xref: /openbmc/linux/drivers/iio/adc/ad7298.c (revision fc062ad8)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * AD7298 SPI ADC driver
4  *
5  * Copyright 2011 Analog Devices Inc.
6  */
7 
8 #include <linux/device.h>
9 #include <linux/kernel.h>
10 #include <linux/slab.h>
11 #include <linux/sysfs.h>
12 #include <linux/spi/spi.h>
13 #include <linux/regulator/consumer.h>
14 #include <linux/err.h>
15 #include <linux/delay.h>
16 #include <linux/mod_devicetable.h>
17 #include <linux/module.h>
18 #include <linux/interrupt.h>
19 #include <linux/bitops.h>
20 
21 #include <linux/iio/iio.h>
22 #include <linux/iio/sysfs.h>
23 #include <linux/iio/buffer.h>
24 #include <linux/iio/trigger_consumer.h>
25 #include <linux/iio/triggered_buffer.h>
26 
27 #define AD7298_WRITE	BIT(15) /* write to the control register */
28 #define AD7298_REPEAT	BIT(14) /* repeated conversion enable */
29 #define AD7298_CH(x)	BIT(13 - (x)) /* channel select */
30 #define AD7298_TSENSE	BIT(5) /* temperature conversion enable */
31 #define AD7298_EXTREF	BIT(2) /* external reference enable */
32 #define AD7298_TAVG	BIT(1) /* temperature sensor averaging enable */
33 #define AD7298_PDD	BIT(0) /* partial power down enable */
34 
35 #define AD7298_MAX_CHAN		8
36 #define AD7298_INTREF_mV	2500
37 
38 #define AD7298_CH_TEMP		9
39 
40 struct ad7298_state {
41 	struct spi_device		*spi;
42 	struct regulator		*reg;
43 	unsigned			ext_ref;
44 	struct spi_transfer		ring_xfer[10];
45 	struct spi_transfer		scan_single_xfer[3];
46 	struct spi_message		ring_msg;
47 	struct spi_message		scan_single_msg;
48 	/*
49 	 * DMA (thus cache coherency maintenance) requires the
50 	 * transfer buffers to live in their own cache lines.
51 	 */
52 	__be16				rx_buf[12] ____cacheline_aligned;
53 	__be16				tx_buf[2];
54 };
55 
56 #define AD7298_V_CHAN(index)						\
57 	{								\
58 		.type = IIO_VOLTAGE,					\
59 		.indexed = 1,						\
60 		.channel = index,					\
61 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
62 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
63 		.address = index,					\
64 		.scan_index = index,					\
65 		.scan_type = {						\
66 			.sign = 'u',					\
67 			.realbits = 12,					\
68 			.storagebits = 16,				\
69 			.endianness = IIO_BE,				\
70 		},							\
71 	}
72 
73 static const struct iio_chan_spec ad7298_channels[] = {
74 	{
75 		.type = IIO_TEMP,
76 		.indexed = 1,
77 		.channel = 0,
78 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
79 			BIT(IIO_CHAN_INFO_SCALE) |
80 			BIT(IIO_CHAN_INFO_OFFSET),
81 		.address = AD7298_CH_TEMP,
82 		.scan_index = -1,
83 		.scan_type = {
84 			.sign = 's',
85 			.realbits = 32,
86 			.storagebits = 32,
87 		},
88 	},
89 	AD7298_V_CHAN(0),
90 	AD7298_V_CHAN(1),
91 	AD7298_V_CHAN(2),
92 	AD7298_V_CHAN(3),
93 	AD7298_V_CHAN(4),
94 	AD7298_V_CHAN(5),
95 	AD7298_V_CHAN(6),
96 	AD7298_V_CHAN(7),
97 	IIO_CHAN_SOFT_TIMESTAMP(8),
98 };
99 
100 /*
101  * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
102  */
103 static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
104 	const unsigned long *active_scan_mask)
105 {
106 	struct ad7298_state *st = iio_priv(indio_dev);
107 	int i, m;
108 	unsigned short command;
109 	int scan_count;
110 
111 	/* Now compute overall size */
112 	scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);
113 
114 	command = AD7298_WRITE | st->ext_ref;
115 
116 	for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
117 		if (test_bit(i, active_scan_mask))
118 			command |= m;
119 
120 	st->tx_buf[0] = cpu_to_be16(command);
121 
122 	/* build spi ring message */
123 	st->ring_xfer[0].tx_buf = &st->tx_buf[0];
124 	st->ring_xfer[0].len = 2;
125 	st->ring_xfer[0].cs_change = 1;
126 	st->ring_xfer[1].tx_buf = &st->tx_buf[1];
127 	st->ring_xfer[1].len = 2;
128 	st->ring_xfer[1].cs_change = 1;
129 
130 	spi_message_init(&st->ring_msg);
131 	spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
132 	spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
133 
134 	for (i = 0; i < scan_count; i++) {
135 		st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
136 		st->ring_xfer[i + 2].len = 2;
137 		st->ring_xfer[i + 2].cs_change = 1;
138 		spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
139 	}
140 	/* make sure last transfer cs_change is not set */
141 	st->ring_xfer[i + 1].cs_change = 0;
142 
143 	return 0;
144 }
145 
146 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
147 {
148 	struct iio_poll_func *pf = p;
149 	struct iio_dev *indio_dev = pf->indio_dev;
150 	struct ad7298_state *st = iio_priv(indio_dev);
151 	int b_sent;
152 
153 	b_sent = spi_sync(st->spi, &st->ring_msg);
154 	if (b_sent)
155 		goto done;
156 
157 	iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
158 		iio_get_time_ns(indio_dev));
159 
160 done:
161 	iio_trigger_notify_done(indio_dev->trig);
162 
163 	return IRQ_HANDLED;
164 }
165 
166 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
167 {
168 	int ret;
169 	st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
170 				   (AD7298_CH(0) >> ch));
171 
172 	ret = spi_sync(st->spi, &st->scan_single_msg);
173 	if (ret)
174 		return ret;
175 
176 	return be16_to_cpu(st->rx_buf[0]);
177 }
178 
179 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
180 {
181 	int ret;
182 	__be16 buf;
183 
184 	buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
185 			  AD7298_TAVG | st->ext_ref);
186 
187 	ret = spi_write(st->spi, (u8 *)&buf, 2);
188 	if (ret)
189 		return ret;
190 
191 	buf = cpu_to_be16(0);
192 
193 	ret = spi_write(st->spi, (u8 *)&buf, 2);
194 	if (ret)
195 		return ret;
196 
197 	usleep_range(101, 1000); /* sleep > 100us */
198 
199 	ret = spi_read(st->spi, (u8 *)&buf, 2);
200 	if (ret)
201 		return ret;
202 
203 	*val = sign_extend32(be16_to_cpu(buf), 11);
204 
205 	return 0;
206 }
207 
208 static int ad7298_get_ref_voltage(struct ad7298_state *st)
209 {
210 	int vref;
211 
212 	if (st->reg) {
213 		vref = regulator_get_voltage(st->reg);
214 		if (vref < 0)
215 			return vref;
216 
217 		return vref / 1000;
218 	} else {
219 		return AD7298_INTREF_mV;
220 	}
221 }
222 
223 static int ad7298_read_raw(struct iio_dev *indio_dev,
224 			   struct iio_chan_spec const *chan,
225 			   int *val,
226 			   int *val2,
227 			   long m)
228 {
229 	int ret;
230 	struct ad7298_state *st = iio_priv(indio_dev);
231 
232 	switch (m) {
233 	case IIO_CHAN_INFO_RAW:
234 		ret = iio_device_claim_direct_mode(indio_dev);
235 		if (ret)
236 			return ret;
237 
238 		if (chan->address == AD7298_CH_TEMP)
239 			ret = ad7298_scan_temp(st, val);
240 		else
241 			ret = ad7298_scan_direct(st, chan->address);
242 
243 		iio_device_release_direct_mode(indio_dev);
244 
245 		if (ret < 0)
246 			return ret;
247 
248 		if (chan->address != AD7298_CH_TEMP)
249 			*val = ret & GENMASK(chan->scan_type.realbits - 1, 0);
250 
251 		return IIO_VAL_INT;
252 	case IIO_CHAN_INFO_SCALE:
253 		switch (chan->type) {
254 		case IIO_VOLTAGE:
255 			*val = ad7298_get_ref_voltage(st);
256 			*val2 = chan->scan_type.realbits;
257 			return IIO_VAL_FRACTIONAL_LOG2;
258 		case IIO_TEMP:
259 			*val = ad7298_get_ref_voltage(st);
260 			*val2 = 10;
261 			return IIO_VAL_FRACTIONAL;
262 		default:
263 			return -EINVAL;
264 		}
265 	case IIO_CHAN_INFO_OFFSET:
266 		*val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
267 		return IIO_VAL_INT;
268 	}
269 	return -EINVAL;
270 }
271 
272 static const struct iio_info ad7298_info = {
273 	.read_raw = &ad7298_read_raw,
274 	.update_scan_mode = ad7298_update_scan_mode,
275 };
276 
277 static void ad7298_reg_disable(void *data)
278 {
279 	struct regulator *reg = data;
280 
281 	regulator_disable(reg);
282 }
283 
284 static int ad7298_probe(struct spi_device *spi)
285 {
286 	struct ad7298_state *st;
287 	struct iio_dev *indio_dev;
288 	int ret;
289 
290 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
291 	if (indio_dev == NULL)
292 		return -ENOMEM;
293 
294 	st = iio_priv(indio_dev);
295 
296 	st->reg = devm_regulator_get_optional(&spi->dev, "vref");
297 	if (!IS_ERR(st->reg)) {
298 		st->ext_ref = AD7298_EXTREF;
299 	} else {
300 		ret = PTR_ERR(st->reg);
301 		if (ret != -ENODEV)
302 			return ret;
303 
304 		st->reg = NULL;
305 	}
306 
307 	if (st->reg) {
308 		ret = regulator_enable(st->reg);
309 		if (ret)
310 			return ret;
311 
312 		ret = devm_add_action_or_reset(&spi->dev, ad7298_reg_disable,
313 					       st->reg);
314 		if (ret)
315 			return ret;
316 	}
317 
318 	st->spi = spi;
319 
320 	indio_dev->name = spi_get_device_id(spi)->name;
321 	indio_dev->modes = INDIO_DIRECT_MODE;
322 	indio_dev->channels = ad7298_channels;
323 	indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
324 	indio_dev->info = &ad7298_info;
325 
326 	/* Setup default message */
327 
328 	st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
329 	st->scan_single_xfer[0].len = 2;
330 	st->scan_single_xfer[0].cs_change = 1;
331 	st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
332 	st->scan_single_xfer[1].len = 2;
333 	st->scan_single_xfer[1].cs_change = 1;
334 	st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
335 	st->scan_single_xfer[2].len = 2;
336 
337 	spi_message_init(&st->scan_single_msg);
338 	spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
339 	spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
340 	spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
341 
342 	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
343 			&ad7298_trigger_handler, NULL);
344 	if (ret)
345 		return ret;
346 
347 	return devm_iio_device_register(&spi->dev, indio_dev);
348 }
349 
350 static const struct acpi_device_id ad7298_acpi_ids[] = {
351 	{ "INT3494", 0 },
352 	{ }
353 };
354 MODULE_DEVICE_TABLE(acpi, ad7298_acpi_ids);
355 
356 static const struct spi_device_id ad7298_id[] = {
357 	{"ad7298", 0},
358 	{}
359 };
360 MODULE_DEVICE_TABLE(spi, ad7298_id);
361 
362 static struct spi_driver ad7298_driver = {
363 	.driver = {
364 		.name	= "ad7298",
365 		.acpi_match_table = ad7298_acpi_ids,
366 	},
367 	.probe		= ad7298_probe,
368 	.id_table	= ad7298_id,
369 };
370 module_spi_driver(ad7298_driver);
371 
372 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
373 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
374 MODULE_LICENSE("GPL v2");
375