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/mod_devicetable.h>
   9 #include <linux/spi/spi.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
  24 struct 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
  39 static 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
  44 static int max5487_write_cmd(struct spi_device *spi, u16 cmd)
  45 {
  46         return spi_write(spi, (const void *) &cmd, sizeof(u16));
  47 }
  48
  49 static 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
  64 static 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
  79 static const struct iio_info max5487_info = {
  80         .read_raw = max5487_read_raw,
  81         .write_raw = max5487_write_raw,
  82 };
  83
  84 static 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
 115 static void max5487_spi_remove(struct spi_device *spi)
 116 {
 117         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 118         int ret;
 119
 120         iio_device_unregister(indio_dev);
 121
 122         /* save both wiper regs to NV regs */
 123         ret = max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
 124         if (ret)
 125                 dev_warn(&spi->dev, "Failed to save wiper regs to NV regs\n");
 126 }
 127
 128 static const struct spi_device_id max5487_id[] = {
 129         { "MAX5487", 10 },
 130         { "MAX5488", 50 },
 131         { "MAX5489", 100 },
 132         { }
 133 };
 134 MODULE_DEVICE_TABLE(spi, max5487_id);
 135
 136 static const struct acpi_device_id max5487_acpi_match[] = {
 137         { "MAX5487", 10 },
 138         { "MAX5488", 50 },
 139         { "MAX5489", 100 },
 140         { },
 141 };
 142 MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
 143
 144 static struct spi_driver max5487_driver = {
 145         .driver = {
 146                 .name = "max5487",
 147                 .acpi_match_table = max5487_acpi_match,
 148         },
 149         .id_table = max5487_id,
 150         .probe = max5487_spi_probe,
 151         .remove = max5487_spi_remove
 152 };
 153 module_spi_driver(max5487_driver);
 154
 155 MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>");
 156 MODULE_DESCRIPTION("max5487 SPI driver");
 157 MODULE_LICENSE("GPL v2");