xref: /linux/drivers/iio/adc/ti-adc108s102.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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 
59 struct adc108s102_state {
60 	struct spi_device		*spi;
61 	u32				va_millivolt;
62 	/* SPI transfer used by triggered buffer handler*/
63 	struct spi_transfer		ring_xfer;
64 	/* SPI transfer used by direct scan */
65 	struct spi_transfer		scan_single_xfer;
66 	/* SPI message used by ring_xfer SPI transfer */
67 	struct spi_message		ring_msg;
68 	/* SPI message used by scan_single_xfer SPI transfer */
69 	struct spi_message		scan_single_msg;
70 
71 	/*
72 	 * SPI message buffers:
73 	 *  tx_buf: |C0|C1|C2|C3|C4|C5|C6|C7|XX|
74 	 *  rx_buf: |XX|R0|R1|R2|R3|R4|R5|R6|R7|tt|tt|tt|tt|
75 	 *
76 	 *  tx_buf: 8 channel read commands, plus 1 dummy command
77 	 *  rx_buf: 1 dummy response, 8 channel responses
78 	 */
79 	__be16				rx_buf[9] __aligned(IIO_DMA_MINALIGN);
80 	__be16				tx_buf[9] __aligned(IIO_DMA_MINALIGN);
81 };
82 
83 #define ADC108S102_V_CHAN(index)					\
84 	{								\
85 		.type = IIO_VOLTAGE,					\
86 		.indexed = 1,						\
87 		.channel = index,					\
88 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
89 			BIT(IIO_CHAN_INFO_SCALE),			\
90 		.address = index,					\
91 		.scan_index = index,					\
92 		.scan_type = {						\
93 			.sign = 'u',					\
94 			.realbits = ADC108S102_BITS,			\
95 			.storagebits = 16,				\
96 			.endianness = IIO_BE,				\
97 		},							\
98 	}
99 
100 static const struct iio_chan_spec adc108s102_channels[] = {
101 	ADC108S102_V_CHAN(0),
102 	ADC108S102_V_CHAN(1),
103 	ADC108S102_V_CHAN(2),
104 	ADC108S102_V_CHAN(3),
105 	ADC108S102_V_CHAN(4),
106 	ADC108S102_V_CHAN(5),
107 	ADC108S102_V_CHAN(6),
108 	ADC108S102_V_CHAN(7),
109 	IIO_CHAN_SOFT_TIMESTAMP(8),
110 };
111 
adc108s102_update_scan_mode(struct iio_dev * indio_dev,unsigned long const * active_scan_mask)112 static int adc108s102_update_scan_mode(struct iio_dev *indio_dev,
113 		unsigned long const *active_scan_mask)
114 {
115 	struct adc108s102_state *st = iio_priv(indio_dev);
116 	unsigned int bit, cmds;
117 
118 	/*
119 	 * Fill in the first x shorts of tx_buf with the number of channels
120 	 * enabled for sampling by the triggered buffer.
121 	 */
122 	cmds = 0;
123 	for_each_set_bit(bit, active_scan_mask, ADC108S102_MAX_CHANNELS)
124 		st->tx_buf[cmds++] = cpu_to_be16(ADC108S102_CMD(bit));
125 
126 	/* One dummy command added, to clock in the last response */
127 	st->tx_buf[cmds++] = 0x00;
128 
129 	/* build SPI ring message */
130 	st->ring_xfer.tx_buf = &st->tx_buf[0];
131 	st->ring_xfer.rx_buf = &st->rx_buf[0];
132 	st->ring_xfer.len = cmds * sizeof(st->tx_buf[0]);
133 
134 	spi_message_init_with_transfers(&st->ring_msg, &st->ring_xfer, 1);
135 
136 	return 0;
137 }
138 
adc108s102_trigger_handler(int irq,void * p)139 static irqreturn_t adc108s102_trigger_handler(int irq, void *p)
140 {
141 	struct iio_poll_func *pf = p;
142 	struct iio_dev *indio_dev = pf->indio_dev;
143 	struct adc108s102_state *st = iio_priv(indio_dev);
144 	int ret;
145 
146 	ret = spi_sync(st->spi, &st->ring_msg);
147 	if (ret < 0)
148 		goto out_notify;
149 
150 	/* Skip the dummy response in the first slot */
151 	iio_push_to_buffers_with_ts_unaligned(indio_dev,
152 					      &st->rx_buf[1],
153 					      st->ring_xfer.len - sizeof(st->rx_buf[1]),
154 					      iio_get_time_ns(indio_dev));
155 
156 out_notify:
157 	iio_trigger_notify_done(indio_dev->trig);
158 
159 	return IRQ_HANDLED;
160 }
161 
adc108s102_scan_direct(struct adc108s102_state * st,unsigned int ch)162 static int adc108s102_scan_direct(struct adc108s102_state *st, unsigned int ch)
163 {
164 	int ret;
165 
166 	st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch));
167 	ret = spi_sync(st->spi, &st->scan_single_msg);
168 	if (ret)
169 		return ret;
170 
171 	/* Skip the dummy response in the first slot */
172 	return be16_to_cpu(st->rx_buf[1]);
173 }
174 
adc108s102_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)175 static int adc108s102_read_raw(struct iio_dev *indio_dev,
176 			       struct iio_chan_spec const *chan,
177 			       int *val, int *val2, long m)
178 {
179 	struct adc108s102_state *st = iio_priv(indio_dev);
180 	int ret;
181 
182 	switch (m) {
183 	case IIO_CHAN_INFO_RAW:
184 		ret = iio_device_claim_direct_mode(indio_dev);
185 		if (ret)
186 			return ret;
187 
188 		ret = adc108s102_scan_direct(st, chan->address);
189 
190 		iio_device_release_direct_mode(indio_dev);
191 
192 		if (ret < 0)
193 			return ret;
194 
195 		*val = ADC108S102_RES_DATA(ret);
196 
197 		return IIO_VAL_INT;
198 	case IIO_CHAN_INFO_SCALE:
199 		if (chan->type != IIO_VOLTAGE)
200 			break;
201 
202 		*val = st->va_millivolt;
203 		*val2 = chan->scan_type.realbits;
204 
205 		return IIO_VAL_FRACTIONAL_LOG2;
206 	default:
207 		break;
208 	}
209 
210 	return -EINVAL;
211 }
212 
213 static const struct iio_info adc108s102_info = {
214 	.read_raw		= &adc108s102_read_raw,
215 	.update_scan_mode	= &adc108s102_update_scan_mode,
216 };
217 
adc108s102_probe(struct spi_device * spi)218 static int adc108s102_probe(struct spi_device *spi)
219 {
220 	struct adc108s102_state *st;
221 	struct iio_dev *indio_dev;
222 	int ret;
223 
224 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
225 	if (!indio_dev)
226 		return -ENOMEM;
227 
228 	st = iio_priv(indio_dev);
229 
230 	if (ACPI_COMPANION(&spi->dev)) {
231 		st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT;
232 	} else {
233 		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref");
234 		if (ret < 0)
235 			return dev_err_probe(&spi->dev, ret, "failed get vref voltage\n");
236 
237 		st->va_millivolt = ret / 1000;
238 	}
239 
240 	st->spi = spi;
241 
242 	indio_dev->name = spi->modalias;
243 	indio_dev->modes = INDIO_DIRECT_MODE;
244 	indio_dev->channels = adc108s102_channels;
245 	indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
246 	indio_dev->info = &adc108s102_info;
247 
248 	/* Setup default message */
249 	st->scan_single_xfer.tx_buf = st->tx_buf;
250 	st->scan_single_xfer.rx_buf = st->rx_buf;
251 	st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);
252 
253 	spi_message_init_with_transfers(&st->scan_single_msg,
254 					&st->scan_single_xfer, 1);
255 
256 	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
257 					      &adc108s102_trigger_handler,
258 					      NULL);
259 	if (ret)
260 		return ret;
261 
262 	ret = devm_iio_device_register(&spi->dev, indio_dev);
263 	if (ret)
264 		dev_err(&spi->dev, "Failed to register IIO device\n");
265 	return ret;
266 }
267 
268 static const struct of_device_id adc108s102_of_match[] = {
269 	{ .compatible = "ti,adc108s102" },
270 	{ }
271 };
272 MODULE_DEVICE_TABLE(of, adc108s102_of_match);
273 
274 static const struct acpi_device_id adc108s102_acpi_ids[] = {
275 	{ "INT3495", 0 },
276 	{ }
277 };
278 MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
279 
280 static const struct spi_device_id adc108s102_id[] = {
281 	{ "adc108s102", 0 },
282 	{ }
283 };
284 MODULE_DEVICE_TABLE(spi, adc108s102_id);
285 
286 static struct spi_driver adc108s102_driver = {
287 	.driver = {
288 		.name   = "adc108s102",
289 		.of_match_table = adc108s102_of_match,
290 		.acpi_match_table = adc108s102_acpi_ids,
291 	},
292 	.probe		= adc108s102_probe,
293 	.id_table	= adc108s102_id,
294 };
295 module_spi_driver(adc108s102_driver);
296 
297 MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
298 MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver");
299 MODULE_LICENSE("GPL v2");
300