drivers/iio/potentiometer/mcp4131.c

root/drivers/iio/potentiometer/mcp4131.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Industrial I/O driver for Microchip digital potentiometers
 *
 * Copyright (c) 2016 Slawomir Stepien
 * Based on: Peter Rosin's code from mcp4531.c
 *
 * Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/22060b.pdf
 *
 * DEVID        #Wipers #Positions      Resistor Opts (kOhm)
 * mcp4131      1       129             5, 10, 50, 100
 * mcp4132      1       129             5, 10, 50, 100
 * mcp4141      1       129             5, 10, 50, 100
 * mcp4142      1       129             5, 10, 50, 100
 * mcp4151      1       257             5, 10, 50, 100
 * mcp4152      1       257             5, 10, 50, 100
 * mcp4161      1       257             5, 10, 50, 100
 * mcp4162      1       257             5, 10, 50, 100
 * mcp4231      2       129             5, 10, 50, 100
 * mcp4232      2       129             5, 10, 50, 100
 * mcp4241      2       129             5, 10, 50, 100
 * mcp4242      2       129             5, 10, 50, 100
 * mcp4251      2       257             5, 10, 50, 100
 * mcp4252      2       257             5, 10, 50, 100
 * mcp4261      2       257             5, 10, 50, 100
 * mcp4262      2       257             5, 10, 50, 100
 */

/*
 * TODO:
 * 1. Write wiper setting to EEPROM for EEPROM capable models.
 */

#include <linux/cache.h>
#include <linux/err.h>
#include <linux/iio/iio.h>
#include <linux/iio/types.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/property.h>
#include <linux/spi/spi.h>

#define MCP4131_WRITE           (0x00 << 2)
#define MCP4131_READ            (0x03 << 2)

#define MCP4131_WIPER_SHIFT     4
#define MCP4131_CMDERR(r)       ((r[0]) & 0x02)
#define MCP4131_RAW(r)          ((r[0]) == 0xff ? 0x100 : (r[1]))

struct mcp4131_cfg {
        int wipers;
        int max_pos;
        int kohms;
};

enum mcp4131_type {
        MCP413x_502 = 0,
        MCP413x_103,
        MCP413x_503,
        MCP413x_104,
        MCP414x_502,
        MCP414x_103,
        MCP414x_503,
        MCP414x_104,
        MCP415x_502,
        MCP415x_103,
        MCP415x_503,
        MCP415x_104,
        MCP416x_502,
        MCP416x_103,
        MCP416x_503,
        MCP416x_104,
        MCP423x_502,
        MCP423x_103,
        MCP423x_503,
        MCP423x_104,
        MCP424x_502,
        MCP424x_103,
        MCP424x_503,
        MCP424x_104,
        MCP425x_502,
        MCP425x_103,
        MCP425x_503,
        MCP425x_104,
        MCP426x_502,
        MCP426x_103,
        MCP426x_503,
        MCP426x_104,
};

static const struct mcp4131_cfg mcp4131_cfg[] = {
        [MCP413x_502] = { .wipers = 1, .max_pos = 128, .kohms =   5, },
        [MCP413x_103] = { .wipers = 1, .max_pos = 128, .kohms =  10, },
        [MCP413x_503] = { .wipers = 1, .max_pos = 128, .kohms =  50, },
        [MCP413x_104] = { .wipers = 1, .max_pos = 128, .kohms = 100, },
        [MCP414x_502] = { .wipers = 1, .max_pos = 128, .kohms =   5, },
        [MCP414x_103] = { .wipers = 1, .max_pos = 128, .kohms =  10, },
        [MCP414x_503] = { .wipers = 1, .max_pos = 128, .kohms =  50, },
        [MCP414x_104] = { .wipers = 1, .max_pos = 128, .kohms = 100, },
        [MCP415x_502] = { .wipers = 1, .max_pos = 256, .kohms =   5, },
        [MCP415x_103] = { .wipers = 1, .max_pos = 256, .kohms =  10, },
        [MCP415x_503] = { .wipers = 1, .max_pos = 256, .kohms =  50, },
        [MCP415x_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
        [MCP416x_502] = { .wipers = 1, .max_pos = 256, .kohms =   5, },
        [MCP416x_103] = { .wipers = 1, .max_pos = 256, .kohms =  10, },
        [MCP416x_503] = { .wipers = 1, .max_pos = 256, .kohms =  50, },
        [MCP416x_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
        [MCP423x_502] = { .wipers = 2, .max_pos = 128, .kohms =   5, },
        [MCP423x_103] = { .wipers = 2, .max_pos = 128, .kohms =  10, },
        [MCP423x_503] = { .wipers = 2, .max_pos = 128, .kohms =  50, },
        [MCP423x_104] = { .wipers = 2, .max_pos = 128, .kohms = 100, },
        [MCP424x_502] = { .wipers = 2, .max_pos = 128, .kohms =   5, },
        [MCP424x_103] = { .wipers = 2, .max_pos = 128, .kohms =  10, },
        [MCP424x_503] = { .wipers = 2, .max_pos = 128, .kohms =  50, },
        [MCP424x_104] = { .wipers = 2, .max_pos = 128, .kohms = 100, },
        [MCP425x_502] = { .wipers = 2, .max_pos = 256, .kohms =   5, },
        [MCP425x_103] = { .wipers = 2, .max_pos = 256, .kohms =  10, },
        [MCP425x_503] = { .wipers = 2, .max_pos = 256, .kohms =  50, },
        [MCP425x_104] = { .wipers = 2, .max_pos = 256, .kohms = 100, },
        [MCP426x_502] = { .wipers = 2, .max_pos = 256, .kohms =   5, },
        [MCP426x_103] = { .wipers = 2, .max_pos = 256, .kohms =  10, },
        [MCP426x_503] = { .wipers = 2, .max_pos = 256, .kohms =  50, },
        [MCP426x_104] = { .wipers = 2, .max_pos = 256, .kohms = 100, },
};

struct mcp4131_data {
        struct spi_device *spi;
        const struct mcp4131_cfg *cfg;
        struct mutex lock;
        u8 buf[2] __aligned(IIO_DMA_MINALIGN);
};

#define MCP4131_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 mcp4131_channels[] = {
        MCP4131_CHANNEL(0),
        MCP4131_CHANNEL(1),
};

static int mcp4131_read(struct spi_device *spi, void *buf, size_t len)
{
        struct spi_transfer t = {
                .tx_buf = buf, /* We need to send addr, cmd and 12 bits */
                .rx_buf = buf,
                .len = len,
        };
        struct spi_message m;

        spi_message_init(&m);
        spi_message_add_tail(&t, &m);

        return spi_sync(spi, &m);
}

static int mcp4131_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
{
        int err;
        struct mcp4131_data *data = iio_priv(indio_dev);
        int address = chan->channel;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&data->lock);

                data->buf[0] = (address << MCP4131_WIPER_SHIFT) | MCP4131_READ;
                data->buf[1] = 0;

                err = mcp4131_read(data->spi, data->buf, 2);
                if (err) {
                        mutex_unlock(&data->lock);
                        return err;
                }

                /* Error, bad address/command combination */
                if (!MCP4131_CMDERR(data->buf)) {
                        mutex_unlock(&data->lock);
                        return -EIO;
                }

                *val = MCP4131_RAW(data->buf);
                mutex_unlock(&data->lock);

                return IIO_VAL_INT;

        case IIO_CHAN_INFO_SCALE:
                *val = 1000 * data->cfg->kohms;
                *val2 = data->cfg->max_pos;
                return IIO_VAL_FRACTIONAL;
        }

        return -EINVAL;
}

static int mcp4131_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int val, int val2, long mask)
{
        int err;
        struct mcp4131_data *data = iio_priv(indio_dev);
        int address = chan->channel << MCP4131_WIPER_SHIFT;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                if (val > data->cfg->max_pos || val < 0)
                        return -EINVAL;
                break;

        default:
                return -EINVAL;
        }

        mutex_lock(&data->lock);

        data->buf[0] = address;
        data->buf[0] |= MCP4131_WRITE | (val >> 8);
        data->buf[1] = val & 0xFF; /* 8 bits here */

        err = spi_write(data->spi, data->buf, 2);
        mutex_unlock(&data->lock);

        return err;
}

static const struct iio_info mcp4131_info = {
        .read_raw = mcp4131_read_raw,
        .write_raw = mcp4131_write_raw,
};

static int mcp4131_probe(struct spi_device *spi)
{
        int err;
        struct device *dev = &spi->dev;
        unsigned long devid;
        struct mcp4131_data *data;
        struct iio_dev *indio_dev;

        indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
        if (!indio_dev)
                return -ENOMEM;

        data = iio_priv(indio_dev);
        spi_set_drvdata(spi, indio_dev);
        data->spi = spi;
        data->cfg = device_get_match_data(&spi->dev);
        if (!data->cfg) {
                devid = spi_get_device_id(spi)->driver_data;
                data->cfg = &mcp4131_cfg[devid];
        }

        mutex_init(&data->lock);

        indio_dev->info = &mcp4131_info;
        indio_dev->channels = mcp4131_channels;
        indio_dev->num_channels = data->cfg->wipers;
        indio_dev->name = spi_get_device_id(spi)->name;

        err = devm_iio_device_register(dev, indio_dev);
        if (err) {
                dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
                return err;
        }

        return 0;
}

static const struct of_device_id mcp4131_dt_ids[] = {
        { .compatible = "microchip,mcp4131-502",
                .data = &mcp4131_cfg[MCP413x_502] },
        { .compatible = "microchip,mcp4131-103",
                .data = &mcp4131_cfg[MCP413x_103] },
        { .compatible = "microchip,mcp4131-503",
                .data = &mcp4131_cfg[MCP413x_503] },
        { .compatible = "microchip,mcp4131-104",
                .data = &mcp4131_cfg[MCP413x_104] },
        { .compatible = "microchip,mcp4132-502",
                .data = &mcp4131_cfg[MCP413x_502] },
        { .compatible = "microchip,mcp4132-103",
                .data = &mcp4131_cfg[MCP413x_103] },
        { .compatible = "microchip,mcp4132-503",
                .data = &mcp4131_cfg[MCP413x_503] },
        { .compatible = "microchip,mcp4132-104",
                .data = &mcp4131_cfg[MCP413x_104] },
        { .compatible = "microchip,mcp4141-502",
                .data = &mcp4131_cfg[MCP414x_502] },
        { .compatible = "microchip,mcp4141-103",
                .data = &mcp4131_cfg[MCP414x_103] },
        { .compatible = "microchip,mcp4141-503",
                .data = &mcp4131_cfg[MCP414x_503] },
        { .compatible = "microchip,mcp4141-104",
                .data = &mcp4131_cfg[MCP414x_104] },
        { .compatible = "microchip,mcp4142-502",
                .data = &mcp4131_cfg[MCP414x_502] },
        { .compatible = "microchip,mcp4142-103",
                .data = &mcp4131_cfg[MCP414x_103] },
        { .compatible = "microchip,mcp4142-503",
                .data = &mcp4131_cfg[MCP414x_503] },
        { .compatible = "microchip,mcp4142-104",
                .data = &mcp4131_cfg[MCP414x_104] },
        { .compatible = "microchip,mcp4151-502",
                .data = &mcp4131_cfg[MCP415x_502] },
        { .compatible = "microchip,mcp4151-103",
                .data = &mcp4131_cfg[MCP415x_103] },
        { .compatible = "microchip,mcp4151-503",
                .data = &mcp4131_cfg[MCP415x_503] },
        { .compatible = "microchip,mcp4151-104",
                .data = &mcp4131_cfg[MCP415x_104] },
        { .compatible = "microchip,mcp4152-502",
                .data = &mcp4131_cfg[MCP415x_502] },
        { .compatible = "microchip,mcp4152-103",
                .data = &mcp4131_cfg[MCP415x_103] },
        { .compatible = "microchip,mcp4152-503",
                .data = &mcp4131_cfg[MCP415x_503] },
        { .compatible = "microchip,mcp4152-104",
                .data = &mcp4131_cfg[MCP415x_104] },
        { .compatible = "microchip,mcp4161-502",
                .data = &mcp4131_cfg[MCP416x_502] },
        { .compatible = "microchip,mcp4161-103",
                .data = &mcp4131_cfg[MCP416x_103] },
        { .compatible = "microchip,mcp4161-503",
                .data = &mcp4131_cfg[MCP416x_503] },
        { .compatible = "microchip,mcp4161-104",
                .data = &mcp4131_cfg[MCP416x_104] },
        { .compatible = "microchip,mcp4162-502",
                .data = &mcp4131_cfg[MCP416x_502] },
        { .compatible = "microchip,mcp4162-103",
                .data = &mcp4131_cfg[MCP416x_103] },
        { .compatible = "microchip,mcp4162-503",
                .data = &mcp4131_cfg[MCP416x_503] },
        { .compatible = "microchip,mcp4162-104",
                .data = &mcp4131_cfg[MCP416x_104] },
        { .compatible = "microchip,mcp4231-502",
                .data = &mcp4131_cfg[MCP423x_502] },
        { .compatible = "microchip,mcp4231-103",
                .data = &mcp4131_cfg[MCP423x_103] },
        { .compatible = "microchip,mcp4231-503",
                .data = &mcp4131_cfg[MCP423x_503] },
        { .compatible = "microchip,mcp4231-104",
                .data = &mcp4131_cfg[MCP423x_104] },
        { .compatible = "microchip,mcp4232-502",
                .data = &mcp4131_cfg[MCP423x_502] },
        { .compatible = "microchip,mcp4232-103",
                .data = &mcp4131_cfg[MCP423x_103] },
        { .compatible = "microchip,mcp4232-503",
                .data = &mcp4131_cfg[MCP423x_503] },
        { .compatible = "microchip,mcp4232-104",
                .data = &mcp4131_cfg[MCP423x_104] },
        { .compatible = "microchip,mcp4241-502",
                .data = &mcp4131_cfg[MCP424x_502] },
        { .compatible = "microchip,mcp4241-103",
                .data = &mcp4131_cfg[MCP424x_103] },
        { .compatible = "microchip,mcp4241-503",
                .data = &mcp4131_cfg[MCP424x_503] },
        { .compatible = "microchip,mcp4241-104",
                .data = &mcp4131_cfg[MCP424x_104] },
        { .compatible = "microchip,mcp4242-502",
                .data = &mcp4131_cfg[MCP424x_502] },
        { .compatible = "microchip,mcp4242-103",
                .data = &mcp4131_cfg[MCP424x_103] },
        { .compatible = "microchip,mcp4242-503",
                .data = &mcp4131_cfg[MCP424x_503] },
        { .compatible = "microchip,mcp4242-104",
                .data = &mcp4131_cfg[MCP424x_104] },
        { .compatible = "microchip,mcp4251-502",
                .data = &mcp4131_cfg[MCP425x_502] },
        { .compatible = "microchip,mcp4251-103",
                .data = &mcp4131_cfg[MCP425x_103] },
        { .compatible = "microchip,mcp4251-503",
                .data = &mcp4131_cfg[MCP425x_503] },
        { .compatible = "microchip,mcp4251-104",
                .data = &mcp4131_cfg[MCP425x_104] },
        { .compatible = "microchip,mcp4252-502",
                .data = &mcp4131_cfg[MCP425x_502] },
        { .compatible = "microchip,mcp4252-103",
                .data = &mcp4131_cfg[MCP425x_103] },
        { .compatible = "microchip,mcp4252-503",
                .data = &mcp4131_cfg[MCP425x_503] },
        { .compatible = "microchip,mcp4252-104",
                .data = &mcp4131_cfg[MCP425x_104] },
        { .compatible = "microchip,mcp4261-502",
                .data = &mcp4131_cfg[MCP426x_502] },
        { .compatible = "microchip,mcp4261-103",
                .data = &mcp4131_cfg[MCP426x_103] },
        { .compatible = "microchip,mcp4261-503",
                .data = &mcp4131_cfg[MCP426x_503] },
        { .compatible = "microchip,mcp4261-104",
                .data = &mcp4131_cfg[MCP426x_104] },
        { .compatible = "microchip,mcp4262-502",
                .data = &mcp4131_cfg[MCP426x_502] },
        { .compatible = "microchip,mcp4262-103",
                .data = &mcp4131_cfg[MCP426x_103] },
        { .compatible = "microchip,mcp4262-503",
                .data = &mcp4131_cfg[MCP426x_503] },
        { .compatible = "microchip,mcp4262-104",
                .data = &mcp4131_cfg[MCP426x_104] },
        { }
};
MODULE_DEVICE_TABLE(of, mcp4131_dt_ids);

static const struct spi_device_id mcp4131_id[] = {
        { "mcp4131-502", MCP413x_502 },
        { "mcp4131-103", MCP413x_103 },
        { "mcp4131-503", MCP413x_503 },
        { "mcp4131-104", MCP413x_104 },
        { "mcp4132-502", MCP413x_502 },
        { "mcp4132-103", MCP413x_103 },
        { "mcp4132-503", MCP413x_503 },
        { "mcp4132-104", MCP413x_104 },
        { "mcp4141-502", MCP414x_502 },
        { "mcp4141-103", MCP414x_103 },
        { "mcp4141-503", MCP414x_503 },
        { "mcp4141-104", MCP414x_104 },
        { "mcp4142-502", MCP414x_502 },
        { "mcp4142-103", MCP414x_103 },
        { "mcp4142-503", MCP414x_503 },
        { "mcp4142-104", MCP414x_104 },
        { "mcp4151-502", MCP415x_502 },
        { "mcp4151-103", MCP415x_103 },
        { "mcp4151-503", MCP415x_503 },
        { "mcp4151-104", MCP415x_104 },
        { "mcp4152-502", MCP415x_502 },
        { "mcp4152-103", MCP415x_103 },
        { "mcp4152-503", MCP415x_503 },
        { "mcp4152-104", MCP415x_104 },
        { "mcp4161-502", MCP416x_502 },
        { "mcp4161-103", MCP416x_103 },
        { "mcp4161-503", MCP416x_503 },
        { "mcp4161-104", MCP416x_104 },
        { "mcp4162-502", MCP416x_502 },
        { "mcp4162-103", MCP416x_103 },
        { "mcp4162-503", MCP416x_503 },
        { "mcp4162-104", MCP416x_104 },
        { "mcp4231-502", MCP423x_502 },
        { "mcp4231-103", MCP423x_103 },
        { "mcp4231-503", MCP423x_503 },
        { "mcp4231-104", MCP423x_104 },
        { "mcp4232-502", MCP423x_502 },
        { "mcp4232-103", MCP423x_103 },
        { "mcp4232-503", MCP423x_503 },
        { "mcp4232-104", MCP423x_104 },
        { "mcp4241-502", MCP424x_502 },
        { "mcp4241-103", MCP424x_103 },
        { "mcp4241-503", MCP424x_503 },
        { "mcp4241-104", MCP424x_104 },
        { "mcp4242-502", MCP424x_502 },
        { "mcp4242-103", MCP424x_103 },
        { "mcp4242-503", MCP424x_503 },
        { "mcp4242-104", MCP424x_104 },
        { "mcp4251-502", MCP425x_502 },
        { "mcp4251-103", MCP425x_103 },
        { "mcp4251-503", MCP425x_503 },
        { "mcp4251-104", MCP425x_104 },
        { "mcp4252-502", MCP425x_502 },
        { "mcp4252-103", MCP425x_103 },
        { "mcp4252-503", MCP425x_503 },
        { "mcp4252-104", MCP425x_104 },
        { "mcp4261-502", MCP426x_502 },
        { "mcp4261-103", MCP426x_103 },
        { "mcp4261-503", MCP426x_503 },
        { "mcp4261-104", MCP426x_104 },
        { "mcp4262-502", MCP426x_502 },
        { "mcp4262-103", MCP426x_103 },
        { "mcp4262-503", MCP426x_503 },
        { "mcp4262-104", MCP426x_104 },
        { }
};
MODULE_DEVICE_TABLE(spi, mcp4131_id);

static struct spi_driver mcp4131_driver = {
        .driver = {
                .name   = "mcp4131",
                .of_match_table = mcp4131_dt_ids,
        },
        .probe          = mcp4131_probe,
        .id_table       = mcp4131_id,
};

module_spi_driver(mcp4131_driver);

MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
MODULE_DESCRIPTION("MCP4131 digital potentiometer");
MODULE_LICENSE("GPL v2");
Linux
