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
32enum ad7314_variant {
33	adt7301,
34	adt7302,
35	ad7314,
36};
37
38struct ad7314_data {
39	struct spi_device	*spi_dev;
40	struct device		*hwmon_dev;
41	u16 rx ____cacheline_aligned;
42};
43
44static int ad7314_spi_read(struct ad7314_data *chip)
45{
46	int ret;
47
48	ret = spi_read(chip->spi_dev, (u8 *)&chip->rx, sizeof(chip->rx));
49	if (ret < 0) {
50		dev_err(&chip->spi_dev->dev, "SPI read error\n");
51		return ret;
52	}
53
54	return be16_to_cpu(chip->rx);
55}
56
57static ssize_t ad7314_show_temperature(struct device *dev,
58		struct device_attribute *attr,
59		char *buf)
60{
61	struct ad7314_data *chip = dev_get_drvdata(dev);
62	s16 data;
63	int ret;
64
65	ret = ad7314_spi_read(chip);
66	if (ret < 0)
67		return ret;
68	switch (spi_get_device_id(chip->spi_dev)->driver_data) {
69	case ad7314:
70		data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
71		data = sign_extend32(data, 9);
72
73		return sprintf(buf, "%d\n", 250 * data);
74	case adt7301:
75	case adt7302:
76		/*
77		 * Documented as a 13 bit twos complement register
78		 * with a sign bit - which is a 14 bit 2's complement
79		 * register.  1lsb - 31.25 milli degrees centigrade
80		 */
81		data = ret & ADT7301_TEMP_MASK;
82		data = sign_extend32(data, 13);
83
84		return sprintf(buf, "%d\n",
85			       DIV_ROUND_CLOSEST(data * 3125, 100));
86	default:
87		return -EINVAL;
88	}
89}
90
91static ssize_t ad7314_show_name(struct device *dev,
92				struct device_attribute *devattr, char *buf)
93{
94	return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
95}
96
97static DEVICE_ATTR(name, S_IRUGO, ad7314_show_name, NULL);
98static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
99			  ad7314_show_temperature, NULL, 0);
100
101static struct attribute *ad7314_attributes[] = {
102	&dev_attr_name.attr,
103	&sensor_dev_attr_temp1_input.dev_attr.attr,
104	NULL,
105};
106
107static const struct attribute_group ad7314_group = {
108	.attrs = ad7314_attributes,
109};
110
111static int ad7314_probe(struct spi_device *spi_dev)
112{
113	int ret;
114	struct ad7314_data *chip;
115
116	chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
117	if (chip == NULL)
118		return -ENOMEM;
119
120	spi_set_drvdata(spi_dev, chip);
121
122	ret = sysfs_create_group(&spi_dev->dev.kobj, &ad7314_group);
123	if (ret < 0)
124		return ret;
125
126	chip->hwmon_dev = hwmon_device_register(&spi_dev->dev);
127	if (IS_ERR(chip->hwmon_dev)) {
128		ret = PTR_ERR(chip->hwmon_dev);
129		goto error_remove_group;
130	}
131	chip->spi_dev = spi_dev;
132
133	return 0;
134error_remove_group:
135	sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
136	return ret;
137}
138
139static int ad7314_remove(struct spi_device *spi_dev)
140{
141	struct ad7314_data *chip = spi_get_drvdata(spi_dev);
142
143	hwmon_device_unregister(chip->hwmon_dev);
144	sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
145
146	return 0;
147}
148
149static const struct spi_device_id ad7314_id[] = {
150	{ "adt7301", adt7301 },
151	{ "adt7302", adt7302 },
152	{ "ad7314", ad7314 },
153	{ }
154};
155MODULE_DEVICE_TABLE(spi, ad7314_id);
156
157static struct spi_driver ad7314_driver = {
158	.driver = {
159		.name = "ad7314",
160	},
161	.probe = ad7314_probe,
162	.remove = ad7314_remove,
163	.id_table = ad7314_id,
164};
165
166module_spi_driver(ad7314_driver);
167
168MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
169MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital temperature sensor driver");
170MODULE_LICENSE("GPL v2");
171