1/*
2 * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI
3 * digital thermometer and thermostats.
4 *
5 * Copyright (c) 2016, Intel Corporation.
6 *
7 * This file is subject to the terms and conditions of version 2 of
8 * the GNU General Public License. See the file COPYING in the main
9 * directory of this archive for more details.
10 */
11
12#include <linux/acpi.h>
13#include <linux/hwmon.h>
14#include <linux/hwmon-sysfs.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/spi/spi.h>
18
19#define MAX31722_REG_CFG 0x00
20#define MAX31722_REG_TEMP_LSB 0x01
21
22#define MAX31722_MODE_CONTINUOUS 0x00
23#define MAX31722_MODE_STANDBY 0x01
24#define MAX31722_MODE_MASK 0xFE
25#define MAX31722_RESOLUTION_12BIT 0x06
26#define MAX31722_WRITE_MASK 0x80
27
28struct max31722_data {
29 struct device *hwmon_dev;
30 struct spi_device *spi_device;
31 u8 mode;
32};
33
34static int max31722_set_mode(struct max31722_data *data, u8 mode)
35{
36 int ret;
37 struct spi_device *spi = data->spi_device;
38 u8 buf[2] = {
39 MAX31722_REG_CFG | MAX31722_WRITE_MASK,
40 (data->mode & MAX31722_MODE_MASK) | mode
41 };
42
43 ret = spi_write(spi, &buf, sizeof(buf));
44 if (ret < 0) {
45 dev_err(&spi->dev, "failed to set sensor mode.\n");
46 return ret;
47 }
48 data->mode = (data->mode & MAX31722_MODE_MASK) | mode;
49
50 return 0;
51}
52
53static ssize_t max31722_temp_show(struct device *dev,
54 struct device_attribute *attr, char *buf)
55{
56 ssize_t ret;
57 struct max31722_data *data = dev_get_drvdata(dev);
58
59 ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
60 if (ret < 0)
61 return ret;
62 /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */
63 return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
64}
65
66static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
67
68static struct attribute *max31722_attrs[] = {
69 &sensor_dev_attr_temp1_input.dev_attr.attr,
70 NULL,
71};
72
73ATTRIBUTE_GROUPS(max31722);
74
75static int max31722_probe(struct spi_device *spi)
76{
77 int ret;
78 struct max31722_data *data;
79
80 data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
81 if (!data)
82 return -ENOMEM;
83
84 spi_set_drvdata(spi, data);
85 data->spi_device = spi;
86 /*
87 * Set SD bit to 0 so we can have continuous measurements.
88 * Set resolution to 12 bits for maximum precision.
89 */
90 data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;
91 ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
92 if (ret < 0)
93 return ret;
94
95 data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,
96 spi->modalias,
97 data,
98 max31722_groups);
99 if (IS_ERR(data->hwmon_dev)) {
100 max31722_set_mode(data, MAX31722_MODE_STANDBY);
101 return PTR_ERR(data->hwmon_dev);
102 }
103
104 return 0;
105}
106
107static int max31722_remove(struct spi_device *spi)
108{
109 struct max31722_data *data = spi_get_drvdata(spi);
110
111 hwmon_device_unregister(data->hwmon_dev);
112
113 return max31722_set_mode(data, MAX31722_MODE_STANDBY);
114}
115
116static int __maybe_unused max31722_suspend(struct device *dev)
117{
118 struct spi_device *spi_device = to_spi_device(dev);
119 struct max31722_data *data = spi_get_drvdata(spi_device);
120
121 return max31722_set_mode(data, MAX31722_MODE_STANDBY);
122}
123
124static int __maybe_unused max31722_resume(struct device *dev)
125{
126 struct spi_device *spi_device = to_spi_device(dev);
127 struct max31722_data *data = spi_get_drvdata(spi_device);
128
129 return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
130}
131
132static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
133
134static const struct spi_device_id max31722_spi_id[] = {
135 {"max31722", 0},
136 {"max31723", 0},
137 {}
138};
139
140static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = {
141 {"MAX31722", 0},
142 {"MAX31723", 0},
143 {}
144};
145
146MODULE_DEVICE_TABLE(spi, max31722_spi_id);
147
148static struct spi_driver max31722_driver = {
149 .driver = {
150 .name = "max31722",
151 .pm = &max31722_pm_ops,
152 .acpi_match_table = ACPI_PTR(max31722_acpi_id),
153 },
154 .probe = max31722_probe,
155 .remove = max31722_remove,
156 .id_table = max31722_spi_id,
157};
158
159module_spi_driver(max31722_driver);
160
161MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
162MODULE_DESCRIPTION("max31722 sensor driver");
163MODULE_LICENSE("GPL v2");
164