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([2600:8803:e7e4:500:359b:17f1:d4f9:4949]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7f18f0da951sm3168830a34.24.2026.08.01.08.02.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 01 Aug 2026 08:02:27 -0700 (PDT) Message-ID: <185632fa-8e1d-467a-a194-aafac05dbdea@baylibre.com> Date: Sat, 1 Aug 2026 10:02:27 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] iio: dac: mcp47a1: add support for new device To: Joshua Crofts , Jonathan Cameron , =?UTF-8?Q?Nuno_S=C3=A1?= , Andy Shevchenko , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260727-mcp47a1-add-support-v2-0-d4591a2ce69e@gmail.com> <20260727-mcp47a1-add-support-v2-2-d4591a2ce69e@gmail.com> Content-Language: en-US From: David Lechner In-Reply-To: <20260727-mcp47a1-add-support-v2-2-d4591a2ce69e@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/27/26 1:31 PM, Joshua Crofts wrote: > The Microchip MCP47A1 is a 6-bit volatile Digital-to-Analog converter > which communicates via I2C. > > Signed-off-by: Joshua Crofts > --- > MAINTAINERS | 1 + > drivers/iio/dac/Kconfig | 10 +++ > drivers/iio/dac/Makefile | 1 + > drivers/iio/dac/mcp47a1.c | 169 ++++++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 181 insertions(+) > > diff --git a/MAINTAINERS b/MAINTAINERS > index 8a0b23418a64..552ced65cf75 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -17703,6 +17703,7 @@ MICROCHIP MCP47A1 DAC DRIVER > M: Joshua Crofts > S: Maintained > F: Documentation/devicetree/bindings/iio/dac/microchip,mcp47a1.yaml > +F: drivers/iio/dac/mcp47a1.c > > MICROCHIP MCP9982 TEMPERATURE DRIVER > M: Victor Duicu > diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig > index d6d560c09e25..1d00cd911826 100644 > --- a/drivers/iio/dac/Kconfig > +++ b/drivers/iio/dac/Kconfig > @@ -565,6 +565,16 @@ 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..140e93ff2ba0 > --- /dev/null > +++ b/drivers/iio/dac/mcp47a1.c > @@ -0,0 +1,169 @@ > +// SPDX-License-Identifier: GPL-2.0 Prefer more specific GPL-2.0-only or GPL-2.0-or-later (your choice). > +/* > + * Microchip MCP47A1 DAC driver > + * > + * Copyright (c) 2026 Joshua Crofts > + * > + * Datasheet: https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/25154A.pdf > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > + > +#define MCP47A1_REG_MAX 0x40 Unused macro. > +#define MCP47A1_CMD_CODE 0x00 > +#define MCP47A1_MAX_STEP 63 > + > +struct mcp47a1_data { > + struct i2c_client *client; > + int vref_mV; > +}; > + > +static const int mcp47a1_raw_avail[] = { 0, 1, MCP47A1_MAX_STEP }; > + > +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_MAX_STEP) There is also in_range() which is nice for this sort of check. > + 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_STEP; > + > + 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_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 "); > +MODULE_DESCRIPTION("MCP47A1 DAC"); > +MODULE_LICENSE("GPL"); > If only all drivers were this simple. :-)