Re: [PATCH v6 2/2] iio: mcp4531: Driver for Microchip digital potentiometers

From: Jonathan Cameron
Date: Sun Sep 27 2015 - 11:50:52 EST

On 23/09/15 15:26, Peter Rosin wrote:
> From: Peter Rosin <peda@xxxxxxxxxx>
>
> Add support for Microchip digital potentiometers and rheostats
> MCP4531, MCP4532, MCP4551, MCP4552
> MCP4631, MCP4632, MCP4651, MCP4652
>
> DEVICE Wipers Steps Resistor Opts (kOhm) i2c address
> MCP4531 1 129 5, 10, 50, 100 010111x
> MCP4532 1 129 5, 10, 50, 100 01011xx
> MCP4551 1 257 5, 10, 50, 100 010111x
> MCP4552 1 257 5, 10, 50, 100 01011xx
> MCP4631 2 129 5, 10, 50, 100 0101xxx
> MCP4632 2 129 5, 10, 50, 100 01011xx
> MCP4651 2 257 5, 10, 50, 100 0101xxx
> MCP4652 2 257 5, 10, 50, 100 01011xx
>
> Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22096b.pdf
Applied to the togreg branch of iio.git - initially pushed out as
testing for the autobuilders to play with it.

If anyone wants to add reviewed-by / acked-by then as I'll be
rebasing sometime in next few days anyway there is still time!

Jonathan
>
> Signed-off-by: Peter Rosin <peda@xxxxxxxxxx>
> ---
> 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 | 231 +++++++++++++++++++++++++++++++++++
> 6 files changed, 265 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@xxxxxxxxxx>
> +L: linux-iio@xxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/iio/potentiometer/mcp4531.c
> +
> MEDIA DRIVERS FOR RENESAS - VSP1
> M: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> L: linux-media@xxxxxxxxxxxxxxx
> 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..a3f66874ee2e
> --- /dev/null
> +++ b/drivers/iio/potentiometer/mcp4531.c
> @@ -0,0 +1,231 @@
> +/*
> + * Industrial I/O driver for Microchip digital potentiometers
> + * Copyright (c) 2015 Axentia Technologies AB
> + * Author: Peter Rosin <peda@xxxxxxxxxx>
> + *
> + * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22096b.pdf
> + *
> + * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address
> + * mcp4531 1 129 5, 10, 50, 100 010111x
> + * mcp4532 1 129 5, 10, 50, 100 01011xx
> + * mcp4551 1 257 5, 10, 50, 100 010111x
> + * mcp4552 1 257 5, 10, 50, 100 01011xx
> + * mcp4631 2 129 5, 10, 50, 100 0101xxx
> + * mcp4632 2 129 5, 10, 50, 100 01011xx
> + * mcp4651 2 257 5, 10, 50, 100 0101xxx
> + * mcp4652 2 257 5, 10, 50, 100 01011xx
> + *
> + * 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>
> +
> +struct mcp4531_cfg {
> + int wipers;
> + int max_pos;
> + int kohms;
> +};
> +
> +enum mcp4531_type {
> + MCP453x_502,
> + MCP453x_103,
> + MCP453x_503,
> + MCP453x_104,
> + MCP455x_502,
> + MCP455x_103,
> + MCP455x_503,
> + MCP455x_104,
> + MCP463x_502,
> + MCP463x_103,
> + MCP463x_503,
> + MCP463x_104,
> + MCP465x_502,
> + MCP465x_103,
> + MCP465x_503,
> + MCP465x_104,
> +};
> +
> +static const struct mcp4531_cfg mcp4531_cfg[] = {
> + [MCP453x_502] = { .wipers = 1, .max_pos = 128, .kohms = 5, },
> + [MCP453x_103] = { .wipers = 1, .max_pos = 128, .kohms = 10, },
> + [MCP453x_503] = { .wipers = 1, .max_pos = 128, .kohms = 50, },
> + [MCP453x_104] = { .wipers = 1, .max_pos = 128, .kohms = 100, },
> + [MCP455x_502] = { .wipers = 1, .max_pos = 256, .kohms = 5, },
> + [MCP455x_103] = { .wipers = 1, .max_pos = 256, .kohms = 10, },
> + [MCP455x_503] = { .wipers = 1, .max_pos = 256, .kohms = 50, },
> + [MCP455x_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
> + [MCP463x_502] = { .wipers = 2, .max_pos = 128, .kohms = 5, },
> + [MCP463x_103] = { .wipers = 2, .max_pos = 128, .kohms = 10, },
> + [MCP463x_503] = { .wipers = 2, .max_pos = 128, .kohms = 50, },
> + [MCP463x_104] = { .wipers = 2, .max_pos = 128, .kohms = 100, },
> + [MCP465x_502] = { .wipers = 2, .max_pos = 256, .kohms = 5, },
> + [MCP465x_103] = { .wipers = 2, .max_pos = 256, .kohms = 10, },
> + [MCP465x_503] = { .wipers = 2, .max_pos = 256, .kohms = 50, },
> + [MCP465x_104] = { .wipers = 2, .max_pos = 256, .kohms = 100, },
> +};
> +
> +#define MCP4531_WRITE (0 << 2)
> +#define MCP4531_INCR (1 << 2)
> +#define MCP4531_DECR (2 << 2)
> +#define MCP4531_READ (3 << 2)
> +
> +#define MCP4531_WIPER_SHIFT (4)
> +
> +struct mcp4531_data {
> + struct i2c_client *client;
> + unsigned long devid;
> +};
> +
> +#define MCP4531_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 mcp4531_channels[] = {
> + MCP4531_CHANNEL(0),
> + MCP4531_CHANNEL(1),
> +};
> +
> +static int mcp4531_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct mcp4531_data *data = iio_priv(indio_dev);
> + int address = chan->channel << MCP4531_WIPER_SHIFT;
> + s32 ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = i2c_smbus_read_word_swapped(data->client,
> + MCP4531_READ | address);
> + if (ret < 0)
> + return ret;
> + *val = ret;
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_SCALE:
> + *val = 1000 * mcp4531_cfg[data->devid].kohms;
> + *val2 = mcp4531_cfg[data->devid].max_pos;
> + return IIO_VAL_FRACTIONAL;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int mcp4531_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct mcp4531_data *data = iio_priv(indio_dev);
> + int address = chan->channel << MCP4531_WIPER_SHIFT;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + if (val > mcp4531_cfg[data->devid].max_pos || val < 0)
> + return -EINVAL;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return i2c_smbus_write_byte_data(data->client,
> + MCP4531_WRITE | address | (val >> 8),
> + val & 0xff);
> +}
> +
> +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(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;
> +
> + indio_dev->dev.parent = dev;
> + indio_dev->info = &mcp4531_info;
> + indio_dev->channels = mcp4531_channels;
> + indio_dev->num_channels = mcp4531_cfg[devid].wipers;
> + indio_dev->name = client->name;
> +
> + return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static const struct i2c_device_id mcp4531_id[] = {
> + { "mcp4531-502", MCP453x_502 },
> + { "mcp4531-103", MCP453x_103 },
> + { "mcp4531-503", MCP453x_503 },
> + { "mcp4531-104", MCP453x_104 },
> + { "mcp4532-502", MCP453x_502 },
> + { "mcp4532-103", MCP453x_103 },
> + { "mcp4532-503", MCP453x_503 },
> + { "mcp4532-104", MCP453x_104 },
> + { "mcp4551-502", MCP455x_502 },
> + { "mcp4551-103", MCP455x_103 },
> + { "mcp4551-503", MCP455x_503 },
> + { "mcp4551-104", MCP455x_104 },
> + { "mcp4552-502", MCP455x_502 },
> + { "mcp4552-103", MCP455x_103 },
> + { "mcp4552-503", MCP455x_503 },
> + { "mcp4552-104", MCP455x_104 },
> + { "mcp4631-502", MCP463x_502 },
> + { "mcp4631-103", MCP463x_103 },
> + { "mcp4631-503", MCP463x_503 },
> + { "mcp4631-104", MCP463x_104 },
> + { "mcp4632-502", MCP463x_502 },
> + { "mcp4632-103", MCP463x_103 },
> + { "mcp4632-503", MCP463x_503 },
> + { "mcp4632-104", MCP463x_104 },
> + { "mcp4651-502", MCP465x_502 },
> + { "mcp4651-103", MCP465x_103 },
> + { "mcp4651-503", MCP465x_503 },
> + { "mcp4651-104", MCP465x_104 },
> + { "mcp4652-502", MCP465x_502 },
> + { "mcp4652-103", MCP465x_103 },
> + { "mcp4652-503", MCP465x_503 },
> + { "mcp4652-104", MCP465x_104 },
> + {}
> +};
> +MODULE_DEVICE_TABLE(i2c, mcp4531_id);
> +
> +static struct i2c_driver mcp4531_driver = {
> + .driver = {
> + .name = "mcp4531",
> + },
> + .probe = mcp4531_probe,
> + .id_table = mcp4531_id,
> +};
> +
> +module_i2c_driver(mcp4531_driver);
> +
> +MODULE_AUTHOR("Peter Rosin <peda@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("MCP4531 digital potentiometer");
> +MODULE_LICENSE("GPL");
>

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