[PATCH] iio: max5487: Add support for Maxim digital potentiometers
Daniel Baluta
daniel.baluta at gmail.com
Fri Apr 8 16:38:31 EEST 2016
On Fri, Apr 8, 2016 at 3:06 PM, Cristina Moraru
<cristina.moraru09 at gmail.com> wrote:
> Add implementation for Maxim MAX5487, MAX5488, MAX5489
> digital potentiometers.
>
> Datasheet:
> http://datasheets.maximintegrated.com/en/ds/MAX5487-MAX5489.pdf
>
> Signed-off-by: Cristina Moraru <cristina.moraru09 at gmail.com>
> CC: Daniel Baluta <daniel.baluta at intel.com>
Looks good to me!
> ---
> drivers/iio/potentiometer/Kconfig | 11 +++
> drivers/iio/potentiometer/Makefile | 1 +
> drivers/iio/potentiometer/max5487.c | 169 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 181 insertions(+)
> create mode 100644 drivers/iio/potentiometer/max5487.c
>
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index fd75db7..242c62d 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 8afe492..bc2dfd8 100644
> --- a/drivers/iio/potentiometer/Makefile
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -3,4 +3,5 @@
> #
>
> # When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_MAX5487) += max5487.o
> obj-$(CONFIG_MCP4531) += mcp4531.o
> diff --git a/drivers/iio/potentiometer/max5487.c b/drivers/iio/potentiometer/max5487.c
> new file mode 100644
> index 0000000..467c227
> --- /dev/null
> +++ b/drivers/iio/potentiometer/max5487.c
> @@ -0,0 +1,169 @@
> +/*
> + * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
> + *
> + * Copyright (C) Cristina-Gabriela Moraru <cristina.moraru09 at 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
> +
> +#define MAX5487_MAX_POS 255
> +
> +struct max5487_data {
> + struct regmap *regmap;
> + int kohms;
> +};
> +
> +#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 * data->kohms;
> + *val2 = MAX5487_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_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->kohms = 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", 10 },
> + { "MAX5488", 50 },
> + { "MAX5489", 100 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(spi, max5487_id);
> +
> +static const struct acpi_device_id max5487_acpi_match[] = {
> + { "MAX5487", 10 },
> + { "MAX5488", 50 },
> + { "MAX5489", 100 },
> + { },
> +};
> +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 at gmail.com>");
> +MODULE_DESCRIPTION("max5487 SPI driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.9.1
>
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