158 lines
3.8 KiB
C
158 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
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*
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* Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>
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*/
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#include <linux/module.h>
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#include <linux/spi/spi.h>
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#include <linux/acpi.h>
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#include <linux/iio/sysfs.h>
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#include <linux/iio/iio.h>
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#define MAX5487_WRITE_WIPER_A (0x01 << 8)
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#define MAX5487_WRITE_WIPER_B (0x02 << 8)
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/* copy both wiper regs to NV regs */
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#define MAX5487_COPY_AB_TO_NV (0x23 << 8)
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/* copy both NV regs to wiper regs */
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#define MAX5487_COPY_NV_TO_AB (0x33 << 8)
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#define MAX5487_MAX_POS 255
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struct max5487_data {
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struct spi_device *spi;
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int kohms;
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};
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#define MAX5487_CHANNEL(ch, addr) { \
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.type = IIO_RESISTANCE, \
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.indexed = 1, \
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.output = 1, \
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.channel = ch, \
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.address = addr, \
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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 max5487_channels[] = {
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MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
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MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
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};
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static int max5487_write_cmd(struct spi_device *spi, u16 cmd)
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{
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return spi_write(spi, (const void *) &cmd, sizeof(u16));
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}
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static int max5487_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 max5487_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->kohms;
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*val2 = MAX5487_MAX_POS;
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return IIO_VAL_FRACTIONAL;
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}
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static int max5487_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 max5487_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 > MAX5487_MAX_POS)
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return -EINVAL;
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return max5487_write_cmd(data->spi, chan->address | val);
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}
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static const struct iio_info max5487_info = {
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.read_raw = max5487_read_raw,
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.write_raw = max5487_write_raw,
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};
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static int max5487_spi_probe(struct spi_device *spi)
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{
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struct iio_dev *indio_dev;
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struct max5487_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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spi_set_drvdata(spi, indio_dev);
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data = iio_priv(indio_dev);
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data->spi = spi;
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data->kohms = id->driver_data;
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indio_dev->info = &max5487_info;
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indio_dev->name = id->name;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = max5487_channels;
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indio_dev->num_channels = ARRAY_SIZE(max5487_channels);
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/* restore both wiper regs from NV regs */
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ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
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if (ret < 0)
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return ret;
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return iio_device_register(indio_dev);
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}
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static void max5487_spi_remove(struct spi_device *spi)
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{
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struct iio_dev *indio_dev = spi_get_drvdata(spi);
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int ret;
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iio_device_unregister(indio_dev);
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/* save both wiper regs to NV regs */
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ret = max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
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if (ret)
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dev_warn(&spi->dev, "Failed to save wiper regs to NV regs\n");
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}
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static const struct spi_device_id max5487_id[] = {
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{ "MAX5487", 10 },
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{ "MAX5488", 50 },
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{ "MAX5489", 100 },
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{ }
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};
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MODULE_DEVICE_TABLE(spi, max5487_id);
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static const struct acpi_device_id max5487_acpi_match[] = {
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{ "MAX5487", 10 },
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{ "MAX5488", 50 },
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{ "MAX5489", 100 },
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{ },
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};
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MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
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static struct spi_driver max5487_driver = {
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.driver = {
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.name = "max5487",
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.acpi_match_table = ACPI_PTR(max5487_acpi_match),
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},
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.id_table = max5487_id,
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.probe = max5487_spi_probe,
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.remove = max5487_spi_remove
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};
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module_spi_driver(max5487_driver);
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MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>");
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MODULE_DESCRIPTION("max5487 SPI driver");
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MODULE_LICENSE("GPL v2");
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