1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * TI ADC108S102 SPI ADC driver
4 *
5 * Copyright (c) 2013-2015 Intel Corporation.
6 * Copyright (c) 2017 Siemens AG
7 *
8 * This IIO device driver is designed to work with the following
9 * analog to digital converters from Texas Instruments:
10 *  ADC108S102
11 *  ADC128S102
12 * The communication with ADC chip is via the SPI bus (mode 3).
13 */
14
15#include <linux/acpi.h>
16#include <linux/iio/iio.h>
17#include <linux/iio/buffer.h>
18#include <linux/iio/types.h>
19#include <linux/iio/triggered_buffer.h>
20#include <linux/iio/trigger_consumer.h>
21#include <linux/interrupt.h>
22#include <linux/module.h>
23#include <linux/mod_devicetable.h>
24#include <linux/property.h>
25#include <linux/regulator/consumer.h>
26#include <linux/spi/spi.h>
27
28/*
29 * In case of ACPI, we use the hard-wired 5000 mV of the Galileo and IOT2000
30 * boards as default for the reference pin VA. Device tree users encode that
31 * via the vref-supply regulator.
32 */
33#define ADC108S102_VA_MV_ACPI_DEFAULT	5000
34
35/*
36 * Defining the ADC resolution being 12 bits, we can use the same driver for
37 * both ADC108S102 (10 bits resolution) and ADC128S102 (12 bits resolution)
38 * chips. The ADC108S102 effectively returns a 12-bit result with the 2
39 * least-significant bits unset.
40 */
41#define ADC108S102_BITS		12
42#define ADC108S102_MAX_CHANNELS	8
43
44/*
45 * 16-bit SPI command format:
46 *   [15:14] Ignored
47 *   [13:11] 3-bit channel address
48 *   [10:0]  Ignored
49 */
50#define ADC108S102_CMD(ch)		((u16)(ch) << 11)
51
52/*
53 * 16-bit SPI response format:
54 *   [15:12] Zeros
55 *   [11:0]  12-bit ADC sample (for ADC108S102, [1:0] will always be 0).
56 */
57#define ADC108S102_RES_DATA(res)	((u16)res & GENMASK(11, 0))
58
59struct adc108s102_state {
60	struct spi_device		*spi;
61	struct regulator		*reg;
62	u32				va_millivolt;
63	/* SPI transfer used by triggered buffer handler*/
64	struct spi_transfer		ring_xfer;
65	/* SPI transfer used by direct scan */
66	struct spi_transfer		scan_single_xfer;
67	/* SPI message used by ring_xfer SPI transfer */
68	struct spi_message		ring_msg;
69	/* SPI message used by scan_single_xfer SPI transfer */
70	struct spi_message		scan_single_msg;
71
72	/*
73	 * SPI message buffers:
74	 *  tx_buf: |C0|C1|C2|C3|C4|C5|C6|C7|XX|
75	 *  rx_buf: |XX|R0|R1|R2|R3|R4|R5|R6|R7|tt|tt|tt|tt|
76	 *
77	 *  tx_buf: 8 channel read commands, plus 1 dummy command
78	 *  rx_buf: 1 dummy response, 8 channel responses
79	 */
80	__be16				rx_buf[9] __aligned(IIO_DMA_MINALIGN);
81	__be16				tx_buf[9] __aligned(IIO_DMA_MINALIGN);
82};
83
84#define ADC108S102_V_CHAN(index)					\
85	{								\
86		.type = IIO_VOLTAGE,					\
87		.indexed = 1,						\
88		.channel = index,					\
89		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
90			BIT(IIO_CHAN_INFO_SCALE),			\
91		.address = index,					\
92		.scan_index = index,					\
93		.scan_type = {						\
94			.sign = 'u',					\
95			.realbits = ADC108S102_BITS,			\
96			.storagebits = 16,				\
97			.endianness = IIO_BE,				\
98		},							\
99	}
100
101static const struct iio_chan_spec adc108s102_channels[] = {
102	ADC108S102_V_CHAN(0),
103	ADC108S102_V_CHAN(1),
104	ADC108S102_V_CHAN(2),
105	ADC108S102_V_CHAN(3),
106	ADC108S102_V_CHAN(4),
107	ADC108S102_V_CHAN(5),
108	ADC108S102_V_CHAN(6),
109	ADC108S102_V_CHAN(7),
110	IIO_CHAN_SOFT_TIMESTAMP(8),
111};
112
113static int adc108s102_update_scan_mode(struct iio_dev *indio_dev,
114		unsigned long const *active_scan_mask)
115{
116	struct adc108s102_state *st = iio_priv(indio_dev);
117	unsigned int bit, cmds;
118
119	/*
120	 * Fill in the first x shorts of tx_buf with the number of channels
121	 * enabled for sampling by the triggered buffer.
122	 */
123	cmds = 0;
124	for_each_set_bit(bit, active_scan_mask, ADC108S102_MAX_CHANNELS)
125		st->tx_buf[cmds++] = cpu_to_be16(ADC108S102_CMD(bit));
126
127	/* One dummy command added, to clock in the last response */
128	st->tx_buf[cmds++] = 0x00;
129
130	/* build SPI ring message */
131	st->ring_xfer.tx_buf = &st->tx_buf[0];
132	st->ring_xfer.rx_buf = &st->rx_buf[0];
133	st->ring_xfer.len = cmds * sizeof(st->tx_buf[0]);
134
135	spi_message_init_with_transfers(&st->ring_msg, &st->ring_xfer, 1);
136
137	return 0;
138}
139
140static irqreturn_t adc108s102_trigger_handler(int irq, void *p)
141{
142	struct iio_poll_func *pf = p;
143	struct iio_dev *indio_dev = pf->indio_dev;
144	struct adc108s102_state *st = iio_priv(indio_dev);
145	int ret;
146
147	ret = spi_sync(st->spi, &st->ring_msg);
148	if (ret < 0)
149		goto out_notify;
150
151	/* Skip the dummy response in the first slot */
152	iio_push_to_buffers_with_ts_unaligned(indio_dev,
153					      &st->rx_buf[1],
154					      st->ring_xfer.len - sizeof(st->rx_buf[1]),
155					      iio_get_time_ns(indio_dev));
156
157out_notify:
158	iio_trigger_notify_done(indio_dev->trig);
159
160	return IRQ_HANDLED;
161}
162
163static int adc108s102_scan_direct(struct adc108s102_state *st, unsigned int ch)
164{
165	int ret;
166
167	st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch));
168	ret = spi_sync(st->spi, &st->scan_single_msg);
169	if (ret)
170		return ret;
171
172	/* Skip the dummy response in the first slot */
173	return be16_to_cpu(st->rx_buf[1]);
174}
175
176static int adc108s102_read_raw(struct iio_dev *indio_dev,
177			       struct iio_chan_spec const *chan,
178			       int *val, int *val2, long m)
179{
180	struct adc108s102_state *st = iio_priv(indio_dev);
181	int ret;
182
183	switch (m) {
184	case IIO_CHAN_INFO_RAW:
185		ret = iio_device_claim_direct_mode(indio_dev);
186		if (ret)
187			return ret;
188
189		ret = adc108s102_scan_direct(st, chan->address);
190
191		iio_device_release_direct_mode(indio_dev);
192
193		if (ret < 0)
194			return ret;
195
196		*val = ADC108S102_RES_DATA(ret);
197
198		return IIO_VAL_INT;
199	case IIO_CHAN_INFO_SCALE:
200		if (chan->type != IIO_VOLTAGE)
201			break;
202
203		*val = st->va_millivolt;
204		*val2 = chan->scan_type.realbits;
205
206		return IIO_VAL_FRACTIONAL_LOG2;
207	default:
208		break;
209	}
210
211	return -EINVAL;
212}
213
214static const struct iio_info adc108s102_info = {
215	.read_raw		= &adc108s102_read_raw,
216	.update_scan_mode	= &adc108s102_update_scan_mode,
217};
218
219static void adc108s102_reg_disable(void *reg)
220{
221	regulator_disable(reg);
222}
223
224static int adc108s102_probe(struct spi_device *spi)
225{
226	struct adc108s102_state *st;
227	struct iio_dev *indio_dev;
228	int ret;
229
230	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
231	if (!indio_dev)
232		return -ENOMEM;
233
234	st = iio_priv(indio_dev);
235
236	if (ACPI_COMPANION(&spi->dev)) {
237		st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT;
238	} else {
239		st->reg = devm_regulator_get(&spi->dev, "vref");
240		if (IS_ERR(st->reg))
241			return PTR_ERR(st->reg);
242
243		ret = regulator_enable(st->reg);
244		if (ret < 0) {
245			dev_err(&spi->dev, "Cannot enable vref regulator\n");
246			return ret;
247		}
248		ret = devm_add_action_or_reset(&spi->dev, adc108s102_reg_disable,
249					       st->reg);
250		if (ret)
251			return ret;
252
253		ret = regulator_get_voltage(st->reg);
254		if (ret < 0) {
255			dev_err(&spi->dev, "vref get voltage failed\n");
256			return ret;
257		}
258
259		st->va_millivolt = ret / 1000;
260	}
261
262	st->spi = spi;
263
264	indio_dev->name = spi->modalias;
265	indio_dev->modes = INDIO_DIRECT_MODE;
266	indio_dev->channels = adc108s102_channels;
267	indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
268	indio_dev->info = &adc108s102_info;
269
270	/* Setup default message */
271	st->scan_single_xfer.tx_buf = st->tx_buf;
272	st->scan_single_xfer.rx_buf = st->rx_buf;
273	st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);
274
275	spi_message_init_with_transfers(&st->scan_single_msg,
276					&st->scan_single_xfer, 1);
277
278	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
279					      &adc108s102_trigger_handler,
280					      NULL);
281	if (ret)
282		return ret;
283
284	ret = devm_iio_device_register(&spi->dev, indio_dev);
285	if (ret)
286		dev_err(&spi->dev, "Failed to register IIO device\n");
287	return ret;
288}
289
290static const struct of_device_id adc108s102_of_match[] = {
291	{ .compatible = "ti,adc108s102" },
292	{ }
293};
294MODULE_DEVICE_TABLE(of, adc108s102_of_match);
295
296static const struct acpi_device_id adc108s102_acpi_ids[] = {
297	{ "INT3495", 0 },
298	{ }
299};
300MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
301
302static const struct spi_device_id adc108s102_id[] = {
303	{ "adc108s102", 0 },
304	{ }
305};
306MODULE_DEVICE_TABLE(spi, adc108s102_id);
307
308static struct spi_driver adc108s102_driver = {
309	.driver = {
310		.name   = "adc108s102",
311		.of_match_table = adc108s102_of_match,
312		.acpi_match_table = adc108s102_acpi_ids,
313	},
314	.probe		= adc108s102_probe,
315	.id_table	= adc108s102_id,
316};
317module_spi_driver(adc108s102_driver);
318
319MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
320MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver");
321MODULE_LICENSE("GPL v2");
322