1 /*
2  * Watchdog driver for the RTC based watchdog in STMP3xxx and i.MX23/28
3  *
4  * Author: Wolfram Sang <w.sang@pengutronix.de>
5  *
6  * Copyright (C) 2011-12 Wolfram Sang, Pengutronix
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms of the GNU General Public License version 2 as published by
10  * the Free Software Foundation.
11  */
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/miscdevice.h>
16 #include <linux/watchdog.h>
17 #include <linux/platform_device.h>
18 #include <linux/stmp3xxx_rtc_wdt.h>
19 
20 #define WDOG_TICK_RATE 1000 /* 1 kHz clock */
21 #define STMP3XXX_DEFAULT_TIMEOUT 19
22 #define STMP3XXX_MAX_TIMEOUT (UINT_MAX / WDOG_TICK_RATE)
23 
24 static int heartbeat = STMP3XXX_DEFAULT_TIMEOUT;
25 module_param(heartbeat, uint, 0);
26 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat period in seconds from 1 to "
27 		 __MODULE_STRING(STMP3XXX_MAX_TIMEOUT) ", default "
28 		 __MODULE_STRING(STMP3XXX_DEFAULT_TIMEOUT));
29 
30 static int wdt_start(struct watchdog_device *wdd)
31 {
32 	struct device *dev = watchdog_get_drvdata(wdd);
33 	struct stmp3xxx_wdt_pdata *pdata = dev->platform_data;
34 
35 	pdata->wdt_set_timeout(dev->parent, wdd->timeout * WDOG_TICK_RATE);
36 	return 0;
37 }
38 
39 static int wdt_stop(struct watchdog_device *wdd)
40 {
41 	struct device *dev = watchdog_get_drvdata(wdd);
42 	struct stmp3xxx_wdt_pdata *pdata = dev->platform_data;
43 
44 	pdata->wdt_set_timeout(dev->parent, 0);
45 	return 0;
46 }
47 
48 static int wdt_set_timeout(struct watchdog_device *wdd, unsigned new_timeout)
49 {
50 	wdd->timeout = new_timeout;
51 	return wdt_start(wdd);
52 }
53 
54 static const struct watchdog_info stmp3xxx_wdt_ident = {
55 	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
56 	.identity = "STMP3XXX RTC Watchdog",
57 };
58 
59 static const struct watchdog_ops stmp3xxx_wdt_ops = {
60 	.owner = THIS_MODULE,
61 	.start = wdt_start,
62 	.stop = wdt_stop,
63 	.set_timeout = wdt_set_timeout,
64 };
65 
66 static struct watchdog_device stmp3xxx_wdd = {
67 	.info = &stmp3xxx_wdt_ident,
68 	.ops = &stmp3xxx_wdt_ops,
69 	.min_timeout = 1,
70 	.max_timeout = STMP3XXX_MAX_TIMEOUT,
71 	.status = WATCHDOG_NOWAYOUT_INIT_STATUS,
72 };
73 
74 static int stmp3xxx_wdt_probe(struct platform_device *pdev)
75 {
76 	int ret;
77 
78 	watchdog_set_drvdata(&stmp3xxx_wdd, &pdev->dev);
79 
80 	stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
81 
82 	ret = watchdog_register_device(&stmp3xxx_wdd);
83 	if (ret < 0) {
84 		dev_err(&pdev->dev, "cannot register watchdog device\n");
85 		return ret;
86 	}
87 
88 	dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
89 			stmp3xxx_wdd.timeout);
90 	return 0;
91 }
92 
93 static int stmp3xxx_wdt_remove(struct platform_device *pdev)
94 {
95 	watchdog_unregister_device(&stmp3xxx_wdd);
96 	return 0;
97 }
98 
99 static struct platform_driver stmp3xxx_wdt_driver = {
100 	.driver = {
101 		.name = "stmp3xxx_rtc_wdt",
102 	},
103 	.probe = stmp3xxx_wdt_probe,
104 	.remove = stmp3xxx_wdt_remove,
105 };
106 module_platform_driver(stmp3xxx_wdt_driver);
107 
108 MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
109 MODULE_LICENSE("GPL v2");
110 MODULE_AUTHOR("Wolfram Sang <w.sang@pengutronix.de>");
111 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
112