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] __aligned(IIO_DMA_MINALIGN);
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 */
ad7298_update_scan_mode(struct iio_dev * indio_dev,const unsigned long * active_scan_mask)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,
113 iio_get_masklength(indio_dev));
114
115 command = AD7298_WRITE | st->ext_ref;
116
117 for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
118 if (test_bit(i, active_scan_mask))
119 command |= m;
120
121 st->tx_buf[0] = cpu_to_be16(command);
122
123 /* build spi ring message */
124 st->ring_xfer[0].tx_buf = &st->tx_buf[0];
125 st->ring_xfer[0].len = 2;
126 st->ring_xfer[0].cs_change = 1;
127 st->ring_xfer[1].tx_buf = &st->tx_buf[1];
128 st->ring_xfer[1].len = 2;
129 st->ring_xfer[1].cs_change = 1;
130
131 spi_message_init(&st->ring_msg);
132 spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
133 spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
134
135 for (i = 0; i < scan_count; i++) {
136 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
137 st->ring_xfer[i + 2].len = 2;
138 st->ring_xfer[i + 2].cs_change = 1;
139 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
140 }
141 /* make sure last transfer cs_change is not set */
142 st->ring_xfer[i + 1].cs_change = 0;
143
144 return 0;
145 }
146
ad7298_trigger_handler(int irq,void * p)147 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
148 {
149 struct iio_poll_func *pf = p;
150 struct iio_dev *indio_dev = pf->indio_dev;
151 struct ad7298_state *st = iio_priv(indio_dev);
152 int b_sent;
153
154 b_sent = spi_sync(st->spi, &st->ring_msg);
155 if (b_sent)
156 goto done;
157
158 iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
159 iio_get_time_ns(indio_dev));
160
161 done:
162 iio_trigger_notify_done(indio_dev->trig);
163
164 return IRQ_HANDLED;
165 }
166
ad7298_scan_direct(struct ad7298_state * st,unsigned ch)167 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
168 {
169 int ret;
170 st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
171 (AD7298_CH(0) >> ch));
172
173 ret = spi_sync(st->spi, &st->scan_single_msg);
174 if (ret)
175 return ret;
176
177 return be16_to_cpu(st->rx_buf[0]);
178 }
179
ad7298_scan_temp(struct ad7298_state * st,int * val)180 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
181 {
182 int ret;
183 __be16 buf;
184
185 buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
186 AD7298_TAVG | st->ext_ref);
187
188 ret = spi_write(st->spi, (u8 *)&buf, 2);
189 if (ret)
190 return ret;
191
192 buf = cpu_to_be16(0);
193
194 ret = spi_write(st->spi, (u8 *)&buf, 2);
195 if (ret)
196 return ret;
197
198 usleep_range(101, 1000); /* sleep > 100us */
199
200 ret = spi_read(st->spi, (u8 *)&buf, 2);
201 if (ret)
202 return ret;
203
204 *val = sign_extend32(be16_to_cpu(buf), 11);
205
206 return 0;
207 }
208
ad7298_get_ref_voltage(struct ad7298_state * st)209 static int ad7298_get_ref_voltage(struct ad7298_state *st)
210 {
211 int vref;
212
213 if (st->reg) {
214 vref = regulator_get_voltage(st->reg);
215 if (vref < 0)
216 return vref;
217
218 return vref / 1000;
219 } else {
220 return AD7298_INTREF_mV;
221 }
222 }
223
ad7298_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)224 static int ad7298_read_raw(struct iio_dev *indio_dev,
225 struct iio_chan_spec const *chan,
226 int *val,
227 int *val2,
228 long m)
229 {
230 int ret;
231 struct ad7298_state *st = iio_priv(indio_dev);
232
233 switch (m) {
234 case IIO_CHAN_INFO_RAW:
235 ret = iio_device_claim_direct_mode(indio_dev);
236 if (ret)
237 return ret;
238
239 if (chan->address == AD7298_CH_TEMP)
240 ret = ad7298_scan_temp(st, val);
241 else
242 ret = ad7298_scan_direct(st, chan->address);
243
244 iio_device_release_direct_mode(indio_dev);
245
246 if (ret < 0)
247 return ret;
248
249 if (chan->address != AD7298_CH_TEMP)
250 *val = ret & GENMASK(chan->scan_type.realbits - 1, 0);
251
252 return IIO_VAL_INT;
253 case IIO_CHAN_INFO_SCALE:
254 switch (chan->type) {
255 case IIO_VOLTAGE:
256 *val = ad7298_get_ref_voltage(st);
257 *val2 = chan->scan_type.realbits;
258 return IIO_VAL_FRACTIONAL_LOG2;
259 case IIO_TEMP:
260 *val = ad7298_get_ref_voltage(st);
261 *val2 = 10;
262 return IIO_VAL_FRACTIONAL;
263 default:
264 return -EINVAL;
265 }
266 case IIO_CHAN_INFO_OFFSET:
267 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
268 return IIO_VAL_INT;
269 }
270 return -EINVAL;
271 }
272
273 static const struct iio_info ad7298_info = {
274 .read_raw = &ad7298_read_raw,
275 .update_scan_mode = ad7298_update_scan_mode,
276 };
277
ad7298_reg_disable(void * data)278 static void ad7298_reg_disable(void *data)
279 {
280 struct regulator *reg = data;
281
282 regulator_disable(reg);
283 }
284
ad7298_probe(struct spi_device * spi)285 static int ad7298_probe(struct spi_device *spi)
286 {
287 struct ad7298_state *st;
288 struct iio_dev *indio_dev;
289 int ret;
290
291 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
292 if (indio_dev == NULL)
293 return -ENOMEM;
294
295 st = iio_priv(indio_dev);
296
297 st->reg = devm_regulator_get_optional(&spi->dev, "vref");
298 if (!IS_ERR(st->reg)) {
299 st->ext_ref = AD7298_EXTREF;
300 } else {
301 ret = PTR_ERR(st->reg);
302 if (ret != -ENODEV)
303 return ret;
304
305 st->reg = NULL;
306 }
307
308 if (st->reg) {
309 ret = regulator_enable(st->reg);
310 if (ret)
311 return ret;
312
313 ret = devm_add_action_or_reset(&spi->dev, ad7298_reg_disable,
314 st->reg);
315 if (ret)
316 return ret;
317 }
318
319 st->spi = spi;
320
321 indio_dev->name = spi_get_device_id(spi)->name;
322 indio_dev->modes = INDIO_DIRECT_MODE;
323 indio_dev->channels = ad7298_channels;
324 indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
325 indio_dev->info = &ad7298_info;
326
327 /* Setup default message */
328
329 st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
330 st->scan_single_xfer[0].len = 2;
331 st->scan_single_xfer[0].cs_change = 1;
332 st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
333 st->scan_single_xfer[1].len = 2;
334 st->scan_single_xfer[1].cs_change = 1;
335 st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
336 st->scan_single_xfer[2].len = 2;
337
338 spi_message_init(&st->scan_single_msg);
339 spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
340 spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
341 spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
342
343 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
344 &ad7298_trigger_handler, NULL);
345 if (ret)
346 return ret;
347
348 return devm_iio_device_register(&spi->dev, indio_dev);
349 }
350
351 static const struct acpi_device_id ad7298_acpi_ids[] = {
352 { "INT3494", 0 },
353 { }
354 };
355 MODULE_DEVICE_TABLE(acpi, ad7298_acpi_ids);
356
357 static const struct spi_device_id ad7298_id[] = {
358 { "ad7298", 0 },
359 { }
360 };
361 MODULE_DEVICE_TABLE(spi, ad7298_id);
362
363 static struct spi_driver ad7298_driver = {
364 .driver = {
365 .name = "ad7298",
366 .acpi_match_table = ad7298_acpi_ids,
367 },
368 .probe = ad7298_probe,
369 .id_table = ad7298_id,
370 };
371 module_spi_driver(ad7298_driver);
372
373 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
374 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
375 MODULE_LICENSE("GPL v2");
376