Re: [PATCH v3 2/2] iio: potentiometer: Add driver support for AD5110

Andy Shevchenko
2021-08-14T19:45:46Z

On Sat, Aug 14, 2021 at 8:57 PM Mugilraj Dhavachelvan
<dmugil2000@gmail.com> wrote:
>
> The AD5110/AD5112/AD5114 provide a nonvolatile solution
> for 128-/64-/32-position adjustment applications, offering
> guaranteed low resistor tolerance errors of ±8% and up to
> ±6 mA current density.

Looks good enough to me, thanks!
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD5110_5112_5114.pdf
> Signed-off-by: Mugilraj Dhavachelvan <dmugil2000@gmail.com>
> ---
> MAINTAINERS | 6 +
> drivers/iio/potentiometer/Kconfig | 10 +
> drivers/iio/potentiometer/Makefile | 1 +
> drivers/iio/potentiometer/ad5110.c | 345 +++++++++++++++++++++++++++++
> 4 files changed, 362 insertions(+)
> create mode 100644 drivers/iio/potentiometer/ad5110.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bd7aff0c120f..cf6e73b87b6e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -452,6 +452,12 @@ S: Maintained
> W: https://parisc.wiki.kernel.org/index.php/AD1889
> F: sound/pci/ad1889.*
>
> +AD5110 ANALOG DEVICES DIGITAL POTENTIOMETERS DRIVER
> +M: Mugilraj Dhavachelvan <dmugil2000@gmail.com>
> +L: linux-iio@vger.kernel.org
> +S: Supported
> +F: drivers/iio/potentiometer/ad5110.c
> +
> AD525X ANALOG DEVICES DIGITAL POTENTIOMETERS DRIVER
> M: Michael Hennerich <michael.hennerich@analog.com>
> S: Supported
> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
> index 4cac0173db8b..832df8da2bc6 100644
> --- a/drivers/iio/potentiometer/Kconfig
> +++ b/drivers/iio/potentiometer/Kconfig
> @@ -6,6 +6,16 @@
>
> menu "Digital potentiometers"
>
> +config AD5110
> + tristate "Analog Devices AD5110 and similar Digital Potentiometer driver"
> + depends on I2C
> + help
> + Say yes here to build support for the Analog Devices AD5110, AD5112
> + and AD5114 digital potentiometer chip.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called ad5110.
> +
> config AD5272
> tristate "Analog Devices AD5272 and similar Digital Potentiometer driver"
> depends on I2C
> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
> index 091adf3cdd0b..5ebb8e3bbd76 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-$(CONFIG_AD5110) += ad5110.o
> obj-$(CONFIG_AD5272) += ad5272.o
> obj-$(CONFIG_DS1803) += ds1803.o
> obj-$(CONFIG_MAX5432) += max5432.o
> diff --git a/drivers/iio/potentiometer/ad5110.c b/drivers/iio/potentiometer/ad5110.c
> new file mode 100644
> index 000000000000..ae18f9e115b2
> --- /dev/null
> +++ b/drivers/iio/potentiometer/ad5110.c
> @@ -0,0 +1,345 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Analog Devices AD5110 digital potentiometer driver
> + *
> + * Copyright (C) 2021 Mugilraj Dhavachelvan <dmugil2000@gmail.com>
> + *
> + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD5110_5112_5114.pdf
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +/* AD5110 commands */
> +#define AD5110_EEPROM_WR 1
> +#define AD5110_RDAC_WR 2
> +#define AD5110_SHUTDOWN 3
> +#define AD5110_RESET 4
> +#define AD5110_RDAC_RD 5
> +#define AD5110_EEPROM_RD 6
> +
> +/* AD5110_EEPROM_RD data */
> +#define AD5110_WIPER_POS 0
> +#define AD5110_RESISTOR_TOL 1
> +
> +#define AD5110_WIPER_RESISTANCE 70
> +
> +struct ad5110_cfg {
> + int max_pos;
> + int kohms;
> + int shift;
> +};
> +
> +enum ad5110_type {
> + AD5110_10,
> + AD5110_80,
> + AD5112_05,
> + AD5112_10,
> + AD5112_80,
> + AD5114_10,
> + AD5114_80,
> +};
> +
> +static const struct ad5110_cfg ad5110_cfg[] = {
> + [AD5110_10] = { .max_pos = 128, .kohms = 10 },
> + [AD5110_80] = { .max_pos = 128, .kohms = 80 },
> + [AD5112_05] = { .max_pos = 64, .kohms = 5, .shift = 1 },
> + [AD5112_10] = { .max_pos = 64, .kohms = 10, .shift = 1 },
> + [AD5112_80] = { .max_pos = 64, .kohms = 80, .shift = 1 },
> + [AD5114_10] = { .max_pos = 32, .kohms = 10, .shift = 2 },
> + [AD5114_80] = { .max_pos = 32, .kohms = 80, .shift = 2 },
> +};
> +
> +struct ad5110_data {
> + struct i2c_client *client;
> + s16 tol; /* resistor tolerance */
> + bool enable;
> + struct mutex lock;
> + const struct ad5110_cfg *cfg;
> + /*
> + * DMA (thus cache coherency maintenance) requires the
> + * transfer buffers to live in their own cache lines.
> + */
> + u8 buf[2] ____cacheline_aligned;
> +};
> +
> +static const struct iio_chan_spec ad5110_channels[] = {
> + {
> + .type = IIO_RESISTANCE,
> + .output = 1,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_OFFSET) |
> + BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_ENABLE),
> + },
> +};
> +
> +static int ad5110_read(struct ad5110_data *data, u8 cmd, int *val)
> +{
> + int ret;
> +
> + mutex_lock(&data->lock);
> + data->buf[0] = cmd;
> + data->buf[1] = *val;
> +
> + ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));
> + if (ret < 0) {
> + goto error;
> + } else if (ret != sizeof(data->buf)) {
> + ret = -EIO;
> + goto error;
> + }
> +
> + ret = i2c_master_recv_dmasafe(data->client, data->buf, 1);
> + if (ret < 0) {
> + goto error;
> + } else if (ret != 1) {
> + ret = -EIO;
> + goto error;
> + }
> +
> + *val = data->buf[0];
> + ret = 0;
> +
> +error:
> + mutex_unlock(&data->lock);
> + return ret;
> +}
> +
> +static int ad5110_write(struct ad5110_data *data, u8 cmd, u8 val)
> +{
> + int ret;
> +
> + mutex_lock(&data->lock);
> + data->buf[0] = cmd;
> + data->buf[1] = val;
> +
> + ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));
> + if (ret < 0) {
> + goto error;
> + } else if (ret != sizeof(data->buf)) {
> + ret = -EIO;
> + goto error;
> + }
> +
> + ret = 0;
> +
> +error:
> + mutex_unlock(&data->lock);
> + return ret;
> +}
> +
> +static int ad5110_resistor_tol(struct ad5110_data *data, u8 cmd, int val)
> +{
> + int ret;
> +
> + ret = ad5110_read(data, cmd, &val);
> + if (ret)
> + return ret;
> +
> + data->tol = data->cfg->kohms * (val & GENMASK(6, 0)) * 10 / 8;
> + if (!(val & BIT(7)))
> + data->tol *= -1;
> +
> + return 0;
> +}
> +
> +static ssize_t store_eeprom_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct ad5110_data *data = iio_priv(indio_dev);
> + int val = AD5110_WIPER_POS;
> + int ret;
> +
> + ret = ad5110_read(data, AD5110_EEPROM_RD, &val);
> + if (ret)
> + return ret;
> +
> + val = val >> data->cfg->shift;
> + return iio_format_value(buf, IIO_VAL_INT, 1, &val);
> +}
> +
> +static ssize_t store_eeprom_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t len)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct ad5110_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + ret = ad5110_write(data, AD5110_EEPROM_WR, 0);
> + if (ret) {
> + dev_err(&data->client->dev, "RDAC to EEPROM write failed\n");
> + return ret;
> + }
> +
> + /* The storing of EEPROM data takes approximately 18 ms. */
> + msleep(20);
> +
> + return len;
> +}
> +
> +static IIO_DEVICE_ATTR_RW(store_eeprom, 0);
> +
> +static struct attribute *ad5110_attributes[] = {
> + &iio_dev_attr_store_eeprom.dev_attr.attr,
> + NULL
> +};
> +
> +static const struct attribute_group ad5110_attribute_group = {
> + .attrs = ad5110_attributes,
> +};
> +
> +static int ad5110_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct ad5110_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = ad5110_read(data, AD5110_RDAC_RD, val);
> + if (ret)
> + return ret;
> +
> + *val = *val >> data->cfg->shift;
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_OFFSET:
> + *val = AD5110_WIPER_RESISTANCE * data->cfg->max_pos;
> + *val2 = 1000 * data->cfg->kohms + data->tol;
> + return IIO_VAL_FRACTIONAL;
> + case IIO_CHAN_INFO_SCALE:
> + *val = 1000 * data->cfg->kohms + data->tol;
> + *val2 = data->cfg->max_pos;
> + return IIO_VAL_FRACTIONAL;
> + case IIO_CHAN_INFO_ENABLE:
> + *val = data->enable;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int ad5110_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct ad5110_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + if (val > data->cfg->max_pos || val < 0)
> + return -EINVAL;
> +
> + return ad5110_write(data, AD5110_RDAC_WR, val << data->cfg->shift);
> + case IIO_CHAN_INFO_ENABLE:
> + if (val < 0 || val > 1)
> + return -EINVAL;
> + if (data->enable == val)
> + return 0;
> + ret = ad5110_write(data, AD5110_SHUTDOWN, val ? 0 : 1);
> + if (ret)
> + return ret;
> + data->enable = val;
> + return 0;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_info ad5110_info = {
> + .read_raw = ad5110_read_raw,
> + .write_raw = ad5110_write_raw,
> + .attrs = &ad5110_attribute_group,
> +};
> +
> +#define AD5110_COMPATIBLE(of_compatible, cfg) { \
> + .compatible = of_compatible, \
> + .data = &ad5110_cfg[cfg], \
> +}
> +
> +static const struct of_device_id ad5110_of_match[] = {
> + AD5110_COMPATIBLE("adi,ad5110-10", AD5110_10),
> + AD5110_COMPATIBLE("adi,ad5110-80", AD5110_80),
> + AD5110_COMPATIBLE("adi,ad5112-05", AD5112_05),
> + AD5110_COMPATIBLE("adi,ad5112-10", AD5112_10),
> + AD5110_COMPATIBLE("adi,ad5112-80", AD5112_80),
> + AD5110_COMPATIBLE("adi,ad5114-10", AD5114_10),
> + AD5110_COMPATIBLE("adi,ad5114-80", AD5114_80),
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, ad5110_of_match);
> +
> +static const struct i2c_device_id ad5110_id[] = {
> + { "ad5110-10", AD5110_10 },
> + { "ad5110-80", AD5110_80 },
> + { "ad5112-05", AD5112_05 },
> + { "ad5112-10", AD5112_10 },
> + { "ad5112-80", AD5112_80 },
> + { "ad5114-10", AD5114_10 },
> + { "ad5114-80", AD5114_80 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, ad5110_id);
> +
> +static int ad5110_probe(struct i2c_client *client)
> +{
> + struct device *dev = &client->dev;
> + struct iio_dev *indio_dev;
> + struct ad5110_data *data;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + data = iio_priv(indio_dev);
> + data->client = client;
> + mutex_init(&data->lock);
> + data->enable = 1;
> + data->cfg = device_get_match_data(dev);
> +
> + /* refresh RDAC register with EEPROM */
> + ret = ad5110_write(data, AD5110_RESET, 0);
> + if (ret) {
> + dev_err(dev, "Refresh RDAC with EEPROM failed\n");
> + return ret;
> + }
> +
> + ret = ad5110_resistor_tol(data, AD5110_EEPROM_RD, AD5110_RESISTOR_TOL);
> + if (ret) {
> + dev_err(dev, "Read resistor tolerance failed\n");
> + return ret;
> + }
> +
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = &ad5110_info;
> + indio_dev->channels = ad5110_channels;
> + indio_dev->num_channels = ARRAY_SIZE(ad5110_channels);
> + indio_dev->name = client->name;
> +
> + return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static struct i2c_driver ad5110_driver = {
> + .driver = {
> + .name = "ad5110",
> + .of_match_table = ad5110_of_match,
> + },
> + .probe_new = ad5110_probe,
> + .id_table = ad5110_id,
> +};
> +module_i2c_driver(ad5110_driver);
> +
> +MODULE_AUTHOR("Mugilraj Dhavachelvan <dmugil2000@gmail.com>");
> +MODULE_DESCRIPTION("AD5110 digital potentiometer");
> +MODULE_LICENSE("GPL v2");
> +
> --
> 2.25.1
>

--
With Best Regards,
Andy Shevchenko