LXR linux/drivers/iio/potentiometer/max5487.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
   4 *
   5 * Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>
   6 */
   7#include <linux/module.h>
   8#include <linux/spi/spi.h>
   9#include <linux/acpi.h>
  10
  11#include <linux/iio/sysfs.h>
  12#include <linux/iio/iio.h>
  13
  14#define MAX5487_WRITE_WIPER_A   (0x01 << 8)
  15#define MAX5487_WRITE_WIPER_B   (0x02 << 8)
  16
  17/* copy both wiper regs to NV regs */
  18#define MAX5487_COPY_AB_TO_NV   (0x23 << 8)
  19/* copy both NV regs to wiper regs */
  20#define MAX5487_COPY_NV_TO_AB   (0x33 << 8)
  21
  22#define MAX5487_MAX_POS         255
  23
  24struct max5487_data {
  25        struct spi_device *spi;
  26        int kohms;
  27};
  28
  29#define MAX5487_CHANNEL(ch, addr) {                             \
  30        .type = IIO_RESISTANCE,                                 \
  31        .indexed = 1,                                           \
  32        .output = 1,                                            \
  33        .channel = ch,                                          \
  34        .address = addr,                                        \
  35        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  36        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
  37}
  38
  39static const struct iio_chan_spec max5487_channels[] = {
  40        MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
  41        MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
  42};
  43
  44static int max5487_write_cmd(struct spi_device *spi, u16 cmd)
  45{
  46        return spi_write(spi, (const void *) &cmd, sizeof(u16));
  47}
  48
  49static int max5487_read_raw(struct iio_dev *indio_dev,
  50                            struct iio_chan_spec const *chan,
  51                            int *val, int *val2, long mask)
  52{
  53        struct max5487_data *data = iio_priv(indio_dev);
  54
  55        if (mask != IIO_CHAN_INFO_SCALE)
  56                return -EINVAL;
  57
  58        *val = 1000 * data->kohms;
  59        *val2 = MAX5487_MAX_POS;
  60
  61        return IIO_VAL_FRACTIONAL;
  62}
  63
  64static int max5487_write_raw(struct iio_dev *indio_dev,
  65                             struct iio_chan_spec const *chan,
  66                             int val, int val2, long mask)
  67{
  68        struct max5487_data *data = iio_priv(indio_dev);
  69
  70        if (mask != IIO_CHAN_INFO_RAW)
  71                return -EINVAL;
  72
  73        if (val < 0 || val > MAX5487_MAX_POS)
  74                return -EINVAL;
  75
  76        return max5487_write_cmd(data->spi, chan->address | val);
  77}
  78
  79static const struct iio_info max5487_info = {
  80        .read_raw = max5487_read_raw,
  81        .write_raw = max5487_write_raw,
  82};
  83
  84static int max5487_spi_probe(struct spi_device *spi)
  85{
  86        struct iio_dev *indio_dev;
  87        struct max5487_data *data;
  88        const struct spi_device_id *id = spi_get_device_id(spi);
  89        int ret;
  90
  91        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
  92        if (!indio_dev)
  93                return -ENOMEM;
  94
  95        spi_set_drvdata(spi, indio_dev);
  96        data = iio_priv(indio_dev);
  97
  98        data->spi = spi;
  99        data->kohms = id->driver_data;
 100
 101        indio_dev->info = &max5487_info;
 102        indio_dev->name = id->name;
 103        indio_dev->modes = INDIO_DIRECT_MODE;
 104        indio_dev->channels = max5487_channels;
 105        indio_dev->num_channels = ARRAY_SIZE(max5487_channels);
 106
 107        /* restore both wiper regs from NV regs */
 108        ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
 109        if (ret < 0)
 110                return ret;
 111
 112        return iio_device_register(indio_dev);
 113}
 114
 115static int max5487_spi_remove(struct spi_device *spi)
 116{
 117        struct iio_dev *indio_dev = spi_get_drvdata(spi);
 118
 119        iio_device_unregister(indio_dev);
 120
 121        /* save both wiper regs to NV regs */
 122        return max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
 123}
 124
 125static const struct spi_device_id max5487_id[] = {
 126        { "MAX5487", 10 },
 127        { "MAX5488", 50 },
 128        { "MAX5489", 100 },
 129        { }
 130};
 131MODULE_DEVICE_TABLE(spi, max5487_id);
 132
 133static const struct acpi_device_id max5487_acpi_match[] = {
 134        { "MAX5487", 10 },
 135        { "MAX5488", 50 },
 136        { "MAX5489", 100 },
 137        { },
 138};
 139MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
 140
 141static struct spi_driver max5487_driver = {
 142        .driver = {
 143                .name = "max5487",
 144                .acpi_match_table = ACPI_PTR(max5487_acpi_match),
 145        },
 146        .id_table = max5487_id,
 147        .probe = max5487_spi_probe,
 148        .remove = max5487_spi_remove
 149};
 150module_spi_driver(max5487_driver);
 151
 152MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>");
 153MODULE_DESCRIPTION("max5487 SPI driver");
 154MODULE_LICENSE("GPL v2");
 155