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 
27 struct rtd119x_watchdog_device {
28 	struct watchdog_device wdt_dev;
29 	void __iomem *base;
30 	struct clk *clk;
31 };
32 
33 static 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 
46 static 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 
59 static 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 
68 static 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 
79 static 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 
87 static const struct watchdog_info rtd119x_wdt_info = {
88 	.identity = "rtd119x-wdt",
89 	.options = 0,
90 };
91 
92 static const struct of_device_id rtd119x_wdt_dt_ids[] = {
93 	 { .compatible = "realtek,rtd1295-watchdog" },
94 	 { }
95 };
96 
97 static void rtd119x_clk_disable_unprepare(void *data)
98 {
99 	clk_disable_unprepare(data);
100 }
101 
102 static 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 
146 static 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 };
153 builtin_platform_driver(rtd119x_wdt_driver);
154