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    Subject[PATCH] iio: max5487: Add support for Maxim digital potentiometers
    Date
    Add implementation for Maxim MAX5487, MAX5488, MAX5489
    digital potentiometers.

    Signed-off-by: Cristina Moraru <cristina.moraru09@gmail.com>
    CC: Daniel Baluta <daniel.baluta@intel.com>
    ---
    drivers/iio/potentiometer/Kconfig | 11 +++
    drivers/iio/potentiometer/Makefile | 1 +
    drivers/iio/potentiometer/max5487.c | 185 ++++++++++++++++++++++++++++++++++++
    3 files changed, 197 insertions(+)
    create mode 100644 drivers/iio/potentiometer/max5487.c

    diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
    index ffc735c..3046c79 100644
    --- a/drivers/iio/potentiometer/Kconfig
    +++ b/drivers/iio/potentiometer/Kconfig
    @@ -5,6 +5,17 @@

    menu "Digital potentiometers"

    +config MAX5487
    + tristate "Maxim MAX5487/MAX5488/MAX5489 Digital Potentiometer driver"
    + depends on SPI
    + help
    + Say yes here to build support for the Maxim
    + MAX5487, MAX5488, MAX5489 digital potentiomenter
    + chips.
    +
    + To compile this driver as a module, choose M here: the
    + module will be called max5487.
    +
    config MCP4531
    tristate "Microchip MCP45xx/MCP46xx Digital Potentiometer driver"
    depends on I2C
    diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
    index b563b49..dcc791a 100644
    --- a/drivers/iio/potentiometer/Makefile
    +++ b/drivers/iio/potentiometer/Makefile
    @@ -3,5 +3,6 @@
    #

    # When adding new entries keep the list in alphabetical order
    +obj-$(CONFIG_MAX5487) += max5487.o
    obj-$(CONFIG_MCP4531) += mcp4531.o
    obj-$(CONFIG_TPL0102) += tpl0102.o
    diff --git a/drivers/iio/potentiometer/max5487.c b/drivers/iio/potentiometer/max5487.c
    new file mode 100644
    index 0000000..69db979
    --- /dev/null
    +++ b/drivers/iio/potentiometer/max5487.c
    @@ -0,0 +1,185 @@
    +/*
    + * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
    + *
    + * Copyright (C) Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>
    + *
    + * 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/module.h>
    +#include <linux/spi/spi.h>
    +#include <linux/acpi.h>
    +#include <linux/regmap.h>
    +
    +#include <linux/iio/sysfs.h>
    +#include <linux/iio/iio.h>
    +
    +#define MAX5487_DRV_NAME "max5487"
    +
    +#define MAX5487_WRITE_WIPER_A 0x01
    +#define MAX5487_WRITE_WIPER_B 0x02
    +
    +/* copy both wiper regs to NV regs */
    +#define MAX5487_COPY_AB_TO_NV 0x23
    +/* copy both NV regs to wiper regs */
    +#define MAX5487_COPY_NV_TO_AB 0x33
    +
    +enum {
    + MAX5487,
    + MAX5488,
    + MAX5489,
    +};
    +
    +struct max5487_cfg {
    + int wipers;
    + int max_pos;
    + int kohms;
    +};
    +
    +static const struct max5487_cfg max5487_cfg[] = {
    + [MAX5487] = { .wipers = 2, .max_pos = 256, .kohms = 10,},
    + [MAX5488] = { .wipers = 2, .max_pos = 256, .kohms = 50,},
    + [MAX5489] = { .wipers = 2, .max_pos = 256, .kohms = 100,}
    +};
    +
    +struct max5487_data {
    + struct regmap *regmap;
    + int chip_id;
    +};
    +
    +#define MAX5487_CHANNEL(ch, addr) { \
    + .type = IIO_RESISTANCE, \
    + .indexed = 1, \
    + .output = 1, \
    + .channel = ch, \
    + .address = addr, \
    + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
    + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
    +}
    +
    +static const struct iio_chan_spec max5487_channels[] = {
    + MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
    + MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
    +};
    +
    +static int max5487_read_raw(struct iio_dev *indio_dev,
    + struct iio_chan_spec const *chan,
    + int *val, int *val2, long mask)
    +{
    + struct max5487_data *data = iio_priv(indio_dev);
    +
    + if (mask != IIO_CHAN_INFO_SCALE)
    + return -EINVAL;
    +
    + *val = 1000 * max5487_cfg[data->chip_id].kohms;
    + *val2 = max5487_cfg[data->chip_id].max_pos;
    + return IIO_VAL_FRACTIONAL;
    +}
    +
    +static int max5487_write_raw(struct iio_dev *indio_dev,
    + struct iio_chan_spec const *chan,
    + int val, int val2, long mask)
    +{
    + struct max5487_data *data = iio_priv(indio_dev);
    +
    + switch (mask) {
    + case IIO_CHAN_INFO_RAW:
    + if (val < 0 || val >= max5487_cfg[data->chip_id].max_pos)
    + return -EINVAL;
    + return regmap_write(data->regmap, chan->address, val);
    + default:
    + return -EINVAL;
    + }
    + return -EINVAL;
    +}
    +
    +static const struct iio_info max5487_info = {
    + .read_raw = &max5487_read_raw,
    + .write_raw = &max5487_write_raw,
    + .driver_module = THIS_MODULE,
    +};
    +
    +static const struct regmap_config max5487_regmap_config = {
    + .reg_bits = 8,
    + .val_bits = 8,
    +
    + .max_register = MAX5487_COPY_NV_TO_AB,
    +};
    +
    +static int max5487_spi_probe(struct spi_device *spi)
    +{
    + struct iio_dev *indio_dev;
    + struct max5487_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;
    +
    + dev_set_drvdata(&spi->dev, indio_dev);
    + data = iio_priv(indio_dev);
    +
    + data->regmap = devm_regmap_init_spi(spi, &max5487_regmap_config);
    + if (IS_ERR(data->regmap))
    + return PTR_ERR(data->regmap);
    +
    + data->chip_id = id->driver_data;
    +
    + indio_dev->info = &max5487_info;
    + indio_dev->name = id->name;
    + indio_dev->dev.parent = &spi->dev;
    + indio_dev->modes = INDIO_DIRECT_MODE;
    + indio_dev->channels = max5487_channels;
    + indio_dev->num_channels = ARRAY_SIZE(max5487_channels);
    +
    + /* restore both wiper regs from NV regs */
    + ret = regmap_write(data->regmap, MAX5487_COPY_NV_TO_AB, 0);
    + if (ret < 0)
    + return ret;
    +
    + return devm_iio_device_register(&spi->dev, indio_dev);
    +}
    +
    +static int max5487_spi_remove(struct spi_device *spi)
    +{
    + struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
    + struct max5487_data *data = iio_priv(indio_dev);
    +
    + /* save both wiper regs to NV regs */
    + return regmap_write(data->regmap, MAX5487_COPY_AB_TO_NV, 0);
    +}
    +
    +static const struct spi_device_id max5487_id[] = {
    + { "MAX5487", MAX5487 },
    + { "MAX5488", MAX5488 },
    + { "MAX5489", MAX5489 },
    + { }
    +};
    +MODULE_DEVICE_TABLE(spi, max5487_id);
    +
    +static const struct acpi_device_id max5487_acpi_match[] = {
    + { "MAX5487", MAX5487 },
    + { "MAX5488", MAX5488 },
    + { "MAX5489", MAX5489 },
    + { },
    +};
    +MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
    +
    +static struct spi_driver max5487_driver = {
    + .driver = {
    + .name = MAX5487_DRV_NAME,
    + .owner = THIS_MODULE,
    + .acpi_match_table = ACPI_PTR(max5487_acpi_match),
    + },
    + .id_table = max5487_id,
    + .probe = max5487_spi_probe,
    + .remove = max5487_spi_remove
    +};
    +module_spi_driver(max5487_driver);
    +
    +MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>");
    +MODULE_DESCRIPTION("max5487 SPI driver");
    +MODULE_LICENSE("GPL v2");
    --
    2.5.0
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