Re: [PATCH v3] iio: max5487: Add support for Maxim digital potentiometers

[Matt Ranostay]

Slight nitpick below.

On Tue, May 17, 2016 at 6:11 AM, Cristina Moraru
<cristina.moraru09@xxxxxxxxx> 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@xxxxxxxxx>
> CC: Daniel Baluta <daniel.baluta@xxxxxxxxx>
> ---
> Changes since v2:
>         Change switch statement in max5487_write_raw
>         to if statement for consistency
>         Add blank line before return statement
>         Eliminate regmap support and use spi_write
>         Use iio_device_register instead of devm_ version
> Changes since v1:
>         Fix spacing
>         Eliminate max5487_cfg struct
>         Add kohms as driver data
>
>  drivers/iio/potentiometer/Kconfig   |  11 +++
>  drivers/iio/potentiometer/Makefile  |   1 +
>  drivers/iio/potentiometer/max5487.c | 162 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 174 insertions(+)
>  create mode 100644 drivers/iio/potentiometer/max5487.c
>
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index 6acb238..bb77b50 100644
> --- a/drivers/iio/potentiometer/Kconfig
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -15,6 +15,17 @@ config DS1803
>           To compile this driver as a module, choose M here: the
>           module will be called ds1803.
>
> +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 MCP4131
>         tristate "Microchip MCP413X/414X/415X/416X/423X/424X/425X/426X Digital Potentiometer driver"
>         depends on SPI
> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> index 6007faa..8adb58f 100644
> --- a/drivers/iio/potentiometer/Makefile
> +++ b/drivers/iio/potentiometer/Makefile
> @@ -4,6 +4,7 @@
>
>  # When adding new entries keep the list in alphabetical order
>  obj-$(CONFIG_DS1803) += ds1803.o
> +obj-$(CONFIG_MAX5487) += max5487.o
>  obj-$(CONFIG_MCP4131) += mcp4131.o
>  obj-$(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..d5c9089
> --- /dev/null
> +++ b/drivers/iio/potentiometer/max5487.c
> @@ -0,0 +1,162 @@
> +/*
> + * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
> + *
> + * Copyright (C) Cristina-Gabriela Moraru <cristina.moraru09@xxxxxxxxx>

You'll want to put a year for the copyright.

> + *
> + * 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/iio/sysfs.h>
> +#include <linux/iio/iio.h>
> +
> +#define MAX5487_WRITE_WIPER_A  (0x01 << 8)
> +#define MAX5487_WRITE_WIPER_B  (0x02 << 8)
> +
> +/* copy both wiper regs to NV regs */
> +#define MAX5487_COPY_AB_TO_NV  (0x23 << 8)
> +/* copy both NV regs to wiper regs */
> +#define MAX5487_COPY_NV_TO_AB  (0x33 << 8)
> +
> +#define MAX5487_MAX_POS                255
> +#define MAX5487_REG_SIZE       16
> +
> +struct max5487_data {
> +       struct spi_device *spi;
> +       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_write_cmd(struct spi_device *spi, int cmd)
> +{
> +       return spi_write(spi, (const void *) &cmd, MAX5487_REG_SIZE);
> +}
> +
> +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);
> +
> +       if (mask != IIO_CHAN_INFO_RAW)
> +               return -EINVAL;
> +
> +       if (val < 0 || val > MAX5487_MAX_POS)
> +               return -EINVAL;
> +
> +       return max5487_write_cmd(data->spi, chan->address | val);
> +}
> +
> +static const struct iio_info max5487_info = {
> +       .read_raw = max5487_read_raw,
> +       .write_raw = max5487_write_raw,
> +       .driver_module = THIS_MODULE,
> +};
> +
> +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->spi = spi;
> +       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 = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
> +       if (ret < 0)
> +               return ret;
> +
> +       return iio_device_register(indio_dev);
> +}
> +
> +static int max5487_spi_remove(struct spi_device *spi)
> +{
> +       struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
> +
> +       iio_device_unregister(indio_dev);
> +
> +       /* save both wiper regs to NV regs */
> +       return max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
> +}
> +
> +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",
> +               .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@xxxxxxxxx>");
> +MODULE_DESCRIPTION("max5487 SPI driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.9.1
>