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