sense read routine adjusts gain until it gets a meaningful
 * value; use this structure to retrieve the correct LSB and offset values.
 */
static const unsigned int max9611_gain_conf[][2] = {
	{ /* [0] CSA_GAIN_1x */
		MAX9611_CSA_1X_LSB_nV,
		MAX9611_CSA_1X_OFFS_RAW,
	},
	{ /* [1] CSA_GAIN_4x */
		MAX9611_CSA_4X_LSB_nV,
		MAX9611_CSA_4X_OFFS_RAW,
	},
	{ /* [2] CSA_GAIN_8x */
		MAX9611_CSA_8X_LSB_nV,
		MAX9611_CSA_8X_OFFS_RAW,
	},
};

enum max9611_chan_addrs {
	MAX9611_CHAN_VOLTAGE_INPUT,
	MAX9611_CHAN_VOLTAGE_SENSE,
	MAX9611_CHAN_TEMPERATURE,
	MAX9611_CHAN_CURRENT_LOAD,
	MAX9611_CHAN_POWER_LOAD,
};

static const struct iio_chan_spec max9611_channels[] = {
	{
	  .type			= IIO_TEMP,
	  .info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) |
				  BIT(IIO_CHAN_INFO_SCALE),
	  .address		= MAX9611_CHAN_TEMPERATURE,
	},
	{
	  .type			= IIO_VOLTAGE,
	  .info_mask_separate	= BIT(IIO_CHAN_INFO_PROCESSED),
	  .address		= MAX9611_CHAN_VOLTAGE_SENSE,
	  .indexed		= 1,
	  .channel		= 0,
	},
	{
	  .type			= IIO_VOLTAGE,
	  .info_mask_separate	= BIT(IIO_CHAN_INFO_RAW)   |
				  BIT(IIO_CHAN_INFO_SCALE) |
				  BIT(IIO_CHAN_INFO_OFFSET),
	  .address		= MAX9611_CHAN_VOLTAGE_INPUT,
	  .indexed		= 1,
	  .channel		= 1,
	},
	{
	  .type			= IIO_CURRENT,
	  .info_mask_separate	= BIT(IIO_CHAN_INFO_PROCESSED),
	  .address		= MAX9611_CHAN_CURRENT_LOAD,
	},
	{
	  .type			= IIO_POWER,
	  .info_mask_separate	= BIT(IIO_CHAN_INFO_PROCESSED),
	  .address		= MAX9611_CHAN_POWER_LOAD
	},
};

/**
 * max9611_read_single() - read a single value from ADC interface
 *
 * Data registers are 16 bit long, spread between two 8 bit registers
 * with consecutive addresses.
 * Configure ADC mux first, then read register at address "reg_addr".
 * The smbus_read_word routine asks for 16 bits and the ADC is kind enough
 * to return values from "reg_addr" and "reg_addr + 1" consecutively.
 * Data are transmitted with big-endian ordering: MSB arrives first.
 *
 * @max9611: max9611 device
 * @selector: index for mux and register configuration
 * @raw_val: the value returned from ADC
 */
static int max9611_read_single(struct max9611_dev *max9611,
			       enum max9611_conf_ids selector,
			       u16 *raw_val)
{
	int ret;

	u8 mux_conf = max9611_mux_conf[selector][0] & MAX9611_MUX_MASK;
	u8 reg_addr = max9611_mux_conf[selector][1];

	/*
	 * Keep mutex lock held during read-write to avoid mux register
	 * (CTRL1) re-configuration.
	 */
	mutex_lock(&max9611->lock);
	ret = i2c_smbus_write_byte_data(max9611->i2c_client,
					MAX9611_REG_CTRL1, mux_conf);
	if (ret) {
		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
			MAX9611_REG_CTRL1, mux_conf);
		mutex_unlock(&max9611->lock);
		return ret;
	}

	/*
	 * need a delay here to make register configuration
	 * stabilize. 1 msec at least, from empirical testing.
	 */
	usleep_range(1000, 2000);

	ret = i2c_smbus_read_word_swapped(max9611->i2c_client, reg_addr);
	if (ret < 0) {
		dev_err(max9611->dev, "i2c read word from 0x%2x failed\n",
			reg_addr);
		mutex_unlock(&max9611->lock);
		return ret;
	}

	*raw_val = ret;
	mutex_unlock(&max9611->lock);

	return 0;
}

/**
 * max9611_read_csa_voltage() - read current sense amplifier output voltage
 *
 * Current sense amplifier output voltage is read through a configurable
 * 1x, 4x or 8x gain.
 * Start with plain 1x gain, and adjust gain control properly until a
 * meaningful value is read from ADC output.
 *
 * @max9611: max9611 device
 * @adc_raw: raw value read from ADC output
 * @csa_gain: gain configuration option selector
 */
static int max9611_read_csa_voltage(struct max9611_dev *max9611,
				    u16 *adc_raw,
				    enum max9611_csa_gain *csa_gain)
{
	enum max9611_conf_ids gain_selectors[] = {
		CONF_SENSE_1x,
		CONF_SENSE_4x,
		CONF_SENSE_8x
	};
	unsigned int i;
	int ret;

	for (i = 0; i < ARRAY_SIZE(gain_selectors); ++i) {
		ret = max9611_read_single(max9611, gain_selectors[i], adc_raw);
		if (ret)
			return ret;

		if (*adc_raw > 0) {
			*csa_gain = (enum max9611_csa_gain)gain_selectors[i];
			return 0;
		}
	}

	return -EIO;
}

static int max9611_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	struct max9611_dev *dev = iio_priv(indio_dev);
	enum max9611_csa_gain gain_selector;
	const unsigned int *csa_gain;
	u16 adc_data;
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:

		switch (chan->address) {
		case MAX9611_CHAN_TEMPERATURE:
			ret = max9611_read_single(dev, CONF_TEMP,
						  &adc_data);
			if (ret)
				return -EINVAL;

			*val = MAX9611_TEMP_RAW(adc_data);
			return IIO_VAL_INT;

		case MAX9611_CHAN_VOLTAGE_INPUT:
			ret = max9611_read_single(dev, CONF_IN_VOLT,
						  &adc_data);
			if (ret)
				return -EINVAL;

			*val = MAX9611_VOLTAGE_RAW(adc_data);
			return IIO_VAL_INT;
		}

		break;

	case IIO_CHAN_INFO_OFFSET:
		/* MAX9611_CHAN_VOLTAGE_INPUT */
		*val = MAX9611_CIM_OFFSET_RAW;

		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:

		switch (chan->address) {
		case MAX9611_CHAN_TEMPERATURE:
			*val = MAX9611_TEMP_SCALE_NUM;
			*val2 = MAX9611_TEMP_SCALE_DIV;

			return IIO_VAL_FRACTIONAL;

		case MAX9611_CHAN_VOLTAGE_INPUT:
			*val = MAX9611_CIM_LSB_mV;

			return IIO_VAL_INT;
		}

		break;

	case IIO_CHAN_INFO_PROCESSED:

		switch (chan->address) {
		case MAX9611_CHAN_VOLTAGE_SENSE:
			/*
			 * processed (mV): (raw - offset) * LSB (nV) / 10^6
			 *
			 * Even if max9611 can output raw csa voltage readings,
			 * use a produced value as scale depends on gain.
			 */
			ret = max9611_read_csa_voltage(dev, &adc_data,
						       &gain_selector);
			if (ret)
				return -EINVAL;

			csa_gain = max9611_gain_conf[gain_selector];

			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
			*val = MAX9611_VOLTAGE_RAW(adc_data) *
			       csa_gain[CSA_GAIN_LSB_nV];
			*val2 = 1000000;

			return IIO_VAL_FRACTIONAL;

		case MAX9611_CHAN_CURRENT_LOAD:
			/* processed (mA): Vcsa (nV) / Rshunt (uOhm)  */
			ret = max9611_read_csa_voltage(dev, &adc_data,
						       &gain_selector);
			if (ret)
				return -EINVAL;

			csa_gain = max9611_gain_conf[gain_selector];

			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
			*val = MAX9611_VOLTAGE_RAW(adc_data) *
			       csa_gain[CSA_GAIN_LSB_nV];
			*val2 = dev->shunt_resistor_uohm;

			return IIO_VAL_FRACTIONAL;

		case MAX9611_CHAN_POWER_LOAD:
			/*
			 * processed (mW): Vin (mV) * Vcsa (uV) /
			 *		   Rshunt (uOhm)
			 */
			ret = max9611_read_single(dev, CONF_IN_VOLT,
						  &adc_data);
			if (ret)
				return -EINVAL;

			adc_data -= MAX9611_CIM_OFFSET_RAW;
			*val = MAX9611_VOLTAGE_RAW(adc_data) *
			       MAX9611_CIM_LSB_mV;

			ret = max9611_read_csa_voltage(dev, &adc_data,
						       &gain_selector);
			if (ret)
				return -EINVAL;

			csa_gain = max9611_gain_conf[gain_selector];

			/* divide by 10^3 here to avoid 32bit overflow */
			adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
			*val *= MAX9611_VOLTAGE_RAW(adc_data) *
				csa_gain[CSA_GAIN_LSB_nV] / 1000;
			*val2 = dev->shunt_resistor_uohm;

			return IIO_VAL_FRACTIONAL;
		}

		break;
	}

	return -EINVAL;
}

static ssize_t max9611_shunt_resistor_show(struct device *dev,
					   struct device_attribute *attr,
					   char *buf)
{
	struct max9611_dev *max9611 = iio_priv(dev_to_iio_dev(dev));
	unsigned int i, r;

	i = max9611->shunt_resistor_uohm / 1000000;
	r = max9611->shunt_resistor_uohm % 1000000;

	return sprintf(buf, "%u.%06u\n", i, r);
}

static IIO_DEVICE_ATTR(in_power_shunt_resistor, 0444,
		       max9611_shunt_resistor_show, NULL, 0);
static IIO_DEVICE_ATTR(in_current_shunt_resistor, 0444,
		       max9611_shunt_resistor_show, NULL, 0);

static struct attribute *max9611_attributes[] = {
	&iio_dev_attr_in_power_shunt_resistor.dev_attr.attr,
	&iio_dev_attr_in_current_shunt_resistor.dev_attr.attr,
	NULL,
};

static const struct attribute_group max9611_attribute_group = {
	.attrs = max9611_attributes,
};

static const struct iio_info indio_info = {
	.read_raw	= max9611_read_raw,
	.attrs		= &max9611_attribute_group,
};

static int max9611_init(struct max9611_dev *max9611)
{
	struct i2c_client *client = max9611->i2c_client;
	u16 regval;
	int ret;

	if (!i2c_check_functionality(client->adapter,
				     I2C_FUNC_SMBUS_WRITE_BYTE	|
				     I2C_FUNC_SMBUS_READ_WORD_DATA)) {
		dev_err(max9611->dev,
			"I2c adapter does not support smbus write_byte or read_word functionalities: aborting probe.\n");
		return -EINVAL;
	}

	/* Make sure die temperature is in range to test communications. */
	ret = max9611_read_single(max9611, CONF_TEMP, &regval);
	if (ret)
		return ret;

	regval = ret & MAX9611_TEMP_MASK;

	if ((regval > MAX9611_TEMP_MAX_POS &&
	     regval < MAX9611_TEMP_MIN_NEG) ||
	     regval > MAX9611_TEMP_MAX_NEG) {
		dev_err(max9611->dev,
			"Invalid value received from ADC 0x%4x: aborting\n",
			regval);
		return -EIO;
	}

	/* Mux shall be zeroed back before applying other configurations */
	ret = i2c_smbus_write_byte_data(max9611->i2c_client,
					MAX9611_REG_CTRL1, 0);
	if (ret) {
		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
			MAX9611_REG_CTRL1, 0);
		return ret;
	}

	ret = i2c_smbus_write_byte_data(max9611->i2c_client,
					MAX9611_REG_CTRL2, 0);
	if (ret) {
		dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
			MAX9611_REG_CTRL2, 0);
		return ret;
	}
	usleep_range(1000, 2000);

	return 0;
}

static const struct of_device_id max9611_of_table[] = {
	{.compatible = "maxim,max9611", .data = "max9611"},
	{.compatible = "maxim,max9612", .data = "max9612"},
	{ },
};

MODULE_DEVICE_TABLE(of, max9611_of_table);
static int max9611_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	const char * const shunt_res_prop = "shunt-resistor-micro-ohms";
	const struct device_node *of_node = client->dev.of_node;
	const struct of_device_id *of_id =
		of_match_device(max9611_of_table, &client->dev);
	struct max9611_dev *max9611;
	struct iio_dev *indio_dev;
	unsigned int of_shunt;
	int ret;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max9611));
	if (!indio_dev)
		return -ENOMEM;

	i2c_set_clientdata(client, indio_dev);

	max9611			= iio_priv(indio_dev);
	max9611->dev		= &client->dev;
	max9611->i2c_client	= client;
	mutex_init(&max9611->lock);

	ret = of_property_read_u32(of_node, shunt_res_prop, &of_shunt);
	if (ret) {
		dev_err(&client->dev,
			"Missing %s property for %pOF node\n",
			shunt_res_prop, of_node);
		return ret;
	}
	max9611->shunt_resistor_uohm = of_shunt;

	ret = max9611_init(max9611);
	if (ret)
		return ret;

	indio_dev->dev.parent	= &client->dev;
	indio_dev->dev.of_node	= client->dev.of_node;
	indio_dev->name		= of_id->data;
	indio_dev->modes	= INDIO_DIRECT_MODE;
	indio_dev->info		= &indio_info;
	indio_dev->channels	= max9611_channels;
	indio_dev->num_channels	= ARRAY_SIZE(max9611_channels);

	return devm_iio_device_register(&client->dev, indio_dev);
}

static struct i2c_driver max9611_driver = {
	.driver = {
		   .name = DRIVER_NAME,
		   .of_match_table = max9611_of_table,
	},
	.probe = max9611_probe,
};
module_i2c_driver(max9611_driver);

MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org>");
MODULE_DESCRIPTION("Maxim max9611/12 current sense amplifier with 12bit ADC");
MODULE_LICENSE("GPL v2");