1/*
2 * Realtek RTD129x watchdog
3 *
4 * Copyright (c) 2017 Andreas Färber
5 *
6 * SPDX-License-Identifier: GPL-2.0+
7 */
8
9#include <linux/bitops.h>
10#include <linux/clk.h>
11#include <linux/io.h>
12#include <linux/of.h>
13#include <linux/of_address.h>
14#include <linux/platform_device.h>
15#include <linux/watchdog.h>
16
17#define RTD119X_TCWCR		0x0
18#define RTD119X_TCWTR		0x4
19#define RTD119X_TCWOV		0xc
20
21#define RTD119X_TCWCR_WDEN_DISABLED		0xa5
22#define RTD119X_TCWCR_WDEN_ENABLED		0xff
23#define RTD119X_TCWCR_WDEN_MASK			0xff
24
25#define RTD119X_TCWTR_WDCLR			BIT(0)
26
27struct rtd119x_watchdog_device {
28	struct watchdog_device wdt_dev;
29	void __iomem *base;
30	struct clk *clk;
31};
32
33static int rtd119x_wdt_start(struct watchdog_device *wdev)
34{
35	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
36	u32 val;
37
38	val = readl_relaxed(data->base + RTD119X_TCWCR);
39	val &= ~RTD119X_TCWCR_WDEN_MASK;
40	val |= RTD119X_TCWCR_WDEN_ENABLED;
41	writel(val, data->base + RTD119X_TCWCR);
42
43	return 0;
44}
45
46static int rtd119x_wdt_stop(struct watchdog_device *wdev)
47{
48	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
49	u32 val;
50
51	val = readl_relaxed(data->base + RTD119X_TCWCR);
52	val &= ~RTD119X_TCWCR_WDEN_MASK;
53	val |= RTD119X_TCWCR_WDEN_DISABLED;
54	writel(val, data->base + RTD119X_TCWCR);
55
56	return 0;
57}
58
59static int rtd119x_wdt_ping(struct watchdog_device *wdev)
60{
61	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
62
63	writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
64
65	return rtd119x_wdt_start(wdev);
66}
67
68static int rtd119x_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val)
69{
70	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
71
72	writel(val * clk_get_rate(data->clk), data->base + RTD119X_TCWOV);
73
74	data->wdt_dev.timeout = val;
75
76	return 0;
77}
78
79static const struct watchdog_ops rtd119x_wdt_ops = {
80	.owner = THIS_MODULE,
81	.start		= rtd119x_wdt_start,
82	.stop		= rtd119x_wdt_stop,
83	.ping		= rtd119x_wdt_ping,
84	.set_timeout	= rtd119x_wdt_set_timeout,
85};
86
87static const struct watchdog_info rtd119x_wdt_info = {
88	.identity = "rtd119x-wdt",
89	.options = 0,
90};
91
92static const struct of_device_id rtd119x_wdt_dt_ids[] = {
93	 { .compatible = "realtek,rtd1295-watchdog" },
94	 { }
95};
96
97static void rtd119x_clk_disable_unprepare(void *data)
98{
99	clk_disable_unprepare(data);
100}
101
102static int rtd119x_wdt_probe(struct platform_device *pdev)
103{
104	struct device *dev = &pdev->dev;
105	struct rtd119x_watchdog_device *data;
106	int ret;
107
108	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
109	if (!data)
110		return -ENOMEM;
111
112	data->base = devm_platform_ioremap_resource(pdev, 0);
113	if (IS_ERR(data->base))
114		return PTR_ERR(data->base);
115
116	data->clk = devm_clk_get(dev, NULL);
117	if (IS_ERR(data->clk))
118		return PTR_ERR(data->clk);
119
120	ret = clk_prepare_enable(data->clk);
121	if (ret)
122		return ret;
123	ret = devm_add_action_or_reset(dev, rtd119x_clk_disable_unprepare,
124				       data->clk);
125	if (ret)
126		return ret;
127
128	data->wdt_dev.info = &rtd119x_wdt_info;
129	data->wdt_dev.ops = &rtd119x_wdt_ops;
130	data->wdt_dev.timeout = 120;
131	data->wdt_dev.max_timeout = 0xffffffff / clk_get_rate(data->clk);
132	data->wdt_dev.min_timeout = 1;
133	data->wdt_dev.parent = dev;
134
135	watchdog_stop_on_reboot(&data->wdt_dev);
136	watchdog_set_drvdata(&data->wdt_dev, data);
137	platform_set_drvdata(pdev, data);
138
139	writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
140	rtd119x_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
141	rtd119x_wdt_stop(&data->wdt_dev);
142
143	return devm_watchdog_register_device(dev, &data->wdt_dev);
144}
145
146static struct platform_driver rtd119x_wdt_driver = {
147	.probe = rtd119x_wdt_probe,
148	.driver = {
149		.name = "rtd1295-watchdog",
150		.of_match_table	= rtd119x_wdt_dt_ids,
151	},
152};
153builtin_platform_driver(rtd119x_wdt_driver);
154