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 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, plus 64-bit timestamp
79 */
80 __be16 rx_buf[13] ____cacheline_aligned;
81 __be16 tx_buf[9] ____cacheline_aligned;
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
101 static 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
adc108s102_update_scan_mode(struct iio_dev * indio_dev,unsigned long const * active_scan_mask)113 static 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
adc108s102_trigger_handler(int irq,void * p)140 static 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_timestamp(indio_dev,
153 (u8 *)&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 st->reg = devm_regulator_get(&spi->dev, "vref");
234 if (IS_ERR(st->reg))
235 return PTR_ERR(st->reg);
236
237 ret = regulator_enable(st->reg);
238 if (ret < 0) {
239 dev_err(&spi->dev, "Cannot enable vref regulator\n");
240 return ret;
241 }
242
243 ret = regulator_get_voltage(st->reg);
244 if (ret < 0) {
245 dev_err(&spi->dev, "vref get voltage failed\n");
246 return ret;
247 }
248
249 st->va_millivolt = ret / 1000;
250 }
251
252 spi_set_drvdata(spi, indio_dev);
253 st->spi = spi;
254
255 indio_dev->name = spi->modalias;
256 indio_dev->modes = INDIO_DIRECT_MODE;
257 indio_dev->channels = adc108s102_channels;
258 indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
259 indio_dev->info = &adc108s102_info;
260
261 /* Setup default message */
262 st->scan_single_xfer.tx_buf = st->tx_buf;
263 st->scan_single_xfer.rx_buf = st->rx_buf;
264 st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);
265
266 spi_message_init_with_transfers(&st->scan_single_msg,
267 &st->scan_single_xfer, 1);
268
269 ret = iio_triggered_buffer_setup(indio_dev, NULL,
270 &adc108s102_trigger_handler, NULL);
271 if (ret)
272 goto error_disable_reg;
273
274 ret = iio_device_register(indio_dev);
275 if (ret) {
276 dev_err(&spi->dev, "Failed to register IIO device\n");
277 goto error_cleanup_triggered_buffer;
278 }
279 return 0;
280
281 error_cleanup_triggered_buffer:
282 iio_triggered_buffer_cleanup(indio_dev);
283
284 error_disable_reg:
285 regulator_disable(st->reg);
286
287 return ret;
288 }
289
adc108s102_remove(struct spi_device * spi)290 static int adc108s102_remove(struct spi_device *spi)
291 {
292 struct iio_dev *indio_dev = spi_get_drvdata(spi);
293 struct adc108s102_state *st = iio_priv(indio_dev);
294
295 iio_device_unregister(indio_dev);
296 iio_triggered_buffer_cleanup(indio_dev);
297
298 regulator_disable(st->reg);
299
300 return 0;
301 }
302
303 static const struct of_device_id adc108s102_of_match[] = {
304 { .compatible = "ti,adc108s102" },
305 { }
306 };
307 MODULE_DEVICE_TABLE(of, adc108s102_of_match);
308
309 #ifdef CONFIG_ACPI
310 static const struct acpi_device_id adc108s102_acpi_ids[] = {
311 { "INT3495", 0 },
312 { }
313 };
314 MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
315 #endif
316
317 static const struct spi_device_id adc108s102_id[] = {
318 { "adc108s102", 0 },
319 { }
320 };
321 MODULE_DEVICE_TABLE(spi, adc108s102_id);
322
323 static struct spi_driver adc108s102_driver = {
324 .driver = {
325 .name = "adc108s102",
326 .of_match_table = adc108s102_of_match,
327 .acpi_match_table = ACPI_PTR(adc108s102_acpi_ids),
328 },
329 .probe = adc108s102_probe,
330 .remove = adc108s102_remove,
331 .id_table = adc108s102_id,
332 };
333 module_spi_driver(adc108s102_driver);
334
335 MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
336 MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver");
337 MODULE_LICENSE("GPL v2");
338
