[PATCH] iio: max5487: Add support for Maxim digital potentiometers
Daniel Baluta
daniel.baluta at gmail.com
Wed Mar 9 14:43:31 EET 2016
On Wed, Mar 9, 2016 at 1:07 AM, Cristina Moraru
<cristina.moraru09 at gmail.com> wrote:
> Add implementation for Maxim MAX5487, MAX5488, MAX5489
> digital potentiometers.
>
> Signed-off-by: Cristina Moraru <cristina.moraru09 at gmail.com>
> ---
> drivers/iio/potentiometer/Kconfig | 11 ++
> drivers/iio/potentiometer/Makefile | 1 +
> drivers/iio/potentiometer/max5487.c | 239 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 251 insertions(+)
> create mode 100644 drivers/iio/potentiometer/max5487.c
>
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index fd75db7..a2f8cc2 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..c04d804
> --- /dev/null
> +++ b/drivers/iio/potentiometer/max5487.c
> @@ -0,0 +1,239 @@
> +/*
> + * max5487.c - Support for Maxim 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>
> +
> +/* Register addresses */
> +#define MAX5487_WIPER_A 0x01
> +#define MAX5487_WIPER_B 0x02
> +
> +/* Non-volatile EEPROM memory addresses */
> +#define MAX5487_NONVOLATILE_A 0x11
> +#define MAX5487_NONVOLATILE_B 0x12
> +
> + /* Copy register values to non-volatile memory */
> +#define COPY_WP_NV_A 0x21
> +#define COPY_WP_NV_B 0x22
> +#define COPY_WP_NV_BOTH (COPY_WP_NV_A | COPY_WP_NV_B)
> +
> +/* Copy values from non-volatile memory to registers */
> +#define COPY_NV_WP_A 0x31
> +#define COPY_NV_WP_B 0x32
> +#define COPY_NV_WP_BOTH (COPY_NV_WP_A | COPY_NV_WP_B)
We decided to leave this out for the moment. We can add later patches
to take care of
saving and restoring the wiper position.
> +
> +enum {
> + MAX5487,
> + MAX5488,
> + MAX5489,
> +};
> +
> +struct max5487_cfg {
> + char *name;
This field is never used, remove it.
> + int wipers;
> + int max_pos;
> + int kohms;
> +};
> +
> +#define SUPPORTED_CHIPS 3
> +static const struct max5487_cfg max5487_cfg[] = {
> + [MAX5487] = { .name = "MAX5487", .wipers = 2,
> + .max_pos = 256, .kohms = 10,},
> + [MAX5488] = { .name = "MAX5488", .wipers = 2,
> + .max_pos = 256, .kohms = 50,},
> + [MAX5489] = { .name = "MAX5489", .wipers = 2,
> + .max_pos = 256, .kohms = 100,}
> +};
> +
> +struct max5487_data {
> + struct device *dev;
We don't need dev here. We can always use regamp_get_device to retrieve it.
> + struct mutex lock;
> + struct regmap *regmap;
> + int chip_id;
> +};
> +
> +#define MAX5487_CHANNEL(ch) { \
> + .type = IIO_RESISTANCE, \
> + .indexed = 1, \
> + .output = 1, \
> + .channel = ch, \
> + .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_CHANNEL(1)
> +};
> +
> +static IIO_CONST_ATTR(resistance_available, "0-255");
> +
> +static struct attribute *max5487_attributes[] = {
> + &iio_const_attr_resistance_available.dev_attr.attr,
> + NULL
> +};
> +
There is no standard attribute for restistance available. I'm not sure
if this is the proper way to describe a discrete range of resistor values.
So, for the moment please lets leave this out.
> +static const struct attribute_group max5487_group = {
> + .attrs = max5487_attributes,
> +};
> +
> +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);
> + int wiper, ret;
> +
> + wiper = (chan->channel) ? MAX5487_WIPER_B : MAX5487_WIPER_A;
No need for parenthesis around chan->channel.
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + if (val < 0 || val > max5487_cfg[data->chip_id].max_pos)
> + return -EINVAL;
> + mutex_lock(&data->lock);
> + ret = regmap_write(data->regmap, wiper, val);
> + mutex_unlock(&data->lock);
> + return ret;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +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);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SCALE:
> + *val = 1000 * max5487_cfg[data->chip_id].kohms;
> + *val2 = max5487_cfg[data->chip_id].max_pos;
> + return IIO_VAL_FRACTIONAL;
> + }
> + return -EINVAL;
> +}
> +
> +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);
> + int ret;
> +
> + /* Store wiper values to non-volatile memory */
> + mutex_lock(&data->lock);
> + ret = regmap_write(data->regmap, MAX5487_WIPER_A, 0);
> + if (ret)
> + goto exit_unlock;
> +
> + ret = regmap_write(data->regmap, MAX5487_WIPER_B, 0);
> +
> +exit_unlock:
> + mutex_unlock(&data->lock);
> + return ret;
> +}
> +
> +static const struct iio_info max5487_info = {
> + .attrs = &max5487_group,
> + .read_raw = &max5487_read_raw,
> + .write_raw = &max5487_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static const struct regmap_range max5487_writable_ranges[] = {
> + regmap_reg_range(0, 0x22)
> +};
> +
> +static const struct regmap_access_table max5487_writable_table = {
> + .yes_ranges = max5487_writable_ranges,
> + .n_yes_ranges = ARRAY_SIZE(max5487_writable_ranges),
> +};
> +
> +static const struct regmap_config max5487_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> + .wr_table = &max5487_writable_table,
> +};
> +
> +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, i;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
> + if (indio_dev == NULL)
> + return -ENOMEM;
> +
> + spi->mode = SPI_MODE_3;
> + spi->max_speed_hz = 5000000;
> + spi->bits_per_word = 16;
> + ret = spi_setup(spi);
> + if (ret)
> + return ret;
> +
> + dev_set_drvdata(&spi->dev, indio_dev);
> + data = iio_priv(indio_dev);
> + data->dev = &spi->dev;
> + data->regmap = devm_regmap_init_spi(spi, &max5487_regmap_config);
> + mutex_init(&data->lock);
> + for (i = 0; i < SUPPORTED_CHIPS; i++)
> + if (!strcmp(indio_dev->name, max5487_cfg[i].name))
> + data->chip_id = i;
> +
We should know by now for which chip the probe function was called. So, here
we can directly use 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);
> +
> + return iio_device_register(indio_dev);
> +}
> +
> +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",
> + .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");
> --
> 1.9.1
>
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