| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Maxim Integrated MAX5481-MAX5484 digital potentiometer driver |
| * Copyright 2016 Rockwell Collins |
| * |
| * Datasheet: |
| * https://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf |
| */ |
| |
| #include <linux/iio/iio.h> |
| #include <linux/iio/sysfs.h> |
| #include <linux/module.h> |
| #include <linux/mod_devicetable.h> |
| #include <linux/property.h> |
| #include <linux/spi/spi.h> |
| |
| /* write wiper reg */ |
| #define MAX5481_WRITE_WIPER (0 << 4) |
| /* copy wiper reg to NV reg */ |
| #define MAX5481_COPY_AB_TO_NV (2 << 4) |
| /* copy NV reg to wiper reg */ |
| #define MAX5481_COPY_NV_TO_AB (3 << 4) |
| |
| #define MAX5481_MAX_POS 1023 |
| |
| enum max5481_variant { |
| max5481, |
| max5482, |
| max5483, |
| max5484, |
| }; |
| |
| struct max5481_cfg { |
| int kohms; |
| }; |
| |
| static const struct max5481_cfg max5481_cfg[] = { |
| [max5481] = { .kohms = 10, }, |
| [max5482] = { .kohms = 50, }, |
| [max5483] = { .kohms = 10, }, |
| [max5484] = { .kohms = 50, }, |
| }; |
| |
| struct max5481_data { |
| struct spi_device *spi; |
| const struct max5481_cfg *cfg; |
| u8 msg[3] __aligned(IIO_DMA_MINALIGN); |
| }; |
| |
| #define MAX5481_CHANNEL { \ |
| .type = IIO_RESISTANCE, \ |
| .indexed = 1, \ |
| .output = 1, \ |
| .channel = 0, \ |
| .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ |
| .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ |
| } |
| |
| static const struct iio_chan_spec max5481_channels[] = { |
| MAX5481_CHANNEL, |
| }; |
| |
| static int max5481_write_cmd(struct max5481_data *data, u8 cmd, u16 val) |
| { |
| struct spi_device *spi = data->spi; |
| |
| data->msg[0] = cmd; |
| |
| switch (cmd) { |
| case MAX5481_WRITE_WIPER: |
| data->msg[1] = val >> 2; |
| data->msg[2] = (val & 0x3) << 6; |
| return spi_write(spi, data->msg, 3); |
| |
| case MAX5481_COPY_AB_TO_NV: |
| case MAX5481_COPY_NV_TO_AB: |
| return spi_write(spi, data->msg, 1); |
| |
| default: |
| return -EIO; |
| } |
| } |
| |
| static int max5481_read_raw(struct iio_dev *indio_dev, |
| struct iio_chan_spec const *chan, |
| int *val, int *val2, long mask) |
| { |
| struct max5481_data *data = iio_priv(indio_dev); |
| |
| if (mask != IIO_CHAN_INFO_SCALE) |
| return -EINVAL; |
| |
| *val = 1000 * data->cfg->kohms; |
| *val2 = MAX5481_MAX_POS; |
| |
| return IIO_VAL_FRACTIONAL; |
| } |
| |
| static int max5481_write_raw(struct iio_dev *indio_dev, |
| struct iio_chan_spec const *chan, |
| int val, int val2, long mask) |
| { |
| struct max5481_data *data = iio_priv(indio_dev); |
| |
| if (mask != IIO_CHAN_INFO_RAW) |
| return -EINVAL; |
| |
| if (val < 0 || val > MAX5481_MAX_POS) |
| return -EINVAL; |
| |
| return max5481_write_cmd(data, MAX5481_WRITE_WIPER, val); |
| } |
| |
| static const struct iio_info max5481_info = { |
| .read_raw = max5481_read_raw, |
| .write_raw = max5481_write_raw, |
| }; |
| |
| static const struct of_device_id max5481_match[] = { |
| { .compatible = "maxim,max5481", .data = &max5481_cfg[max5481] }, |
| { .compatible = "maxim,max5482", .data = &max5481_cfg[max5482] }, |
| { .compatible = "maxim,max5483", .data = &max5481_cfg[max5483] }, |
| { .compatible = "maxim,max5484", .data = &max5481_cfg[max5484] }, |
| { } |
| }; |
| MODULE_DEVICE_TABLE(of, max5481_match); |
| |
| static void max5481_wiper_save(void *data) |
| { |
| max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0); |
| } |
| |
| static int max5481_probe(struct spi_device *spi) |
| { |
| struct iio_dev *indio_dev; |
| struct max5481_data *data; |
| const struct spi_device_id *id = spi_get_device_id(spi); |
| int ret; |
| |
| indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); |
| if (!indio_dev) |
| return -ENOMEM; |
| |
| data = iio_priv(indio_dev); |
| |
| data->spi = spi; |
| |
| data->cfg = device_get_match_data(&spi->dev); |
| if (!data->cfg) |
| data->cfg = &max5481_cfg[id->driver_data]; |
| |
| indio_dev->name = id->name; |
| indio_dev->modes = INDIO_DIRECT_MODE; |
| |
| /* variant specific configuration */ |
| indio_dev->info = &max5481_info; |
| indio_dev->channels = max5481_channels; |
| indio_dev->num_channels = ARRAY_SIZE(max5481_channels); |
| |
| /* restore wiper from NV */ |
| ret = max5481_write_cmd(data, MAX5481_COPY_NV_TO_AB, 0); |
| if (ret < 0) |
| return ret; |
| |
| ret = devm_add_action(&spi->dev, max5481_wiper_save, data); |
| if (ret < 0) |
| return ret; |
| |
| return devm_iio_device_register(&spi->dev, indio_dev); |
| } |
| |
| static const struct spi_device_id max5481_id_table[] = { |
| { "max5481", max5481 }, |
| { "max5482", max5482 }, |
| { "max5483", max5483 }, |
| { "max5484", max5484 }, |
| { } |
| }; |
| MODULE_DEVICE_TABLE(spi, max5481_id_table); |
| |
| static struct spi_driver max5481_driver = { |
| .driver = { |
| .name = "max5481", |
| .of_match_table = max5481_match, |
| }, |
| .probe = max5481_probe, |
| .id_table = max5481_id_table, |
| }; |
| |
| module_spi_driver(max5481_driver); |
| |
| MODULE_AUTHOR("Maury Anderson <maury.anderson@rockwellcollins.com>"); |
| MODULE_DESCRIPTION("max5481 SPI driver"); |
| MODULE_LICENSE("GPL v2"); |