ti-adc084s021.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2017 Axis Communications AB
  4 *
  5 * Driver for Texas Instruments' ADC084S021 ADC chip.
  6 * Datasheets can be found here:
  7 * https://www.ti.com/lit/ds/symlink/adc084s021.pdf
  8 */
  9
 10#include <linux/err.h>
 11#include <linux/spi/spi.h>
 12#include <linux/module.h>
 13#include <linux/mod_devicetable.h>
 14#include <linux/interrupt.h>
 15#include <linux/iio/iio.h>
 16#include <linux/iio/buffer.h>
 17#include <linux/iio/triggered_buffer.h>
 18#include <linux/iio/trigger_consumer.h>
 19#include <linux/regulator/consumer.h>
 20
 21#define ADC084S021_DRIVER_NAME "adc084s021"
 22
 23struct adc084s021 {
 24	struct spi_device *spi;
 25	struct spi_message message;
 26	struct spi_transfer spi_trans;
 27	struct regulator *reg;
 28	struct mutex lock;
 29	/* Buffer used to align data */
 30	struct {
 31		__be16 channels[4];
 32		aligned_s64 ts;
 33	} scan;
 34	/*
 35	 * DMA (thus cache coherency maintenance) may require the
 36	 * transfer buffers to live in their own cache line.
 37	 */
 38	u16 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
 39	__be16 rx_buf[5]; /* First 16-bits are trash */
 40};
 41
 42#define ADC084S021_VOLTAGE_CHANNEL(num)                  \
 43	{                                                      \
 44		.type = IIO_VOLTAGE,                                 \
 45		.channel = (num),                                    \
 46		.indexed = 1,                                        \
 47		.scan_index = (num),                                 \
 48		.scan_type = {                                       \
 49			.sign = 'u',                                       \
 50			.realbits = 8,                                     \
 51			.storagebits = 16,                                 \
 52			.shift = 4,                                        \
 53			.endianness = IIO_BE,                              \
 54		},                                                   \
 55		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),        \
 56		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
 57	}
 58
 59static const struct iio_chan_spec adc084s021_channels[] = {
 60	ADC084S021_VOLTAGE_CHANNEL(0),
 61	ADC084S021_VOLTAGE_CHANNEL(1),
 62	ADC084S021_VOLTAGE_CHANNEL(2),
 63	ADC084S021_VOLTAGE_CHANNEL(3),
 64	IIO_CHAN_SOFT_TIMESTAMP(4),
 65};
 66
 67/**
 68 * adc084s021_adc_conversion() - Read an ADC channel and return its value.
 69 *
 70 * @adc: The ADC SPI data.
 71 * @data: Buffer for converted data.
 72 */
 73static int adc084s021_adc_conversion(struct adc084s021 *adc, __be16 *data)
 74{
 75	int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
 76	int ret, i = 0;
 77
 78	/* Do the transfer */
 79	ret = spi_sync(adc->spi, &adc->message);
 80	if (ret < 0)
 81		return ret;
 82
 83	for (; i < n_words; i++)
 84		*(data + i) = adc->rx_buf[i + 1];
 85
 86	return ret;
 87}
 88
 89static int adc084s021_read_raw(struct iio_dev *indio_dev,
 90			   struct iio_chan_spec const *channel, int *val,
 91			   int *val2, long mask)
 92{
 93	struct adc084s021 *adc = iio_priv(indio_dev);
 94	int ret;
 95	__be16 be_val;
 96
 97	switch (mask) {
 98	case IIO_CHAN_INFO_RAW:
 99		if (!iio_device_claim_direct(indio_dev))
100			return -EBUSY;
101
102		ret = regulator_enable(adc->reg);
103		if (ret) {
104			iio_device_release_direct(indio_dev);
105			return ret;
106		}
107
108		adc->tx_buf[0] = channel->channel << 3;
109		ret = adc084s021_adc_conversion(adc, &be_val);
110		iio_device_release_direct(indio_dev);
111		regulator_disable(adc->reg);
112		if (ret < 0)
113			return ret;
114
115		*val = be16_to_cpu(be_val);
116		*val = (*val >> channel->scan_type.shift) & 0xff;
117
118		return IIO_VAL_INT;
119	case IIO_CHAN_INFO_SCALE:
120		ret = regulator_enable(adc->reg);
121		if (ret)
122			return ret;
123
124		ret = regulator_get_voltage(adc->reg);
125		regulator_disable(adc->reg);
126		if (ret < 0)
127			return ret;
128
129		*val = ret / 1000;
130
131		return IIO_VAL_INT;
132	default:
133		return -EINVAL;
134	}
135}
136
137/**
138 * adc084s021_buffer_trigger_handler() - Read ADC channels and push to buffer.
139 *
140 * @irq: The interrupt number (not used).
141 * @pollfunc: Pointer to the poll func.
142 */
143static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
144{
145	struct iio_poll_func *pf = pollfunc;
146	struct iio_dev *indio_dev = pf->indio_dev;
147	struct adc084s021 *adc = iio_priv(indio_dev);
148
149	mutex_lock(&adc->lock);
150
151	if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0)
152		dev_err(&adc->spi->dev, "Failed to read data\n");
153
154	iio_push_to_buffers_with_ts(indio_dev, &adc->scan, sizeof(adc->scan),
155				    iio_get_time_ns(indio_dev));
156	mutex_unlock(&adc->lock);
157	iio_trigger_notify_done(indio_dev->trig);
158
159	return IRQ_HANDLED;
160}
161
162static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
163{
164	struct adc084s021 *adc = iio_priv(indio_dev);
165	int scan_index;
166	int i = 0;
167
168	iio_for_each_active_channel(indio_dev, scan_index) {
169		const struct iio_chan_spec *channel =
170			&indio_dev->channels[scan_index];
171		adc->tx_buf[i++] = channel->channel << 3;
172	}
173	adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
174
175	return regulator_enable(adc->reg);
176}
177
178static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
179{
180	struct adc084s021 *adc = iio_priv(indio_dev);
181
182	adc->spi_trans.len = 4; /* Trash + single channel */
183
184	return regulator_disable(adc->reg);
185}
186
187static const struct iio_info adc084s021_info = {
188	.read_raw = adc084s021_read_raw,
189};
190
191static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
192	.preenable = adc084s021_buffer_preenable,
193	.postdisable = adc084s021_buffer_postdisable,
194};
195
196static int adc084s021_probe(struct spi_device *spi)
197{
198	struct iio_dev *indio_dev;
199	struct adc084s021 *adc;
200	int ret;
201
202	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
203	if (!indio_dev)
204		return -ENOMEM;
205
206	adc = iio_priv(indio_dev);
207	adc->spi = spi;
208
209	/* Initiate the Industrial I/O device */
210	indio_dev->name = spi_get_device_id(spi)->name;
211	indio_dev->modes = INDIO_DIRECT_MODE;
212	indio_dev->info = &adc084s021_info;
213	indio_dev->channels = adc084s021_channels;
214	indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
215
216	/* Create SPI transfer for channel reads */
217	adc->spi_trans.tx_buf = adc->tx_buf;
218	adc->spi_trans.rx_buf = adc->rx_buf;
219	adc->spi_trans.len = 4; /* Trash + single channel */
220	spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
221
222	adc->reg = devm_regulator_get(&spi->dev, "vref");
223	if (IS_ERR(adc->reg))
224		return PTR_ERR(adc->reg);
225
226	mutex_init(&adc->lock);
227
228	/* Setup triggered buffer with pollfunction */
229	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
230					    adc084s021_buffer_trigger_handler,
231					    &adc084s021_buffer_setup_ops);
232	if (ret) {
233		dev_err(&spi->dev, "Failed to setup triggered buffer\n");
234		return ret;
235	}
236
237	return devm_iio_device_register(&spi->dev, indio_dev);
238}
239
240static const struct of_device_id adc084s021_of_match[] = {
241	{ .compatible = "ti,adc084s021", },
242	{ }
243};
244MODULE_DEVICE_TABLE(of, adc084s021_of_match);
245
246static const struct spi_device_id adc084s021_id[] = {
247	{ ADC084S021_DRIVER_NAME, 0 },
248	{ }
249};
250MODULE_DEVICE_TABLE(spi, adc084s021_id);
251
252static struct spi_driver adc084s021_driver = {
253	.driver = {
254		.name = ADC084S021_DRIVER_NAME,
255		.of_match_table = adc084s021_of_match,
256	},
257	.probe = adc084s021_probe,
258	.id_table = adc084s021_id,
259};
260module_spi_driver(adc084s021_driver);
261
262MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>");
263MODULE_DESCRIPTION("Texas Instruments ADC084S021");
264MODULE_LICENSE("GPL v2");
265MODULE_VERSION("1.0");