1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Analog Devices AD7292 SPI ADC driver
4 *
5 * Copyright 2019 Analog Devices Inc.
6 */
7
8 #include <linux/bitfield.h>
9 #include <linux/device.h>
10 #include <linux/module.h>
11 #include <linux/regulator/consumer.h>
12 #include <linux/spi/spi.h>
13
14 #include <linux/iio/iio.h>
15
16 #define ADI_VENDOR_ID 0x0018
17
18 /* AD7292 registers definition */
19 #define AD7292_REG_VENDOR_ID 0x00
20 #define AD7292_REG_CONF_BANK 0x05
21 #define AD7292_REG_CONV_COMM 0x0E
22 #define AD7292_REG_ADC_CH(x) (0x10 + (x))
23
24 /* AD7292 configuration bank subregisters definition */
25 #define AD7292_BANK_REG_VIN_RNG0 0x10
26 #define AD7292_BANK_REG_VIN_RNG1 0x11
27 #define AD7292_BANK_REG_SAMP_MODE 0x12
28
29 #define AD7292_RD_FLAG_MSK(x) (BIT(7) | ((x) & 0x3F))
30
31 /* AD7292_REG_ADC_CONVERSION */
32 #define AD7292_ADC_DATA_MASK GENMASK(15, 6)
33 #define AD7292_ADC_DATA(x) FIELD_GET(AD7292_ADC_DATA_MASK, x)
34
35 /* AD7292_CHANNEL_SAMPLING_MODE */
36 #define AD7292_CH_SAMP_MODE(reg, ch) (((reg) >> 8) & BIT(ch))
37
38 /* AD7292_CHANNEL_VIN_RANGE */
39 #define AD7292_CH_VIN_RANGE(reg, ch) ((reg) & BIT(ch))
40
41 #define AD7292_VOLTAGE_CHAN(_chan) \
42 { \
43 .type = IIO_VOLTAGE, \
44 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
45 BIT(IIO_CHAN_INFO_SCALE), \
46 .indexed = 1, \
47 .channel = _chan, \
48 }
49
50 static const struct iio_chan_spec ad7292_channels[] = {
51 AD7292_VOLTAGE_CHAN(0),
52 AD7292_VOLTAGE_CHAN(1),
53 AD7292_VOLTAGE_CHAN(2),
54 AD7292_VOLTAGE_CHAN(3),
55 AD7292_VOLTAGE_CHAN(4),
56 AD7292_VOLTAGE_CHAN(5),
57 AD7292_VOLTAGE_CHAN(6),
58 AD7292_VOLTAGE_CHAN(7)
59 };
60
61 static const struct iio_chan_spec ad7292_channels_diff[] = {
62 {
63 .type = IIO_VOLTAGE,
64 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
65 .indexed = 1,
66 .differential = 1,
67 .channel = 0,
68 .channel2 = 1,
69 },
70 AD7292_VOLTAGE_CHAN(2),
71 AD7292_VOLTAGE_CHAN(3),
72 AD7292_VOLTAGE_CHAN(4),
73 AD7292_VOLTAGE_CHAN(5),
74 AD7292_VOLTAGE_CHAN(6),
75 AD7292_VOLTAGE_CHAN(7)
76 };
77
78 struct ad7292_state {
79 struct spi_device *spi;
80 struct regulator *reg;
81 unsigned short vref_mv;
82
83 __be16 d16 __aligned(IIO_DMA_MINALIGN);
84 u8 d8[2];
85 };
86
ad7292_spi_reg_read(struct ad7292_state * st,unsigned int addr)87 static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr)
88 {
89 int ret;
90
91 st->d8[0] = AD7292_RD_FLAG_MSK(addr);
92
93 ret = spi_write_then_read(st->spi, st->d8, 1, &st->d16, 2);
94 if (ret < 0)
95 return ret;
96
97 return be16_to_cpu(st->d16);
98 }
99
ad7292_spi_subreg_read(struct ad7292_state * st,unsigned int addr,unsigned int sub_addr,unsigned int len)100 static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr,
101 unsigned int sub_addr, unsigned int len)
102 {
103 unsigned int shift = 16 - (8 * len);
104 int ret;
105
106 st->d8[0] = AD7292_RD_FLAG_MSK(addr);
107 st->d8[1] = sub_addr;
108
109 ret = spi_write_then_read(st->spi, st->d8, 2, &st->d16, len);
110 if (ret < 0)
111 return ret;
112
113 return (be16_to_cpu(st->d16) >> shift);
114 }
115
ad7292_single_conversion(struct ad7292_state * st,unsigned int chan_addr)116 static int ad7292_single_conversion(struct ad7292_state *st,
117 unsigned int chan_addr)
118 {
119 int ret;
120
121 struct spi_transfer t[] = {
122 {
123 .tx_buf = &st->d8,
124 .len = 4,
125 .delay = {
126 .value = 6,
127 .unit = SPI_DELAY_UNIT_USECS
128 },
129 }, {
130 .rx_buf = &st->d16,
131 .len = 2,
132 },
133 };
134
135 st->d8[0] = chan_addr;
136 st->d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM);
137
138 ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
139
140 if (ret < 0)
141 return ret;
142
143 return be16_to_cpu(st->d16);
144 }
145
ad7292_vin_range_multiplier(struct ad7292_state * st,int channel)146 static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel)
147 {
148 int samp_mode, range0, range1, factor = 1;
149
150 /*
151 * Every AD7292 ADC channel may have its input range adjusted according
152 * to the settings at the ADC sampling mode and VIN range subregisters.
153 * For a given channel, the minimum input range is equal to Vref, and it
154 * may be increased by a multiplier factor of 2 or 4 according to the
155 * following rule:
156 * If channel is being sampled with respect to AGND:
157 * factor = 4 if VIN range0 and VIN range1 equal 0
158 * factor = 2 if only one of VIN ranges equal 1
159 * factor = 1 if both VIN range0 and VIN range1 equal 1
160 * If channel is being sampled with respect to AVDD:
161 * factor = 4 if VIN range0 and VIN range1 equal 0
162 * Behavior is undefined if any of VIN range doesn't equal 0
163 */
164
165 samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
166 AD7292_BANK_REG_SAMP_MODE, 2);
167
168 if (samp_mode < 0)
169 return samp_mode;
170
171 range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
172 AD7292_BANK_REG_VIN_RNG0, 2);
173
174 if (range0 < 0)
175 return range0;
176
177 range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
178 AD7292_BANK_REG_VIN_RNG1, 2);
179
180 if (range1 < 0)
181 return range1;
182
183 if (AD7292_CH_SAMP_MODE(samp_mode, channel)) {
184 /* Sampling with respect to AGND */
185 if (!AD7292_CH_VIN_RANGE(range0, channel))
186 factor *= 2;
187
188 if (!AD7292_CH_VIN_RANGE(range1, channel))
189 factor *= 2;
190
191 } else {
192 /* Sampling with respect to AVDD */
193 if (AD7292_CH_VIN_RANGE(range0, channel) ||
194 AD7292_CH_VIN_RANGE(range1, channel))
195 return -EPERM;
196
197 factor = 4;
198 }
199
200 return factor;
201 }
202
ad7292_read_raw(struct iio_dev * indio_dev,const struct iio_chan_spec * chan,int * val,int * val2,long info)203 static int ad7292_read_raw(struct iio_dev *indio_dev,
204 const struct iio_chan_spec *chan,
205 int *val, int *val2, long info)
206 {
207 struct ad7292_state *st = iio_priv(indio_dev);
208 unsigned int ch_addr;
209 int ret;
210
211 switch (info) {
212 case IIO_CHAN_INFO_RAW:
213 ch_addr = AD7292_REG_ADC_CH(chan->channel);
214 ret = ad7292_single_conversion(st, ch_addr);
215 if (ret < 0)
216 return ret;
217
218 *val = AD7292_ADC_DATA(ret);
219
220 return IIO_VAL_INT;
221 case IIO_CHAN_INFO_SCALE:
222 /*
223 * To convert a raw value to standard units, the IIO defines
224 * this formula: Scaled value = (raw + offset) * scale.
225 * For the scale to be a correct multiplier for (raw + offset),
226 * it must be calculated as the input range divided by the
227 * number of possible distinct input values. Given the ADC data
228 * is 10 bit long, it may assume 2^10 distinct values.
229 * Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2
230 * return type indicates to the IIO API to divide *val by 2 to
231 * the power of *val2 when returning from read_raw.
232 */
233
234 ret = ad7292_vin_range_multiplier(st, chan->channel);
235 if (ret < 0)
236 return ret;
237
238 *val = st->vref_mv * ret;
239 *val2 = 10;
240 return IIO_VAL_FRACTIONAL_LOG2;
241 default:
242 break;
243 }
244 return -EINVAL;
245 }
246
247 static const struct iio_info ad7292_info = {
248 .read_raw = ad7292_read_raw,
249 };
250
ad7292_regulator_disable(void * data)251 static void ad7292_regulator_disable(void *data)
252 {
253 struct ad7292_state *st = data;
254
255 regulator_disable(st->reg);
256 }
257
ad7292_probe(struct spi_device * spi)258 static int ad7292_probe(struct spi_device *spi)
259 {
260 struct ad7292_state *st;
261 struct iio_dev *indio_dev;
262 struct device_node *child;
263 bool diff_channels = false;
264 int ret;
265
266 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
267 if (!indio_dev)
268 return -ENOMEM;
269
270 st = iio_priv(indio_dev);
271 st->spi = spi;
272
273 ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID);
274 if (ret != ADI_VENDOR_ID) {
275 dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret);
276 return -EINVAL;
277 }
278
279 st->reg = devm_regulator_get_optional(&spi->dev, "vref");
280 if (!IS_ERR(st->reg)) {
281 ret = regulator_enable(st->reg);
282 if (ret) {
283 dev_err(&spi->dev,
284 "Failed to enable external vref supply\n");
285 return ret;
286 }
287
288 ret = devm_add_action_or_reset(&spi->dev,
289 ad7292_regulator_disable, st);
290 if (ret)
291 return ret;
292
293 ret = regulator_get_voltage(st->reg);
294 if (ret < 0)
295 return ret;
296
297 st->vref_mv = ret / 1000;
298 } else {
299 /* Use the internal voltage reference. */
300 st->vref_mv = 1250;
301 }
302
303 indio_dev->name = spi_get_device_id(spi)->name;
304 indio_dev->modes = INDIO_DIRECT_MODE;
305 indio_dev->info = &ad7292_info;
306
307 for_each_available_child_of_node(spi->dev.of_node, child) {
308 diff_channels = of_property_read_bool(child, "diff-channels");
309 if (diff_channels) {
310 of_node_put(child);
311 break;
312 }
313 }
314
315 if (diff_channels) {
316 indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff);
317 indio_dev->channels = ad7292_channels_diff;
318 } else {
319 indio_dev->num_channels = ARRAY_SIZE(ad7292_channels);
320 indio_dev->channels = ad7292_channels;
321 }
322
323 return devm_iio_device_register(&spi->dev, indio_dev);
324 }
325
326 static const struct spi_device_id ad7292_id_table[] = {
327 { "ad7292", 0 },
328 {}
329 };
330 MODULE_DEVICE_TABLE(spi, ad7292_id_table);
331
332 static const struct of_device_id ad7292_of_match[] = {
333 { .compatible = "adi,ad7292" },
334 { },
335 };
336 MODULE_DEVICE_TABLE(of, ad7292_of_match);
337
338 static struct spi_driver ad7292_driver = {
339 .driver = {
340 .name = "ad7292",
341 .of_match_table = ad7292_of_match,
342 },
343 .probe = ad7292_probe,
344 .id_table = ad7292_id_table,
345 };
346 module_spi_driver(ad7292_driver);
347
348 MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt1@gmail.com>");
349 MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver");
350 MODULE_LICENSE("GPL v2");
351