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// SPDX-License-Identifier: GPL-2.0+
/*
* mcp9600.c - Support for Microchip MCP9600 thermocouple EMF converter
*
* Copyright (c) 2022 Andrew Hepp
* Author: <andrew.hepp@ahepp.dev>
*/
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
/* MCP9600 registers */
#define MCP9600_HOT_JUNCTION 0x0
#define MCP9600_COLD_JUNCTION 0x2
#define MCP9600_DEVICE_ID 0x20
/* MCP9600 device id value */
#define MCP9600_DEVICE_ID_MCP9600 0x40
static const struct iio_chan_spec mcp9600_channels[] = {
{
.type = IIO_TEMP,
.address = MCP9600_HOT_JUNCTION,
.info_mask_separate =
BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
},
{
.type = IIO_TEMP,
.address = MCP9600_COLD_JUNCTION,
.channel2 = IIO_MOD_TEMP_AMBIENT,
.modified = 1,
.info_mask_separate =
BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
},
};
struct mcp9600_data {
struct i2c_client *client;
};
static int mcp9600_read(struct mcp9600_data *data,
struct iio_chan_spec const *chan, int *val)
{
int ret;
ret = i2c_smbus_read_word_swapped(data->client, chan->address);
if (ret < 0)
return ret;
*val = sign_extend32(ret, 15);
return 0;
}
static int mcp9600_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
struct mcp9600_data *data = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = mcp9600_read(data, chan, val);
if (ret)
return ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = 62;
*val2 = 500000;
return IIO_VAL_INT_PLUS_MICRO;
default:
return -EINVAL;
}
}
static const struct iio_info mcp9600_info = {
.read_raw = mcp9600_read_raw,
};
static int mcp9600_probe(struct i2c_client *client)
{
struct iio_dev *indio_dev;
struct mcp9600_data *data;
int ret;
ret = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
if (ret < 0)
return dev_err_probe(&client->dev, ret, "Failed to read device ID\n");
if (ret != MCP9600_DEVICE_ID_MCP9600)
dev_warn(&client->dev, "Expected ID %x, got %x\n",
MCP9600_DEVICE_ID_MCP9600, ret);
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
data->client = client;
indio_dev->info = &mcp9600_info;
indio_dev->name = "mcp9600";
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = mcp9600_channels;
indio_dev->num_channels = ARRAY_SIZE(mcp9600_channels);
return devm_iio_device_register(&client->dev, indio_dev);
}
static const struct i2c_device_id mcp9600_id[] = {
{ "mcp9600" },
{}
};
MODULE_DEVICE_TABLE(i2c, mcp9600_id);
static const struct of_device_id mcp9600_of_match[] = {
{ .compatible = "microchip,mcp9600" },
{}
};
MODULE_DEVICE_TABLE(of, mcp9600_of_match);
static struct i2c_driver mcp9600_driver = {
.driver = {
.name = "mcp9600",
.of_match_table = mcp9600_of_match,
},
.probe = mcp9600_probe,
.id_table = mcp9600_id
};
module_i2c_driver(mcp9600_driver);
MODULE_AUTHOR("Andrew Hepp <andrew.hepp@ahepp.dev>");
MODULE_DESCRIPTION("Microchip MCP9600 thermocouple EMF converter driver");
MODULE_LICENSE("GPL");
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