/* * Maxim Integrated MAX5481-MAX5484 digital potentiometer driver * Copyright 2016 Rockwell Collins * * Datasheet: * http://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf * * This program is free software; you can redistribute it and/or modify * it under the terms of the gnu general public license version 2 as * published by the free software foundation. * */ #include <linux/acpi.h> #include <linux/iio/iio.h> #include <linux/iio/sysfs.h> #include <linux/module.h> #include <linux/of.h> #include <linux/of_device.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] ____cacheline_aligned; }; #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, }; #if defined(CONFIG_OF) 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); #endif 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); const struct of_device_id *match; int ret; indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); if (!indio_dev) return -ENOMEM; dev_set_drvdata(&spi->dev, indio_dev); data = iio_priv(indio_dev); data->spi = spi; match = of_match_device(of_match_ptr(max5481_match), &spi->dev); if (match) data->cfg = of_device_get_match_data(&spi->dev); else data->cfg = &max5481_cfg[id->driver_data]; indio_dev->name = id->name; indio_dev->dev.parent = &spi->dev; 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; return iio_device_register(indio_dev); } static int max5481_remove(struct spi_device *spi) { struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev); struct max5481_data *data = iio_priv(indio_dev); iio_device_unregister(indio_dev); /* save wiper reg to NV reg */ return max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0); } static const struct spi_device_id max5481_id_table[] = { { "max5481", max5481 }, { "max5482", max5482 }, { "max5483", max5483 }, { "max5484", max5484 }, { } }; MODULE_DEVICE_TABLE(spi, max5481_id_table); #if defined(CONFIG_ACPI) static const struct acpi_device_id max5481_acpi_match[] = { { "max5481", max5481 }, { "max5482", max5482 }, { "max5483", max5483 }, { "max5484", max5484 }, { } }; MODULE_DEVICE_TABLE(acpi, max5481_acpi_match); #endif static struct spi_driver max5481_driver = { .driver = { .name = "max5481", .of_match_table = of_match_ptr(max5481_match), .acpi_match_table = ACPI_PTR(max5481_acpi_match), }, .probe = max5481_probe, .remove = max5481_remove, .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");