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Date: Tue, 22 Sep 2015 15:01:02 +0200 (CEST)
From: Peter Meerwald <pmeerw@...erw.net>
To: Peter Rosin <peda@...ator.liu.se>
cc: linux-iio@...r.kernel.org, Peter Rosin <peda@...ntia.se>,
Crt Mori <cmo@...exis.com>,
Daniel Baluta <daniel.baluta@...il.com>,
Andreas Dannenberg <dannenberg@...com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jonathan Cameron <jic23@...nel.org>,
Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] iio: mcp4531: Driver for Microchip digital
potentiometers
> Add support for Microchip digital potentiometers and rheostats
> MCP4531, MCP4532, MCP4551, MCP4552
> MCP4631, MCP4632, MCP4651, MCP4652
>
> These are either single (45xx) or dual (46xx) wipers with either
> 129 (4x3x) or 257 (4x5x) steps, and configured either as
> potentiometers (4xx1) or rheostats (4xx2).
>
> Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22096b.pdf
some comments below
I find it useful to state the 7-bit i2c slave address somewhere,
0101xxx in this case
> Signed-off-by: Peter Rosin <peda@...ntia.se>
> ---
> MAINTAINERS | 6 ++
> drivers/iio/Kconfig | 1 +
> drivers/iio/Makefile | 1 +
> drivers/iio/potentiometer/Kconfig | 20 ++++
> drivers/iio/potentiometer/Makefile | 6 ++
> drivers/iio/potentiometer/mcp4531.c | 200 +++++++++++++++++++++++++++++++++++
> 6 files changed, 234 insertions(+)
> create mode 100644 drivers/iio/potentiometer/Kconfig
> create mode 100644 drivers/iio/potentiometer/Makefile
> create mode 100644 drivers/iio/potentiometer/mcp4531.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b60e2b2369d2..27862156c7a7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6600,6 +6600,12 @@ W: http://linuxtv.org
> S: Maintained
> F: drivers/media/radio/radio-maxiradio*
>
> +MCP4531 MICROCHIP DIGITAL POTENTIOMETER DRIVER
> +M: Peter Rosin <peda@...ntia.se>
> +L: linux-iio@...r.kernel.org
> +S: Maintained
> +F: drivers/iio/potentiometer/mcp4531.c
> +
> MEDIA DRIVERS FOR RENESAS - VSP1
> M: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> L: linux-media@...r.kernel.org
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 4011effe4c05..7cc87f322655 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -73,6 +73,7 @@ source "drivers/iio/orientation/Kconfig"
> if IIO_TRIGGER
> source "drivers/iio/trigger/Kconfig"
> endif #IIO_TRIGGER
> +source "drivers/iio/potentiometer/Kconfig"
> source "drivers/iio/pressure/Kconfig"
> source "drivers/iio/proximity/Kconfig"
> source "drivers/iio/temperature/Kconfig"
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index 698afc2d17ce..121c814e366b 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -23,6 +23,7 @@ obj-y += imu/
> obj-y += light/
> obj-y += magnetometer/
> obj-y += orientation/
> +obj-y += potentiometer/
> obj-y += pressure/
> obj-y += proximity/
> obj-y += temperature/
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> new file mode 100644
> index 000000000000..fd75db73e582
> --- /dev/null
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -0,0 +1,20 @@
> +#
> +# Potentiometer drivers
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "Digital potentiometers"
> +
> +config MCP4531
> + tristate "Microchip MCP45xx/MCP46xx Digital Potentiometer driver"
> + depends on I2C
> + help
> + Say yes here to build support for the Microchip
> + MCP4531, MCP4532, MCP4551, MCP4552,
> + MCP4631, MCP4632, MCP4651, MCP4652
> + digital potentiomenter chips.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called mcp4531.
> +
> +endmenu
> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> new file mode 100644
> index 000000000000..8afe49227012
> --- /dev/null
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -0,0 +1,6 @@
> +#
> +# Makefile for industrial I/O potentiometer drivers
> +#
> +
> +# When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_MCP4531) += mcp4531.o
> diff --git a/drivers/iio/potentiometer/mcp4531.c b/drivers/iio/potentiometer/mcp4531.c
> new file mode 100644
> index 000000000000..11039b215080
> --- /dev/null
> +++ b/drivers/iio/potentiometer/mcp4531.c
> @@ -0,0 +1,200 @@
> +/*
> + * Industrial I/O driver for Microchip digital potentiometers
> + * Copyright (c) 2015 Axentia Technologies AB
> + * Author: Peter Rosin <peda@...ntia.se>
> + *
> + * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22096b.pdf
> + *
> + * DEVID #Wipers #Positions Resistor Options (kOhm)
> + * mcp4531 1 129 5, 10, 50, 100
> + * mcp4532 1 129 5, 10, 50, 100
> + * mcp4551 1 257 5, 10, 50, 100
> + * mcp4552 1 257 5, 10, 50, 100
> + * mcp4631 2 129 5, 10, 50, 100
> + * mcp4632 2 129 5, 10, 50, 100
> + * mcp4651 2 257 5, 10, 50, 100
> + * mcp4652 2 257 5, 10, 50, 100
> + *
> + * 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/module.h>
> +#include <linux/i2c.h>
> +#include <linux/err.h>
> +
> +#include <linux/iio/iio.h>
> +
drop extra newline
> +
> +#define MCP4531_CONF(wipers, max_pos, uid) \
> + ((((wipers) & 0xf) << 10) | \
> + (((max_pos) & 0xf) << 6) | \
> + ((uid) & 0x3f))
> +
> +#define MCP4531_UID(conf) ((conf) & 0x3f)
> +#define MCP4531_MAX_POS(conf) (((conf) >> 6) & 0xf)
> +#define MCP4531_WIPERS(conf) (((conf) >> 10) & 0xf)
> +
> +enum mcp4531_devid {
> + MCP4531_ID = MCP4531_CONF(1, 7, 0),
> + MCP4532_ID = MCP4531_CONF(1, 7, 1),
> + MCP4551_ID = MCP4531_CONF(1, 8, 2),
> + MCP4552_ID = MCP4531_CONF(1, 8, 3),
> + MCP4631_ID = MCP4531_CONF(2, 7, 4),
> + MCP4632_ID = MCP4531_CONF(2, 7, 5),
> + MCP4651_ID = MCP4531_CONF(2, 8, 6),
> + MCP4652_ID = MCP4531_CONF(2, 8, 7),
> +};
> +
> +struct mcp4531_data {
> + struct i2c_client *client;
> + unsigned int max_pos;
> + unsigned long devid;
> +};
> +
> +static const struct iio_chan_spec mcp4531_channels[] = {
> + {
could use a MACRO to deduplicate common channel parameters
> + .type = IIO_RESISTANCE,
> + .indexed = 1,
> + .output = 1,
> + .channel = 0,
> + .address = 0 << 4,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + }, {
> + .type = IIO_RESISTANCE,
> + .indexed = 1,
> + .output = 1,
> + .channel = 1,
> + .address = 1 << 4,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + }
> +};
> +
> +static int mcp4531_get_value(struct iio_dev *indio_dev,
> + int address, int *val)
> +{
> + struct mcp4531_data *data = iio_priv(indio_dev);
> + s32 value;
ret is arguably a more commonly used name
> +
> + value = i2c_smbus_read_word_data(data->client, address | 0xc);
extra space before address
what is 0xc? use a #define maybe
> + if (value < 0)
> + return value;
> + *val = ((value >> 8) & 0xff) | ((value & 0xff) << 8);
use i2c_smbus_read_word_swapped(), the chip uses MSB first; no need to
shuffle bytes for endianness
> + return 0;
> +}
> +
> +static int mcp4531_set_value(struct iio_dev *indio_dev,
> + int address, int val)
> +{
> + struct mcp4531_data *data = iio_priv(indio_dev);
> +
> + if (val >= data->max_pos || val < 0)
> + return -EINVAL;
> +
> + return i2c_smbus_write_byte_data(data->client,
> + address | (val >> 8),
> + val & 0xff);
> +}
> +
> +static int mcp4531_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + int err;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + err = mcp4531_get_value(indio_dev, chan->address, val);
> + if (err < 0)
> + return err;
> + return IIO_VAL_INT;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int mcp4531_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + return mcp4531_set_value(indio_dev, chan->address, val);
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const struct iio_info mcp4531_info = {
> + .read_raw = mcp4531_read_raw,
> + .write_raw = mcp4531_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static int mcp4531_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct device *dev = &client->dev;
> + unsigned long devid = id->driver_data;
> + struct mcp4531_data *data;
> + struct iio_dev *indio_dev;
> +
> + if (!i2c_check_functionality(client->adapter,
> + I2C_FUNC_SMBUS_WORD_DATA)) {
> + dev_err(dev, "SMBUS Word Data not supported\n");
> + return -EIO;
> + }
> +
> + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> + data = iio_priv(indio_dev);
> + i2c_set_clientdata(client, indio_dev);
> + data->client = client;
> + data->devid = devid;
> +
> + data->max_pos = (1 << MCP4531_MAX_POS(devid)) + 1;
> +
> + indio_dev->dev.parent = dev;
> + indio_dev->info = &mcp4531_info;
> + indio_dev->channels = mcp4531_channels;
> + indio_dev->num_channels = MCP4531_WIPERS(devid);
> + indio_dev->name = client->name;
> +
> + return iio_device_register(indio_dev);
use devm_ ...
> +}
> +
> +static int mcp4531_remove(struct i2c_client *client)
> +{
... and drop _remove()
> + iio_device_unregister(i2c_get_clientdata(client));
> + return 0;
> +}
> +
> +static const struct i2c_device_id mcp4531_id[] = {
> + { "mcp4531", MCP4531_ID },
> + { "mcp4532", MCP4532_ID },
> + { "mcp4551", MCP4551_ID },
> + { "mcp4552", MCP4552_ID },
> + { "mcp4631", MCP4631_ID },
> + { "mcp4632", MCP4632_ID },
> + { "mcp4651", MCP4651_ID },
> + { "mcp4652", MCP4652_ID },
> + {}
> +};
> +MODULE_DEVICE_TABLE(i2c, mcp4531_id);
> +
> +static struct i2c_driver mcp4531_driver = {
> + .driver = {
> + .name = "mcp4531",
> + },
> + .probe = mcp4531_probe,
> + .remove = mcp4531_remove,
> + .id_table = mcp4531_id,
> +};
> +
> +module_i2c_driver(mcp4531_driver);
> +
> +MODULE_AUTHOR("Peter Rosin <peda@...ntia.se>");
> +MODULE_DESCRIPTION("MCP4531 digital potentiometer");
> +MODULE_LICENSE("GPL");
>
--
Peter Meerwald
+43-664-2444418 (mobile)
--
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