summaryrefslogtreecommitdiffstats
path: root/drivers/iio/adc/ti-adc108s102.c
blob: 841203edaac578686bb65ee118d797d6043d5685 (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
/*
 * TI ADC108S102 SPI ADC driver
 *
 * Copyright (c) 2013-2015 Intel Corporation.
 * Copyright (c) 2017 Siemens AG
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * This IIO device driver is designed to work with the following
 * analog to digital converters from Texas Instruments:
 *  ADC108S102
 *  ADC128S102
 * The communication with ADC chip is via the SPI bus (mode 3).
 */

#include <linux/acpi.h>
#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/types.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

/*
 * In case of ACPI, we use the hard-wired 5000 mV of the Galileo and IOT2000
 * boards as default for the reference pin VA. Device tree users encode that
 * via the vref-supply regulator.
 */
#define ADC108S102_VA_MV_ACPI_DEFAULT	5000

/*
 * Defining the ADC resolution being 12 bits, we can use the same driver for
 * both ADC108S102 (10 bits resolution) and ADC128S102 (12 bits resolution)
 * chips. The ADC108S102 effectively returns a 12-bit result with the 2
 * least-significant bits unset.
 */
#define ADC108S102_BITS		12
#define ADC108S102_MAX_CHANNELS	8

/*
 * 16-bit SPI command format:
 *   [15:14] Ignored
 *   [13:11] 3-bit channel address
 *   [10:0]  Ignored
 */
#define ADC108S102_CMD(ch)		((u16)(ch) << 11)

/*
 * 16-bit SPI response format:
 *   [15:12] Zeros
 *   [11:0]  12-bit ADC sample (for ADC108S102, [1:0] will always be 0).
 */
#define ADC108S102_RES_DATA(res)	((u16)res & GENMASK(11, 0))

struct adc108s102_state {
	struct spi_device		*spi;
	struct regulator		*reg;
	u32				va_millivolt;
	/* SPI transfer used by triggered buffer handler*/
	struct spi_transfer		ring_xfer;
	/* SPI transfer used by direct scan */
	struct spi_transfer		scan_single_xfer;
	/* SPI message used by ring_xfer SPI transfer */
	struct spi_message		ring_msg;
	/* SPI message used by scan_single_xfer SPI transfer */
	struct spi_message		scan_single_msg;

	/*
	 * SPI message buffers:
	 *  tx_buf: |C0|C1|C2|C3|C4|C5|C6|C7|XX|
	 *  rx_buf: |XX|R0|R1|R2|R3|R4|R5|R6|R7|tt|tt|tt|tt|
	 *
	 *  tx_buf: 8 channel read commands, plus 1 dummy command
	 *  rx_buf: 1 dummy response, 8 channel responses, plus 64-bit timestamp
	 */
	__be16				rx_buf[13] ____cacheline_aligned;
	__be16				tx_buf[9] ____cacheline_aligned;
};

#define ADC108S102_V_CHAN(index)					\
	{								\
		.type = IIO_VOLTAGE,					\
		.indexed = 1,						\
		.channel = index,					\
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
			BIT(IIO_CHAN_INFO_SCALE),			\
		.address = index,					\
		.scan_index = index,					\
		.scan_type = {						\
			.sign = 'u',					\
			.realbits = ADC108S102_BITS,			\
			.storagebits = 16,				\
			.endianness = IIO_BE,				\
		},							\
	}

static const struct iio_chan_spec adc108s102_channels[] = {
	ADC108S102_V_CHAN(0),
	ADC108S102_V_CHAN(1),
	ADC108S102_V_CHAN(2),
	ADC108S102_V_CHAN(3),
	ADC108S102_V_CHAN(4),
	ADC108S102_V_CHAN(5),
	ADC108S102_V_CHAN(6),
	ADC108S102_V_CHAN(7),
	IIO_CHAN_SOFT_TIMESTAMP(8),
};

static int adc108s102_update_scan_mode(struct iio_dev *indio_dev,
		unsigned long const *active_scan_mask)
{
	struct adc108s102_state *st = iio_priv(indio_dev);
	unsigned int bit, cmds;

	/*
	 * Fill in the first x shorts of tx_buf with the number of channels
	 * enabled for sampling by the triggered buffer.
	 */
	cmds = 0;
	for_each_set_bit(bit, active_scan_mask, ADC108S102_MAX_CHANNELS)
		st->tx_buf[cmds++] = cpu_to_be16(ADC108S102_CMD(bit));

	/* One dummy command added, to clock in the last response */
	st->tx_buf[cmds++] = 0x00;

	/* build SPI ring message */
	st->ring_xfer.tx_buf = &st->tx_buf[0];
	st->ring_xfer.rx_buf = &st->rx_buf[0];
	st->ring_xfer.len = cmds * sizeof(st->tx_buf[0]);

	spi_message_init_with_transfers(&st->ring_msg, &st->ring_xfer, 1);

	return 0;
}

static irqreturn_t adc108s102_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct adc108s102_state *st = iio_priv(indio_dev);
	int ret;

	ret = spi_sync(st->spi, &st->ring_msg);
	if (ret < 0)
		goto out_notify;

	/* Skip the dummy response in the first slot */
	iio_push_to_buffers_with_timestamp(indio_dev,
					   (u8 *)&st->rx_buf[1],
					   iio_get_time_ns(indio_dev));

out_notify:
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

static int adc108s102_scan_direct(struct adc108s102_state *st, unsigned int ch)
{
	int ret;

	st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch));
	ret = spi_sync(st->spi, &st->scan_single_msg);
	if (ret)
		return ret;

	/* Skip the dummy response in the first slot */
	return be16_to_cpu(st->rx_buf[1]);
}

static int adc108s102_read_raw(struct iio_dev *indio_dev,
			       struct iio_chan_spec const *chan,
			       int *val, int *val2, long m)
{
	struct adc108s102_state *st = iio_priv(indio_dev);
	int ret;

	switch (m) {
	case IIO_CHAN_INFO_RAW:
		ret = iio_device_claim_direct_mode(indio_dev);
		if (ret)
			return ret;

		ret = adc108s102_scan_direct(st, chan->address);

		iio_device_release_direct_mode(indio_dev);

		if (ret < 0)
			return ret;

		*val = ADC108S102_RES_DATA(ret);

		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		if (chan->type != IIO_VOLTAGE)
			break;

		*val = st->va_millivolt;
		*val2 = chan->scan_type.realbits;

		return IIO_VAL_FRACTIONAL_LOG2;
	default:
		break;
	}

	return -EINVAL;
}

static const struct iio_info adc108s102_info = {
	.read_raw		= &adc108s102_read_raw,
	.update_scan_mode	= &adc108s102_update_scan_mode,
};

static int adc108s102_probe(struct spi_device *spi)
{
	struct adc108s102_state *st;
	struct iio_dev *indio_dev;
	int ret;

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

	st = iio_priv(indio_dev);

	if (ACPI_COMPANION(&spi->dev)) {
		st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT;
	} else {
		st->reg = devm_regulator_get(&spi->dev, "vref");
		if (IS_ERR(st->reg))
			return PTR_ERR(st->reg);

		ret = regulator_enable(st->reg);
		if (ret < 0) {
			dev_err(&spi->dev, "Cannot enable vref regulator\n");
			return ret;
		}

		ret = regulator_get_voltage(st->reg);
		if (ret < 0) {
			dev_err(&spi->dev, "vref get voltage failed\n");
			return ret;
		}

		st->va_millivolt = ret / 1000;
	}

	spi_set_drvdata(spi, indio_dev);
	st->spi = spi;

	indio_dev->name = spi->modalias;
	indio_dev->dev.parent = &spi->dev;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = adc108s102_channels;
	indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
	indio_dev->info = &adc108s102_info;

	/* Setup default message */
	st->scan_single_xfer.tx_buf = st->tx_buf;
	st->scan_single_xfer.rx_buf = st->rx_buf;
	st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);

	spi_message_init_with_transfers(&st->scan_single_msg,
					&st->scan_single_xfer, 1);

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
					 &adc108s102_trigger_handler, NULL);
	if (ret)
		goto error_disable_reg;

	ret = iio_device_register(indio_dev);
	if (ret) {
		dev_err(&spi->dev, "Failed to register IIO device\n");
		goto error_cleanup_triggered_buffer;
	}
	return 0;

error_cleanup_triggered_buffer:
	iio_triggered_buffer_cleanup(indio_dev);

error_disable_reg:
	regulator_disable(st->reg);

	return ret;
}

static int adc108s102_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct adc108s102_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);

	regulator_disable(st->reg);

	return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id adc108s102_of_match[] = {
	{ .compatible = "ti,adc108s102" },
	{ }
};
MODULE_DEVICE_TABLE(of, adc108s102_of_match);
#endif

#ifdef CONFIG_ACPI
static const struct acpi_device_id adc108s102_acpi_ids[] = {
	{ "INT3495", 0 },
	{ }
};
MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
#endif

static const struct spi_device_id adc108s102_id[] = {
	{ "adc108s102", 0 },
	{ }
};
MODULE_DEVICE_TABLE(spi, adc108s102_id);

static struct spi_driver adc108s102_driver = {
	.driver = {
		.name   = "adc108s102",
		.of_match_table = of_match_ptr(adc108s102_of_match),
		.acpi_match_table = ACPI_PTR(adc108s102_acpi_ids),
	},
	.probe		= adc108s102_probe,
	.remove		= adc108s102_remove,
	.id_table	= adc108s102_id,
};
module_spi_driver(adc108s102_driver);

MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver");
MODULE_LICENSE("GPL v2");