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		s64 ts __aligned(8);
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		ret = iio_device_claim_direct_mode(indio_dev);
100		if (ret < 0)
101			return ret;
102
103		ret = regulator_enable(adc->reg);
104		if (ret) {
105			iio_device_release_direct_mode(indio_dev);
106			return ret;
107		}
108
109		adc->tx_buf[0] = channel->channel << 3;
110		ret = adc084s021_adc_conversion(adc, &be_val);
111		iio_device_release_direct_mode(indio_dev);
112		regulator_disable(adc->reg);
113		if (ret < 0)
114			return ret;
115
116		*val = be16_to_cpu(be_val);
117		*val = (*val >> channel->scan_type.shift) & 0xff;
118
119		return IIO_VAL_INT;
120	case IIO_CHAN_INFO_SCALE:
121		ret = regulator_enable(adc->reg);
122		if (ret)
123			return ret;
124
125		ret = regulator_get_voltage(adc->reg);
126		regulator_disable(adc->reg);
127		if (ret < 0)
128			return ret;
129
130		*val = ret / 1000;
131
132		return IIO_VAL_INT;
133	default:
134		return -EINVAL;
135	}
136}
137
138/**
139 * adc084s021_buffer_trigger_handler() - Read ADC channels and push to buffer.
140 *
141 * @irq: The interrupt number (not used).
142 * @pollfunc: Pointer to the poll func.
143 */
144static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc)
145{
146	struct iio_poll_func *pf = pollfunc;
147	struct iio_dev *indio_dev = pf->indio_dev;
148	struct adc084s021 *adc = iio_priv(indio_dev);
149
150	mutex_lock(&adc->lock);
151
152	if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0)
153		dev_err(&adc->spi->dev, "Failed to read data\n");
154
155	iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
156					   iio_get_time_ns(indio_dev));
157	mutex_unlock(&adc->lock);
158	iio_trigger_notify_done(indio_dev->trig);
159
160	return IRQ_HANDLED;
161}
162
163static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
164{
165	struct adc084s021 *adc = iio_priv(indio_dev);
166	int scan_index;
167	int i = 0;
168
169	for_each_set_bit(scan_index, indio_dev->active_scan_mask,
170			 indio_dev->masklength) {
171		const struct iio_chan_spec *channel =
172			&indio_dev->channels[scan_index];
173		adc->tx_buf[i++] = channel->channel << 3;
174	}
175	adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
176
177	return regulator_enable(adc->reg);
178}
179
180static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
181{
182	struct adc084s021 *adc = iio_priv(indio_dev);
183
184	adc->spi_trans.len = 4; /* Trash + single channel */
185
186	return regulator_disable(adc->reg);
187}
188
189static const struct iio_info adc084s021_info = {
190	.read_raw = adc084s021_read_raw,
191};
192
193static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
194	.preenable = adc084s021_buffer_preenable,
195	.postdisable = adc084s021_buffer_postdisable,
196};
197
198static int adc084s021_probe(struct spi_device *spi)
199{
200	struct iio_dev *indio_dev;
201	struct adc084s021 *adc;
202	int ret;
203
204	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
205	if (!indio_dev) {
206		dev_err(&spi->dev, "Failed to allocate IIO device\n");
207		return -ENOMEM;
208	}
209
210	adc = iio_priv(indio_dev);
211	adc->spi = spi;
212
213	/* Initiate the Industrial I/O device */
214	indio_dev->name = spi_get_device_id(spi)->name;
215	indio_dev->modes = INDIO_DIRECT_MODE;
216	indio_dev->info = &adc084s021_info;
217	indio_dev->channels = adc084s021_channels;
218	indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
219
220	/* Create SPI transfer for channel reads */
221	adc->spi_trans.tx_buf = adc->tx_buf;
222	adc->spi_trans.rx_buf = adc->rx_buf;
223	adc->spi_trans.len = 4; /* Trash + single channel */
224	spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
225
226	adc->reg = devm_regulator_get(&spi->dev, "vref");
227	if (IS_ERR(adc->reg))
228		return PTR_ERR(adc->reg);
229
230	mutex_init(&adc->lock);
231
232	/* Setup triggered buffer with pollfunction */
233	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
234					    adc084s021_buffer_trigger_handler,
235					    &adc084s021_buffer_setup_ops);
236	if (ret) {
237		dev_err(&spi->dev, "Failed to setup triggered buffer\n");
238		return ret;
239	}
240
241	return devm_iio_device_register(&spi->dev, indio_dev);
242}
243
244static const struct of_device_id adc084s021_of_match[] = {
245	{ .compatible = "ti,adc084s021", },
246	{},
247};
248MODULE_DEVICE_TABLE(of, adc084s021_of_match);
249
250static const struct spi_device_id adc084s021_id[] = {
251	{ ADC084S021_DRIVER_NAME, 0 },
252	{}
253};
254MODULE_DEVICE_TABLE(spi, adc084s021_id);
255
256static struct spi_driver adc084s021_driver = {
257	.driver = {
258		.name = ADC084S021_DRIVER_NAME,
259		.of_match_table = adc084s021_of_match,
260	},
261	.probe = adc084s021_probe,
262	.id_table = adc084s021_id,
263};
264module_spi_driver(adc084s021_driver);
265
266MODULE_AUTHOR("M��rten Lindahl <martenli@axis.com>");
267MODULE_DESCRIPTION("Texas Instruments ADC084S021");
268MODULE_LICENSE("GPL v2");
269MODULE_VERSION("1.0");
270