2 * Copyright (C) 2015 Prevas A/S
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 #include <linux/device.h>
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/sysfs.h>
13 #include <linux/spi/spi.h>
14 #include <linux/regulator/consumer.h>
15 #include <linux/err.h>
16 #include <linux/module.h>
19 #include <linux/iio/iio.h>
20 #include <linux/iio/sysfs.h>
22 #define ADS8688_CMD_REG(x) (x << 8)
23 #define ADS8688_CMD_REG_NOOP 0x00
24 #define ADS8688_CMD_REG_RST 0x85
25 #define ADS8688_CMD_REG_MAN_CH(chan) (0xC0 | (4 * chan))
26 #define ADS8688_CMD_DONT_CARE_BITS 16
28 #define ADS8688_PROG_REG(x) (x << 9)
29 #define ADS8688_PROG_REG_RANGE_CH(chan) (0x05 + chan)
30 #define ADS8688_PROG_WR_BIT BIT(8)
31 #define ADS8688_PROG_DONT_CARE_BITS 8
33 #define ADS8688_REG_PLUSMINUS25VREF 0
34 #define ADS8688_REG_PLUSMINUS125VREF 1
35 #define ADS8688_REG_PLUSMINUS0625VREF 2
36 #define ADS8688_REG_PLUS25VREF 5
37 #define ADS8688_REG_PLUS125VREF 6
39 #define ADS8688_VREF_MV 4096
40 #define ADS8688_REALBITS 16
43 * enum ads8688_range - ADS8688 reference voltage range
44 * @ADS8688_PLUSMINUS25VREF: Device is configured for input range ±2.5 * VREF
45 * @ADS8688_PLUSMINUS125VREF: Device is configured for input range ±1.25 * VREF
46 * @ADS8688_PLUSMINUS0625VREF: Device is configured for input range ±0.625 * VREF
47 * @ADS8688_PLUS25VREF: Device is configured for input range 0 - 2.5 * VREF
48 * @ADS8688_PLUS125VREF: Device is configured for input range 0 - 1.25 * VREF
51 ADS8688_PLUSMINUS25VREF,
52 ADS8688_PLUSMINUS125VREF,
53 ADS8688_PLUSMINUS0625VREF,
58 struct ads8688_chip_info {
59 const struct iio_chan_spec *channels;
60 unsigned int num_channels;
63 struct ads8688_state {
65 const struct ads8688_chip_info *chip_info;
66 struct spi_device *spi;
67 struct regulator *reg;
69 enum ads8688_range range[8];
73 } data[2] ____cacheline_aligned;
81 struct ads8688_ranges {
82 enum ads8688_range range;
88 static const struct ads8688_ranges ads8688_range_def[5] = {
90 .range = ADS8688_PLUSMINUS25VREF,
92 .offset = -(1 << (ADS8688_REALBITS - 1)),
93 .reg = ADS8688_REG_PLUSMINUS25VREF,
95 .range = ADS8688_PLUSMINUS125VREF,
97 .offset = -(1 << (ADS8688_REALBITS - 1)),
98 .reg = ADS8688_REG_PLUSMINUS125VREF,
100 .range = ADS8688_PLUSMINUS0625VREF,
102 .offset = -(1 << (ADS8688_REALBITS - 1)),
103 .reg = ADS8688_REG_PLUSMINUS0625VREF,
105 .range = ADS8688_PLUS25VREF,
108 .reg = ADS8688_REG_PLUS25VREF,
110 .range = ADS8688_PLUS125VREF,
113 .reg = ADS8688_REG_PLUS125VREF,
117 static ssize_t ads8688_show_scales(struct device *dev,
118 struct device_attribute *attr, char *buf)
120 struct ads8688_state *st = iio_priv(dev_to_iio_dev(dev));
122 return sprintf(buf, "0.%09u 0.%09u 0.%09u\n",
123 ads8688_range_def[0].scale * st->vref_mv,
124 ads8688_range_def[1].scale * st->vref_mv,
125 ads8688_range_def[2].scale * st->vref_mv);
128 static ssize_t ads8688_show_offsets(struct device *dev,
129 struct device_attribute *attr, char *buf)
131 return sprintf(buf, "%d %d\n", ads8688_range_def[0].offset,
132 ads8688_range_def[3].offset);
135 static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
136 ads8688_show_scales, NULL, 0);
137 static IIO_DEVICE_ATTR(in_voltage_offset_available, S_IRUGO,
138 ads8688_show_offsets, NULL, 0);
140 static struct attribute *ads8688_attributes[] = {
141 &iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
142 &iio_dev_attr_in_voltage_offset_available.dev_attr.attr,
146 static const struct attribute_group ads8688_attribute_group = {
147 .attrs = ads8688_attributes,
150 #define ADS8688_CHAN(index) \
152 .type = IIO_VOLTAGE, \
155 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
156 | BIT(IIO_CHAN_INFO_SCALE) \
157 | BIT(IIO_CHAN_INFO_OFFSET), \
160 static const struct iio_chan_spec ads8684_channels[] = {
167 static const struct iio_chan_spec ads8688_channels[] = {
178 static int ads8688_prog_write(struct iio_dev *indio_dev, unsigned int addr,
181 struct ads8688_state *st = iio_priv(indio_dev);
184 tmp = ADS8688_PROG_REG(addr) | ADS8688_PROG_WR_BIT | val;
185 tmp <<= ADS8688_PROG_DONT_CARE_BITS;
186 st->data[0].d32 = cpu_to_be32(tmp);
188 return spi_write(st->spi, &st->data[0].d8[1], 3);
191 static int ads8688_reset(struct iio_dev *indio_dev)
193 struct ads8688_state *st = iio_priv(indio_dev);
196 tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_RST);
197 tmp <<= ADS8688_CMD_DONT_CARE_BITS;
198 st->data[0].d32 = cpu_to_be32(tmp);
200 return spi_write(st->spi, &st->data[0].d8[0], 4);
203 static int ads8688_read(struct iio_dev *indio_dev, unsigned int chan)
205 struct ads8688_state *st = iio_priv(indio_dev);
208 struct spi_transfer t[] = {
210 .tx_buf = &st->data[0].d8[0],
214 .tx_buf = &st->data[1].d8[0],
215 .rx_buf = &st->data[1].d8[0],
220 tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_MAN_CH(chan));
221 tmp <<= ADS8688_CMD_DONT_CARE_BITS;
222 st->data[0].d32 = cpu_to_be32(tmp);
224 tmp = ADS8688_CMD_REG(ADS8688_CMD_REG_NOOP);
225 tmp <<= ADS8688_CMD_DONT_CARE_BITS;
226 st->data[1].d32 = cpu_to_be32(tmp);
228 ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
232 return be32_to_cpu(st->data[1].d32) & 0xffff;
235 static int ads8688_read_raw(struct iio_dev *indio_dev,
236 struct iio_chan_spec const *chan,
237 int *val, int *val2, long m)
240 unsigned long scale_mv;
242 struct ads8688_state *st = iio_priv(indio_dev);
244 mutex_lock(&st->lock);
246 case IIO_CHAN_INFO_RAW:
247 ret = ads8688_read(indio_dev, chan->channel);
248 mutex_unlock(&st->lock);
253 case IIO_CHAN_INFO_SCALE:
254 scale_mv = st->vref_mv;
255 scale_mv *= ads8688_range_def[st->range[chan->channel]].scale;
258 mutex_unlock(&st->lock);
259 return IIO_VAL_INT_PLUS_NANO;
260 case IIO_CHAN_INFO_OFFSET:
261 offset = ads8688_range_def[st->range[chan->channel]].offset;
263 mutex_unlock(&st->lock);
266 mutex_unlock(&st->lock);
271 static int ads8688_write_reg_range(struct iio_dev *indio_dev,
272 struct iio_chan_spec const *chan,
273 enum ads8688_range range)
278 tmp = ADS8688_PROG_REG_RANGE_CH(chan->channel);
279 ret = ads8688_prog_write(indio_dev, tmp, range);
284 static int ads8688_write_raw(struct iio_dev *indio_dev,
285 struct iio_chan_spec const *chan,
286 int val, int val2, long mask)
288 struct ads8688_state *st = iio_priv(indio_dev);
289 unsigned int scale = 0;
290 int ret = -EINVAL, i, offset = 0;
292 mutex_lock(&st->lock);
294 case IIO_CHAN_INFO_SCALE:
295 /* If the offset is 0 the ±2.5 * VREF mode is not available */
296 offset = ads8688_range_def[st->range[chan->channel]].offset;
297 if (offset == 0 && val2 == ads8688_range_def[0].scale * st->vref_mv) {
298 mutex_unlock(&st->lock);
302 /* Lookup new mode */
303 for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++)
304 if (val2 == ads8688_range_def[i].scale * st->vref_mv &&
305 offset == ads8688_range_def[i].offset) {
306 ret = ads8688_write_reg_range(indio_dev, chan,
307 ads8688_range_def[i].reg);
311 case IIO_CHAN_INFO_OFFSET:
313 * There are only two available offsets:
314 * 0 and -(1 << (ADS8688_REALBITS - 1))
316 if (!(ads8688_range_def[0].offset == val ||
317 ads8688_range_def[3].offset == val)) {
318 mutex_unlock(&st->lock);
323 * If the device are in ±2.5 * VREF mode, it's not allowed to
324 * switch to a mode where the offset is 0
327 st->range[chan->channel] == ADS8688_PLUSMINUS25VREF) {
328 mutex_unlock(&st->lock);
332 scale = ads8688_range_def[st->range[chan->channel]].scale;
334 /* Lookup new mode */
335 for (i = 0; i < ARRAY_SIZE(ads8688_range_def); i++)
336 if (val == ads8688_range_def[i].offset &&
337 scale == ads8688_range_def[i].scale) {
338 ret = ads8688_write_reg_range(indio_dev, chan,
339 ads8688_range_def[i].reg);
346 st->range[chan->channel] = ads8688_range_def[i].range;
348 mutex_unlock(&st->lock);
353 static int ads8688_write_raw_get_fmt(struct iio_dev *indio_dev,
354 struct iio_chan_spec const *chan,
358 case IIO_CHAN_INFO_SCALE:
359 return IIO_VAL_INT_PLUS_NANO;
360 case IIO_CHAN_INFO_OFFSET:
367 static const struct iio_info ads8688_info = {
368 .read_raw = &ads8688_read_raw,
369 .write_raw = &ads8688_write_raw,
370 .write_raw_get_fmt = &ads8688_write_raw_get_fmt,
371 .attrs = &ads8688_attribute_group,
374 static const struct ads8688_chip_info ads8688_chip_info_tbl[] = {
376 .channels = ads8684_channels,
377 .num_channels = ARRAY_SIZE(ads8684_channels),
380 .channels = ads8688_channels,
381 .num_channels = ARRAY_SIZE(ads8688_channels),
385 static int ads8688_probe(struct spi_device *spi)
387 struct ads8688_state *st;
388 struct iio_dev *indio_dev;
391 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
392 if (indio_dev == NULL)
395 st = iio_priv(indio_dev);
397 st->reg = devm_regulator_get_optional(&spi->dev, "vref");
398 if (!IS_ERR(st->reg)) {
399 ret = regulator_enable(st->reg);
403 ret = regulator_get_voltage(st->reg);
407 st->vref_mv = ret / 1000;
409 /* Use internal reference */
410 st->vref_mv = ADS8688_VREF_MV;
413 st->chip_info = &ads8688_chip_info_tbl[spi_get_device_id(spi)->driver_data];
415 spi->mode = SPI_MODE_1;
417 spi_set_drvdata(spi, indio_dev);
421 indio_dev->name = spi_get_device_id(spi)->name;
422 indio_dev->dev.parent = &spi->dev;
423 indio_dev->dev.of_node = spi->dev.of_node;
424 indio_dev->modes = INDIO_DIRECT_MODE;
425 indio_dev->channels = st->chip_info->channels;
426 indio_dev->num_channels = st->chip_info->num_channels;
427 indio_dev->info = &ads8688_info;
429 ads8688_reset(indio_dev);
431 mutex_init(&st->lock);
433 ret = iio_device_register(indio_dev);
440 if (!IS_ERR(st->reg))
441 regulator_disable(st->reg);
446 static int ads8688_remove(struct spi_device *spi)
448 struct iio_dev *indio_dev = spi_get_drvdata(spi);
449 struct ads8688_state *st = iio_priv(indio_dev);
451 iio_device_unregister(indio_dev);
453 if (!IS_ERR(st->reg))
454 regulator_disable(st->reg);
459 static const struct spi_device_id ads8688_id[] = {
460 {"ads8684", ID_ADS8684},
461 {"ads8688", ID_ADS8688},
464 MODULE_DEVICE_TABLE(spi, ads8688_id);
466 static const struct of_device_id ads8688_of_match[] = {
467 { .compatible = "ti,ads8684" },
468 { .compatible = "ti,ads8688" },
471 MODULE_DEVICE_TABLE(of, ads8688_of_match);
473 static struct spi_driver ads8688_driver = {
477 .probe = ads8688_probe,
478 .remove = ads8688_remove,
479 .id_table = ads8688_id,
481 module_spi_driver(ads8688_driver);
483 MODULE_AUTHOR("Sean Nyekjaer <sean.nyekjaer@prevas.dk>");
484 MODULE_DESCRIPTION("Texas Instruments ADS8688 driver");
485 MODULE_LICENSE("GPL v2");