Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
  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
/*
 * AD5421 Digital to analog converters  driver
 *
 * Copyright 2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 */

#include <linux/device.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/events.h>
#include <linux/iio/dac/ad5421.h>


#define AD5421_REG_DAC_DATA		0x1
#define AD5421_REG_CTRL			0x2
#define AD5421_REG_OFFSET		0x3
#define AD5421_REG_GAIN			0x4
/* load dac and fault shared the same register number. Writing to it will cause
 * a dac load command, reading from it will return the fault status register */
#define AD5421_REG_LOAD_DAC		0x5
#define AD5421_REG_FAULT		0x5
#define AD5421_REG_FORCE_ALARM_CURRENT	0x6
#define AD5421_REG_RESET		0x7
#define AD5421_REG_START_CONVERSION	0x8
#define AD5421_REG_NOOP			0x9

#define AD5421_CTRL_WATCHDOG_DISABLE	BIT(12)
#define AD5421_CTRL_AUTO_FAULT_READBACK	BIT(11)
#define AD5421_CTRL_MIN_CURRENT		BIT(9)
#define AD5421_CTRL_ADC_SOURCE_TEMP	BIT(8)
#define AD5421_CTRL_ADC_ENABLE		BIT(7)
#define AD5421_CTRL_PWR_DOWN_INT_VREF	BIT(6)

#define AD5421_FAULT_SPI			BIT(15)
#define AD5421_FAULT_PEC			BIT(14)
#define AD5421_FAULT_OVER_CURRENT		BIT(13)
#define AD5421_FAULT_UNDER_CURRENT		BIT(12)
#define AD5421_FAULT_TEMP_OVER_140		BIT(11)
#define AD5421_FAULT_TEMP_OVER_100		BIT(10)
#define AD5421_FAULT_UNDER_VOLTAGE_6V		BIT(9)
#define AD5421_FAULT_UNDER_VOLTAGE_12V		BIT(8)

/* These bits will cause the fault pin to go high */
#define AD5421_FAULT_TRIGGER_IRQ \
	(AD5421_FAULT_SPI | AD5421_FAULT_PEC | AD5421_FAULT_OVER_CURRENT | \
	AD5421_FAULT_UNDER_CURRENT | AD5421_FAULT_TEMP_OVER_140)

/**
 * struct ad5421_state - driver instance specific data
 * @spi:		spi_device
 * @ctrl:		control register cache
 * @current_range:	current range which the device is configured for
 * @data:		spi transfer buffers
 * @fault_mask:		software masking of events
 */
struct ad5421_state {
	struct spi_device		*spi;
	unsigned int			ctrl;
	enum ad5421_current_range	current_range;
	unsigned int			fault_mask;

	/*
	 * DMA (thus cache coherency maintenance) requires the
	 * transfer buffers to live in their own cache lines.
	 */
	union {
		u32 d32;
		u8 d8[4];
	} data[2] ____cacheline_aligned;
};

static const struct iio_chan_spec ad5421_channels[] = {
	{
		.type = IIO_CURRENT,
		.indexed = 1,
		.output = 1,
		.channel = 0,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
			BIT(IIO_CHAN_INFO_CALIBSCALE) |
			BIT(IIO_CHAN_INFO_CALIBBIAS),
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
			BIT(IIO_CHAN_INFO_OFFSET),
		.scan_type = IIO_ST('u', 16, 16, 0),
		.event_mask = IIO_EV_BIT(IIO_EV_TYPE_THRESH, IIO_EV_DIR_RISING) |
			IIO_EV_BIT(IIO_EV_TYPE_THRESH, IIO_EV_DIR_FALLING),
	},
	{
		.type = IIO_TEMP,
		.channel = -1,
		.event_mask = IIO_EV_BIT(IIO_EV_TYPE_THRESH, IIO_EV_DIR_RISING),
	},
};

static int ad5421_write_unlocked(struct iio_dev *indio_dev,
	unsigned int reg, unsigned int val)
{
	struct ad5421_state *st = iio_priv(indio_dev);

	st->data[0].d32 = cpu_to_be32((reg << 16) | val);

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

static int ad5421_write(struct iio_dev *indio_dev, unsigned int reg,
	unsigned int val)
{
	int ret;

	mutex_lock(&indio_dev->mlock);
	ret = ad5421_write_unlocked(indio_dev, reg, val);
	mutex_unlock(&indio_dev->mlock);

	return ret;
}

static int ad5421_read(struct iio_dev *indio_dev, unsigned int reg)
{
	struct ad5421_state *st = iio_priv(indio_dev);
	int ret;
	struct spi_transfer t[] = {
		{
			.tx_buf = &st->data[0].d8[1],
			.len = 3,
			.cs_change = 1,
		}, {
			.rx_buf = &st->data[1].d8[1],
			.len = 3,
		},
	};

	mutex_lock(&indio_dev->mlock);

	st->data[0].d32 = cpu_to_be32((1 << 23) | (reg << 16));

	ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
	if (ret >= 0)
		ret = be32_to_cpu(st->data[1].d32) & 0xffff;

	mutex_unlock(&indio_dev->mlock);

	return ret;
}

static int ad5421_update_ctrl(struct iio_dev *indio_dev, unsigned int set,
	unsigned int clr)
{
	struct ad5421_state *st = iio_priv(indio_dev);
	unsigned int ret;

	mutex_lock(&indio_dev->mlock);

	st->ctrl &= ~clr;
	st->ctrl |= set;

	ret = ad5421_write_unlocked(indio_dev, AD5421_REG_CTRL, st->ctrl);

	mutex_unlock(&indio_dev->mlock);

	return ret;
}

static irqreturn_t ad5421_fault_handler(int irq, void *data)
{
	struct iio_dev *indio_dev = data;
	struct ad5421_state *st = iio_priv(indio_dev);
	unsigned int fault;
	unsigned int old_fault = 0;
	unsigned int events;

	fault = ad5421_read(indio_dev, AD5421_REG_FAULT);
	if (!fault)
		return IRQ_NONE;

	/* If we had a fault, this might mean that the DAC has lost its state
	 * and has been reset. Make sure that the control register actually
	 * contains what we expect it to contain. Otherwise the watchdog might
	 * be enabled and we get watchdog timeout faults, which will render the
	 * DAC unusable. */
	ad5421_update_ctrl(indio_dev, 0, 0);


	/* The fault pin stays high as long as a fault condition is present and
	 * it is not possible to mask fault conditions. For certain fault
	 * conditions for example like over-temperature it takes some time
	 * until the fault condition disappears. If we would exit the interrupt
	 * handler immediately after handling the event it would be entered
	 * again instantly. Thus we fall back to polling in case we detect that
	 * a interrupt condition is still present.
	 */
	do {
		/* 0xffff is a invalid value for the register and will only be
		 * read if there has been a communication error */
		if (fault == 0xffff)
			fault = 0;

		/* we are only interested in new events */
		events = (old_fault ^ fault) & fault;
		events &= st->fault_mask;

		if (events & AD5421_FAULT_OVER_CURRENT) {
			iio_push_event(indio_dev,
				IIO_UNMOD_EVENT_CODE(IIO_CURRENT,
					0,
					IIO_EV_TYPE_THRESH,
					IIO_EV_DIR_RISING),
			iio_get_time_ns());
		}

		if (events & AD5421_FAULT_UNDER_CURRENT) {
			iio_push_event(indio_dev,
				IIO_UNMOD_EVENT_CODE(IIO_CURRENT,
					0,
					IIO_EV_TYPE_THRESH,
					IIO_EV_DIR_FALLING),
				iio_get_time_ns());
		}

		if (events & AD5421_FAULT_TEMP_OVER_140) {
			iio_push_event(indio_dev,
				IIO_UNMOD_EVENT_CODE(IIO_TEMP,
					0,
					IIO_EV_TYPE_MAG,
					IIO_EV_DIR_RISING),
				iio_get_time_ns());
		}

		old_fault = fault;
		fault = ad5421_read(indio_dev, AD5421_REG_FAULT);

		/* still active? go to sleep for some time */
		if (fault & AD5421_FAULT_TRIGGER_IRQ)
			msleep(1000);

	} while (fault & AD5421_FAULT_TRIGGER_IRQ);


	return IRQ_HANDLED;
}

static void ad5421_get_current_min_max(struct ad5421_state *st,
	unsigned int *min, unsigned int *max)
{
	/* The current range is configured using external pins, which are
	 * usually hard-wired and not run-time switchable. */
	switch (st->current_range) {
	case AD5421_CURRENT_RANGE_4mA_20mA:
		*min = 4000;
		*max = 20000;
		break;
	case AD5421_CURRENT_RANGE_3mA8_21mA:
		*min = 3800;
		*max = 21000;
		break;
	case AD5421_CURRENT_RANGE_3mA2_24mA:
		*min = 3200;
		*max = 24000;
		break;
	default:
		*min = 0;
		*max = 1;
		break;
	}
}

static inline unsigned int ad5421_get_offset(struct ad5421_state *st)
{
	unsigned int min, max;

	ad5421_get_current_min_max(st, &min, &max);
	return (min * (1 << 16)) / (max - min);
}

static inline unsigned int ad5421_get_scale(struct ad5421_state *st)
{
	unsigned int min, max;

	ad5421_get_current_min_max(st, &min, &max);
	return ((max - min) * 1000) / (1 << 16);
}

static int ad5421_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan, int *val, int *val2, long m)
{
	struct ad5421_state *st = iio_priv(indio_dev);
	int ret;

	if (chan->type != IIO_CURRENT)
		return -EINVAL;

	switch (m) {
	case IIO_CHAN_INFO_RAW:
		ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);
		if (ret < 0)
			return ret;
		*val = ret;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		*val = 0;
		*val2 = ad5421_get_scale(st);
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_OFFSET:
		*val = ad5421_get_offset(st);
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_CALIBBIAS:
		ret = ad5421_read(indio_dev, AD5421_REG_OFFSET);
		if (ret < 0)
			return ret;
		*val = ret - 32768;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_CALIBSCALE:
		ret = ad5421_read(indio_dev, AD5421_REG_GAIN);
		if (ret < 0)
			return ret;
		*val = ret;
		return IIO_VAL_INT;
	}

	return -EINVAL;
}

static int ad5421_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan, int val, int val2, long mask)
{
	const unsigned int max_val = 1 << 16;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		if (val >= max_val || val < 0)
			return -EINVAL;

		return ad5421_write(indio_dev, AD5421_REG_DAC_DATA, val);
	case IIO_CHAN_INFO_CALIBBIAS:
		val += 32768;
		if (val >= max_val || val < 0)
			return -EINVAL;

		return ad5421_write(indio_dev, AD5421_REG_OFFSET, val);
	case IIO_CHAN_INFO_CALIBSCALE:
		if (val >= max_val || val < 0)
			return -EINVAL;

		return ad5421_write(indio_dev, AD5421_REG_GAIN, val);
	default:
		break;
	}

	return -EINVAL;
}

static int ad5421_write_event_config(struct iio_dev *indio_dev,
	u64 event_code, int state)
{
	struct ad5421_state *st = iio_priv(indio_dev);
	unsigned int mask;

	switch (IIO_EVENT_CODE_EXTRACT_CHAN_TYPE(event_code)) {
	case IIO_CURRENT:
		if (IIO_EVENT_CODE_EXTRACT_DIR(event_code) ==
			IIO_EV_DIR_RISING)
			mask = AD5421_FAULT_OVER_CURRENT;
		else
			mask = AD5421_FAULT_UNDER_CURRENT;
		break;
	case IIO_TEMP:
		mask = AD5421_FAULT_TEMP_OVER_140;
		break;
	default:
		return -EINVAL;
	}

	mutex_lock(&indio_dev->mlock);
	if (state)
		st->fault_mask |= mask;
	else
		st->fault_mask &= ~mask;
	mutex_unlock(&indio_dev->mlock);

	return 0;
}

static int ad5421_read_event_config(struct iio_dev *indio_dev,
	u64 event_code)
{
	struct ad5421_state *st = iio_priv(indio_dev);
	unsigned int mask;

	switch (IIO_EVENT_CODE_EXTRACT_CHAN_TYPE(event_code)) {
	case IIO_CURRENT:
		if (IIO_EVENT_CODE_EXTRACT_DIR(event_code) ==
			IIO_EV_DIR_RISING)
			mask = AD5421_FAULT_OVER_CURRENT;
		else
			mask = AD5421_FAULT_UNDER_CURRENT;
		break;
	case IIO_TEMP:
		mask = AD5421_FAULT_TEMP_OVER_140;
		break;
	default:
		return -EINVAL;
	}

	return (bool)(st->fault_mask & mask);
}

static int ad5421_read_event_value(struct iio_dev *indio_dev, u64 event_code,
	int *val)
{
	int ret;

	switch (IIO_EVENT_CODE_EXTRACT_CHAN_TYPE(event_code)) {
	case IIO_CURRENT:
		ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);
		if (ret < 0)
			return ret;
		*val = ret;
		break;
	case IIO_TEMP:
		*val = 140000;
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static const struct iio_info ad5421_info = {
	.read_raw =		ad5421_read_raw,
	.write_raw =		ad5421_write_raw,
	.read_event_config =	ad5421_read_event_config,
	.write_event_config =	ad5421_write_event_config,
	.read_event_value =	ad5421_read_event_value,
	.driver_module =	THIS_MODULE,
};

static int ad5421_probe(struct spi_device *spi)
{
	struct ad5421_platform_data *pdata = dev_get_platdata(&spi->dev);
	struct iio_dev *indio_dev;
	struct ad5421_state *st;
	int ret;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
	if (indio_dev == NULL) {
		dev_err(&spi->dev, "Failed to allocate iio device\n");
		return  -ENOMEM;
	}

	st = iio_priv(indio_dev);
	spi_set_drvdata(spi, indio_dev);

	st->spi = spi;

	indio_dev->dev.parent = &spi->dev;
	indio_dev->name = "ad5421";
	indio_dev->info = &ad5421_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = ad5421_channels;
	indio_dev->num_channels = ARRAY_SIZE(ad5421_channels);

	st->ctrl = AD5421_CTRL_WATCHDOG_DISABLE |
			AD5421_CTRL_AUTO_FAULT_READBACK;

	if (pdata) {
		st->current_range = pdata->current_range;
		if (pdata->external_vref)
			st->ctrl |= AD5421_CTRL_PWR_DOWN_INT_VREF;
	} else {
		st->current_range = AD5421_CURRENT_RANGE_4mA_20mA;
	}

	/* write initial ctrl register value */
	ad5421_update_ctrl(indio_dev, 0, 0);

	if (spi->irq) {
		ret = devm_request_threaded_irq(&spi->dev, spi->irq,
					   NULL,
					   ad5421_fault_handler,
					   IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
					   "ad5421 fault",
					   indio_dev);
		if (ret)
			return ret;
	}

	ret = iio_device_register(indio_dev);
	if (ret) {
		dev_err(&spi->dev, "Failed to register iio device: %d\n", ret);
		return ret;
	}

	return 0;
}

static int ad5421_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);

	iio_device_unregister(indio_dev);

	return 0;
}

static struct spi_driver ad5421_driver = {
	.driver = {
		   .name = "ad5421",
		   .owner = THIS_MODULE,
	},
	.probe = ad5421_probe,
	.remove = ad5421_remove,
};
module_spi_driver(ad5421_driver);

MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Analog Devices AD5421 DAC");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:ad5421");