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 = 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");