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

Mugilraj Dhavachelvan
2021-08-14T17:57:22Z

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.

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