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. According to Marvell internal
53	 * documentation the formula for this is:
54	 * Celsius = (322-reg)/1.3625
55	 */
56	reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
57		KIRKWOOD_THERMAL_TEMP_MASK;
58	*temp = ((3220000000UL - (10000000UL * reg)) / 13625);
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	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
79	if (!priv)
80		return -ENOMEM;
81
82	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
83	priv->sensor = devm_ioremap_resource(&pdev->dev, res);
84	if (IS_ERR(priv->sensor))
85		return PTR_ERR(priv->sensor);
86
87	thermal = thermal_zone_device_register("kirkwood_thermal", 0, 0,
88					       priv, &ops, NULL, 0, 0);
89	if (IS_ERR(thermal)) {
90		dev_err(&pdev->dev,
91			"Failed to register thermal zone device\n");
92		return PTR_ERR(thermal);
93	}
94
95	platform_set_drvdata(pdev, thermal);
96
97	return 0;
98}
99
100static int kirkwood_thermal_exit(struct platform_device *pdev)
101{
102	struct thermal_zone_device *kirkwood_thermal =
103		platform_get_drvdata(pdev);
104
105	thermal_zone_device_unregister(kirkwood_thermal);
106
107	return 0;
108}
109
110MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
111
112static struct platform_driver kirkwood_thermal_driver = {
113	.probe = kirkwood_thermal_probe,
114	.remove = kirkwood_thermal_exit,
115	.driver = {
116		.name = "kirkwood_thermal",
117		.of_match_table = kirkwood_thermal_id_table,
118	},
119};
120
121module_platform_driver(kirkwood_thermal_driver);
122
123MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
124MODULE_DESCRIPTION("kirkwood thermal driver");
125MODULE_LICENSE("GPL");
126