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Message-Id: <20190721175915.27192-1-martin@kaiser.cx>
Date: Sun, 21 Jul 2019 19:59:15 +0200
From: Martin Kaiser <martin@...ser.cx>
To: Jonathan Cameron <jic23@...nel.org>,
Hartmut Knaack <knaack.h@....de>,
Lars-Peter Clausen <lars@...afoo.de>,
Rob Herring <robh+dt@...nel.org>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, Martin Kaiser <martin@...ser.cx>
Subject: [PATCH] iio: potentiometer: add a driver for Maxim 5432-5435
Add a driver for the Maxim Integrated MAX5432-MAX5435 family of digital
potentiometers.
These potentiometers are connected via I2C and have 32 wiper positions.
Supported functionality
- set the volatile wiper position
- read the potentiometer scale
Datasheet:
https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf
Signed-off-by: Martin Kaiser <martin@...ser.cx>
---
.../bindings/iio/potentiometer/max5432.txt | 22 ++++
drivers/iio/potentiometer/Kconfig | 11 ++
drivers/iio/potentiometer/Makefile | 1 +
drivers/iio/potentiometer/max5432.c | 131 +++++++++++++++++++++
4 files changed, 165 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/max5432.txt
create mode 100644 drivers/iio/potentiometer/max5432.c
diff --git a/Documentation/devicetree/bindings/iio/potentiometer/max5432.txt b/Documentation/devicetree/bindings/iio/potentiometer/max5432.txt
new file mode 100644
index 000000000000..89ccc8fc7df1
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/potentiometer/max5432.txt
@@ -0,0 +1,22 @@
+* Maxim Integrated MAX5432-MAX5435 Digital Potentiometers.
+
+The node for this driver must be a child node of an 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,max5432"
+ "maxim,max5433"
+ "maxim,max5434"
+ "maxim,max5435"
+
+Example:
+max5434@28 {
+ compatible = "maxim,max5434";
+ reg = <0x28>;
+};
diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index ebc7c72a5e36..4cac0173db8b 100644
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -26,6 +26,17 @@ config DS1803
To compile this driver as a module, choose M here: the
module will be called ds1803.
+config MAX5432
+ tristate "Maxim MAX5432-MAX5435 Digital Potentiometer driver"
+ depends on I2C
+ help
+ Say yes here to build support for the Maxim
+ MAX5432, MAX5433, MAX5434 and MAX5435 digital
+ potentiometer chips.
+
+ To compile this driver as a module, choose M here: the
+ module will be called max5432.
+
config MAX5481
tristate "Maxim MAX5481-MAX5484 Digital Potentiometer driver"
depends on SPI
diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
index 8ff55138cf12..091adf3cdd0b 100644
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -6,6 +6,7 @@
# When adding new entries keep the list in alphabetical order
obj-$(CONFIG_AD5272) += ad5272.o
obj-$(CONFIG_DS1803) += ds1803.o
+obj-$(CONFIG_MAX5432) += max5432.o
obj-$(CONFIG_MAX5481) += max5481.o
obj-$(CONFIG_MAX5487) += max5487.o
obj-$(CONFIG_MCP4018) += mcp4018.o
diff --git a/drivers/iio/potentiometer/max5432.c b/drivers/iio/potentiometer/max5432.c
new file mode 100644
index 000000000000..959883297fb5
--- /dev/null
+++ b/drivers/iio/potentiometer/max5432.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Maxim Integrated MAX5432-MAX5435 digital potentiometer driver
+ * Copyright (C) 2019 Martin Kaiser <martin@...ser.cx>
+ *
+ * Datasheet:
+ * https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf
+ */
+
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* All chip variants have 32 wiper positions. */
+#define MAX5432_MAX_POS 31
+
+#define OHM_50K (50 * 1000)
+#define OHM_100K (100 * 1000)
+
+/* Update the volatile (currently active) setting. */
+#define CMD_VREG 0x11
+
+struct max5432_data {
+ struct i2c_client *client;
+ u32 ohm;
+};
+
+static const struct iio_chan_spec max5432_channels[] = {
+ {
+ .type = IIO_RESISTANCE,
+ .indexed = 1,
+ .output = 1,
+ .channel = 0,
+ .address = CMD_VREG,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+ }
+};
+
+static int max5432_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct max5432_data *data = iio_priv(indio_dev);
+
+ if (mask != IIO_CHAN_INFO_SCALE)
+ return -EINVAL;
+
+ *val = data->ohm;
+ *val2 = MAX5432_MAX_POS;
+
+ return IIO_VAL_FRACTIONAL;
+}
+
+static int max5432_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct max5432_data *data = iio_priv(indio_dev);
+ u8 data_byte;
+
+ if (mask != IIO_CHAN_INFO_RAW)
+ return -EINVAL;
+
+ if (val < 0 || val > MAX5432_MAX_POS)
+ return -EINVAL;
+
+ if (val2 != 0)
+ return -EINVAL;
+
+ /* Wiper position is in bits D7-D3. (D2-D0 are don't care bits.) */
+ data_byte = val << 3;
+ return i2c_smbus_write_byte_data(
+ data->client, chan->address, data_byte);
+}
+
+static const struct iio_info max5432_info = {
+ .read_raw = max5432_read_raw,
+ .write_raw = max5432_write_raw,
+};
+
+static int max5432_probe(
+ struct i2c_client *client, const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct iio_dev *indio_dev;
+ struct max5432_data *data;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(struct max5432_data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ i2c_set_clientdata(client, indio_dev);
+
+ data = iio_priv(indio_dev);
+ data->client = client;
+ data->ohm = (u32)of_device_get_match_data(dev);
+
+ indio_dev->dev.parent = dev;
+ indio_dev->info = &max5432_info;
+ indio_dev->channels = max5432_channels;
+ indio_dev->num_channels = ARRAY_SIZE(max5432_channels);
+ indio_dev->name = client->name;
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id max5432_dt_ids[] = {
+ { .compatible = "maxim,max5432", .data = (void *)OHM_50K },
+ { .compatible = "maxim,max5433", .data = (void *)OHM_100K },
+ { .compatible = "maxim,max5434", .data = (void *)OHM_50K },
+ { .compatible = "maxim,max5435", .data = (void *)OHM_100K },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, max5432_dt_ids);
+
+static struct i2c_driver max5432_driver = {
+ .driver = {
+ .name = "max5432",
+ .of_match_table = of_match_ptr(max5432_dt_ids),
+ },
+ .probe = max5432_probe,
+};
+
+module_i2c_driver(max5432_driver);
+
+MODULE_AUTHOR("Martin Kaiser <martin@...ser.cx>");
+MODULE_DESCRIPTION("max5432-max5435 digital potentiometers");
+MODULE_LICENSE("GPL v2");
--
2.11.0
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