1/*
2 * An hwmon driver for the Microchip TC74
3 *
4 * Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>
5 *
6 * Based on ad7414.c:
7 * Copyright 2006 Stefan Roese, DENX Software Engineering
8 * Copyright 2008 Sean MacLennan, PIKA Technologies
9 * Copyright 2008 Frank Edelhaeuser, Spansion Inc.
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 */
16
17#include <linux/bitops.h>
18#include <linux/err.h>
19#include <linux/hwmon.h>
20#include <linux/hwmon-sysfs.h>
21#include <linux/i2c.h>
22#include <linux/jiffies.h>
23#include <linux/module.h>
24#include <linux/mutex.h>
25#include <linux/slab.h>
26#include <linux/sysfs.h>
27
28/* TC74 registers */
29#define TC74_REG_TEMP 0x00
30#define TC74_REG_CONFIG 0x01
31
32struct tc74_data {
33 struct i2c_client *client;
34 struct mutex lock; /* atomic read data updates */
35 bool valid; /* validity of fields below */
36 unsigned long next_update; /* In jiffies */
37 s8 temp_input; /* Temp value in dC */
38};
39
40static int tc74_update_device(struct device *dev)
41{
42 struct tc74_data *data = dev_get_drvdata(dev);
43 struct i2c_client *client = data->client;
44 int ret;
45
46 ret = mutex_lock_interruptible(&data->lock);
47 if (ret)
48 return ret;
49
50 if (time_after(jiffies, data->next_update) || !data->valid) {
51 s32 value;
52
53 value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
54 if (value < 0) {
55 dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
56 (int)value);
57
58 ret = value;
59 goto ret_unlock;
60 }
61
62 if (!(value & BIT(6))) {
63 /* not ready yet */
64
65 ret = -EAGAIN;
66 goto ret_unlock;
67 }
68
69 value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);
70 if (value < 0) {
71 dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
72 (int)value);
73
74 ret = value;
75 goto ret_unlock;
76 }
77
78 data->temp_input = value;
79 data->next_update = jiffies + HZ / 4;
80 data->valid = true;
81 }
82
83ret_unlock:
84 mutex_unlock(&data->lock);
85
86 return ret;
87}
88
89static ssize_t temp_input_show(struct device *dev,
90 struct device_attribute *attr, char *buf)
91{
92 struct tc74_data *data = dev_get_drvdata(dev);
93 int ret;
94
95 ret = tc74_update_device(dev);
96 if (ret)
97 return ret;
98
99 return sprintf(buf, "%d\n", data->temp_input * 1000);
100}
101static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);
102
103static struct attribute *tc74_attrs[] = {
104 &sensor_dev_attr_temp1_input.dev_attr.attr,
105 NULL
106};
107
108ATTRIBUTE_GROUPS(tc74);
109
110static int tc74_probe(struct i2c_client *client,
111 const struct i2c_device_id *dev_id)
112{
113 struct device *dev = &client->dev;
114 struct tc74_data *data;
115 struct device *hwmon_dev;
116 s32 conf;
117
118 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
119 return -EOPNOTSUPP;
120
121 data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
122 if (!data)
123 return -ENOMEM;
124
125 data->client = client;
126 mutex_init(&data->lock);
127
128 /* Make sure the chip is powered up. */
129 conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
130 if (conf < 0) {
131 dev_err(dev, "unable to read config register\n");
132
133 return conf;
134 }
135
136 if (conf & 0x3f) {
137 dev_err(dev, "invalid config register value\n");
138
139 return -ENODEV;
140 }
141
142 if (conf & BIT(7)) {
143 s32 ret;
144
145 conf &= ~BIT(7);
146
147 ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
148 if (ret)
149 dev_warn(dev, "unable to disable STANDBY\n");
150 }
151
152 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
153 client->name,
154 data, tc74_groups);
155 return PTR_ERR_OR_ZERO(hwmon_dev);
156}
157
158static const struct i2c_device_id tc74_id[] = {
159 { "tc74", 0 },
160 {}
161};
162MODULE_DEVICE_TABLE(i2c, tc74_id);
163
164static struct i2c_driver tc74_driver = {
165 .driver = {
166 .name = "tc74",
167 },
168 .probe = tc74_probe,
169 .id_table = tc74_id,
170};
171
172module_i2c_driver(tc74_driver);
173
174MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
175
176MODULE_DESCRIPTION("TC74 driver");
177MODULE_LICENSE("GPL");
178