[PATCH v3 2/2] iio: dac: mcp47a1: add support for new device

The Microchip MCP47A1 is a 6-bit volatile Digital-to-Analog converter
which communicates via I2C.

Signed-off-by: Joshua Crofts <[email protected]>
---
 MAINTAINERS               |   1 +
 drivers/iio/dac/Kconfig   |  10 +++
 drivers/iio/dac/Makefile  |   1 +
 drivers/iio/dac/mcp47a1.c | 166 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 178 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8c8118eb4141..fc76a2159e1f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17703,6 +17703,7 @@ MICROCHIP MCP47A1 DAC DRIVER
 M:	Joshua Crofts <[email protected]>
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/dac/microchip,mcp47a1.yaml
+F:	drivers/iio/dac/mcp47a1.c
 
 MICROCHIP MCP9982 TEMPERATURE DRIVER
 M:	Victor Duicu <[email protected]>
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 18a27785e28b..04c90d98f86f 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -582,6 +582,16 @@ config MCP4728
 	  To compile this driver as a module, choose M here: the module
 	  will be called mcp4728.
 
+config MCP47A1
+	tristate "MCP47A1 DAC driver"
+	depends on I2C
+	help
+	  Say Y here if you want to build a driver for the Microchip
+	  MCP47A1 digital-to-analog converter with an I2C interface.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mcp47a1.
+
 config MCP47FEB02
 	tristate "MCP47F(E/V)B01/02/04/08/11/12/14/18/21/22/24/28 DAC driver"
 	depends on I2C
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 5d20d37e44ce..992f8930f95c 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -55,6 +55,7 @@ obj-$(CONFIG_MAX5821) += max5821.o
 obj-$(CONFIG_MCF54415_DAC) += mcf54415_dac.o
 obj-$(CONFIG_MCP4725) += mcp4725.o
 obj-$(CONFIG_MCP4728) += mcp4728.o
+obj-$(CONFIG_MCP47A1) += mcp47a1.o
 obj-$(CONFIG_MCP47FEB02) += mcp47feb02.o
 obj-$(CONFIG_MCP4821) += mcp4821.o
 obj-$(CONFIG_MCP4922) += mcp4922.o
diff --git a/drivers/iio/dac/mcp47a1.c b/drivers/iio/dac/mcp47a1.c
new file mode 100644
index 000000000000..0bf994aa0e4f
--- /dev/null
+++ b/drivers/iio/dac/mcp47a1.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Microchip MCP47A1 DAC driver
+ *
+ * Copyright (c) 2026 Joshua Crofts <[email protected]>
+ *
+ * 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 <[email protected]>");
+MODULE_DESCRIPTION("Microchip MCP47A1 DAC Driver");
+MODULE_LICENSE("GPL");

-- 
2.55.0