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 */
22struct kirkwood_thermal_priv {
23	void __iomem *sensor;
24};
25
26static 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
54static struct thermal_zone_device_ops ops = {
55	.get_temp = kirkwood_get_temp,
56};
57
58static const struct of_device_id kirkwood_thermal_id_table[] = {
59	{ .compatible = "marvell,kirkwood-thermal" },
60	{}
61};
62
63static 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
98static 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
108MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
109
110static 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
119module_platform_driver(kirkwood_thermal_driver);
120
121MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
122MODULE_DESCRIPTION("kirkwood thermal driver");
123MODULE_LICENSE("GPL");
124