4 files changed, 207 insertions, 1 deletions

diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index 8daf6d1f4e05..79ec2eba4969 100644
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -47,6 +47,17 @@ config MAX5487
           To compile this driver as a module, choose M here: the
           module will be called max5487.
 
+config MCP4018
+	tristate "Microchip MCP4017/18/19 Digital Potentiometer driver"
+	depends on I2C
+	help
+	  Say yes here to build support for the Microchip
+	  MCP4017, MCP4018, MCP4019
+	  digital potentiometer chips.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mcp4018.
+
 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 dbc139cec376..4af657883c3f 100644
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_AD5272) += ad5272.o
 obj-$(CONFIG_DS1803) += ds1803.o
 obj-$(CONFIG_MAX5481) += max5481.o
 obj-$(CONFIG_MAX5487) += max5487.o
+obj-$(CONFIG_MCP4018) += mcp4018.o
 obj-$(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
index 9b0ff4ab2f9c..6bf12c9eccbd 100644
--- a/drivers/iio/potentiometer/ds1803.c
+++ b/drivers/iio/potentiometer/ds1803.c
@@ -64,7 +64,7 @@ static int ds1803_read_raw(struct iio_dev *indio_dev,
 	struct ds1803_data *data = iio_priv(indio_dev);
 	int pot = chan->channel;
 	int ret;
-	u8 result[indio_dev->num_channels];
+	u8 result[ARRAY_SIZE(ds1803_channels)];
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
diff --git a/drivers/iio/potentiometer/mcp4018.c b/drivers/iio/potentiometer/mcp4018.c
new file mode 100644
index 000000000000..601b25d1f387
--- /dev/null
+++ b/drivers/iio/potentiometer/mcp4018.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Industrial I/O driver for Microchip digital potentiometers
+ * Copyright (c) 2018  Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22147a.pdf
+ *
+ * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)
+ * mcp4017	1	128		5, 10, 50, 100
+ * mcp4018	1	128		5, 10, 50, 100
+ * mcp4019	1	128		5, 10, 50, 100
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#define MCP4018_WIPER_MAX 127
+
+struct mcp4018_cfg {
+	int kohms;
+};
+
+enum mcp4018_type {
+	MCP4018_502,
+	MCP4018_103,
+	MCP4018_503,
+	MCP4018_104,
+};
+
+static const struct mcp4018_cfg mcp4018_cfg[] = {
+	[MCP4018_502] = { .kohms =   5, },
+	[MCP4018_103] = { .kohms =  10, },
+	[MCP4018_503] = { .kohms =  50, },
+	[MCP4018_104] = { .kohms = 100, },
+};
+
+struct mcp4018_data {
+	struct i2c_client *client;
+	const struct mcp4018_cfg *cfg;
+};
+
+static const struct iio_chan_spec mcp4018_channel = {
+	.type = IIO_RESISTANCE,
+	.indexed = 1,
+	.output = 1,
+	.channel = 0,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+};
+
+static int mcp4018_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct mcp4018_data *data = iio_priv(indio_dev);
+	s32 ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = i2c_smbus_read_byte(data->client);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1000 * data->cfg->kohms;
+		*val2 = MCP4018_WIPER_MAX;
+		return IIO_VAL_FRACTIONAL;
+	}
+
+	return -EINVAL;
+}
+
+static int mcp4018_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct mcp4018_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (val > MCP4018_WIPER_MAX || val < 0)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return i2c_smbus_write_byte(data->client, val);
+}
+
+static const struct iio_info mcp4018_info = {
+	.read_raw = mcp4018_read_raw,
+	.write_raw = mcp4018_write_raw,
+};
+
+#ifdef CONFIG_OF
+
+#define MCP4018_COMPATIBLE(of_compatible, cfg) {	\
+	.compatible = of_compatible,			\
+	.data = &mcp4018_cfg[cfg],			\
+}
+
+static const struct of_device_id mcp4018_of_match[] = {
+	MCP4018_COMPATIBLE("microchip,mcp4017-502", MCP4018_502),
+	MCP4018_COMPATIBLE("microchip,mcp4017-103", MCP4018_103),
+	MCP4018_COMPATIBLE("microchip,mcp4017-503", MCP4018_503),
+	MCP4018_COMPATIBLE("microchip,mcp4017-104", MCP4018_104),
+	MCP4018_COMPATIBLE("microchip,mcp4018-502", MCP4018_502),
+	MCP4018_COMPATIBLE("microchip,mcp4018-103", MCP4018_103),
+	MCP4018_COMPATIBLE("microchip,mcp4018-503", MCP4018_503),
+	MCP4018_COMPATIBLE("microchip,mcp4018-104", MCP4018_104),
+	MCP4018_COMPATIBLE("microchip,mcp4019-502", MCP4018_502),
+	MCP4018_COMPATIBLE("microchip,mcp4019-103", MCP4018_103),
+	MCP4018_COMPATIBLE("microchip,mcp4019-503", MCP4018_503),
+	MCP4018_COMPATIBLE("microchip,mcp4019-104", MCP4018_104),
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mcp4018_of_match);
+
+#endif
+
+static int mcp4018_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct mcp4018_data *data;
+	struct iio_dev *indio_dev;
+	const struct of_device_id *match;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_BYTE)) {
+		dev_err(dev, "SMBUS Byte transfers not supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	match = of_match_device(of_match_ptr(mcp4018_of_match), dev);
+	if (match)
+		data->cfg = of_device_get_match_data(dev);
+	else
+		data->cfg = &mcp4018_cfg[id->driver_data];
+
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &mcp4018_info;
+	indio_dev->channels = &mcp4018_channel;
+	indio_dev->num_channels = 1;
+	indio_dev->name = client->name;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct i2c_device_id mcp4018_id[] = {
+	{ "mcp4017-502", MCP4018_502 },
+	{ "mcp4017-103", MCP4018_103 },
+	{ "mcp4017-503", MCP4018_503 },
+	{ "mcp4017-104", MCP4018_104 },
+	{ "mcp4018-502", MCP4018_502 },
+	{ "mcp4018-103", MCP4018_103 },
+	{ "mcp4018-503", MCP4018_503 },
+	{ "mcp4018-104", MCP4018_104 },
+	{ "mcp4019-502", MCP4018_502 },
+	{ "mcp4019-103", MCP4018_103 },
+	{ "mcp4019-503", MCP4018_503 },
+	{ "mcp4019-104", MCP4018_104 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, mcp4018_id);
+
+static struct i2c_driver mcp4018_driver = {
+	.driver = {
+		.name	= "mcp4018",
+		.of_match_table = of_match_ptr(mcp4018_of_match),
+	},
+	.probe		= mcp4018_probe,
+	.id_table	= mcp4018_id,
+};
+
+module_i2c_driver(mcp4018_driver);
+
+MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
+MODULE_DESCRIPTION("MCP4018 digital potentiometer");
+MODULE_LICENSE("GPL");