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
22static void ltq_cputemp_enable(void)
23{
24	ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
25}
26
27static 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
32static 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
55static 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
69static 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
77static const struct hwmon_ops ltq_hwmon_ops = {
78	.is_visible = ltq_is_visible,
79	.read = ltq_read,
80};
81
82static const struct hwmon_chip_info ltq_chip_info = {
83	.ops = &ltq_hwmon_ops,
84	.info = ltq_info,
85};
86
87static 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							 &ltq_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
116const struct of_device_id ltq_cputemp_match[] = {
117	{ .compatible = "lantiq,cputemp" },
118	{},
119};
120MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
121
122static 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
130module_platform_driver(ltq_cputemp_driver);
131
132MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
133MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
134MODULE_LICENSE("GPL");
135