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
79 	 */
80 	__be16				rx_buf[9] __aligned(IIO_DMA_MINALIGN);
81 	__be16				tx_buf[9] __aligned(IIO_DMA_MINALIGN);
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_ts_unaligned(indio_dev,
153 					      &st->rx_buf[1],
154 					      st->ring_xfer.len - sizeof(st->rx_buf[1]),
155 					      iio_get_time_ns(indio_dev));
156 
157 out_notify:
158 	iio_trigger_notify_done(indio_dev->trig);
159 
160 	return IRQ_HANDLED;
161 }
162 
adc108s102_scan_direct(struct adc108s102_state * st,unsigned int ch)163 static int adc108s102_scan_direct(struct adc108s102_state *st, unsigned int ch)
164 {
165 	int ret;
166 
167 	st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch));
168 	ret = spi_sync(st->spi, &st->scan_single_msg);
169 	if (ret)
170 		return ret;
171 
172 	/* Skip the dummy response in the first slot */
173 	return be16_to_cpu(st->rx_buf[1]);
174 }
175 
adc108s102_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)176 static int adc108s102_read_raw(struct iio_dev *indio_dev,
177 			       struct iio_chan_spec const *chan,
178 			       int *val, int *val2, long m)
179 {
180 	struct adc108s102_state *st = iio_priv(indio_dev);
181 	int ret;
182 
183 	switch (m) {
184 	case IIO_CHAN_INFO_RAW:
185 		ret = iio_device_claim_direct_mode(indio_dev);
186 		if (ret)
187 			return ret;
188 
189 		ret = adc108s102_scan_direct(st, chan->address);
190 
191 		iio_device_release_direct_mode(indio_dev);
192 
193 		if (ret < 0)
194 			return ret;
195 
196 		*val = ADC108S102_RES_DATA(ret);
197 
198 		return IIO_VAL_INT;
199 	case IIO_CHAN_INFO_SCALE:
200 		if (chan->type != IIO_VOLTAGE)
201 			break;
202 
203 		*val = st->va_millivolt;
204 		*val2 = chan->scan_type.realbits;
205 
206 		return IIO_VAL_FRACTIONAL_LOG2;
207 	default:
208 		break;
209 	}
210 
211 	return -EINVAL;
212 }
213 
214 static const struct iio_info adc108s102_info = {
215 	.read_raw		= &adc108s102_read_raw,
216 	.update_scan_mode	= &adc108s102_update_scan_mode,
217 };
218 
adc108s102_reg_disable(void * reg)219 static void adc108s102_reg_disable(void *reg)
220 {
221 	regulator_disable(reg);
222 }
223 
adc108s102_probe(struct spi_device * spi)224 static int adc108s102_probe(struct spi_device *spi)
225 {
226 	struct adc108s102_state *st;
227 	struct iio_dev *indio_dev;
228 	int ret;
229 
230 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
231 	if (!indio_dev)
232 		return -ENOMEM;
233 
234 	st = iio_priv(indio_dev);
235 
236 	if (ACPI_COMPANION(&spi->dev)) {
237 		st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT;
238 	} else {
239 		st->reg = devm_regulator_get(&spi->dev, "vref");
240 		if (IS_ERR(st->reg))
241 			return PTR_ERR(st->reg);
242 
243 		ret = regulator_enable(st->reg);
244 		if (ret < 0) {
245 			dev_err(&spi->dev, "Cannot enable vref regulator\n");
246 			return ret;
247 		}
248 		ret = devm_add_action_or_reset(&spi->dev, adc108s102_reg_disable,
249 					       st->reg);
250 		if (ret)
251 			return ret;
252 
253 		ret = regulator_get_voltage(st->reg);
254 		if (ret < 0) {
255 			dev_err(&spi->dev, "vref get voltage failed\n");
256 			return ret;
257 		}
258 
259 		st->va_millivolt = ret / 1000;
260 	}
261 
262 	st->spi = spi;
263 
264 	indio_dev->name = spi->modalias;
265 	indio_dev->modes = INDIO_DIRECT_MODE;
266 	indio_dev->channels = adc108s102_channels;
267 	indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
268 	indio_dev->info = &adc108s102_info;
269 
270 	/* Setup default message */
271 	st->scan_single_xfer.tx_buf = st->tx_buf;
272 	st->scan_single_xfer.rx_buf = st->rx_buf;
273 	st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);
274 
275 	spi_message_init_with_transfers(&st->scan_single_msg,
276 					&st->scan_single_xfer, 1);
277 
278 	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
279 					      &adc108s102_trigger_handler,
280 					      NULL);
281 	if (ret)
282 		return ret;
283 
284 	ret = devm_iio_device_register(&spi->dev, indio_dev);
285 	if (ret)
286 		dev_err(&spi->dev, "Failed to register IIO device\n");
287 	return ret;
288 }
289 
290 static const struct of_device_id adc108s102_of_match[] = {
291 	{ .compatible = "ti,adc108s102" },
292 	{ }
293 };
294 MODULE_DEVICE_TABLE(of, adc108s102_of_match);
295 
296 #ifdef CONFIG_ACPI
297 static const struct acpi_device_id adc108s102_acpi_ids[] = {
298 	{ "INT3495", 0 },
299 	{ }
300 };
301 MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
302 #endif
303 
304 static const struct spi_device_id adc108s102_id[] = {
305 	{ "adc108s102", 0 },
306 	{ }
307 };
308 MODULE_DEVICE_TABLE(spi, adc108s102_id);
309 
310 static struct spi_driver adc108s102_driver = {
311 	.driver = {
312 		.name   = "adc108s102",
313 		.of_match_table = adc108s102_of_match,
314 		.acpi_match_table = ACPI_PTR(adc108s102_acpi_ids),
315 	},
316 	.probe		= adc108s102_probe,
317 	.id_table	= adc108s102_id,
318 };
319 module_spi_driver(adc108s102_driver);
320 
321 MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
322 MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver");
323 MODULE_LICENSE("GPL v2");
324