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// SPDX-License-Identifier: GPL-2.0-only
/*
* Microchip MCP47A1 DAC driver
*
* Copyright (c) 2026 Joshua Crofts <joshua.crofts1@gmail.com>
*
* Datasheet: https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/25154A.pdf
*/
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/types.h>
#include <linux/units.h>
#include <linux/iio/iio.h>
#define MCP47A1_CMD_CODE 0x00
#define MCP47A1_MAX_STEPS 64
struct mcp47a1_data {
struct i2c_client *client;
int vref_mV;
};
static const int mcp47a1_raw_avail[] = { 0, 1, MCP47A1_MAX_STEPS - 1 };
static const struct iio_chan_spec mcp47a1_channel = {
.type = IIO_VOLTAGE,
.indexed = 1,
.output = 1,
.channel = 0,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
};
static int mcp47a1_write(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct mcp47a1_data *data = iio_priv(indio_dev);
switch (mask) {
case IIO_CHAN_INFO_RAW:
if (!in_range(val, 0, MCP47A1_MAX_STEPS))
return -EINVAL;
return i2c_smbus_write_byte_data(data->client, MCP47A1_CMD_CODE,
val);
default:
return -EINVAL;
}
}
static int mcp47a1_read(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct mcp47a1_data *data = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = i2c_smbus_read_byte_data(data->client, MCP47A1_CMD_CODE);
if (ret < 0)
return ret;
*val = ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = data->vref_mV;
*val2 = MCP47A1_MAX_STEPS;
return IIO_VAL_FRACTIONAL;
default:
return -EINVAL;
}
}
static int mcp47a1_read_avail(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
const int **vals, int *type, int *length,
long mask)
{
switch (mask) {
case IIO_CHAN_INFO_RAW:
*vals = mcp47a1_raw_avail;
*type = IIO_VAL_INT;
return IIO_AVAIL_RANGE;
default:
return -EINVAL;
}
}
static const struct iio_info mcp47a1_info = {
.write_raw = mcp47a1_write,
.read_raw = mcp47a1_read,
.read_avail = mcp47a1_read_avail,
};
static int mcp47a1_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct mcp47a1_data *data;
struct iio_dev *indio_dev;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
data->client = client;
ret = devm_regulator_get_enable(dev, "vdd");
if (ret)
return dev_err_probe(dev, ret, "Failed to enable regulator\n");
/* Delay after device exits reset state (see AC/DC characteristics) */
fsleep(20);
ret = devm_regulator_get_enable_read_voltage(dev, "vref");
if (ret < 0)
return dev_err_probe(dev, ret, "Failed to read vref\n");
data->vref_mV = ret / (MICRO / MILLI);
indio_dev->name = "mcp47a1";
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &mcp47a1_info;
indio_dev->channels = &mcp47a1_channel;
indio_dev->num_channels = 1;
return devm_iio_device_register(dev, indio_dev);
}
static const struct of_device_id mcp47a1_of_match[] = {
{ .compatible = "microchip,mcp47a1" },
{ }
};
MODULE_DEVICE_TABLE(of, mcp47a1_of_match);
static const struct i2c_device_id mcp47a1_id[] = {
{ .name = "mcp47a1" },
{ }
};
MODULE_DEVICE_TABLE(i2c, mcp47a1_id);
static struct i2c_driver mcp47a1_driver = {
.driver = {
.name = "mcp47a1",
.of_match_table = mcp47a1_of_match,
},
.probe = mcp47a1_probe,
.id_table = mcp47a1_id,
};
module_i2c_driver(mcp47a1_driver);
MODULE_AUTHOR("Joshua Crofts <joshua.crofts1@gmail.com>");
MODULE_DESCRIPTION("Microchip MCP47A1 DAC Driver");
MODULE_LICENSE("GPL");
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