tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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 const struct i2c_device_id *dev_id)
108{
109 struct device *dev = &client->dev;
110 struct tc74_data *data;
111 struct device *hwmon_dev;
112 s32 conf;
113
114 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
115 return -EOPNOTSUPP;
116
117 data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
118 if (!data)
119 return -ENOMEM;
120
121 data->client = client;
122 mutex_init(&data->lock);
123
124 /* Make sure the chip is powered up. */
125 conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
126 if (conf < 0) {
127 dev_err(dev, "unable to read config register\n");
128
129 return conf;
130 }
131
132 if (conf & 0x3f) {
133 dev_err(dev, "invalid config register value\n");
134
135 return -ENODEV;
136 }
137
138 if (conf & BIT(7)) {
139 s32 ret;
140
141 conf &= ~BIT(7);
142
143 ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
144 if (ret)
145 dev_warn(dev, "unable to disable STANDBY\n");
146 }
147
148 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
149 client->name,
150 data, tc74_groups);
151 return PTR_ERR_OR_ZERO(hwmon_dev);
152}
153
154static const struct i2c_device_id tc74_id[] = {
155 { "tc74", 0 },
156 {}
157};
158MODULE_DEVICE_TABLE(i2c, tc74_id);
159
160static struct i2c_driver tc74_driver = {
161 .driver = {
162 .name = "tc74",
163 },
164 .probe = tc74_probe,
165 .id_table = tc74_id,
166};
167
168module_i2c_driver(tc74_driver);
169
170MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
171
172MODULE_DESCRIPTION("TC74 driver");
173MODULE_LICENSE("GPL");