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 */
31 struct kirkwood_thermal_priv {
32 	void __iomem *sensor;
33 };
34 
35 static int kirkwood_get_temp(struct thermal_zone_device *thermal,
36 			  int *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 
63 static struct thermal_zone_device_ops ops = {
64 	.get_temp = kirkwood_get_temp,
65 };
66 
67 static const struct of_device_id kirkwood_thermal_id_table[] = {
68 	{ .compatible = "marvell,kirkwood-thermal" },
69 	{}
70 };
71 
72 static 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 
100 static 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 
110 MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
111 
112 static 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 
121 module_platform_driver(kirkwood_thermal_driver);
122 
123 MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
124 MODULE_DESCRIPTION("kirkwood thermal driver");
125 MODULE_LICENSE("GPL");
126