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    SubjectRe: [PATCH 2/2] iio: potentiometer: mcp4018: driver for Microchip digital potentiometers
    On Thu,  8 Mar 2018 20:58:30 +0100
    Peter Rosin <peda@axentia.se> wrote:

    > Add support for Microchip digital potentiometers and rheostats
    > MCP4017, MCP4018, MCP4019
    >
    > They all have one wiper with 128 steps and come in 5, 10, 50 and 100 kOhm
    > variations.
    >
    > Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22147a.pdf
    >
    > Signed-off-by: Peter Rosin <peda@axentia.se>
    Nice little driver.

    Applied to the togreg branch of iio.git and pushed out as testing
    for the autobuilders to play with it.

    Thanks,

    Jonathan

    > ---
    > MAINTAINERS | 3 +-
    > drivers/iio/potentiometer/Kconfig | 11 ++
    > drivers/iio/potentiometer/Makefile | 1 +
    > drivers/iio/potentiometer/mcp4018.c | 194 ++++++++++++++++++++++++++++++++++++
    > 4 files changed, 208 insertions(+), 1 deletion(-)
    > create mode 100644 drivers/iio/potentiometer/mcp4018.c
    >
    > diff --git a/MAINTAINERS b/MAINTAINERS
    > index 4623caf8d72d..81527c75adee 100644
    > --- a/MAINTAINERS
    > +++ b/MAINTAINERS
    > @@ -8589,11 +8589,12 @@ W: https://linuxtv.org
    > S: Maintained
    > F: drivers/media/radio/radio-maxiradio*
    >
    > -MCP4531 MICROCHIP DIGITAL POTENTIOMETER DRIVER
    > +MCP4018 AND MCP4531 MICROCHIP DIGITAL POTENTIOMETER DRIVERS
    > M: Peter Rosin <peda@axentia.se>
    > L: linux-iio@vger.kernel.org
    > S: Maintained
    > F: Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp4531
    > +F: drivers/iio/potentiometer/mcp4018.c
    > F: drivers/iio/potentiometer/mcp4531.c
    >
    > MEASUREMENT COMPUTING CIO-DAC IIO DRIVER
    > diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
    > index 8bf282510be6..84bdbcd53114 100644
    > --- a/drivers/iio/potentiometer/Kconfig
    > +++ b/drivers/iio/potentiometer/Kconfig
    > @@ -37,6 +37,17 @@ config MAX5487
    > To compile this driver as a module, choose M here: the
    > module will be called max5487.
    >
    > +config MCP4018
    > + tristate "Microchip MCP4017/18/19 Digital Potentiometer driver"
    > + depends on I2Cs
    > + help
    > + Say yes here to build support for the Microchip
    > + MCP4017, MCP4018, MCP4019
    > + digital potentiometer chips.
    > +
    > + To compile this driver as a module, choose M here: the
    > + module will be called mcp4018.
    > +
    > config MCP4131
    > tristate "Microchip MCP413X/414X/415X/416X/423X/424X/425X/426X Digital Potentiometer driver"
    > depends on SPI
    > diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
    > index 1afd1e70f8cc..0cff8a2916d5 100644
    > --- a/drivers/iio/potentiometer/Makefile
    > +++ b/drivers/iio/potentiometer/Makefile
    > @@ -7,6 +7,7 @@
    > obj-$(CONFIG_DS1803) += ds1803.o
    > obj-$(CONFIG_MAX5481) += max5481.o
    > obj-$(CONFIG_MAX5487) += max5487.o
    > +obj-$(CONFIG_MCP4018) += mcp4018.o
    > obj-$(CONFIG_MCP4131) += mcp4131.o
    > obj-$(CONFIG_MCP4531) += mcp4531.o
    > obj-$(CONFIG_TPL0102) += tpl0102.o
    > diff --git a/drivers/iio/potentiometer/mcp4018.c b/drivers/iio/potentiometer/mcp4018.c
    > new file mode 100644
    > index 000000000000..601b25d1f387
    > --- /dev/null
    > +++ b/drivers/iio/potentiometer/mcp4018.c
    > @@ -0,0 +1,194 @@
    > +// SPDX-License-Identifier: GPL-2.0
    > +/*
    > + * Industrial I/O driver for Microchip digital potentiometers
    > + * Copyright (c) 2018 Axentia Technologies AB
    > + * Author: Peter Rosin <peda@axentia.se>
    > + *
    > + * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22147a.pdf
    > + *
    > + * DEVID #Wipers #Positions Resistor Opts (kOhm)
    > + * mcp4017 1 128 5, 10, 50, 100
    > + * mcp4018 1 128 5, 10, 50, 100
    > + * mcp4019 1 128 5, 10, 50, 100
    > + */
    > +
    > +#include <linux/err.h>
    > +#include <linux/i2c.h>
    > +#include <linux/iio/iio.h>
    > +#include <linux/module.h>
    > +#include <linux/of.h>
    > +#include <linux/of_device.h>
    > +
    > +#define MCP4018_WIPER_MAX 127
    > +
    > +struct mcp4018_cfg {
    > + int kohms;
    > +};
    > +
    > +enum mcp4018_type {
    > + MCP4018_502,
    > + MCP4018_103,
    > + MCP4018_503,
    > + MCP4018_104,
    > +};
    > +
    > +static const struct mcp4018_cfg mcp4018_cfg[] = {
    > + [MCP4018_502] = { .kohms = 5, },
    > + [MCP4018_103] = { .kohms = 10, },
    > + [MCP4018_503] = { .kohms = 50, },
    > + [MCP4018_104] = { .kohms = 100, },
    > +};
    > +
    > +struct mcp4018_data {
    > + struct i2c_client *client;
    > + const struct mcp4018_cfg *cfg;
    > +};
    > +
    > +static const struct iio_chan_spec mcp4018_channel = {
    > + .type = IIO_RESISTANCE,
    > + .indexed = 1,
    > + .output = 1,
    > + .channel = 0,
    > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
    > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
    > +};
    > +
    > +static int mcp4018_read_raw(struct iio_dev *indio_dev,
    > + struct iio_chan_spec const *chan,
    > + int *val, int *val2, long mask)
    > +{
    > + struct mcp4018_data *data = iio_priv(indio_dev);
    > + s32 ret;
    > +
    > + switch (mask) {
    > + case IIO_CHAN_INFO_RAW:
    > + ret = i2c_smbus_read_byte(data->client);
    > + if (ret < 0)
    > + return ret;
    > + *val = ret;
    > + return IIO_VAL_INT;
    > + case IIO_CHAN_INFO_SCALE:
    > + *val = 1000 * data->cfg->kohms;
    > + *val2 = MCP4018_WIPER_MAX;
    > + return IIO_VAL_FRACTIONAL;
    > + }
    > +
    > + return -EINVAL;
    > +}
    > +
    > +static int mcp4018_write_raw(struct iio_dev *indio_dev,
    > + struct iio_chan_spec const *chan,
    > + int val, int val2, long mask)
    > +{
    > + struct mcp4018_data *data = iio_priv(indio_dev);
    > +
    > + switch (mask) {
    > + case IIO_CHAN_INFO_RAW:
    > + if (val > MCP4018_WIPER_MAX || val < 0)
    > + return -EINVAL;
    > + break;
    > + default:
    > + return -EINVAL;
    > + }
    > +
    > + return i2c_smbus_write_byte(data->client, val);
    > +}
    > +
    > +static const struct iio_info mcp4018_info = {
    > + .read_raw = mcp4018_read_raw,
    > + .write_raw = mcp4018_write_raw,
    > +};
    > +
    > +#ifdef CONFIG_OF
    > +
    > +#define MCP4018_COMPATIBLE(of_compatible, cfg) { \
    > + .compatible = of_compatible, \
    > + .data = &mcp4018_cfg[cfg], \
    > +}
    > +
    > +static const struct of_device_id mcp4018_of_match[] = {
    > + MCP4018_COMPATIBLE("microchip,mcp4017-502", MCP4018_502),
    > + MCP4018_COMPATIBLE("microchip,mcp4017-103", MCP4018_103),
    > + MCP4018_COMPATIBLE("microchip,mcp4017-503", MCP4018_503),
    > + MCP4018_COMPATIBLE("microchip,mcp4017-104", MCP4018_104),
    > + MCP4018_COMPATIBLE("microchip,mcp4018-502", MCP4018_502),
    > + MCP4018_COMPATIBLE("microchip,mcp4018-103", MCP4018_103),
    > + MCP4018_COMPATIBLE("microchip,mcp4018-503", MCP4018_503),
    > + MCP4018_COMPATIBLE("microchip,mcp4018-104", MCP4018_104),
    > + MCP4018_COMPATIBLE("microchip,mcp4019-502", MCP4018_502),
    > + MCP4018_COMPATIBLE("microchip,mcp4019-103", MCP4018_103),
    > + MCP4018_COMPATIBLE("microchip,mcp4019-503", MCP4018_503),
    > + MCP4018_COMPATIBLE("microchip,mcp4019-104", MCP4018_104),
    > + { /* sentinel */ }
    > +};
    > +MODULE_DEVICE_TABLE(of, mcp4018_of_match);
    > +
    > +#endif
    > +
    > +static int mcp4018_probe(struct i2c_client *client,
    > + const struct i2c_device_id *id)
    > +{
    > + struct device *dev = &client->dev;
    > + struct mcp4018_data *data;
    > + struct iio_dev *indio_dev;
    > + const struct of_device_id *match;
    > +
    > + if (!i2c_check_functionality(client->adapter,
    > + I2C_FUNC_SMBUS_BYTE)) {
    > + dev_err(dev, "SMBUS Byte transfers not supported\n");
    > + return -EOPNOTSUPP;
    > + }
    > +
    > + 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->client = client;
    > +
    > + match = of_match_device(of_match_ptr(mcp4018_of_match), dev);
    > + if (match)
    > + data->cfg = of_device_get_match_data(dev);
    > + else
    > + data->cfg = &mcp4018_cfg[id->driver_data];
    > +
    > + indio_dev->dev.parent = dev;
    > + indio_dev->info = &mcp4018_info;
    > + indio_dev->channels = &mcp4018_channel;
    > + indio_dev->num_channels = 1;
    > + indio_dev->name = client->name;
    > +
    > + return devm_iio_device_register(dev, indio_dev);
    > +}
    > +
    > +static const struct i2c_device_id mcp4018_id[] = {
    > + { "mcp4017-502", MCP4018_502 },
    > + { "mcp4017-103", MCP4018_103 },
    > + { "mcp4017-503", MCP4018_503 },
    > + { "mcp4017-104", MCP4018_104 },
    > + { "mcp4018-502", MCP4018_502 },
    > + { "mcp4018-103", MCP4018_103 },
    > + { "mcp4018-503", MCP4018_503 },
    > + { "mcp4018-104", MCP4018_104 },
    > + { "mcp4019-502", MCP4018_502 },
    > + { "mcp4019-103", MCP4018_103 },
    > + { "mcp4019-503", MCP4018_503 },
    > + { "mcp4019-104", MCP4018_104 },
    > + {}
    > +};
    > +MODULE_DEVICE_TABLE(i2c, mcp4018_id);
    > +
    > +static struct i2c_driver mcp4018_driver = {
    > + .driver = {
    > + .name = "mcp4018",
    > + .of_match_table = of_match_ptr(mcp4018_of_match),
    > + },
    > + .probe = mcp4018_probe,
    > + .id_table = mcp4018_id,
    > +};
    > +
    > +module_i2c_driver(mcp4018_driver);
    > +
    > +MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
    > +MODULE_DESCRIPTION("MCP4018 digital potentiometer");
    > +MODULE_LICENSE("GPL");

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