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
msc313e_wdt_start(struct watchdog_device * wdev)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
msc313e_wdt_ping(struct watchdog_device * wdev)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
msc313e_wdt_stop(struct watchdog_device * wdev)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
msc313e_wdt_settimeout(struct watchdog_device * wdev,unsigned int new_time)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
msc313e_wdt_probe(struct platform_device * pdev)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
msc313e_wdt_suspend(struct device * dev)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
msc313e_wdt_resume(struct device * dev)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