cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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tc74.c (3719B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * An hwmon driver for the Microchip TC74
      4 *
      5 * Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>
      6 *
      7 * Based on ad7414.c:
      8 *	Copyright 2006 Stefan Roese, DENX Software Engineering
      9 *	Copyright 2008 Sean MacLennan, PIKA Technologies
     10 *	Copyright 2008 Frank Edelhaeuser, Spansion Inc.
     11 */
     12
     13#include <linux/bitops.h>
     14#include <linux/err.h>
     15#include <linux/hwmon.h>
     16#include <linux/hwmon-sysfs.h>
     17#include <linux/i2c.h>
     18#include <linux/jiffies.h>
     19#include <linux/module.h>
     20#include <linux/mutex.h>
     21#include <linux/slab.h>
     22#include <linux/sysfs.h>
     23
     24/* TC74 registers */
     25#define TC74_REG_TEMP		0x00
     26#define TC74_REG_CONFIG		0x01
     27
     28struct tc74_data {
     29	struct i2c_client	*client;
     30	struct mutex		lock;	/* atomic read data updates */
     31	bool			valid;	/* validity of fields below */
     32	unsigned long		next_update;	/* In jiffies */
     33	s8			temp_input;	/* Temp value in dC */
     34};
     35
     36static int tc74_update_device(struct device *dev)
     37{
     38	struct tc74_data *data = dev_get_drvdata(dev);
     39	struct i2c_client *client = data->client;
     40	int ret;
     41
     42	ret = mutex_lock_interruptible(&data->lock);
     43	if (ret)
     44		return ret;
     45
     46	if (time_after(jiffies, data->next_update) || !data->valid) {
     47		s32 value;
     48
     49		value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
     50		if (value < 0) {
     51			dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
     52				(int)value);
     53
     54			ret = value;
     55			goto ret_unlock;
     56		}
     57
     58		if (!(value & BIT(6))) {
     59			/* not ready yet */
     60
     61			ret = -EAGAIN;
     62			goto ret_unlock;
     63		}
     64
     65		value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);
     66		if (value < 0) {
     67			dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
     68				(int)value);
     69
     70			ret = value;
     71			goto ret_unlock;
     72		}
     73
     74		data->temp_input = value;
     75		data->next_update = jiffies + HZ / 4;
     76		data->valid = true;
     77	}
     78
     79ret_unlock:
     80	mutex_unlock(&data->lock);
     81
     82	return ret;
     83}
     84
     85static ssize_t temp_input_show(struct device *dev,
     86			       struct device_attribute *attr, char *buf)
     87{
     88	struct tc74_data *data = dev_get_drvdata(dev);
     89	int ret;
     90
     91	ret = tc74_update_device(dev);
     92	if (ret)
     93		return ret;
     94
     95	return sprintf(buf, "%d\n", data->temp_input * 1000);
     96}
     97static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);
     98
     99static struct attribute *tc74_attrs[] = {
    100	&sensor_dev_attr_temp1_input.dev_attr.attr,
    101	NULL
    102};
    103
    104ATTRIBUTE_GROUPS(tc74);
    105
    106static int tc74_probe(struct i2c_client *client)
    107{
    108	struct device *dev = &client->dev;
    109	struct tc74_data *data;
    110	struct device *hwmon_dev;
    111	s32 conf;
    112
    113	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
    114		return -EOPNOTSUPP;
    115
    116	data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
    117	if (!data)
    118		return -ENOMEM;
    119
    120	data->client = client;
    121	mutex_init(&data->lock);
    122
    123	/* Make sure the chip is powered up. */
    124	conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
    125	if (conf < 0) {
    126		dev_err(dev, "unable to read config register\n");
    127
    128		return conf;
    129	}
    130
    131	if (conf & 0x3f) {
    132		dev_err(dev, "invalid config register value\n");
    133
    134		return -ENODEV;
    135	}
    136
    137	if (conf & BIT(7)) {
    138		s32 ret;
    139
    140		conf &= ~BIT(7);
    141
    142		ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
    143		if (ret)
    144			dev_warn(dev, "unable to disable STANDBY\n");
    145	}
    146
    147	hwmon_dev = devm_hwmon_device_register_with_groups(dev,
    148							   client->name,
    149							   data, tc74_groups);
    150	return PTR_ERR_OR_ZERO(hwmon_dev);
    151}
    152
    153static const struct i2c_device_id tc74_id[] = {
    154	{ "tc74", 0 },
    155	{}
    156};
    157MODULE_DEVICE_TABLE(i2c, tc74_id);
    158
    159static struct i2c_driver tc74_driver = {
    160	.driver = {
    161		.name	= "tc74",
    162	},
    163	.probe_new = tc74_probe,
    164	.id_table = tc74_id,
    165};
    166
    167module_i2c_driver(tc74_driver);
    168
    169MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
    170
    171MODULE_DESCRIPTION("TC74 driver");
    172MODULE_LICENSE("GPL");