Linux preempt-rt

Check our new training course

Real-Time Linux with PREEMPT_RT

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Digital temperature sensor with integrated Non-volatile memory
 * Copyright (c) 2021 Puranjay Mohan <puranjay12@gmail.com>
 *
 * Driver for the Texas Instruments TMP117 Temperature Sensor
 * (7-bit I2C slave address (0x48 - 0x4B), changeable via ADD pins)
 *
 * Note: This driver assumes that the sensor has been calibrated beforehand.
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/limits.h>

#include <linux/iio/iio.h>

#define TMP117_REG_TEMP			0x0
#define TMP117_REG_CFGR			0x1
#define TMP117_REG_HIGH_LIM		0x2
#define TMP117_REG_LOW_LIM		0x3
#define TMP117_REG_EEPROM_UL		0x4
#define TMP117_REG_EEPROM1		0x5
#define TMP117_REG_EEPROM2		0x6
#define TMP117_REG_TEMP_OFFSET		0x7
#define TMP117_REG_EEPROM3		0x8
#define TMP117_REG_DEVICE_ID		0xF

#define TMP117_RESOLUTION_10UC		78125
#define TMP117_DEVICE_ID		0x0117
#define MICRODEGREE_PER_10MILLIDEGREE	10000

struct tmp117_data {
	struct i2c_client *client;
	s16 calibbias;
};

static int tmp117_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *channel, int *val,
		int *val2, long mask)
{
	struct tmp117_data *data = iio_priv(indio_dev);
	s32 ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = i2c_smbus_read_word_swapped(data->client,
						TMP117_REG_TEMP);
		if (ret < 0)
			return ret;
		*val = sign_extend32(ret, 15);
		return IIO_VAL_INT;

	case IIO_CHAN_INFO_CALIBBIAS:
		ret = i2c_smbus_read_word_swapped(data->client,
					TMP117_REG_TEMP_OFFSET);
		if (ret < 0)
			return ret;
		*val = sign_extend32(ret, 15);
		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
		/*
		 * Conversion from 10s of uC to mC
		 * as IIO reports temperature in mC
		 */
		*val = TMP117_RESOLUTION_10UC / MICRODEGREE_PER_10MILLIDEGREE;
		*val2 = (TMP117_RESOLUTION_10UC %
					MICRODEGREE_PER_10MILLIDEGREE) * 100;

		return IIO_VAL_INT_PLUS_MICRO;

	default:
		return -EINVAL;
	}
}

static int tmp117_write_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *channel, int val,
		int val2, long mask)
{
	struct tmp117_data *data = iio_priv(indio_dev);
	s16 off;

	switch (mask) {
	case IIO_CHAN_INFO_CALIBBIAS:
		off = clamp_t(int, val, S16_MIN, S16_MAX);
		if (off == data->calibbias)
			return 0;
		data->calibbias = off;
		return i2c_smbus_write_word_swapped(data->client,
						TMP117_REG_TEMP_OFFSET, off);

	default:
		return -EINVAL;
	}
}

static const struct iio_chan_spec tmp117_channels[] = {
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
			BIT(IIO_CHAN_INFO_CALIBBIAS) | BIT(IIO_CHAN_INFO_SCALE),
	},
};

static const struct iio_info tmp117_info = {
	.read_raw = tmp117_read_raw,
	.write_raw = tmp117_write_raw,
};

static int tmp117_identify(struct i2c_client *client)
{
	int dev_id;

	dev_id = i2c_smbus_read_word_swapped(client, TMP117_REG_DEVICE_ID);
	if (dev_id < 0)
		return dev_id;
	if (dev_id != TMP117_DEVICE_ID) {
		dev_err(&client->dev, "TMP117 not found\n");
		return -ENODEV;
	}
	return 0;
}

static int tmp117_probe(struct i2c_client *client)
{
	struct tmp117_data *data;
	struct iio_dev *indio_dev;
	int ret;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
		return -EOPNOTSUPP;

	ret = tmp117_identify(client);
	if (ret < 0)
		return ret;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev)
		return -ENOMEM;

	data = iio_priv(indio_dev);
	data->client = client;
	data->calibbias = 0;

	indio_dev->name = "tmp117";
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &tmp117_info;

	indio_dev->channels = tmp117_channels;
	indio_dev->num_channels = ARRAY_SIZE(tmp117_channels);

	return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct of_device_id tmp117_of_match[] = {
	{ .compatible = "ti,tmp117", },
	{ }
};
MODULE_DEVICE_TABLE(of, tmp117_of_match);

static const struct i2c_device_id tmp117_id[] = {
	{ "tmp117", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, tmp117_id);

static struct i2c_driver tmp117_driver = {
	.driver = {
		.name	= "tmp117",
		.of_match_table = tmp117_of_match,
	},
	.probe_new	= tmp117_probe,
	.id_table	= tmp117_id,
};
module_i2c_driver(tmp117_driver);

MODULE_AUTHOR("Puranjay Mohan <puranjay12@gmail.com>");
MODULE_DESCRIPTION("TI TMP117 Temperature sensor driver");
MODULE_LICENSE("GPL");