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 	struct device *dev = &pdev->dev;
93 	int ret;
94 
95 	watchdog_set_drvdata(&stmp3xxx_wdd, dev);
96 
97 	stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
98 	stmp3xxx_wdd.parent = dev;
99 
100 	ret = devm_watchdog_register_device(dev, &stmp3xxx_wdd);
101 	if (ret < 0)
102 		return ret;
103 
104 	if (register_reboot_notifier(&wdt_notifier))
105 		dev_warn(dev, "cannot register reboot notifier\n");
106 
107 	dev_info(dev, "initialized watchdog with heartbeat %ds\n",
108 		 stmp3xxx_wdd.timeout);
109 	return 0;
110 }
111 
112 static int stmp3xxx_wdt_remove(struct platform_device *pdev)
113 {
114 	unregister_reboot_notifier(&wdt_notifier);
115 	return 0;
116 }
117 
118 static int __maybe_unused stmp3xxx_wdt_suspend(struct device *dev)
119 {
120 	struct watchdog_device *wdd = &stmp3xxx_wdd;
121 
122 	if (watchdog_active(wdd))
123 		return wdt_stop(wdd);
124 
125 	return 0;
126 }
127 
128 static int __maybe_unused stmp3xxx_wdt_resume(struct device *dev)
129 {
130 	struct watchdog_device *wdd = &stmp3xxx_wdd;
131 
132 	if (watchdog_active(wdd))
133 		return wdt_start(wdd);
134 
135 	return 0;
136 }
137 
138 static SIMPLE_DEV_PM_OPS(stmp3xxx_wdt_pm_ops,
139 			 stmp3xxx_wdt_suspend, stmp3xxx_wdt_resume);
140 
141 static struct platform_driver stmp3xxx_wdt_driver = {
142 	.driver = {
143 		.name = "stmp3xxx_rtc_wdt",
144 		.pm = &stmp3xxx_wdt_pm_ops,
145 	},
146 	.probe = stmp3xxx_wdt_probe,
147 	.remove = stmp3xxx_wdt_remove,
148 };
149 module_platform_driver(stmp3xxx_wdt_driver);
150 
151 MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
152 MODULE_LICENSE("GPL v2");
153 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
154