1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Lantiq cpu temperature sensor driver
3 *
4 * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>
5 */
6
7 #include <linux/bitops.h>
8 #include <linux/delay.h>
9 #include <linux/hwmon.h>
10 #include <linux/hwmon-sysfs.h>
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/of_device.h>
14
15 #include <lantiq_soc.h>
16
17 /* gphy1 configuration register contains cpu temperature */
18 #define CGU_GPHY1_CR 0x0040
19 #define CGU_TEMP_PD BIT(19)
20
ltq_cputemp_enable(void)21 static void ltq_cputemp_enable(void)
22 {
23 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
24 }
25
ltq_cputemp_disable(void * data)26 static void ltq_cputemp_disable(void *data)
27 {
28 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
29 }
30
ltq_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * temp)31 static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
32 u32 attr, int channel, long *temp)
33 {
34 int value;
35
36 switch (attr) {
37 case hwmon_temp_input:
38 /* get the temperature including one decimal place */
39 value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
40 value = value * 5;
41 /* range -38 to +154 °C, register value zero is -38.0 °C */
42 value -= 380;
43 /* scale temp to millidegree */
44 value = value * 100;
45 break;
46 default:
47 return -EOPNOTSUPP;
48 }
49
50 *temp = value;
51 return 0;
52 }
53
ltq_is_visible(const void * _data,enum hwmon_sensor_types type,u32 attr,int channel)54 static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type,
55 u32 attr, int channel)
56 {
57 if (type != hwmon_temp)
58 return 0;
59
60 switch (attr) {
61 case hwmon_temp_input:
62 return 0444;
63 default:
64 return 0;
65 }
66 }
67
68 static const struct hwmon_channel_info *ltq_info[] = {
69 HWMON_CHANNEL_INFO(chip,
70 HWMON_C_REGISTER_TZ),
71 HWMON_CHANNEL_INFO(temp,
72 HWMON_T_INPUT),
73 NULL
74 };
75
76 static const struct hwmon_ops ltq_hwmon_ops = {
77 .is_visible = ltq_is_visible,
78 .read = ltq_read,
79 };
80
81 static const struct hwmon_chip_info ltq_chip_info = {
82 .ops = <q_hwmon_ops,
83 .info = ltq_info,
84 };
85
ltq_cputemp_probe(struct platform_device * pdev)86 static int ltq_cputemp_probe(struct platform_device *pdev)
87 {
88 struct device *hwmon_dev;
89 int err = 0;
90
91 /* available on vr9 v1.2 SoCs only */
92 if (ltq_soc_type() != SOC_TYPE_VR9_2)
93 return -ENODEV;
94
95 err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
96 if (err)
97 return err;
98
99 ltq_cputemp_enable();
100
101 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
102 "ltq_cputemp",
103 NULL,
104 <q_chip_info,
105 NULL);
106
107 if (IS_ERR(hwmon_dev)) {
108 dev_err(&pdev->dev, "Failed to register as hwmon device");
109 return PTR_ERR(hwmon_dev);
110 }
111
112 return 0;
113 }
114
115 const struct of_device_id ltq_cputemp_match[] = {
116 { .compatible = "lantiq,cputemp" },
117 {},
118 };
119 MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
120
121 static struct platform_driver ltq_cputemp_driver = {
122 .probe = ltq_cputemp_probe,
123 .driver = {
124 .name = "ltq-cputemp",
125 .of_match_table = ltq_cputemp_match,
126 },
127 };
128
129 module_platform_driver(ltq_cputemp_driver);
130
131 MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
132 MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
133 MODULE_LICENSE("GPL");
134