Re: [PATCH v2] iio: potentiometer: add driver for Maxim Integrated DS1803

[Jonathan Cameron <jic23@kernel.org>]

On 08/04/16 22:27, Slawomir Stepien wrote:
> The following functions are supported:
>  - write, read potentiometer value
>  - potentiometer scale
> 
> Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
> 
> Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Looks good to me, but as you pointed out a slight cleanup I'll wait for v3
before taking this one.
> ---
> Changes since v1:
> - Removed unnecessary include file
> - Use i2c_master_recv() in place of i2c_smbus_read_word_swapped()
> - On raw write make sure val2 is zero
> - Use ARRAY_SIZE when possible
> 
>  .../bindings/iio/potentiometer/ds1803.txt          |  21 +++
>  drivers/iio/potentiometer/Kconfig                  |  10 ++
>  drivers/iio/potentiometer/Makefile                 |   1 +
>  drivers/iio/potentiometer/ds1803.c                 | 174 +++++++++++++++++++++
>  4 files changed, 206 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt
>  create mode 100644 drivers/iio/potentiometer/ds1803.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt b/Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt
> new file mode 100644
> index 0000000..df77bf5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt
> @@ -0,0 +1,21 @@
> +* Maxim Integrated DS1803 digital potentiometer driver
> +
> +The node for this driver must be a child node of a I2C controller, hence
> +all mandatory properties for your controller must be specified. See directory:
> +
> +        Documentation/devicetree/bindings/i2c
> +
> +for more details.
> +
> +Required properties:
> +	- compatible:  	Must be one of the following, depending on the
> +			model:
> +			"maxim,ds1803-010",
> +			"maxim,ds1803-050",
> +			"maxim,ds1803-100"
> +
> +Example:
> +ds1803: ds1803@1 {
> +	reg = <0x28>;
> +	compatible = "maxim,ds1803-010";
> +};
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index 7ea069b..6acb238 100644
> --- a/drivers/iio/potentiometer/Kconfig
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -5,6 +5,16 @@
>  
>  menu "Digital potentiometers"
>  
> +config DS1803
> +	tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
> +	depends on I2C
> +	help
> +	  Say yes here to build support for the Maxim Integrated DS1803
> +	  digital potentiomenter chip.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ds1803.
> +
>  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 91a80f8..6007faa 100644
> --- a/drivers/iio/potentiometer/Makefile
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -3,6 +3,7 @@
>  #
>  
>  # When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_DS1803) += ds1803.o
>  obj-$(CONFIG_MCP4131) += mcp4131.o
>  obj-$(CONFIG_MCP4531) += mcp4531.o
>  obj-$(CONFIG_TPL0102) += tpl0102.o
> diff --git a/drivers/iio/potentiometer/ds1803.c b/drivers/iio/potentiometer/ds1803.c
> new file mode 100644
> index 0000000..cfa4cc1
> --- /dev/null
> +++ b/drivers/iio/potentiometer/ds1803.c
> @@ -0,0 +1,174 @@
> +/*
> + * Maxim Integrated DS1803 digital potentiometer driver
> + * Copyright (c) 2016 Slawomir Stepien
> + *
> + * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
> + *
> + * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
> + * ds1803	2	256		10, 50, 100		0101xxx
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/export.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +
> +#define DS1803_MAX_POS		255
> +#define DS1803_WRITE(chan)	(0xa8 | ((chan) + 1))
> +
> +enum ds1803_type {
> +	DS1803_010,
> +	DS1803_050,
> +	DS1803_100,
> +};
> +
> +struct ds1803_cfg {
> +	int kohms;
> +};
> +
> +static const struct ds1803_cfg ds1803_cfg[] = {
> +	[DS1803_010] = { .kohms =  10, },
> +	[DS1803_050] = { .kohms =  50, },
> +	[DS1803_100] = { .kohms = 100, },
> +};
> +
> +struct ds1803_data {
> +	struct i2c_client *client;
> +	const struct ds1803_cfg *cfg;
> +};
> +
> +#define DS1803_CHANNEL(ch) {					\
> +	.type = IIO_RESISTANCE,					\
> +	.indexed = 1,						\
> +	.output = 1,						\
> +	.channel = (ch),					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +}
> +
> +static const struct iio_chan_spec ds1803_channels[] = {
> +	DS1803_CHANNEL(0),
> +	DS1803_CHANNEL(1),
> +};
> +
> +static int ds1803_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val, int *val2, long mask)
> +{
> +	struct ds1803_data *data = iio_priv(indio_dev);
> +	int pot = chan->channel;
> +	int ret;
> +	u16 result;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = i2c_master_recv(data->client, (char *)&result,
> +				indio_dev->num_channels);
> +		if (ret < 0)
> +			return ret;
> +
> +		/* Get bits for given pot */
> +		*val = (pot == 0 ? result & 0xff : result >> 8);
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 1000 * data->cfg->kohms;
> +		*val2 = DS1803_MAX_POS;
> +		return IIO_VAL_FRACTIONAL;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ds1803_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	struct ds1803_data *data = iio_priv(indio_dev);
> +	int pot = chan->channel;
> +
> +	if (val2 != 0)
> +		return -EINVAL;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (val > DS1803_MAX_POS || val < 0)
> +			return -EINVAL;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return i2c_smbus_write_byte_data(data->client, DS1803_WRITE(pot), val);
> +}
> +
> +static const struct iio_info ds1803_info = {
> +	.read_raw = ds1803_read_raw,
> +	.write_raw = ds1803_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int ds1803_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct ds1803_data *data;
> +	struct iio_dev *indio_dev;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	data = iio_priv(indio_dev);
> +	data->client = client;
> +	data->cfg = &ds1803_cfg[id->driver_data];
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->info = &ds1803_info;
> +	indio_dev->channels = ds1803_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ds1803_channels);
> +	indio_dev->name = client->name;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +#if defined(CONFIG_OF)
> +static const struct of_device_id ds1803_dt_ids[] = {
> +	{ .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
> +	{ .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
> +	{ .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
> +#endif /* CONFIG_OF */
> +
> +static const struct i2c_device_id ds1803_id[] = {
> +	{ "ds1803-010", DS1803_010 },
> +	{ "ds1803-050", DS1803_050 },
> +	{ "ds1803-100", DS1803_100 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, ds1803_id);
> +
> +static struct i2c_driver ds1803_driver = {
> +	.driver = {
> +		.name	= "ds1803",
> +		.of_match_table = of_match_ptr(ds1803_dt_ids),
> +	},
> +	.probe		= ds1803_probe,
> +	.id_table	= ds1803_id,
> +};
> +
> +module_i2c_driver(ds1803_driver);
> +
> +MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
> +MODULE_DESCRIPTION("DS1803 digital potentiometer");
> +MODULE_LICENSE("GPL v2");
>