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Message-ID: <20190805143041.3c6f8aac@archlinux>
Date: Mon, 5 Aug 2019 14:30:41 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Martin Kaiser <martin@...ser.cx>
Cc: Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Rob Herring <robh+dt@...nel.org>, linux-iio@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] iio: potentiometer: add a driver for Maxim
5432-5435
On Wed, 31 Jul 2019 16:07:05 +0200
Martin Kaiser <martin@...ser.cx> wrote:
> Add a driver for the Maxim Integrated MAX5432-MAX5435 family of digital
> potentiometers.
>
> These potentiometers are connected via I2C and have 32 wiper
> positions.
>
> Supported functionality
> - set the volatile wiper position
> - read the potentiometer scale
>
> Datasheet:
> https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf
>
> Signed-off-by: Martin Kaiser <martin@...ser.cx>
Looks good.
Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.
Thanks,
Jonathan
> ---
> changes in v4
> - fix the dt bindings
> - replace ic20 with i2c
> - document the reg property
> - add additionalProperties and required
>
> changes in v3
> - split dt bindings and driver code into separate patches
> - use yaml format for dt bindings
> - fix formatting of parameter lists
>
> changes in v2
> - use MAX5432_ prefix for all defines
> - fix indentation
> - convert void * to unsigned long, not to u32
> (warning from kbuild test robot)
>
> drivers/iio/potentiometer/Kconfig | 11 +++
> drivers/iio/potentiometer/Makefile | 1 +
> drivers/iio/potentiometer/max5432.c | 135 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 147 insertions(+)
> create mode 100644 drivers/iio/potentiometer/max5432.c
>
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index ebc7c72a5e36..4cac0173db8b 100644
> --- a/drivers/iio/potentiometer/Kconfig
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -26,6 +26,17 @@ config DS1803
> To compile this driver as a module, choose M here: the
> module will be called ds1803.
>
> +config MAX5432
> + tristate "Maxim MAX5432-MAX5435 Digital Potentiometer driver"
> + depends on I2C
> + help
> + Say yes here to build support for the Maxim
> + MAX5432, MAX5433, MAX5434 and MAX5435 digital
> + potentiometer chips.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called max5432.
> +
> config MAX5481
> tristate "Maxim MAX5481-MAX5484 Digital Potentiometer driver"
> depends on SPI
> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> index 8ff55138cf12..091adf3cdd0b 100644
> --- a/drivers/iio/potentiometer/Makefile
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -6,6 +6,7 @@
> # When adding new entries keep the list in alphabetical order
> obj-$(CONFIG_AD5272) += ad5272.o
> obj-$(CONFIG_DS1803) += ds1803.o
> +obj-$(CONFIG_MAX5432) += max5432.o
> obj-$(CONFIG_MAX5481) += max5481.o
> obj-$(CONFIG_MAX5487) += max5487.o
> obj-$(CONFIG_MCP4018) += mcp4018.o
> diff --git a/drivers/iio/potentiometer/max5432.c b/drivers/iio/potentiometer/max5432.c
> new file mode 100644
> index 000000000000..641b1821fdf6
> --- /dev/null
> +++ b/drivers/iio/potentiometer/max5432.c
> @@ -0,0 +1,135 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Maxim Integrated MAX5432-MAX5435 digital potentiometer driver
> + * Copyright (C) 2019 Martin Kaiser <martin@...ser.cx>
> + *
> + * Datasheet:
> + * https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/limits.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +
> +/* All chip variants have 32 wiper positions. */
> +#define MAX5432_MAX_POS 31
> +
> +#define MAX5432_OHM_50K (50 * 1000)
> +#define MAX5432_OHM_100K (100 * 1000)
> +
> +/* Update the volatile (currently active) setting. */
> +#define MAX5432_CMD_VREG 0x11
> +
> +struct max5432_data {
> + struct i2c_client *client;
> + unsigned long ohm;
> +};
> +
> +static const struct iio_chan_spec max5432_channels[] = {
> + {
> + .type = IIO_RESISTANCE,
> + .indexed = 1,
> + .output = 1,
> + .channel = 0,
> + .address = MAX5432_CMD_VREG,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> + }
> +};
> +
> +static int max5432_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct max5432_data *data = iio_priv(indio_dev);
> +
> + if (mask != IIO_CHAN_INFO_SCALE)
> + return -EINVAL;
> +
> + if (unlikely(data->ohm > INT_MAX))
> + return -ERANGE;
> +
> + *val = data->ohm;
> + *val2 = MAX5432_MAX_POS;
> +
> + return IIO_VAL_FRACTIONAL;
> +}
> +
> +static int max5432_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct max5432_data *data = iio_priv(indio_dev);
> + u8 data_byte;
> +
> + if (mask != IIO_CHAN_INFO_RAW)
> + return -EINVAL;
> +
> + if (val < 0 || val > MAX5432_MAX_POS)
> + return -EINVAL;
> +
> + if (val2 != 0)
> + return -EINVAL;
> +
> + /* Wiper position is in bits D7-D3. (D2-D0 are don't care bits.) */
> + data_byte = val << 3;
> + return i2c_smbus_write_byte_data(data->client, chan->address,
> + data_byte);
> +}
> +
> +static const struct iio_info max5432_info = {
> + .read_raw = max5432_read_raw,
> + .write_raw = max5432_write_raw,
> +};
> +
> +static int max5432_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct device *dev = &client->dev;
> + struct iio_dev *indio_dev;
> + struct max5432_data *data;
> +
> + indio_dev = devm_iio_device_alloc(dev, sizeof(struct max5432_data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + i2c_set_clientdata(client, indio_dev);
> +
> + data = iio_priv(indio_dev);
> + data->client = client;
> + data->ohm = (unsigned long)of_device_get_match_data(dev);
> +
> + indio_dev->dev.parent = dev;
> + indio_dev->info = &max5432_info;
> + indio_dev->channels = max5432_channels;
> + indio_dev->num_channels = ARRAY_SIZE(max5432_channels);
> + indio_dev->name = client->name;
> +
> + return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static const struct of_device_id max5432_dt_ids[] = {
> + { .compatible = "maxim,max5432", .data = (void *)MAX5432_OHM_50K },
> + { .compatible = "maxim,max5433", .data = (void *)MAX5432_OHM_100K },
> + { .compatible = "maxim,max5434", .data = (void *)MAX5432_OHM_50K },
> + { .compatible = "maxim,max5435", .data = (void *)MAX5432_OHM_100K },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, max5432_dt_ids);
> +
> +static struct i2c_driver max5432_driver = {
> + .driver = {
> + .name = "max5432",
> + .of_match_table = of_match_ptr(max5432_dt_ids),
> + },
> + .probe = max5432_probe,
> +};
> +
> +module_i2c_driver(max5432_driver);
> +
> +MODULE_AUTHOR("Martin Kaiser <martin@...ser.cx>");
> +MODULE_DESCRIPTION("max5432-max5435 digital potentiometers");
> +MODULE_LICENSE("GPL v2");
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