ad8801.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * IIO DAC driver for Analog Devices AD8801 DAC
  4 *
  5 * Copyright (C) 2016 Gwenhael Goavec-Merou
  6 */
  7
  8#include <linux/iio/iio.h>
  9#include <linux/module.h>
 10#include <linux/regulator/consumer.h>
 11#include <linux/spi/spi.h>
 12#include <linux/sysfs.h>
 13
 14#define AD8801_CFG_ADDR_OFFSET 8
 15
 16enum ad8801_device_ids {
 17	ID_AD8801,
 18	ID_AD8803,
 19};
 20
 21struct ad8801_state {
 22	struct spi_device *spi;
 23	unsigned char dac_cache[8]; /* Value write on each channel */
 24	unsigned int vrefh_mv;
 25	unsigned int vrefl_mv;
 26
 27	__be16 data __aligned(IIO_DMA_MINALIGN);
 28};
 29
 30static int ad8801_spi_write(struct ad8801_state *state,
 31	u8 channel, unsigned char value)
 32{
 33	state->data = cpu_to_be16((channel << AD8801_CFG_ADDR_OFFSET) | value);
 34	return spi_write(state->spi, &state->data, sizeof(state->data));
 35}
 36
 37static int ad8801_write_raw(struct iio_dev *indio_dev,
 38	struct iio_chan_spec const *chan, int val, int val2, long mask)
 39{
 40	struct ad8801_state *state = iio_priv(indio_dev);
 41	int ret;
 42
 43	switch (mask) {
 44	case IIO_CHAN_INFO_RAW:
 45		if (val >= 256 || val < 0)
 46			return -EINVAL;
 47
 48		ret = ad8801_spi_write(state, chan->channel, val);
 49		if (ret == 0)
 50			state->dac_cache[chan->channel] = val;
 51		break;
 52	default:
 53		ret = -EINVAL;
 54	}
 55
 56	return ret;
 57}
 58
 59static int ad8801_read_raw(struct iio_dev *indio_dev,
 60	struct iio_chan_spec const *chan, int *val, int *val2, long info)
 61{
 62	struct ad8801_state *state = iio_priv(indio_dev);
 63
 64	switch (info) {
 65	case IIO_CHAN_INFO_RAW:
 66		*val = state->dac_cache[chan->channel];
 67		return IIO_VAL_INT;
 68	case IIO_CHAN_INFO_SCALE:
 69		*val = state->vrefh_mv - state->vrefl_mv;
 70		*val2 = 8;
 71		return IIO_VAL_FRACTIONAL_LOG2;
 72	case IIO_CHAN_INFO_OFFSET:
 73		*val = state->vrefl_mv;
 74		return IIO_VAL_INT;
 75	default:
 76		return -EINVAL;
 77	}
 78
 79	return -EINVAL;
 80}
 81
 82static const struct iio_info ad8801_info = {
 83	.read_raw = ad8801_read_raw,
 84	.write_raw = ad8801_write_raw,
 85};
 86
 87#define AD8801_CHANNEL(chan) {		\
 88	.type = IIO_VOLTAGE,			\
 89	.indexed = 1,				\
 90	.output = 1,				\
 91	.channel = chan,			\
 92	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 93	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |	\
 94		BIT(IIO_CHAN_INFO_OFFSET), \
 95}
 96
 97static const struct iio_chan_spec ad8801_channels[] = {
 98	AD8801_CHANNEL(0),
 99	AD8801_CHANNEL(1),
100	AD8801_CHANNEL(2),
101	AD8801_CHANNEL(3),
102	AD8801_CHANNEL(4),
103	AD8801_CHANNEL(5),
104	AD8801_CHANNEL(6),
105	AD8801_CHANNEL(7),
106};
107
108static int ad8801_probe(struct spi_device *spi)
109{
110	struct iio_dev *indio_dev;
111	struct ad8801_state *state;
112	const struct spi_device_id *id;
113	int ret;
114
115	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
116	if (indio_dev == NULL)
117		return -ENOMEM;
118
119	state = iio_priv(indio_dev);
120	state->spi = spi;
121	id = spi_get_device_id(spi);
122
123	ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefh");
124	if (ret < 0)
125		return dev_err_probe(&spi->dev, ret,
126				     "failed to get Vrefh voltage\n");
127
128	state->vrefh_mv = ret / 1000;
129
130	if (id->driver_data == ID_AD8803) {
131		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefl");
132		if (ret < 0)
133			return dev_err_probe(&spi->dev, ret,
134					     "failed to get Vrefl voltage\n");
135
136		state->vrefl_mv = ret / 1000;
137	}
138
139	indio_dev->info = &ad8801_info;
140	indio_dev->modes = INDIO_DIRECT_MODE;
141	indio_dev->channels = ad8801_channels;
142	indio_dev->num_channels = ARRAY_SIZE(ad8801_channels);
143	indio_dev->name = id->name;
144
145	ret = devm_iio_device_register(&spi->dev, indio_dev);
146	if (ret)
147		return dev_err_probe(&spi->dev, ret,
148				     "Failed to register iio device\n");
149
150	return 0;
151}
152
153static const struct spi_device_id ad8801_ids[] = {
154	{"ad8801", ID_AD8801},
155	{"ad8803", ID_AD8803},
156	{ }
157};
158MODULE_DEVICE_TABLE(spi, ad8801_ids);
159
160static struct spi_driver ad8801_driver = {
161	.driver = {
162		.name	= "ad8801",
163	},
164	.probe		= ad8801_probe,
165	.id_table	= ad8801_ids,
166};
167module_spi_driver(ad8801_driver);
168
169MODULE_AUTHOR("Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>");
170MODULE_DESCRIPTION("Analog Devices AD8801/AD8803 DAC");
171MODULE_LICENSE("GPL v2");