178 lines
3.9 KiB
C
178 lines
3.9 KiB
C
/*
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* An hwmon driver for the Microchip TC74
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*
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* Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>
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*
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* Based on ad7414.c:
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* Copyright 2006 Stefan Roese, DENX Software Engineering
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* Copyright 2008 Sean MacLennan, PIKA Technologies
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* Copyright 2008 Frank Edelhaeuser, Spansion Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/bitops.h>
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#include <linux/err.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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#include <linux/i2c.h>
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#include <linux/jiffies.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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/* TC74 registers */
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#define TC74_REG_TEMP 0x00
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#define TC74_REG_CONFIG 0x01
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struct tc74_data {
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struct i2c_client *client;
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struct mutex lock; /* atomic read data updates */
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bool valid; /* validity of fields below */
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unsigned long next_update; /* In jiffies */
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s8 temp_input; /* Temp value in dC */
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};
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static int tc74_update_device(struct device *dev)
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{
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struct tc74_data *data = dev_get_drvdata(dev);
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struct i2c_client *client = data->client;
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int ret;
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ret = mutex_lock_interruptible(&data->lock);
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if (ret)
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return ret;
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if (time_after(jiffies, data->next_update) || !data->valid) {
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s32 value;
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value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
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if (value < 0) {
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dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
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(int)value);
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ret = value;
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goto ret_unlock;
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}
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if (!(value & BIT(6))) {
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/* not ready yet */
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ret = -EAGAIN;
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goto ret_unlock;
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}
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value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);
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if (value < 0) {
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dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
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(int)value);
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ret = value;
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goto ret_unlock;
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}
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data->temp_input = value;
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data->next_update = jiffies + HZ / 4;
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data->valid = true;
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}
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ret_unlock:
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mutex_unlock(&data->lock);
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return ret;
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}
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static ssize_t show_temp_input(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct tc74_data *data = dev_get_drvdata(dev);
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int ret;
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ret = tc74_update_device(dev);
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if (ret)
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return ret;
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return sprintf(buf, "%d\n", data->temp_input * 1000);
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}
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static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
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static struct attribute *tc74_attrs[] = {
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&sensor_dev_attr_temp1_input.dev_attr.attr,
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NULL
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};
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ATTRIBUTE_GROUPS(tc74);
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static int tc74_probe(struct i2c_client *client,
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const struct i2c_device_id *dev_id)
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{
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struct device *dev = &client->dev;
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struct tc74_data *data;
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struct device *hwmon_dev;
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s32 conf;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
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return -EOPNOTSUPP;
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data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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data->client = client;
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mutex_init(&data->lock);
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/* Make sure the chip is powered up. */
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conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
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if (conf < 0) {
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dev_err(dev, "unable to read config register\n");
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return conf;
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}
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if (conf & 0x3f) {
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dev_err(dev, "invalid config register value\n");
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return -ENODEV;
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}
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if (conf & BIT(7)) {
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s32 ret;
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conf &= ~BIT(7);
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ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
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if (ret)
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dev_warn(dev, "unable to disable STANDBY\n");
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}
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hwmon_dev = devm_hwmon_device_register_with_groups(dev,
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client->name,
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data, tc74_groups);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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static const struct i2c_device_id tc74_id[] = {
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{ "tc74", 0 },
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{}
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};
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MODULE_DEVICE_TABLE(i2c, tc74_id);
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static struct i2c_driver tc74_driver = {
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.driver = {
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.name = "tc74",
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},
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.probe = tc74_probe,
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.id_table = tc74_id,
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};
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module_i2c_driver(tc74_driver);
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MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
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MODULE_DESCRIPTION("TC74 driver");
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MODULE_LICENSE("GPL");
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