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// SPDX-License-Identifier: GPL-2.0-only
/*
* BD79703 ROHM Digital to Analog converter
*
* Copyright (c) 2024, ROHM Semiconductor.
*/
#include <linux/bits.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#define BD79703_MAX_REGISTER 0xf
#define BD79703_DAC_BITS 8
#define BD79703_REG_OUT_ALL GENMASK(2, 0)
/*
* The BD79703 uses 12-bit SPI commands. First four bits (high bits) define
* channel(s) which are operated on, and also the mode. The mode can be to set
* a DAC word only, or set DAC word and output. The data-sheet is not very
* specific on how a previously set DAC word can be 'taken in to use'. Thus
* this driver only uses the 'set DAC and output it' -mode.
*
* The BD79703 latches last 12-bits when the chip-select is toggled. Thus we
* can use 16-bit transfers which should be widely supported. To simplify this
* further, we treat the last 8 bits as a value, and first 8 bits as an
* address. This allows us to separate channels/mode by address and treat the
* 8-bit register value as DAC word. The highest 4 bits of address will be
* discarded when the transfer is latched.
*/
static const struct regmap_config bd79703_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = BD79703_MAX_REGISTER,
.cache_type = REGCACHE_RBTREE,
};
struct bd79703_data {
struct regmap *regmap;
int vfs;
};
static int bd79703_read_raw(struct iio_dev *idev,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
struct bd79703_data *data = iio_priv(idev);
if (mask != IIO_CHAN_INFO_SCALE)
return -EINVAL;
*val = data->vfs / 1000;
*val2 = BD79703_DAC_BITS;
return IIO_VAL_FRACTIONAL_LOG2;
}
static int bd79703_write_raw(struct iio_dev *idev,
struct iio_chan_spec const *chan, int val,
int val2, long mask)
{
struct bd79703_data *data = iio_priv(idev);
if (val < 0 || val >= 1 << BD79703_DAC_BITS)
return -EINVAL;
return regmap_write(data->regmap, chan->channel + 1, val);
};
static const struct iio_info bd79703_info = {
.read_raw = bd79703_read_raw,
.write_raw = bd79703_write_raw,
};
#define BD79703_CHAN(_chan) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.output = 1, \
.channel = (_chan), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.address = (_chan), \
}
static const struct iio_chan_spec bd79703_channels[] = {
BD79703_CHAN(0),
BD79703_CHAN(1),
BD79703_CHAN(2),
BD79703_CHAN(3),
BD79703_CHAN(4),
BD79703_CHAN(5),
};
static int bd79703_probe(struct spi_device *spi)
{
struct device *dev = &spi->dev;
struct bd79703_data *data;
struct iio_dev *idev;
int ret;
idev = devm_iio_device_alloc(dev, sizeof(*data));
if (!idev)
return -ENOMEM;
data = iio_priv(idev);
data->regmap = devm_regmap_init_spi(spi, &bd79703_regmap_config);
if (IS_ERR(data->regmap))
return dev_err_probe(dev, PTR_ERR(data->regmap),
"Failed to initialize Regmap\n");
ret = devm_regulator_get_enable(dev, "vcc");
if (ret)
return dev_err_probe(dev, ret, "Failed to enable VCC\n");
ret = devm_regulator_get_enable_read_voltage(dev, "vfs");
if (ret < 0)
return dev_err_probe(dev, ret, "Failed to get Vfs\n");
data->vfs = ret;
idev->channels = bd79703_channels;
idev->num_channels = ARRAY_SIZE(bd79703_channels);
idev->modes = INDIO_DIRECT_MODE;
idev->info = &bd79703_info;
idev->name = "bd79703";
/* Initialize all to output zero */
ret = regmap_write(data->regmap, BD79703_REG_OUT_ALL, 0);
if (ret)
return ret;
return devm_iio_device_register(dev, idev);
}
static const struct spi_device_id bd79703_id[] = {
{ "bd79703", },
{ }
};
MODULE_DEVICE_TABLE(spi, bd79703_id);
static const struct of_device_id bd79703_of_match[] = {
{ .compatible = "rohm,bd79703", },
{ }
};
MODULE_DEVICE_TABLE(of, bd79703_of_match);
static struct spi_driver bd79703_driver = {
.driver = {
.name = "bd79703",
.of_match_table = bd79703_of_match,
},
.probe = bd79703_probe,
.id_table = bd79703_id,
};
module_spi_driver(bd79703_driver);
MODULE_AUTHOR("Matti Vaittinen <mazziesaccount@gmail.com>");
MODULE_DESCRIPTION("ROHM BD79703 DAC driver");
MODULE_LICENSE("GPL");
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