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 
28 struct 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 
tc74_update_device(struct device * dev)36 static 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 
79 ret_unlock:
80 	mutex_unlock(&data->lock);
81 
82 	return ret;
83 }
84 
temp_input_show(struct device * dev,struct device_attribute * attr,char * buf)85 static 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 }
97 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);
98 
99 static struct attribute *tc74_attrs[] = {
100 	&sensor_dev_attr_temp1_input.dev_attr.attr,
101 	NULL
102 };
103 
104 ATTRIBUTE_GROUPS(tc74);
105 
tc74_probe(struct i2c_client * client)106 static 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 
153 static const struct i2c_device_id tc74_id[] = {
154 	{ "tc74", 0 },
155 	{}
156 };
157 MODULE_DEVICE_TABLE(i2c, tc74_id);
158 
159 static struct i2c_driver tc74_driver = {
160 	.driver = {
161 		.name	= "tc74",
162 	},
163 	.probe_new = tc74_probe,
164 	.id_table = tc74_id,
165 };
166 
167 module_i2c_driver(tc74_driver);
168 
169 MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
170 
171 MODULE_DESCRIPTION("TC74 driver");
172 MODULE_LICENSE("GPL");
173