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827dca3129
Temperature is stored as 16bit value in two's complement format. Current
implementation ignores the sign bit. Make it aware of the sign bit by
using sign_extend32.
Fixes: 3f6b9598b6 ("iio: temperature: Add MCP9600 thermocouple EMF converter")
Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Tested-by: Andrew Hepp <andrew.hepp@ahepp.dev>
Link: https://lore.kernel.org/r/20240424185913.1177127-1-dima.fedrau@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
141 lines
3.1 KiB
C
141 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* mcp9600.c - Support for Microchip MCP9600 thermocouple EMF converter
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*
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* Copyright (c) 2022 Andrew Hepp
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* Author: <andrew.hepp@ahepp.dev>
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*/
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/init.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/iio/iio.h>
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/* MCP9600 registers */
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#define MCP9600_HOT_JUNCTION 0x0
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#define MCP9600_COLD_JUNCTION 0x2
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#define MCP9600_DEVICE_ID 0x20
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/* MCP9600 device id value */
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#define MCP9600_DEVICE_ID_MCP9600 0x40
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static const struct iio_chan_spec mcp9600_channels[] = {
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{
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.type = IIO_TEMP,
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.address = MCP9600_HOT_JUNCTION,
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.info_mask_separate =
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BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
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},
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{
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.type = IIO_TEMP,
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.address = MCP9600_COLD_JUNCTION,
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.channel2 = IIO_MOD_TEMP_AMBIENT,
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.modified = 1,
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.info_mask_separate =
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BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
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},
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};
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struct mcp9600_data {
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struct i2c_client *client;
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};
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static int mcp9600_read(struct mcp9600_data *data,
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struct iio_chan_spec const *chan, int *val)
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{
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int ret;
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ret = i2c_smbus_read_word_swapped(data->client, chan->address);
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if (ret < 0)
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return ret;
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*val = sign_extend32(ret, 15);
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return 0;
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}
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static int mcp9600_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int *val,
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int *val2, long mask)
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{
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struct mcp9600_data *data = iio_priv(indio_dev);
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int ret;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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ret = mcp9600_read(data, chan, val);
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if (ret)
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return ret;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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*val = 62;
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*val2 = 500000;
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return IIO_VAL_INT_PLUS_MICRO;
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default:
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return -EINVAL;
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}
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}
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static const struct iio_info mcp9600_info = {
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.read_raw = mcp9600_read_raw,
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};
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static int mcp9600_probe(struct i2c_client *client)
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{
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struct iio_dev *indio_dev;
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struct mcp9600_data *data;
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int ret;
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ret = i2c_smbus_read_byte_data(client, MCP9600_DEVICE_ID);
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if (ret < 0)
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return dev_err_probe(&client->dev, ret, "Failed to read device ID\n");
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if (ret != MCP9600_DEVICE_ID_MCP9600)
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dev_warn(&client->dev, "Expected ID %x, got %x\n",
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MCP9600_DEVICE_ID_MCP9600, ret);
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indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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data = iio_priv(indio_dev);
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data->client = client;
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indio_dev->info = &mcp9600_info;
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indio_dev->name = "mcp9600";
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = mcp9600_channels;
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indio_dev->num_channels = ARRAY_SIZE(mcp9600_channels);
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return devm_iio_device_register(&client->dev, indio_dev);
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}
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static const struct i2c_device_id mcp9600_id[] = {
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{ "mcp9600" },
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{}
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};
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MODULE_DEVICE_TABLE(i2c, mcp9600_id);
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static const struct of_device_id mcp9600_of_match[] = {
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{ .compatible = "microchip,mcp9600" },
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{}
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};
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MODULE_DEVICE_TABLE(of, mcp9600_of_match);
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static struct i2c_driver mcp9600_driver = {
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.driver = {
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.name = "mcp9600",
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.of_match_table = mcp9600_of_match,
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},
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.probe = mcp9600_probe,
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.id_table = mcp9600_id
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};
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module_i2c_driver(mcp9600_driver);
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MODULE_AUTHOR("Andrew Hepp <andrew.hepp@ahepp.dev>");
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MODULE_DESCRIPTION("Microchip MCP9600 thermocouple EMF converter driver");
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MODULE_LICENSE("GPL");
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