// 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/mod_devicetable.h>
#include <linux/property.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,
};

#define MCP4018_ID_TABLE(_name, cfg) {				\
	.name = _name,						\
	.driver_data = (kernel_ulong_t)&mcp4018_cfg[cfg],	\
}

static const struct i2c_device_id mcp4018_id[] = {
	MCP4018_ID_TABLE("mcp4017-502", MCP4018_502),
	MCP4018_ID_TABLE("mcp4017-103", MCP4018_103),
	MCP4018_ID_TABLE("mcp4017-503", MCP4018_503),
	MCP4018_ID_TABLE("mcp4017-104", MCP4018_104),
	MCP4018_ID_TABLE("mcp4018-502", MCP4018_502),
	MCP4018_ID_TABLE("mcp4018-103", MCP4018_103),
	MCP4018_ID_TABLE("mcp4018-503", MCP4018_503),
	MCP4018_ID_TABLE("mcp4018-104", MCP4018_104),
	MCP4018_ID_TABLE("mcp4019-502", MCP4018_502),
	MCP4018_ID_TABLE("mcp4019-103", MCP4018_103),
	MCP4018_ID_TABLE("mcp4019-503", MCP4018_503),
	MCP4018_ID_TABLE("mcp4019-104", MCP4018_104),
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, mcp4018_id);

#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);

static int mcp4018_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct mcp4018_data *data;
	struct iio_dev *indio_dev;

	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;

	data->cfg = i2c_get_match_data(client);

	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 struct i2c_driver mcp4018_driver = {
	.driver = {
		.name	= "mcp4018",
		.of_match_table = 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 v2");