tc74.c
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/*
* An hwmon driver for the Microchip TC74
*
* Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>
*
* 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",
(int)value);
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",
(int)value);
ret = value;
goto ret_unlock;
}
data->temp_input = value;
data->next_update = jiffies + HZ / 4;
data->valid = true;
}
ret_unlock:
mutex_unlock(&data->lock);
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[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
NULL
};
ATTRIBUTE_GROUPS(tc74);
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))
return -EOPNOTSUPP;
data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->client = client;
mutex_init(&data->lock);
/* 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,
client->name,
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_i2c_driver(tc74_driver);
MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
MODULE_DESCRIPTION("TC74 driver");
MODULE_LICENSE("GPL");