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/mod_devicetable.h>
13 #include <linux/module.h>
14 #include <linux/platform_device.h>
15
16 #include <lantiq_soc.h>
17
18 /* gphy1 configuration register contains cpu temperature */
19 #define CGU_GPHY1_CR 0x0040
20 #define CGU_TEMP_PD BIT(19)
21
ltq_cputemp_enable(void)22 static void ltq_cputemp_enable(void)
23 {
24 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
25 }
26
ltq_cputemp_disable(void * data)27 static void ltq_cputemp_disable(void *data)
28 {
29 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
30 }
31
ltq_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * temp)32 static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
33 u32 attr, int channel, long *temp)
34 {
35 int value;
36
37 switch (attr) {
38 case hwmon_temp_input:
39 /* get the temperature including one decimal place */
40 value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
41 value = value * 5;
42 /* range -38 to +154 °C, register value zero is -38.0 °C */
43 value -= 380;
44 /* scale temp to millidegree */
45 value = value * 100;
46 break;
47 default:
48 return -EOPNOTSUPP;
49 }
50
51 *temp = value;
52 return 0;
53 }
54
ltq_is_visible(const void * _data,enum hwmon_sensor_types type,u32 attr,int channel)55 static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type,
56 u32 attr, int channel)
57 {
58 if (type != hwmon_temp)
59 return 0;
60
61 switch (attr) {
62 case hwmon_temp_input:
63 return 0444;
64 default:
65 return 0;
66 }
67 }
68
69 static const struct hwmon_channel_info * const ltq_info[] = {
70 HWMON_CHANNEL_INFO(chip,
71 HWMON_C_REGISTER_TZ),
72 HWMON_CHANNEL_INFO(temp,
73 HWMON_T_INPUT),
74 NULL
75 };
76
77 static const struct hwmon_ops ltq_hwmon_ops = {
78 .is_visible = ltq_is_visible,
79 .read = ltq_read,
80 };
81
82 static const struct hwmon_chip_info ltq_chip_info = {
83 .ops = <q_hwmon_ops,
84 .info = ltq_info,
85 };
86
ltq_cputemp_probe(struct platform_device * pdev)87 static int ltq_cputemp_probe(struct platform_device *pdev)
88 {
89 struct device *hwmon_dev;
90 int err = 0;
91
92 /* available on vr9 v1.2 SoCs only */
93 if (ltq_soc_type() != SOC_TYPE_VR9_2)
94 return -ENODEV;
95
96 err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
97 if (err)
98 return err;
99
100 ltq_cputemp_enable();
101
102 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
103 "ltq_cputemp",
104 NULL,
105 <q_chip_info,
106 NULL);
107
108 if (IS_ERR(hwmon_dev)) {
109 dev_err(&pdev->dev, "Failed to register as hwmon device");
110 return PTR_ERR(hwmon_dev);
111 }
112
113 return 0;
114 }
115
116 const struct of_device_id ltq_cputemp_match[] = {
117 { .compatible = "lantiq,cputemp" },
118 {},
119 };
120 MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
121
122 static struct platform_driver ltq_cputemp_driver = {
123 .probe = ltq_cputemp_probe,
124 .driver = {
125 .name = "ltq-cputemp",
126 .of_match_table = ltq_cputemp_match,
127 },
128 };
129
130 module_platform_driver(ltq_cputemp_driver);
131
132 MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
133 MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
134 MODULE_LICENSE("GPL");
135