1 // SPDX-License-Identifier: GPL-2.0-only
3 * AD7298 SPI ADC driver
5 * Copyright 2011 Analog Devices Inc.
8 #include <linux/device.h>
9 #include <linux/kernel.h>
10 #include <linux/slab.h>
11 #include <linux/sysfs.h>
12 #include <linux/spi/spi.h>
13 #include <linux/regulator/consumer.h>
14 #include <linux/err.h>
15 #include <linux/delay.h>
16 #include <linux/module.h>
17 #include <linux/interrupt.h>
18 #include <linux/bitops.h>
20 #include <linux/iio/iio.h>
21 #include <linux/iio/sysfs.h>
22 #include <linux/iio/buffer.h>
23 #include <linux/iio/trigger_consumer.h>
24 #include <linux/iio/triggered_buffer.h>
26 #include <linux/platform_data/ad7298.h>
28 #define AD7298_WRITE BIT(15) /* write to the control register */
29 #define AD7298_REPEAT BIT(14) /* repeated conversion enable */
30 #define AD7298_CH(x) BIT(13 - (x)) /* channel select */
31 #define AD7298_TSENSE BIT(5) /* temperature conversion enable */
32 #define AD7298_EXTREF BIT(2) /* external reference enable */
33 #define AD7298_TAVG BIT(1) /* temperature sensor averaging enable */
34 #define AD7298_PDD BIT(0) /* partial power down enable */
36 #define AD7298_MAX_CHAN 8
37 #define AD7298_INTREF_mV 2500
39 #define AD7298_CH_TEMP 9
42 struct spi_device *spi;
43 struct regulator *reg;
45 struct spi_transfer ring_xfer[10];
46 struct spi_transfer scan_single_xfer[3];
47 struct spi_message ring_msg;
48 struct spi_message scan_single_msg;
50 * DMA (thus cache coherency maintenance) requires the
51 * transfer buffers to live in their own cache lines.
53 __be16 rx_buf[12] ____cacheline_aligned;
57 #define AD7298_V_CHAN(index) \
59 .type = IIO_VOLTAGE, \
62 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
63 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
65 .scan_index = index, \
70 .endianness = IIO_BE, \
74 static const struct iio_chan_spec ad7298_channels[] = {
79 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
80 BIT(IIO_CHAN_INFO_SCALE) |
81 BIT(IIO_CHAN_INFO_OFFSET),
82 .address = AD7298_CH_TEMP,
98 IIO_CHAN_SOFT_TIMESTAMP(8),
102 * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
104 static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
105 const unsigned long *active_scan_mask)
107 struct ad7298_state *st = iio_priv(indio_dev);
109 unsigned short command;
112 /* Now compute overall size */
113 scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);
115 command = AD7298_WRITE | st->ext_ref;
117 for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
118 if (test_bit(i, active_scan_mask))
121 st->tx_buf[0] = cpu_to_be16(command);
123 /* build spi ring message */
124 st->ring_xfer[0].tx_buf = &st->tx_buf[0];
125 st->ring_xfer[0].len = 2;
126 st->ring_xfer[0].cs_change = 1;
127 st->ring_xfer[1].tx_buf = &st->tx_buf[1];
128 st->ring_xfer[1].len = 2;
129 st->ring_xfer[1].cs_change = 1;
131 spi_message_init(&st->ring_msg);
132 spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
133 spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);
135 for (i = 0; i < scan_count; i++) {
136 st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
137 st->ring_xfer[i + 2].len = 2;
138 st->ring_xfer[i + 2].cs_change = 1;
139 spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
141 /* make sure last transfer cs_change is not set */
142 st->ring_xfer[i + 1].cs_change = 0;
148 * ad7298_trigger_handler() bh of trigger launched polling to ring buffer
150 * Currently there is no option in this driver to disable the saving of
151 * timestamps within the ring.
153 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
155 struct iio_poll_func *pf = p;
156 struct iio_dev *indio_dev = pf->indio_dev;
157 struct ad7298_state *st = iio_priv(indio_dev);
160 b_sent = spi_sync(st->spi, &st->ring_msg);
164 iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
165 iio_get_time_ns(indio_dev));
168 iio_trigger_notify_done(indio_dev->trig);
173 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
176 st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
177 (AD7298_CH(0) >> ch));
179 ret = spi_sync(st->spi, &st->scan_single_msg);
183 return be16_to_cpu(st->rx_buf[0]);
186 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
191 buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
192 AD7298_TAVG | st->ext_ref);
194 ret = spi_write(st->spi, (u8 *)&buf, 2);
198 buf = cpu_to_be16(0);
200 ret = spi_write(st->spi, (u8 *)&buf, 2);
204 usleep_range(101, 1000); /* sleep > 100us */
206 ret = spi_read(st->spi, (u8 *)&buf, 2);
210 *val = sign_extend32(be16_to_cpu(buf), 11);
215 static int ad7298_get_ref_voltage(struct ad7298_state *st)
220 vref = regulator_get_voltage(st->reg);
226 return AD7298_INTREF_mV;
230 static int ad7298_read_raw(struct iio_dev *indio_dev,
231 struct iio_chan_spec const *chan,
237 struct ad7298_state *st = iio_priv(indio_dev);
240 case IIO_CHAN_INFO_RAW:
241 ret = iio_device_claim_direct_mode(indio_dev);
245 if (chan->address == AD7298_CH_TEMP)
246 ret = ad7298_scan_temp(st, val);
248 ret = ad7298_scan_direct(st, chan->address);
250 iio_device_release_direct_mode(indio_dev);
255 if (chan->address != AD7298_CH_TEMP)
256 *val = ret & GENMASK(chan->scan_type.realbits - 1, 0);
259 case IIO_CHAN_INFO_SCALE:
260 switch (chan->type) {
262 *val = ad7298_get_ref_voltage(st);
263 *val2 = chan->scan_type.realbits;
264 return IIO_VAL_FRACTIONAL_LOG2;
266 *val = ad7298_get_ref_voltage(st);
268 return IIO_VAL_FRACTIONAL;
272 case IIO_CHAN_INFO_OFFSET:
273 *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
279 static const struct iio_info ad7298_info = {
280 .read_raw = &ad7298_read_raw,
281 .update_scan_mode = ad7298_update_scan_mode,
284 static int ad7298_probe(struct spi_device *spi)
286 struct ad7298_platform_data *pdata = spi->dev.platform_data;
287 struct ad7298_state *st;
288 struct iio_dev *indio_dev;
291 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
292 if (indio_dev == NULL)
295 st = iio_priv(indio_dev);
297 if (pdata && pdata->ext_ref)
298 st->ext_ref = AD7298_EXTREF;
301 st->reg = devm_regulator_get(&spi->dev, "vref");
303 return PTR_ERR(st->reg);
305 ret = regulator_enable(st->reg);
310 spi_set_drvdata(spi, indio_dev);
314 indio_dev->name = spi_get_device_id(spi)->name;
315 indio_dev->modes = INDIO_DIRECT_MODE;
316 indio_dev->channels = ad7298_channels;
317 indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
318 indio_dev->info = &ad7298_info;
320 /* Setup default message */
322 st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
323 st->scan_single_xfer[0].len = 2;
324 st->scan_single_xfer[0].cs_change = 1;
325 st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
326 st->scan_single_xfer[1].len = 2;
327 st->scan_single_xfer[1].cs_change = 1;
328 st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
329 st->scan_single_xfer[2].len = 2;
331 spi_message_init(&st->scan_single_msg);
332 spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
333 spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
334 spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
336 ret = iio_triggered_buffer_setup(indio_dev, NULL,
337 &ad7298_trigger_handler, NULL);
339 goto error_disable_reg;
341 ret = iio_device_register(indio_dev);
343 goto error_cleanup_ring;
348 iio_triggered_buffer_cleanup(indio_dev);
351 regulator_disable(st->reg);
356 static int ad7298_remove(struct spi_device *spi)
358 struct iio_dev *indio_dev = spi_get_drvdata(spi);
359 struct ad7298_state *st = iio_priv(indio_dev);
361 iio_device_unregister(indio_dev);
362 iio_triggered_buffer_cleanup(indio_dev);
364 regulator_disable(st->reg);
369 static const struct spi_device_id ad7298_id[] = {
373 MODULE_DEVICE_TABLE(spi, ad7298_id);
375 static struct spi_driver ad7298_driver = {
379 .probe = ad7298_probe,
380 .remove = ad7298_remove,
381 .id_table = ad7298_id,
383 module_spi_driver(ad7298_driver);
385 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
386 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
387 MODULE_LICENSE("GPL v2");