summaryrefslogtreecommitdiffstats
path: root/drivers/iio/adc/ti-ads8688.c
blob: c400439900afd611b9444c86b8f28031fef85c66 (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
/*
 * Copyright (C) 2015 Prevas A/S
 *
 * 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.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/spi/spi.h>
#include <linux/regulator/consumer.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/of.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

#define ADS8688_CMD_REG(x)		(x << 8)
#define ADS8688_CMD_REG_NOOP		0x00
#define ADS8688_CMD_REG_RST		0x85
#define ADS8688_CMD_REG_MAN_CH(chan)	(0xC0 | (4 * chan))
#define ADS8688_CMD_DONT_CARE_BITS	16

#define ADS8688_PROG_REG(x)		(x << 9)
#define ADS8688_PROG_REG_RANGE_CH(chan)	(0x05 + chan)
#define ADS8688_PROG_WR_BIT		BIT(8)
#define ADS8688_PROG_DONT_CARE_BITS	8

#define ADS8688_REG_PLUSMINUS25VREF	0
#define ADS8688_REG_PLUSMINUS125VREF	1
#define ADS8688_REG_PLUSMINUS0625VREF	2
#define ADS8688_REG_PLUS25VREF		5
#define ADS8688_REG_PLUS125VREF		6

#define ADS8688_VREF_MV			4096
#define ADS8688_REALBITS		16

/*
 * enum ads8688_range - ADS8688 reference voltage range
 * @ADS8688_PLUSMINUS25VREF: Device is configured for input range ±2.5 * VREF
 * @ADS8688_PLUSMINUS125VREF: Device is configured for input range ±1.25 * VREF
 * @ADS8688_PLUSMINUS0625VREF: Device is configured for input range ±0.625 * VREF
 * @ADS8688_PLUS25VREF: Device is configured for input range 0 - 2.5 * VREF
 * @ADS8688_PLUS125VREF: Device is configured for input range 0 - 1.25 * VREF
 */
enum ads8688_range {
	ADS8688_PLUSMINUS25VREF,
	ADS8688_PLUSMINUS125VREF,
	ADS8688_PLUSMINUS0625VREF,
	ADS8688_PLUS25VREF,
	ADS8688_PLUS125VREF,
};

struct ads8688_chip_info {
	const struct iio_chan_spec *channels;
	unsigned int num_channels;
};

struct ads8688_state {
	struct mutex			lock;
	const struct ads8688_chip_info	*chip_info;
	struct spi_device		*spi;
	struct regulator		*reg;
	unsigned int			vref_mv;
	enum ads8688_range		range[8];
	union {
		__be32 d32;
		u8 d8[4];
	} data[2] ____cacheline_aligned;
};

enum ads8688_id {
	ID_ADS8684,
	ID_ADS8688,
};

struct ads8688_ranges {
	enum ads8688_range range;
	unsigned int scale;
	int offset;
	u8 reg;
};

static const struct ads8688_ranges ads8688_range_def[5] = {
	{
		.range = ADS8688_PLUSMINUS25VREF,
		.scale = 76295,
		.offset = -(1 << (ADS8688_REALBITS - 1)),
		.reg = ADS8688_REG_PLUSMINUS25VREF,
	}, {
		.range = ADS8688_PLUSMINUS125VREF,
		.scale = 38148,
		.offset = -(1 << (ADS8688_REALBITS - 1)),
		.reg = ADS8688_REG_PLUSMINUS125VREF,
	}, {
		.range = ADS8688_PLUSMINUS0625VREF,
		.scale = 19074,
		.offset = -(1 << (ADS8688_REALBITS - 1)),
		.reg = ADS8688_REG_PLUSMINUS0625VREF,
	}, {
		.range = ADS8688_PLUS25VREF,
		.scale = 38148,
		.offset = 0,
		.reg = ADS8688_REG_PLUS25VREF,
	}, {
		.range = ADS8688_PLUS125VREF,
		.scale = 19074,
		.offset = 0,
		.reg = ADS8688_REG_PLUS125VREF,
	}
};

static ssize_t ads8688_show_scales(struct device *dev,
				   struct device_attribute *attr, char *buf)
{
	struct ads8688_state *st = iio_priv(dev_to_iio_dev(dev));

	return sprintf(buf, "0.%09u 0.%09u 0.%09u\n",
		       ads8688_range_def[0].scale * st->vref_mv,
		       ads8688_range_def[1].scale * st->vref_mv,
		       ads8688_range_def[2].scale * st->vref_mv);
}

static ssize_t ads8688_show_offsets(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%d %d\n", ads8688_range_def[0].offset,
		       ads8688_range_def[3].offset);
}

static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
		       ads8688_show_scales, NULL, 0);
static IIO_DEVICE_ATTR(in_voltage_offset_available, S_IRUGO,
		       ads8688_show_offsets, NULL, 0);

static struct attribute *ads8688_attributes[] = {
	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
	&iio_dev_attr_in_voltage_offset_available.dev_attr.attr,
	NULL,
};

static const struct attribute_group ads8688_attribute_group = {
	.attrs = ads8688_attributes,
};

#define ADS8688_CHAN(index)					\
{								\
	.type = IIO_VOLTAGE,					\
	.indexed = 1,						\
	.channel = index,					\
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)		\
			      | BIT(IIO_CHAN_INFO_SCALE)	\
			      | BIT(IIO_CHAN_INFO_OFFSET),	\
}

static const struct iio_chan_spec ads8684_channels[] = {
	ADS8688_CHAN(0),
	ADS8688_CHAN(1),
	ADS8688_CHAN(2),
	ADS8688_CHAN(3),
};

static const struct iio_chan_spec ads8688_channels[] = {
	ADS8688_CHAN(0),
	ADS8688_CHAN(1),
	ADS8688_CHAN(2),
	ADS8688_CHAN(3),
	ADS8688_CHAN(4),
	ADS8688_CHAN(5),
	ADS8688_CHAN(6),
	ADS8688_CHAN(7),
};

static int ads8688_prog_write(struct iio_dev *indio_dev, unsigned int addr,
			      unsigned int val)
{
	struct ads8688_state *st = iio_priv(indio_dev);
	u32 tmp;

	tmp = ADS8688_PROG_REG(addr) | ADS8688_PROG_WR_BIT | val;
	tmp <<= ADS8688_PROG_DONT_CARE_BITS;
	st->data[0].d32 = cpu_to_be32(tmp);

	return spi_write(st->spi, &st->data[0].d8[1], 3);
}

static int ads8688_reset(struct iio_dev *indio_dev)
{
	struct ads8688_state *st = iio_priv(indio_dev);
	u32 tmp;

	tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_RST);
	tmp <<= ADS8688_CMD_DONT_CARE_BITS;
	st->data[0].d32 = cpu_to_be32(tmp);

	return spi_write(st->spi, &st->data[0].d8[0], 4);
}

static int ads8688_read(struct iio_dev *indio_dev, unsigned int chan)
{
	struct ads8688_state *st = iio_priv(indio_dev);
	int ret;
	u32 tmp;
	struct spi_transfer t[] = {
		{
			.tx_buf = &st->data[0].d8[0],
			.len = 4,
			.cs_change = 1,
		}, {
			.tx_buf = &st->data[1].d8[0],
			.rx_buf = &st->data[1].d8[0],
			.len = 4,
		},
	};

	tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_MAN_CH(chan));
	tmp <<= ADS8688_CMD_DONT_CARE_BITS;
	st->data[0].d32 = cpu_to_be32(tmp);

	tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_NOOP);
	tmp <<= ADS8688_CMD_DONT_CARE_BITS;
	st->data[1].d32 = cpu_to_be32(tmp);

	ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
	if (ret < 0)
		return ret;

	return be32_to_cpu(st->data[1].d32) & 0xffff;
}

static int ads8688_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long m)
{
	int ret, offset;
	unsigned long scale_mv;

	struct ads8688_state *st = iio_priv(indio_dev);

	mutex_lock(&st->lock);
	switch (m) {
	case IIO_CHAN_INFO_RAW:
		ret = ads8688_read(indio_dev, chan->channel);
		mutex_unlock(&st->lock);
		if (ret < 0)
			return ret;
		*val = ret;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		scale_mv = st->vref_mv;
		scale_mv *= ads8688_range_def[st->range[chan->channel]].scale;
		*val = 0;
		*val2 = scale_mv;
		mutex_unlock(&st->lock);
		return IIO_VAL_INT_PLUS_NANO;
	case IIO_CHAN_INFO_OFFSET:
		offset = ads8688_range_def[st->range[chan->channel]].offset;
		*val = offset;
		mutex_unlock(&st->lock);
		return IIO_VAL_INT;
	}
	mutex_unlock(&st->lock);

	return -EINVAL;
}

static int ads8688_write_reg_range(struct iio_dev *indio_dev,
				   struct iio_chan_spec const *chan,
				   enum ads8688_range range)
{
	unsigned int tmp;
	int ret;

	tmp = ADS8688_PROG_REG_RANGE_CH(chan->channel);
	ret = ads8688_prog_write(indio_dev, tmp, range);

	return ret;
}

static int ads8688_write_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int val, int val2, long mask)
{
	struct ads8688_state *st = iio_priv(indio_dev);
	unsigned int scale = 0;
	int ret = -EINVAL, i, offset = 0;

	mutex_lock(&st->lock);
	switch (mask) {
	case IIO_CHAN_INFO_SCALE:
		/* If the offset is 0 the ±2.5 * VREF mode is not available */
		offset = ads8688_range_def[st->range[chan->channel]].offset;
		if (offset == 0 && val2 == ads8688_range_def[0].scale * st->vref_mv) {
			mutex_unlock(&st->lock);
			return -EINVAL;
		}

		/* Lookup new mode */
		for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++)
			if (val2 == ads8688_range_def[i].scale * st->vref_mv &&
			    offset == ads8688_range_def[i].offset) {
				ret = ads8688_write_reg_range(indio_dev, chan,
					ads8688_range_def[i].reg);
				break;
			}
		break;
	case IIO_CHAN_INFO_OFFSET:
		/*
		 * There are only two available offsets:
		 * 0 and -(1 << (ADS8688_REALBITS - 1))
		 */
		if (!(ads8688_range_def[0].offset == val ||
		    ads8688_range_def[3].offset == val)) {
			mutex_unlock(&st->lock);
			return -EINVAL;
		}

		/*
		 * If the device are in ±2.5 * VREF mode, it's not allowed to
		 * switch to a mode where the offset is 0
		 */
		if (val == 0 &&
		    st->range[chan->channel] == ADS8688_PLUSMINUS25VREF) {
			mutex_unlock(&st->lock);
			return -EINVAL;
		}

		scale = ads8688_range_def[st->range[chan->channel]].scale;

		/* Lookup new mode */
		for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++)
			if (val == ads8688_range_def[i].offset &&
			    scale == ads8688_range_def[i].scale) {
				ret = ads8688_write_reg_range(indio_dev, chan,
					ads8688_range_def[i].reg);
				break;
			}
		break;
	}

	if (!ret)
		st->range[chan->channel] = ads8688_range_def[i].range;

	mutex_unlock(&st->lock);

	return ret;
}

static int ads8688_write_raw_get_fmt(struct iio_dev *indio_dev,
				     struct iio_chan_spec const *chan,
				     long mask)
{
	switch (mask) {
	case IIO_CHAN_INFO_SCALE:
		return IIO_VAL_INT_PLUS_NANO;
	case IIO_CHAN_INFO_OFFSET:
		return IIO_VAL_INT;
	}

	return -EINVAL;
}

static const struct iio_info ads8688_info = {
	.read_raw = &ads8688_read_raw,
	.write_raw = &ads8688_write_raw,
	.write_raw_get_fmt = &ads8688_write_raw_get_fmt,
	.attrs = &ads8688_attribute_group,
	.driver_module = THIS_MODULE,
};

static const struct ads8688_chip_info ads8688_chip_info_tbl[] = {
	[ID_ADS8684] = {
		.channels = ads8684_channels,
		.num_channels = ARRAY_SIZE(ads8684_channels),
	},
	[ID_ADS8688] = {
		.channels = ads8688_channels,
		.num_channels = ARRAY_SIZE(ads8688_channels),
	},
};

static int ads8688_probe(struct spi_device *spi)
{
	struct ads8688_state *st;
	struct iio_dev *indio_dev;
	int ret;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
	if (indio_dev == NULL)
		return -ENOMEM;

	st = iio_priv(indio_dev);

	st->reg = devm_regulator_get_optional(&spi->dev, "vref");
	if (!IS_ERR(st->reg)) {
		ret = regulator_enable(st->reg);
		if (ret)
			return ret;

		ret = regulator_get_voltage(st->reg);
		if (ret < 0)
			goto error_out;

		st->vref_mv = ret / 1000;
	} else {
		/* Use internal reference */
		st->vref_mv = ADS8688_VREF_MV;
	}

	st->chip_info =	&ads8688_chip_info_tbl[spi_get_device_id(spi)->driver_data];

	spi->mode = SPI_MODE_1;

	spi_set_drvdata(spi, indio_dev);

	st->spi = spi;

	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->dev.parent = &spi->dev;
	indio_dev->dev.of_node = spi->dev.of_node;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = st->chip_info->channels;
	indio_dev->num_channels = st->chip_info->num_channels;
	indio_dev->info = &ads8688_info;

	ads8688_reset(indio_dev);

	mutex_init(&st->lock);

	ret = iio_device_register(indio_dev);
	if (ret)
		goto error_out;

	return 0;

error_out:
	if (!IS_ERR_OR_NULL(st->reg))
		regulator_disable(st->reg);

	return ret;
}

static int ads8688_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct ads8688_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);

	if (!IS_ERR_OR_NULL(st->reg))
		regulator_disable(st->reg);

	return 0;
}

static const struct spi_device_id ads8688_id[] = {
	{"ads8684", ID_ADS8684},
	{"ads8688", ID_ADS8688},
	{}
};
MODULE_DEVICE_TABLE(spi, ads8688_id);

static const struct of_device_id ads8688_of_match[] = {
	{ .compatible = "ti,ads8684" },
	{ .compatible = "ti,ads8688" },
	{ }
};
MODULE_DEVICE_TABLE(of, ads8688_of_match);

static struct spi_driver ads8688_driver = {
	.driver = {
		.name	= "ads8688",
		.owner	= THIS_MODULE,
	},
	.probe		= ads8688_probe,
	.remove		= ads8688_remove,
	.id_table	= ads8688_id,
};
module_spi_driver(ads8688_driver);

MODULE_AUTHOR("Sean Nyekjaer <sean.nyekjaer@prevas.dk>");
MODULE_DESCRIPTION("Texas Instruments ADS8688 driver");
MODULE_LICENSE("GPL v2");
OpenPOWER on IntegriCloud