1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI
4 * digital thermometer and thermostats.
5 *
6 * Copyright (c) 2016, Intel Corporation.
7 */
8
9 #include <linux/acpi.h>
10 #include <linux/hwmon.h>
11 #include <linux/hwmon-sysfs.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/spi/spi.h>
15
16 #define MAX31722_REG_CFG 0x00
17 #define MAX31722_REG_TEMP_LSB 0x01
18
19 #define MAX31722_MODE_CONTINUOUS 0x00
20 #define MAX31722_MODE_STANDBY 0x01
21 #define MAX31722_MODE_MASK 0xFE
22 #define MAX31722_RESOLUTION_12BIT 0x06
23 #define MAX31722_WRITE_MASK 0x80
24
25 struct max31722_data {
26 struct device *hwmon_dev;
27 struct spi_device *spi_device;
28 u8 mode;
29 };
30
max31722_set_mode(struct max31722_data * data,u8 mode)31 static int max31722_set_mode(struct max31722_data *data, u8 mode)
32 {
33 int ret;
34 struct spi_device *spi = data->spi_device;
35 u8 buf[2] = {
36 MAX31722_REG_CFG | MAX31722_WRITE_MASK,
37 (data->mode & MAX31722_MODE_MASK) | mode
38 };
39
40 ret = spi_write(spi, &buf, sizeof(buf));
41 if (ret < 0) {
42 dev_err(&spi->dev, "failed to set sensor mode.\n");
43 return ret;
44 }
45 data->mode = (data->mode & MAX31722_MODE_MASK) | mode;
46
47 return 0;
48 }
49
max31722_temp_show(struct device * dev,struct device_attribute * attr,char * buf)50 static ssize_t max31722_temp_show(struct device *dev,
51 struct device_attribute *attr, char *buf)
52 {
53 ssize_t ret;
54 struct max31722_data *data = dev_get_drvdata(dev);
55
56 ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
57 if (ret < 0)
58 return ret;
59 /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */
60 return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
61 }
62
63 static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
64
65 static struct attribute *max31722_attrs[] = {
66 &sensor_dev_attr_temp1_input.dev_attr.attr,
67 NULL,
68 };
69
70 ATTRIBUTE_GROUPS(max31722);
71
max31722_probe(struct spi_device * spi)72 static int max31722_probe(struct spi_device *spi)
73 {
74 int ret;
75 struct max31722_data *data;
76
77 data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
78 if (!data)
79 return -ENOMEM;
80
81 spi_set_drvdata(spi, data);
82 data->spi_device = spi;
83 /*
84 * Set SD bit to 0 so we can have continuous measurements.
85 * Set resolution to 12 bits for maximum precision.
86 */
87 data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;
88 ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
89 if (ret < 0)
90 return ret;
91
92 data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,
93 spi->modalias,
94 data,
95 max31722_groups);
96 if (IS_ERR(data->hwmon_dev)) {
97 max31722_set_mode(data, MAX31722_MODE_STANDBY);
98 return PTR_ERR(data->hwmon_dev);
99 }
100
101 return 0;
102 }
103
max31722_remove(struct spi_device * spi)104 static int max31722_remove(struct spi_device *spi)
105 {
106 struct max31722_data *data = spi_get_drvdata(spi);
107
108 hwmon_device_unregister(data->hwmon_dev);
109
110 return max31722_set_mode(data, MAX31722_MODE_STANDBY);
111 }
112
max31722_suspend(struct device * dev)113 static int __maybe_unused max31722_suspend(struct device *dev)
114 {
115 struct spi_device *spi_device = to_spi_device(dev);
116 struct max31722_data *data = spi_get_drvdata(spi_device);
117
118 return max31722_set_mode(data, MAX31722_MODE_STANDBY);
119 }
120
max31722_resume(struct device * dev)121 static int __maybe_unused max31722_resume(struct device *dev)
122 {
123 struct spi_device *spi_device = to_spi_device(dev);
124 struct max31722_data *data = spi_get_drvdata(spi_device);
125
126 return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
127 }
128
129 static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
130
131 static const struct spi_device_id max31722_spi_id[] = {
132 {"max31722", 0},
133 {"max31723", 0},
134 {}
135 };
136
137 static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = {
138 {"MAX31722", 0},
139 {"MAX31723", 0},
140 {}
141 };
142
143 MODULE_DEVICE_TABLE(spi, max31722_spi_id);
144
145 static struct spi_driver max31722_driver = {
146 .driver = {
147 .name = "max31722",
148 .pm = &max31722_pm_ops,
149 .acpi_match_table = ACPI_PTR(max31722_acpi_id),
150 },
151 .probe = max31722_probe,
152 .remove = max31722_remove,
153 .id_table = max31722_spi_id,
154 };
155
156 module_spi_driver(max31722_driver);
157
158 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
159 MODULE_DESCRIPTION("max31722 sensor driver");
160 MODULE_LICENSE("GPL v2");
161