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linux
1/* Lantiq cpu temperature sensor driver
2 *
3 * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version
9 *
10 * This program is distributed in the hope that it will be useful
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>
17 */
18
19#include <linux/bitops.h>
20#include <linux/delay.h>
21#include <linux/hwmon.h>
22#include <linux/hwmon-sysfs.h>
23#include <linux/init.h>
24#include <linux/module.h>
25#include <linux/of_device.h>
26
27#include <lantiq_soc.h>
28
29/* gphy1 configuration register contains cpu temperature */
30#define CGU_GPHY1_CR 0x0040
31#define CGU_TEMP_PD BIT(19)
32
33static void ltq_cputemp_enable(void)
34{
35 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
36}
37
38static void ltq_cputemp_disable(void *data)
39{
40 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
41}
42
43static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
44 u32 attr, int channel, long *temp)
45{
46 int value;
47
48 switch (attr) {
49 case hwmon_temp_input:
50 /* get the temperature including one decimal place */
51 value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
52 value = value * 5;
53 /* range -38 to +154 °C, register value zero is -38.0 °C */
54 value -= 380;
55 /* scale temp to millidegree */
56 value = value * 100;
57 break;
58 default:
59 return -EOPNOTSUPP;
60 }
61
62 *temp = value;
63 return 0;
64}
65
66static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type,
67 u32 attr, int channel)
68{
69 if (type != hwmon_temp)
70 return 0;
71
72 switch (attr) {
73 case hwmon_temp_input:
74 return 0444;
75 default:
76 return 0;
77 }
78}
79
80static const u32 ltq_chip_config[] = {
81 HWMON_C_REGISTER_TZ,
82 0
83};
84
85static const struct hwmon_channel_info ltq_chip = {
86 .type = hwmon_chip,
87 .config = ltq_chip_config,
88};
89
90static const u32 ltq_temp_config[] = {
91 HWMON_T_INPUT,
92 0
93};
94
95static const struct hwmon_channel_info ltq_temp = {
96 .type = hwmon_temp,
97 .config = ltq_temp_config,
98};
99
100static const struct hwmon_channel_info *ltq_info[] = {
101 <q_chip,
102 <q_temp,
103 NULL
104};
105
106static const struct hwmon_ops ltq_hwmon_ops = {
107 .is_visible = ltq_is_visible,
108 .read = ltq_read,
109};
110
111static const struct hwmon_chip_info ltq_chip_info = {
112 .ops = <q_hwmon_ops,
113 .info = ltq_info,
114};
115
116static int ltq_cputemp_probe(struct platform_device *pdev)
117{
118 struct device *hwmon_dev;
119 int err = 0;
120
121 /* available on vr9 v1.2 SoCs only */
122 if (ltq_soc_type() != SOC_TYPE_VR9_2)
123 return -ENODEV;
124
125 err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
126 if (err)
127 return err;
128
129 ltq_cputemp_enable();
130
131 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
132 "ltq_cputemp",
133 NULL,
134 <q_chip_info,
135 NULL);
136
137 if (IS_ERR(hwmon_dev)) {
138 dev_err(&pdev->dev, "Failed to register as hwmon device");
139 return PTR_ERR(hwmon_dev);
140 }
141
142 return 0;
143}
144
145const struct of_device_id ltq_cputemp_match[] = {
146 { .compatible = "lantiq,cputemp" },
147 {},
148};
149MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
150
151static struct platform_driver ltq_cputemp_driver = {
152 .probe = ltq_cputemp_probe,
153 .driver = {
154 .name = "ltq-cputemp",
155 .of_match_table = ltq_cputemp_match,
156 },
157};
158
159module_platform_driver(ltq_cputemp_driver);
160
161MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
162MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
163MODULE_LICENSE("GPL");