1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Watchdog driver for the RTC based watchdog in STMP3xxx and i.MX23/28
4  *
5  * Author: Wolfram Sang <kernel@pengutronix.de>
6  *
7  * Copyright (C) 2011-12 Wolfram Sang, Pengutronix
8  */
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/watchdog.h>
12 #include <linux/platform_device.h>
13 #include <linux/stmp3xxx_rtc_wdt.h>
14 #include <linux/notifier.h>
15 #include <linux/reboot.h>
16 
17 #define WDOG_TICK_RATE 1000 /* 1 kHz clock */
18 #define STMP3XXX_DEFAULT_TIMEOUT 19
19 #define STMP3XXX_MAX_TIMEOUT (UINT_MAX / WDOG_TICK_RATE)
20 
21 static int heartbeat = STMP3XXX_DEFAULT_TIMEOUT;
22 module_param(heartbeat, uint, 0);
23 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat period in seconds from 1 to "
24 		 __MODULE_STRING(STMP3XXX_MAX_TIMEOUT) ", default "
25 		 __MODULE_STRING(STMP3XXX_DEFAULT_TIMEOUT));
26 
27 static int wdt_start(struct watchdog_device *wdd)
28 {
29 	struct device *dev = watchdog_get_drvdata(wdd);
30 	struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);
31 
32 	pdata->wdt_set_timeout(dev->parent, wdd->timeout * WDOG_TICK_RATE);
33 	return 0;
34 }
35 
36 static int wdt_stop(struct watchdog_device *wdd)
37 {
38 	struct device *dev = watchdog_get_drvdata(wdd);
39 	struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);
40 
41 	pdata->wdt_set_timeout(dev->parent, 0);
42 	return 0;
43 }
44 
45 static int wdt_set_timeout(struct watchdog_device *wdd, unsigned new_timeout)
46 {
47 	wdd->timeout = new_timeout;
48 	return wdt_start(wdd);
49 }
50 
51 static const struct watchdog_info stmp3xxx_wdt_ident = {
52 	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
53 	.identity = "STMP3XXX RTC Watchdog",
54 };
55 
56 static const struct watchdog_ops stmp3xxx_wdt_ops = {
57 	.owner = THIS_MODULE,
58 	.start = wdt_start,
59 	.stop = wdt_stop,
60 	.set_timeout = wdt_set_timeout,
61 };
62 
63 static struct watchdog_device stmp3xxx_wdd = {
64 	.info = &stmp3xxx_wdt_ident,
65 	.ops = &stmp3xxx_wdt_ops,
66 	.min_timeout = 1,
67 	.max_timeout = STMP3XXX_MAX_TIMEOUT,
68 	.status = WATCHDOG_NOWAYOUT_INIT_STATUS,
69 };
70 
71 static int wdt_notify_sys(struct notifier_block *nb, unsigned long code,
72 			  void *unused)
73 {
74 	switch (code) {
75 	case SYS_DOWN:	/* keep enabled, system might crash while going down */
76 		break;
77 	case SYS_HALT:	/* allow the system to actually halt */
78 	case SYS_POWER_OFF:
79 		wdt_stop(&stmp3xxx_wdd);
80 		break;
81 	}
82 
83 	return NOTIFY_DONE;
84 }
85 
86 static struct notifier_block wdt_notifier = {
87 	.notifier_call = wdt_notify_sys,
88 };
89 
90 static int stmp3xxx_wdt_probe(struct platform_device *pdev)
91 {
92 	int ret;
93 
94 	watchdog_set_drvdata(&stmp3xxx_wdd, &pdev->dev);
95 
96 	stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
97 	stmp3xxx_wdd.parent = &pdev->dev;
98 
99 	ret = watchdog_register_device(&stmp3xxx_wdd);
100 	if (ret < 0) {
101 		dev_err(&pdev->dev, "cannot register watchdog device\n");
102 		return ret;
103 	}
104 
105 	if (register_reboot_notifier(&wdt_notifier))
106 		dev_warn(&pdev->dev, "cannot register reboot notifier\n");
107 
108 	dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
109 			stmp3xxx_wdd.timeout);
110 	return 0;
111 }
112 
113 static int stmp3xxx_wdt_remove(struct platform_device *pdev)
114 {
115 	unregister_reboot_notifier(&wdt_notifier);
116 	watchdog_unregister_device(&stmp3xxx_wdd);
117 	return 0;
118 }
119 
120 static int __maybe_unused stmp3xxx_wdt_suspend(struct device *dev)
121 {
122 	struct watchdog_device *wdd = &stmp3xxx_wdd;
123 
124 	if (watchdog_active(wdd))
125 		return wdt_stop(wdd);
126 
127 	return 0;
128 }
129 
130 static int __maybe_unused stmp3xxx_wdt_resume(struct device *dev)
131 {
132 	struct watchdog_device *wdd = &stmp3xxx_wdd;
133 
134 	if (watchdog_active(wdd))
135 		return wdt_start(wdd);
136 
137 	return 0;
138 }
139 
140 static SIMPLE_DEV_PM_OPS(stmp3xxx_wdt_pm_ops,
141 			 stmp3xxx_wdt_suspend, stmp3xxx_wdt_resume);
142 
143 static struct platform_driver stmp3xxx_wdt_driver = {
144 	.driver = {
145 		.name = "stmp3xxx_rtc_wdt",
146 		.pm = &stmp3xxx_wdt_pm_ops,
147 	},
148 	.probe = stmp3xxx_wdt_probe,
149 	.remove = stmp3xxx_wdt_remove,
150 };
151 module_platform_driver(stmp3xxx_wdt_driver);
152 
153 MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
154 MODULE_LICENSE("GPL v2");
155 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
156