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->devdata;
31 
32 	reg = readl_relaxed(priv->sensor);
33 
34 	/* Valid check */
35 	if (!((reg >> KIRKWOOD_THERMAL_VALID_OFFSET) &
36 	    KIRKWOOD_THERMAL_VALID_MASK)) {
37 		dev_err(&thermal->device,
38 			"Temperature sensor reading not valid\n");
39 		return -EIO;
40 	}
41 
42 	/*
43 	 * Calculate temperature. According to Marvell internal
44 	 * documentation the formula for this is:
45 	 * Celsius = (322-reg)/1.3625
46 	 */
47 	reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
48 		KIRKWOOD_THERMAL_TEMP_MASK;
49 	*temp = ((3220000000UL - (10000000UL * reg)) / 13625);
50 
51 	return 0;
52 }
53 
54 static struct thermal_zone_device_ops ops = {
55 	.get_temp = kirkwood_get_temp,
56 };
57 
58 static const struct of_device_id kirkwood_thermal_id_table[] = {
59 	{ .compatible = "marvell,kirkwood-thermal" },
60 	{}
61 };
62 
63 static int kirkwood_thermal_probe(struct platform_device *pdev)
64 {
65 	struct thermal_zone_device *thermal = NULL;
66 	struct kirkwood_thermal_priv *priv;
67 	struct resource *res;
68 	int ret;
69 
70 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
71 	if (!priv)
72 		return -ENOMEM;
73 
74 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
75 	priv->sensor = devm_ioremap_resource(&pdev->dev, res);
76 	if (IS_ERR(priv->sensor))
77 		return PTR_ERR(priv->sensor);
78 
79 	thermal = thermal_zone_device_register("kirkwood_thermal", 0, 0,
80 					       priv, &ops, NULL, 0, 0);
81 	if (IS_ERR(thermal)) {
82 		dev_err(&pdev->dev,
83 			"Failed to register thermal zone device\n");
84 		return PTR_ERR(thermal);
85 	}
86 	ret = thermal_zone_device_enable(thermal);
87 	if (ret) {
88 		thermal_zone_device_unregister(thermal);
89 		dev_err(&pdev->dev, "Failed to enable thermal zone device\n");
90 		return ret;
91 	}
92 
93 	platform_set_drvdata(pdev, thermal);
94 
95 	return 0;
96 }
97 
98 static int kirkwood_thermal_exit(struct platform_device *pdev)
99 {
100 	struct thermal_zone_device *kirkwood_thermal =
101 		platform_get_drvdata(pdev);
102 
103 	thermal_zone_device_unregister(kirkwood_thermal);
104 
105 	return 0;
106 }
107 
108 MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
109 
110 static struct platform_driver kirkwood_thermal_driver = {
111 	.probe = kirkwood_thermal_probe,
112 	.remove = kirkwood_thermal_exit,
113 	.driver = {
114 		.name = "kirkwood_thermal",
115 		.of_match_table = kirkwood_thermal_id_table,
116 	},
117 };
118 
119 module_platform_driver(kirkwood_thermal_driver);
120 
121 MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
122 MODULE_DESCRIPTION("kirkwood thermal driver");
123 MODULE_LICENSE("GPL");
124