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