xref: /openbmc/linux/drivers/hwmon/ad7314.c (revision ccb01374)
1 /*
2  * AD7314 digital temperature sensor driver for AD7314, ADT7301 and ADT7302
3  *
4  * Copyright 2010 Analog Devices Inc.
5  *
6  * Licensed under the GPL-2 or later.
7  *
8  * Conversion to hwmon from IIO done by Jonathan Cameron <jic23@cam.ac.uk>
9  */
10 #include <linux/device.h>
11 #include <linux/kernel.h>
12 #include <linux/slab.h>
13 #include <linux/sysfs.h>
14 #include <linux/spi/spi.h>
15 #include <linux/module.h>
16 #include <linux/err.h>
17 #include <linux/hwmon.h>
18 #include <linux/hwmon-sysfs.h>
19 #include <linux/bitops.h>
20 
21 /*
22  * AD7314 temperature masks
23  */
24 #define AD7314_TEMP_MASK		0x7FE0
25 #define AD7314_TEMP_SHIFT		5
26 
27 /*
28  * ADT7301 and ADT7302 temperature masks
29  */
30 #define ADT7301_TEMP_MASK		0x3FFF
31 
32 enum ad7314_variant {
33 	adt7301,
34 	adt7302,
35 	ad7314,
36 };
37 
38 struct ad7314_data {
39 	struct spi_device	*spi_dev;
40 	u16 rx ____cacheline_aligned;
41 };
42 
43 static int ad7314_spi_read(struct ad7314_data *chip)
44 {
45 	int ret;
46 
47 	ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
48 	if (ret < 0) {
49 		dev_err(&chip->spi_dev->dev, "SPI read error\n");
50 		return ret;
51 	}
52 
53 	return be16_to_cpu(chip->rx);
54 }
55 
56 static ssize_t ad7314_temperature_show(struct device *dev,
57 				       struct device_attribute *attr,
58 				       char *buf)
59 {
60 	struct ad7314_data *chip = dev_get_drvdata(dev);
61 	s16 data;
62 	int ret;
63 
64 	ret = ad7314_spi_read(chip);
65 	if (ret < 0)
66 		return ret;
67 	switch (spi_get_device_id(chip->spi_dev)->driver_data) {
68 	case ad7314:
69 		data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
70 		data = sign_extend32(data, 9);
71 
72 		return sprintf(buf, "%d\n", 250 * data);
73 	case adt7301:
74 	case adt7302:
75 		/*
76 		 * Documented as a 13 bit twos complement register
77 		 * with a sign bit - which is a 14 bit 2's complement
78 		 * register.  1lsb - 31.25 milli degrees centigrade
79 		 */
80 		data = ret & ADT7301_TEMP_MASK;
81 		data = sign_extend32(data, 13);
82 
83 		return sprintf(buf, "%d\n",
84 			       DIV_ROUND_CLOSEST(data * 3125, 100));
85 	default:
86 		return -EINVAL;
87 	}
88 }
89 
90 static SENSOR_DEVICE_ATTR_RO(temp1_input, ad7314_temperature, 0);
91 
92 static struct attribute *ad7314_attrs[] = {
93 	&sensor_dev_attr_temp1_input.dev_attr.attr,
94 	NULL,
95 };
96 
97 ATTRIBUTE_GROUPS(ad7314);
98 
99 static int ad7314_probe(struct spi_device *spi_dev)
100 {
101 	struct ad7314_data *chip;
102 	struct device *hwmon_dev;
103 
104 	chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
105 	if (chip == NULL)
106 		return -ENOMEM;
107 
108 	chip->spi_dev = spi_dev;
109 	hwmon_dev = devm_hwmon_device_register_with_groups(&spi_dev->dev,
110 							   spi_dev->modalias,
111 							   chip, ad7314_groups);
112 	return PTR_ERR_OR_ZERO(hwmon_dev);
113 }
114 
115 static const struct spi_device_id ad7314_id[] = {
116 	{ "adt7301", adt7301 },
117 	{ "adt7302", adt7302 },
118 	{ "ad7314", ad7314 },
119 	{ }
120 };
121 MODULE_DEVICE_TABLE(spi, ad7314_id);
122 
123 static struct spi_driver ad7314_driver = {
124 	.driver = {
125 		.name = "ad7314",
126 	},
127 	.probe = ad7314_probe,
128 	.id_table = ad7314_id,
129 };
130 
131 module_spi_driver(ad7314_driver);
132 
133 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
134 MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
135 MODULE_LICENSE("GPL v2");
136