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