Root/drivers/thermal/kirkwood_thermal.c

1/*
2 * Kirkwood thermal sensor driver
3 *
4 * Copyright (C) 2012 Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
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 */
16#include <linux/device.h>
17#include <linux/err.h>
18#include <linux/io.h>
19#include <linux/kernel.h>
20#include <linux/of.h>
21#include <linux/module.h>
22#include <linux/platform_device.h>
23#include <linux/thermal.h>
24
25#define KIRKWOOD_THERMAL_VALID_OFFSET 9
26#define KIRKWOOD_THERMAL_VALID_MASK 0x1
27#define KIRKWOOD_THERMAL_TEMP_OFFSET 10
28#define KIRKWOOD_THERMAL_TEMP_MASK 0x1FF
29
30/* Kirkwood Thermal Sensor Dev Structure */
31struct kirkwood_thermal_priv {
32    void __iomem *sensor;
33};
34
35static int kirkwood_get_temp(struct thermal_zone_device *thermal,
36              unsigned long *temp)
37{
38    unsigned long reg;
39    struct kirkwood_thermal_priv *priv = thermal->devdata;
40
41    reg = readl_relaxed(priv->sensor);
42
43    /* Valid check */
44    if (!(reg >> KIRKWOOD_THERMAL_VALID_OFFSET) &
45        KIRKWOOD_THERMAL_VALID_MASK) {
46        dev_err(&thermal->device,
47            "Temperature sensor reading not valid\n");
48        return -EIO;
49    }
50
51    /*
52     * Calculate temperature. See Section 8.10.1 of the 88AP510,
53     * datasheet, which has the same sensor.
54     * Documentation/arm/Marvell/README
55     */
56    reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
57        KIRKWOOD_THERMAL_TEMP_MASK;
58    *temp = ((2281638UL - (7298*reg)) / 10);
59
60    return 0;
61}
62
63static struct thermal_zone_device_ops ops = {
64    .get_temp = kirkwood_get_temp,
65};
66
67static const struct of_device_id kirkwood_thermal_id_table[] = {
68    { .compatible = "marvell,kirkwood-thermal" },
69    {}
70};
71
72static int kirkwood_thermal_probe(struct platform_device *pdev)
73{
74    struct thermal_zone_device *thermal = NULL;
75    struct kirkwood_thermal_priv *priv;
76    struct resource *res;
77
78    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
79    if (!res) {
80        dev_err(&pdev->dev, "Failed to get platform resource\n");
81        return -ENODEV;
82    }
83
84    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
85    if (!priv)
86        return -ENOMEM;
87
88    priv->sensor = devm_ioremap_resource(&pdev->dev, res);
89    if (IS_ERR(priv->sensor))
90        return PTR_ERR(priv->sensor);
91
92    thermal = thermal_zone_device_register("kirkwood_thermal", 0, 0,
93                           priv, &ops, NULL, 0, 0);
94    if (IS_ERR(thermal)) {
95        dev_err(&pdev->dev,
96            "Failed to register thermal zone device\n");
97        return PTR_ERR(thermal);
98    }
99
100    platform_set_drvdata(pdev, thermal);
101
102    return 0;
103}
104
105static int kirkwood_thermal_exit(struct platform_device *pdev)
106{
107    struct thermal_zone_device *kirkwood_thermal =
108        platform_get_drvdata(pdev);
109
110    thermal_zone_device_unregister(kirkwood_thermal);
111    platform_set_drvdata(pdev, NULL);
112
113    return 0;
114}
115
116MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
117
118static struct platform_driver kirkwood_thermal_driver = {
119    .probe = kirkwood_thermal_probe,
120    .remove = kirkwood_thermal_exit,
121    .driver = {
122        .name = "kirkwood_thermal",
123        .owner = THIS_MODULE,
124        .of_match_table = of_match_ptr(kirkwood_thermal_id_table),
125    },
126};
127
128module_platform_driver(kirkwood_thermal_driver);
129
130MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
131MODULE_DESCRIPTION("kirkwood thermal driver");
132MODULE_LICENSE("GPL");
133

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