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
21static void ltq_cputemp_enable(void)
22{
23	ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
24}
25
26static 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
31static 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
54static 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
68static 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
76static const struct hwmon_ops ltq_hwmon_ops = {
77	.is_visible = ltq_is_visible,
78	.read = ltq_read,
79};
80
81static const struct hwmon_chip_info ltq_chip_info = {
82	.ops = &ltq_hwmon_ops,
83	.info = ltq_info,
84};
85
86static 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							 &ltq_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
115const struct of_device_id ltq_cputemp_match[] = {
116	{ .compatible = "lantiq,cputemp" },
117	{},
118};
119MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
120
121static 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
129module_platform_driver(ltq_cputemp_driver);
130
131MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
132MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
133MODULE_LICENSE("GPL");
134