iio: potentiometer: add TI tpl0102 support

Add support for the TI family of digital potentiometers.
Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/potentiometer/Kconfig

@@ -17,4 +17,16 @@ config MCP4531
 	  To compile this driver as a module, choose M here: the
 	  module will be called mcp4531.
 
+config TPL0102
+	tristate "Texas Instruments digital potentiometer driver"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say yes here to build support for the Texas Instruments
+	  TPL0102, TPL0402
+	  digital potentiometer chips.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called tpl0102.
+
 endmenu

drivers/iio/potentiometer/Makefile

@@ -4,3 +4,4 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_MCP4531) += mcp4531.o
+obj-$(CONFIG_TPL0102) += tpl0102.o

drivers/iio/potentiometer/tpl0102.c

+/*
+ * tpl0102.c - Support for Texas Instruments digital potentiometers
+ *
+ * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * TODO: enable/disable hi-z output control
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/iio/iio.h>
+
+struct tpl0102_cfg {
+	int wipers;
+	int max_pos;
+	int kohms;
+};
+
+enum tpl0102_type {
+	CAT5140_503,
+	CAT5140_104,
+	TPL0102_104,
+	TPL0401_103,
+};
+
+static const struct tpl0102_cfg tpl0102_cfg[] = {
+	/* on-semiconductor parts */
+	[CAT5140_503] = { .wipers = 1, .max_pos = 256, .kohms = 50, },
+	[CAT5140_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
+	/* ti parts */
+	[TPL0102_104] = { .wipers = 2, .max_pos = 256, .kohms = 100 },
+	[TPL0401_103] = { .wipers = 1, .max_pos = 128, .kohms = 10, },
+};
+
+struct tpl0102_data {
+	struct regmap *regmap;
+	unsigned long devid;
+};
+
+static const struct regmap_config tpl0102_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+#define TPL0102_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 tpl0102_channels[] = {
+	TPL0102_CHANNEL(0),
+	TPL0102_CHANNEL(1),
+};
+
+static int tpl0102_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct tpl0102_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		int ret = regmap_read(data->regmap, chan->channel, val);
+
+		return ret ? ret : IIO_VAL_INT;
+	}
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1000 * tpl0102_cfg[data->devid].kohms;
+		*val2 = tpl0102_cfg[data->devid].max_pos;
+		return IIO_VAL_FRACTIONAL;
+	}
+
+	return -EINVAL;
+}
+
+static int tpl0102_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct tpl0102_data *data = iio_priv(indio_dev);
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	if (val >= tpl0102_cfg[data->devid].max_pos || val < 0)
+		return -EINVAL;
+
+	return regmap_write(data->regmap, chan->channel, val);
+}
+
+static const struct iio_info tpl0102_info = {
+	.read_raw = tpl0102_read_raw,
+	.write_raw = tpl0102_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int tpl0102_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct tpl0102_data *data;
+	struct iio_dev *indio_dev;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENOTSUPP;
+
+	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->devid = id->driver_data;
+	data->regmap = devm_regmap_init_i2c(client, &tpl0102_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(dev, "regmap initialization failed\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &tpl0102_info;
+	indio_dev->channels = tpl0102_channels;
+	indio_dev->num_channels = tpl0102_cfg[data->devid].wipers;
+	indio_dev->name = client->name;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct i2c_device_id tpl0102_id[] = {
+	{ "cat5140-503", CAT5140_503 },
+	{ "cat5140-104", CAT5140_104 },
+	{ "tpl0102-104", TPL0102_104 },
+	{ "tpl0401-103", TPL0401_103 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, tpl0102_id);
+
+static struct i2c_driver tpl0102_driver = {
+	.driver = {
+		.name = "tpl0102",
+	},
+	.probe = tpl0102_probe,
+	.id_table = tpl0102_id,
+};
+
+module_i2c_driver(tpl0102_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("TPL0102 digital potentiometer");
+MODULE_LICENSE("GPL");