[PATCH v2] iio: potentiometer: add driver for Maxim Integrated DS1803

Slawomir Stepien
2016-04-08T21:27:39Z

The following functions are supported:
- write, read potentiometer value
- potentiometer scale

Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf

Signed-off-by: Slawomir Stepien <sst@poczta.fm>
---
Changes since v1:
- Removed unnecessary include file
- Use i2c_master_recv() in place of i2c_smbus_read_word_swapped()
- On raw write make sure val2 is zero
- Use ARRAY_SIZE when possible

.../bindings/iio/potentiometer/ds1803.txt | 21 +++
drivers/iio/potentiometer/Kconfig | 10 ++
drivers/iio/potentiometer/Makefile | 1 +
drivers/iio/potentiometer/ds1803.c | 174 +++++++++++++++++++++
4 files changed, 206 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt
create mode 100644 drivers/iio/potentiometer/ds1803.c

diff --git a/Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt b/Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt
new file mode 100644
index 0000000..df77bf5
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/potentiometer/ds1803.txt
@@ -0,0 +1,21 @@
+* Maxim Integrated DS1803 digital potentiometer driver
+
+The node for this driver must be a child node of a I2C controller, hence
+all mandatory properties for your controller must be specified. See directory:
+
+ Documentation/devicetree/bindings/i2c
+
+for more details.
+
+Required properties:
+ - compatible: Must be one of the following, depending on the
+ model:
+ "maxim,ds1803-010",
+ "maxim,ds1803-050",
+ "maxim,ds1803-100"
+
+Example:
+ds1803: ds1803@1 {
+ reg = <0x28>;
+ compatible = "maxim,ds1803-010";
+};
diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index 7ea069b..6acb238 100644
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -5,6 +5,16 @@

menu "Digital potentiometers"

+config DS1803
+ tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
+ depends on I2C
+ help
+ Say yes here to build support for the Maxim Integrated DS1803
+ digital potentiomenter chip.
+
+ To compile this driver as a module, choose M here: the
+ module will be called ds1803.
+
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 91a80f8..6007faa 100644
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -3,6 +3,7 @@
#

# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_DS1803) += ds1803.o
obj-$(CONFIG_MCP4131) += mcp4131.o
obj-$(CONFIG_MCP4531) += mcp4531.o
obj-$(CONFIG_TPL0102) += tpl0102.o
diff --git a/drivers/iio/potentiometer/ds1803.c b/drivers/iio/potentiometer/ds1803.c
new file mode 100644
index 0000000..cfa4cc1
--- /dev/null
+++ b/drivers/iio/potentiometer/ds1803.c
@@ -0,0 +1,174 @@
+/*
+ * Maxim Integrated DS1803 digital potentiometer driver
+ * Copyright (c) 2016 Slawomir Stepien
+ *
+ * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
+ *
+ * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address
+ * ds1803 2 256 10, 50, 100 0101xxx
+ *
+ * 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/err.h>
+#include <linux/export.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#define DS1803_MAX_POS 255
+#define DS1803_WRITE(chan) (0xa8 | ((chan) + 1))
+
+enum ds1803_type {
+ DS1803_010,
+ DS1803_050,
+ DS1803_100,
+};
+
+struct ds1803_cfg {
+ int kohms;
+};
+
+static const struct ds1803_cfg ds1803_cfg[] = {
+ [DS1803_010] = { .kohms = 10, },
+ [DS1803_050] = { .kohms = 50, },
+ [DS1803_100] = { .kohms = 100, },
+};
+
+struct ds1803_data {
+ struct i2c_client *client;
+ const struct ds1803_cfg *cfg;
+};
+
+#define DS1803_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 ds1803_channels[] = {
+ DS1803_CHANNEL(0),
+ DS1803_CHANNEL(1),
+};
+
+static int ds1803_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct ds1803_data *data = iio_priv(indio_dev);
+ int pot = chan->channel;
+ int ret;
+ u16 result;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = i2c_master_recv(data->client, (char *)&result,
+ indio_dev->num_channels);
+ if (ret < 0)
+ return ret;
+
+ /* Get bits for given pot */
+ *val = (pot == 0 ? result & 0xff : result >> 8);
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ *val = 1000 * data->cfg->kohms;
+ *val2 = DS1803_MAX_POS;
+ return IIO_VAL_FRACTIONAL;
+ }
+
+ return -EINVAL;
+}
+
+static int ds1803_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct ds1803_data *data = iio_priv(indio_dev);
+ int pot = chan->channel;
+
+ if (val2 != 0)
+ return -EINVAL;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (val > DS1803_MAX_POS || val < 0)
+ return -EINVAL;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return i2c_smbus_write_byte_data(data->client, DS1803_WRITE(pot), val);
+}
+
+static const struct iio_info ds1803_info = {
+ .read_raw = ds1803_read_raw,
+ .write_raw = ds1803_write_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static int ds1803_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct ds1803_data *data;
+ struct iio_dev *indio_dev;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ i2c_set_clientdata(client, indio_dev);
+
+ data = iio_priv(indio_dev);
+ data->client = client;
+ data->cfg = &ds1803_cfg[id->driver_data];
+
+ indio_dev->dev.parent = dev;
+ indio_dev->info = &ds1803_info;
+ indio_dev->channels = ds1803_channels;
+ indio_dev->num_channels = ARRAY_SIZE(ds1803_channels);
+ indio_dev->name = client->name;
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id ds1803_dt_ids[] = {
+ { .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
+ { .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
+ { .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
+ {}
+};
+MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
+#endif /* CONFIG_OF */
+
+static const struct i2c_device_id ds1803_id[] = {
+ { "ds1803-010", DS1803_010 },
+ { "ds1803-050", DS1803_050 },
+ { "ds1803-100", DS1803_100 },
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, ds1803_id);
+
+static struct i2c_driver ds1803_driver = {
+ .driver = {
+ .name = "ds1803",
+ .of_match_table = of_match_ptr(ds1803_dt_ids),
+ },
+ .probe = ds1803_probe,
+ .id_table = ds1803_id,
+};
+
+module_i2c_driver(ds1803_driver);
+
+MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
+MODULE_DESCRIPTION("DS1803 digital potentiometer");
+MODULE_LICENSE("GPL v2");
--
2.7.4