1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Kirkwood thermal sensor driver
4  *
5  * Copyright (C) 2012 Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
6  */
7 #include <linux/device.h>
8 #include <linux/err.h>
9 #include <linux/io.h>
10 #include <linux/kernel.h>
11 #include <linux/of.h>
12 #include <linux/module.h>
13 #include <linux/platform_device.h>
14 #include <linux/thermal.h>
15 
16 #define KIRKWOOD_THERMAL_VALID_OFFSET	9
17 #define KIRKWOOD_THERMAL_VALID_MASK	0x1
18 #define KIRKWOOD_THERMAL_TEMP_OFFSET	10
19 #define KIRKWOOD_THERMAL_TEMP_MASK	0x1FF
20 
21 /* Kirkwood Thermal Sensor Dev Structure */
22 struct kirkwood_thermal_priv {
23 	void __iomem *sensor;
24 };
25 
26 static int kirkwood_get_temp(struct thermal_zone_device *thermal,
27 			  int *temp)
28 {
29 	unsigned long reg;
30 	struct kirkwood_thermal_priv *priv = thermal_zone_device_priv(thermal);
31 
32 	reg = readl_relaxed(priv->sensor);
33 
34 	/* Valid check */
35 	if (!((reg >> KIRKWOOD_THERMAL_VALID_OFFSET) &
36 	    KIRKWOOD_THERMAL_VALID_MASK))
37 		return -EIO;
38 
39 	/*
40 	 * Calculate temperature. According to Marvell internal
41 	 * documentation the formula for this is:
42 	 * Celsius = (322-reg)/1.3625
43 	 */
44 	reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
45 		KIRKWOOD_THERMAL_TEMP_MASK;
46 	*temp = ((3220000000UL - (10000000UL * reg)) / 13625);
47 
48 	return 0;
49 }
50 
51 static struct thermal_zone_device_ops ops = {
52 	.get_temp = kirkwood_get_temp,
53 };
54 
55 static const struct of_device_id kirkwood_thermal_id_table[] = {
56 	{ .compatible = "marvell,kirkwood-thermal" },
57 	{}
58 };
59 
60 static int kirkwood_thermal_probe(struct platform_device *pdev)
61 {
62 	struct thermal_zone_device *thermal = NULL;
63 	struct kirkwood_thermal_priv *priv;
64 	int ret;
65 
66 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
67 	if (!priv)
68 		return -ENOMEM;
69 
70 	priv->sensor = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
71 	if (IS_ERR(priv->sensor))
72 		return PTR_ERR(priv->sensor);
73 
74 	thermal = thermal_tripless_zone_device_register("kirkwood_thermal",
75 							priv, &ops, NULL);
76 	if (IS_ERR(thermal)) {
77 		dev_err(&pdev->dev,
78 			"Failed to register thermal zone device\n");
79 		return PTR_ERR(thermal);
80 	}
81 	ret = thermal_zone_device_enable(thermal);
82 	if (ret) {
83 		thermal_zone_device_unregister(thermal);
84 		dev_err(&pdev->dev, "Failed to enable thermal zone device\n");
85 		return ret;
86 	}
87 
88 	platform_set_drvdata(pdev, thermal);
89 
90 	return 0;
91 }
92 
93 static int kirkwood_thermal_exit(struct platform_device *pdev)
94 {
95 	struct thermal_zone_device *kirkwood_thermal =
96 		platform_get_drvdata(pdev);
97 
98 	thermal_zone_device_unregister(kirkwood_thermal);
99 
100 	return 0;
101 }
102 
103 MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
104 
105 static struct platform_driver kirkwood_thermal_driver = {
106 	.probe = kirkwood_thermal_probe,
107 	.remove = kirkwood_thermal_exit,
108 	.driver = {
109 		.name = "kirkwood_thermal",
110 		.of_match_table = kirkwood_thermal_id_table,
111 	},
112 };
113 
114 module_platform_driver(kirkwood_thermal_driver);
115 
116 MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
117 MODULE_DESCRIPTION("kirkwood thermal driver");
118 MODULE_LICENSE("GPL");
119