Commit 761c1770 authored by Maciej S. Szmigiero's avatar Maciej S. Szmigiero Committed by Guenter Roeck
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hwmon: add driver for Microchip TC74

Add hwmon driver for the Microchip TC74.

The TC74 is a single-input 8-bit I2C temperature sensor,
with +-2 degrees centigrade accuracy.
Signed-off-by: default avatarMaciej Szmigiero <>
Signed-off-by: default avatarGuenter Roeck <>
parent f6725ae2
Kernel driver tc74
Supported chips:
* Microchip TC74
Prefix: 'tc74'
Datasheet: Publicly available at Microchip website.
Driver supports the above part.
The tc74 has an 8-bit sensor, with 1 degree centigrade resolution
and +- 2 degrees centigrade accuracy.
Currently entering low power standby mode is not supported.
......@@ -1452,6 +1452,16 @@ config SENSORS_INA2XX
This driver can also be built as a module. If so, the module
will be called ina2xx.
config SENSORS_TC74
tristate "Microchip TC74"
depends on I2C
If you say yes here you get support for Microchip TC74 single
input temperature sensor chips.
This driver can also be built as a module. If so, the module
will be called tc74.
tristate "Texas Instruments THMC50 / Analog Devices ADM1022"
depends on I2C
......@@ -140,6 +140,7 @@ obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
obj-$(CONFIG_SENSORS_SMSC47M1) += smsc47m1.o
obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
obj-$(CONFIG_SENSORS_AMC6821) += amc6821.o
obj-$(CONFIG_SENSORS_TC74) += tc74.o
obj-$(CONFIG_SENSORS_THMC50) += thmc50.o
obj-$(CONFIG_SENSORS_TMP102) += tmp102.o
obj-$(CONFIG_SENSORS_TMP103) += tmp103.o
* An hwmon driver for the Microchip TC74
* Copyright 2015 Maciej Szmigiero <>
* Based on ad7414.c:
* Copyright 2006 Stefan Roese, DENX Software Engineering
* Copyright 2008 Sean MacLennan, PIKA Technologies
* Copyright 2008 Frank Edelhaeuser, Spansion Inc.
* 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.
#include <linux/bitops.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/i2c.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
/* TC74 registers */
#define TC74_REG_TEMP 0x00
#define TC74_REG_CONFIG 0x01
struct tc74_data {
struct i2c_client *client;
struct mutex lock; /* atomic read data updates */
bool valid; /* validity of fields below */
unsigned long next_update; /* In jiffies */
s8 temp_input; /* Temp value in dC */
static int tc74_update_device(struct device *dev)
struct tc74_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
int ret;
ret = mutex_lock_interruptible(&data->lock);
if (ret)
return ret;
if (time_after(jiffies, data->next_update) || !data->valid) {
s32 value;
value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
if (value < 0) {
dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
ret = value;
goto ret_unlock;
if (!(value & BIT(6))) {
/* not ready yet */
ret = -EAGAIN;
goto ret_unlock;
value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);
if (value < 0) {
dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
ret = value;
goto ret_unlock;
data->temp_input = value;
data->next_update = jiffies + HZ / 4;
data->valid = true;
return ret;
static ssize_t show_temp_input(struct device *dev,
struct device_attribute *attr, char *buf)
struct tc74_data *data = dev_get_drvdata(dev);
int ret;
ret = tc74_update_device(dev);
if (ret)
return ret;
return sprintf(buf, "%d\n", data->temp_input * 1000);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
static struct attribute *tc74_attrs[] = {
static int tc74_probe(struct i2c_client *client,
const struct i2c_device_id *dev_id)
struct device *dev = &client->dev;
struct tc74_data *data;
struct device *hwmon_dev;
s32 conf;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->client = client;
/* Make sure the chip is powered up. */
conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
if (conf < 0) {
dev_err(dev, "unable to read config register\n");
return conf;
if (conf & 0x3f) {
dev_err(dev, "invalid config register value\n");
return -ENODEV;
if (conf & BIT(7)) {
s32 ret;
conf &= ~BIT(7);
ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
if (ret)
dev_warn(dev, "unable to disable STANDBY\n");
hwmon_dev = devm_hwmon_device_register_with_groups(dev,
data, tc74_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
static const struct i2c_device_id tc74_id[] = {
{ "tc74", 0 },
MODULE_DEVICE_TABLE(i2c, tc74_id);
static struct i2c_driver tc74_driver = {
.driver = {
.name = "tc74",
.probe = tc74_probe,
.id_table = tc74_id,
MODULE_AUTHOR("Maciej Szmigiero <>");
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