[PATCH 2/2] iio: dac: mcp47a1: add support for new device
From: Joshua Crofts
Date: Tue Jul 21 2026 - 15:43:13 EST
The Microchip MCP47A1 is a 6-bit volatile Digital-to-Analog converted
which communicates via I2C.
Signed-off-by: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
---
MAINTAINERS | 1 +
drivers/iio/dac/Kconfig | 11 +++
drivers/iio/dac/Makefile | 1 +
drivers/iio/dac/mcp47a1.c | 193 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 206 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index b44693593b94..9b124bbdd6ff 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17704,6 +17704,7 @@ M: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
L: linux-iio@xxxxxxxxxxxxxxx
S: Maintained
F: Documentation/devicetree/bindings/iio/dac/microchip,mcp47a1.yaml
+F: drivers/iio/dac/mcp47a1.c
MICROCHIP MCP9982 TEMPERATURE DRIVER
M: Victor Duicu <victor.duicu@xxxxxxxxxxxxx>
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 17529509da9d..a7f5711e9c3b 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -563,6 +563,17 @@ 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
+ select REGMAP_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..251c2281634f
--- /dev/null
+++ b/drivers/iio/dac/mcp47a1.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip MCP47A1 DAC driver
+ *
+ * Copyright (c) 2026 Joshua Crofts <joshua.crofts1@xxxxxxxxx>
+ *
+ * Datasheet: https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/25154A.pdf
+ */
+
+#include <linux/array_size.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include <linux/iio/iio.h>
+
+#define MCP47A1_REG_MAX 0x40
+#define MCP47A1_CMD_CODE 0x00
+#define MCP47A1_MAX_STEPS 64
+
+struct mcp47a1_data {
+ struct regmap *regmap;
+ int vref_mv;
+};
+
+static const int mcp47a1_raw_avail[] = { 0, 1, MCP47A1_MAX_STEPS };
+
+static const struct regmap_config mcp47a1_regmap_config = {
+ .name = "mcp47a1",
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = MCP47A1_CMD_CODE,
+};
+
+static const struct iio_chan_spec mcp47a1_channels[] = {
+ {
+ .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 (val < 0 || val > MCP47A1_REG_MAX)
+ return -EINVAL;
+
+ return regmap_write(data->regmap, 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 reg_val;
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = regmap_read(data->regmap, MCP47A1_CMD_CODE, ®_val);
+ if (ret)
+ return ret;
+
+ *val = reg_val;
+
+ 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 reg_val;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ data = iio_priv(indio_dev);
+ i2c_set_clientdata(client, indio_dev);
+
+ data->regmap = devm_regmap_init_i2c(client, &mcp47a1_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, "vdd");
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to enable regulator\n");
+
+ 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 / MILLI;
+
+ /*
+ * This is a volatile DAC which doesn't have an ID register, instead
+ * the value register is set to 0x20 every Power-on-Reset (table 4-1).
+ * Any other read value at startup could indicate that the device is
+ * damaged etc.
+ */
+ ret = regmap_read(data->regmap, MCP47A1_CMD_CODE, ®_val);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to read register on startup\n");
+
+ if (reg_val != 0x20)
+ dev_info(dev, "Read value 0x%02x at startup\n", reg_val);
+
+ indio_dev->name = "mcp47a1";
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->info = &mcp47a1_info;
+ indio_dev->channels = mcp47a1_channels;
+ indio_dev->num_channels = ARRAY_SIZE(mcp47a1_channels);
+
+ 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@xxxxxxxxx>");
+MODULE_DESCRIPTION("MCP47A1 DAC");
+MODULE_LICENSE("GPL");
--
2.55.0