// SPDX-License-Identifier: GPL-2.0
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/*
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* Industrial I/O driver for Microchip digital potentiometers
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*
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* Copyright (c) 2018 Chris Coffey <cmc@babblebit.net>
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* Based on: Slawomir Stepien's code from mcp4131.c
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*
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* Datasheet: https://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
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*
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* DEVID #Wipers #Positions Resistance (kOhm)
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* mcp41010 1 256 10
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* mcp41050 1 256 50
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* mcp41100 1 256 100
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* mcp42010 2 256 10
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* mcp42050 2 256 50
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* mcp42100 2 256 100
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*/
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#include <linux/cache.h>
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#include <linux/err.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/types.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/spi/spi.h>
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#define MCP41010_MAX_WIPERS 2
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#define MCP41010_WRITE BIT(4)
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#define MCP41010_WIPER_MAX 255
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#define MCP41010_WIPER_CHANNEL BIT(0)
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struct mcp41010_cfg {
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char name[16];
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int wipers;
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int kohms;
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};
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enum mcp41010_type {
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MCP41010,
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MCP41050,
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MCP41100,
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MCP42010,
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MCP42050,
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MCP42100,
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};
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static const struct mcp41010_cfg mcp41010_cfg[] = {
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[MCP41010] = { .name = "mcp41010", .wipers = 1, .kohms = 10, },
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[MCP41050] = { .name = "mcp41050", .wipers = 1, .kohms = 50, },
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[MCP41100] = { .name = "mcp41100", .wipers = 1, .kohms = 100, },
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[MCP42010] = { .name = "mcp42010", .wipers = 2, .kohms = 10, },
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[MCP42050] = { .name = "mcp42050", .wipers = 2, .kohms = 50, },
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[MCP42100] = { .name = "mcp42100", .wipers = 2, .kohms = 100, },
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};
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struct mcp41010_data {
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struct spi_device *spi;
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const struct mcp41010_cfg *cfg;
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struct mutex lock; /* Protect write sequences */
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unsigned int value[MCP41010_MAX_WIPERS]; /* Cache wiper values */
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u8 buf[2] ____cacheline_aligned;
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};
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#define MCP41010_CHANNEL(ch) { \
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.type = IIO_RESISTANCE, \
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.indexed = 1, \
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.output = 1, \
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.channel = (ch), \
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
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}
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static const struct iio_chan_spec mcp41010_channels[] = {
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MCP41010_CHANNEL(0),
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MCP41010_CHANNEL(1),
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};
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static int mcp41010_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long mask)
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{
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struct mcp41010_data *data = iio_priv(indio_dev);
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int channel = chan->channel;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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*val = data->value[channel];
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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*val = 1000 * data->cfg->kohms;
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*val2 = MCP41010_WIPER_MAX;
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return IIO_VAL_FRACTIONAL;
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}
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return -EINVAL;
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}
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static int mcp41010_write_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int val, int val2, long mask)
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{
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int err;
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struct mcp41010_data *data = iio_priv(indio_dev);
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int channel = chan->channel;
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if (mask != IIO_CHAN_INFO_RAW)
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return -EINVAL;
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if (val > MCP41010_WIPER_MAX || val < 0)
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return -EINVAL;
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mutex_lock(&data->lock);
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data->buf[0] = MCP41010_WIPER_CHANNEL << channel;
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data->buf[0] |= MCP41010_WRITE;
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data->buf[1] = val & 0xff;
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err = spi_write(data->spi, data->buf, sizeof(data->buf));
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if (!err)
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data->value[channel] = val;
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mutex_unlock(&data->lock);
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return err;
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}
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static const struct iio_info mcp41010_info = {
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.read_raw = mcp41010_read_raw,
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.write_raw = mcp41010_write_raw,
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};
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static int mcp41010_probe(struct spi_device *spi)
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{
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int err;
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struct device *dev = &spi->dev;
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struct mcp41010_data *data;
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struct iio_dev *indio_dev;
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indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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data = iio_priv(indio_dev);
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spi_set_drvdata(spi, indio_dev);
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data->spi = spi;
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data->cfg = of_device_get_match_data(&spi->dev);
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if (!data->cfg)
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data->cfg = &mcp41010_cfg[spi_get_device_id(spi)->driver_data];
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mutex_init(&data->lock);
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indio_dev->info = &mcp41010_info;
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indio_dev->channels = mcp41010_channels;
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indio_dev->num_channels = data->cfg->wipers;
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indio_dev->name = data->cfg->name;
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err = devm_iio_device_register(dev, indio_dev);
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if (err)
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dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
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return err;
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}
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static const struct of_device_id mcp41010_match[] = {
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{ .compatible = "microchip,mcp41010", .data = &mcp41010_cfg[MCP41010] },
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{ .compatible = "microchip,mcp41050", .data = &mcp41010_cfg[MCP41050] },
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{ .compatible = "microchip,mcp41100", .data = &mcp41010_cfg[MCP41100] },
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{ .compatible = "microchip,mcp42010", .data = &mcp41010_cfg[MCP42010] },
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{ .compatible = "microchip,mcp42050", .data = &mcp41010_cfg[MCP42050] },
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{ .compatible = "microchip,mcp42100", .data = &mcp41010_cfg[MCP42100] },
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{}
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};
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MODULE_DEVICE_TABLE(of, mcp41010_match);
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static const struct spi_device_id mcp41010_id[] = {
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{ "mcp41010", MCP41010 },
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{ "mcp41050", MCP41050 },
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{ "mcp41100", MCP41100 },
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{ "mcp42010", MCP42010 },
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{ "mcp42050", MCP42050 },
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{ "mcp42100", MCP42100 },
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{}
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};
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MODULE_DEVICE_TABLE(spi, mcp41010_id);
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static struct spi_driver mcp41010_driver = {
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.driver = {
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.name = "mcp41010",
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.of_match_table = mcp41010_match,
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},
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.probe = mcp41010_probe,
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.id_table = mcp41010_id,
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};
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module_spi_driver(mcp41010_driver);
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MODULE_AUTHOR("Chris Coffey <cmc@babblebit.net>");
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MODULE_DESCRIPTION("MCP41010 digital potentiometer");
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MODULE_LICENSE("GPL v2");
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