1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * MStar WDT driver
4  *
5  * Copyright (C) 2019 - 2021 Daniel Palmer
6  * Copyright (C) 2021 Romain Perier
7  *
8  */
9 
10 #include <linux/clk.h>
11 #include <linux/io.h>
12 #include <linux/mod_devicetable.h>
13 #include <linux/module.h>
14 #include <linux/platform_device.h>
15 #include <linux/watchdog.h>
16 
17 #define REG_WDT_CLR			0x0
18 #define REG_WDT_MAX_PRD_L		0x10
19 #define REG_WDT_MAX_PRD_H		0x14
20 
21 #define MSC313E_WDT_MIN_TIMEOUT		1
22 #define MSC313E_WDT_DEFAULT_TIMEOUT	30
23 
24 static unsigned int timeout;
25 
26 module_param(timeout, int, 0);
27 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
28 
29 struct msc313e_wdt_priv {
30 	void __iomem *base;
31 	struct watchdog_device wdev;
32 	struct clk *clk;
33 };
34 
35 static int msc313e_wdt_start(struct watchdog_device *wdev)
36 {
37 	struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
38 	u32 timeout;
39 	int err;
40 
41 	err = clk_prepare_enable(priv->clk);
42 	if (err)
43 		return err;
44 
45 	timeout = wdev->timeout * clk_get_rate(priv->clk);
46 	writew(timeout & 0xffff, priv->base + REG_WDT_MAX_PRD_L);
47 	writew((timeout >> 16) & 0xffff, priv->base + REG_WDT_MAX_PRD_H);
48 	writew(1, priv->base + REG_WDT_CLR);
49 	return 0;
50 }
51 
52 static int msc313e_wdt_ping(struct watchdog_device *wdev)
53 {
54 	struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
55 
56 	writew(1, priv->base + REG_WDT_CLR);
57 	return 0;
58 }
59 
60 static int msc313e_wdt_stop(struct watchdog_device *wdev)
61 {
62 	struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
63 
64 	writew(0, priv->base + REG_WDT_MAX_PRD_L);
65 	writew(0, priv->base + REG_WDT_MAX_PRD_H);
66 	writew(0, priv->base + REG_WDT_CLR);
67 	clk_disable_unprepare(priv->clk);
68 	return 0;
69 }
70 
71 static int msc313e_wdt_settimeout(struct watchdog_device *wdev, unsigned int new_time)
72 {
73 	wdev->timeout = new_time;
74 
75 	return msc313e_wdt_start(wdev);
76 }
77 
78 static const struct watchdog_info msc313e_wdt_ident = {
79 	.identity = "MSC313e watchdog",
80 	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
81 };
82 
83 static const struct watchdog_ops msc313e_wdt_ops = {
84 	.owner = THIS_MODULE,
85 	.start = msc313e_wdt_start,
86 	.stop = msc313e_wdt_stop,
87 	.ping = msc313e_wdt_ping,
88 	.set_timeout = msc313e_wdt_settimeout,
89 };
90 
91 static const struct of_device_id msc313e_wdt_of_match[] = {
92 	{ .compatible = "mstar,msc313e-wdt", },
93 	{ /* sentinel */ }
94 };
95 MODULE_DEVICE_TABLE(of, msc313e_wdt_of_match);
96 
97 static int msc313e_wdt_probe(struct platform_device *pdev)
98 {
99 	struct device *dev = &pdev->dev;
100 	struct msc313e_wdt_priv *priv;
101 
102 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
103 	if (!priv)
104 		return -ENOMEM;
105 
106 	priv->base = devm_platform_ioremap_resource(pdev, 0);
107 	if (IS_ERR(priv->base))
108 		return PTR_ERR(priv->base);
109 
110 	priv->clk = devm_clk_get(dev, NULL);
111 	if (IS_ERR(priv->clk)) {
112 		dev_err(dev, "No input clock\n");
113 		return PTR_ERR(priv->clk);
114 	}
115 
116 	priv->wdev.info = &msc313e_wdt_ident,
117 	priv->wdev.ops = &msc313e_wdt_ops,
118 	priv->wdev.parent = dev;
119 	priv->wdev.min_timeout = MSC313E_WDT_MIN_TIMEOUT;
120 	priv->wdev.max_timeout = U32_MAX / clk_get_rate(priv->clk);
121 	priv->wdev.timeout = MSC313E_WDT_DEFAULT_TIMEOUT;
122 
123 	/* If the period is non-zero the WDT is running */
124 	if (readw(priv->base + REG_WDT_MAX_PRD_L) | (readw(priv->base + REG_WDT_MAX_PRD_H) << 16))
125 		set_bit(WDOG_HW_RUNNING, &priv->wdev.status);
126 
127 	watchdog_set_drvdata(&priv->wdev, priv);
128 
129 	watchdog_init_timeout(&priv->wdev, timeout, dev);
130 	watchdog_stop_on_reboot(&priv->wdev);
131 	watchdog_stop_on_unregister(&priv->wdev);
132 
133 	return devm_watchdog_register_device(dev, &priv->wdev);
134 }
135 
136 static int __maybe_unused msc313e_wdt_suspend(struct device *dev)
137 {
138 	struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
139 
140 	if (watchdog_active(&priv->wdev))
141 		msc313e_wdt_stop(&priv->wdev);
142 
143 	return 0;
144 }
145 
146 static int __maybe_unused msc313e_wdt_resume(struct device *dev)
147 {
148 	struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
149 
150 	if (watchdog_active(&priv->wdev))
151 		msc313e_wdt_start(&priv->wdev);
152 
153 	return 0;
154 }
155 
156 static SIMPLE_DEV_PM_OPS(msc313e_wdt_pm_ops, msc313e_wdt_suspend, msc313e_wdt_resume);
157 
158 static struct platform_driver msc313e_wdt_driver = {
159 	.driver = {
160 		.name = "msc313e-wdt",
161 		.of_match_table = msc313e_wdt_of_match,
162 		.pm = &msc313e_wdt_pm_ops,
163 	},
164 	.probe = msc313e_wdt_probe,
165 };
166 module_platform_driver(msc313e_wdt_driver);
167 
168 MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
169 MODULE_DESCRIPTION("Watchdog driver for MStar MSC313e");
170 MODULE_LICENSE("GPL v2");
171