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/*
2 
 * watchdog framework
3 
 */
4 
#include	"u.h"
5 
#include	"../port/lib.h"
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#include	"mem.h"
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#include	"dat.h"
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#include	"fns.h"
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#include	"io.h"
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#include	"../port/error.h"
11 
 
12 
enum {
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	Qdir,
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	Qwdctl,
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};
16 
 
17 
/*
18 
 * these are exposed so that delay() and the like can disable the watchdog
19 
 * before busy looping for a long time.
20 
 */
21 
Watchdog*watchdog;
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int	watchdogon;
23 
 
24 
static Watchdog *wd;
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static int wdautopet;
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static int wdclock0called;
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static Ref refs;
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static Dirtab wddir[] = {
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	".",		{ Qdir, 0, QTDIR },	0,		0555,
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	"wdctl",	{ Qwdctl, 0 },		0,		0664,
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};
32 
 
33 
 
34 
void
35 
addwatchdog(Watchdog *wdog)
36 
{
37 
	if(wd){
38 
		print("addwatchdog: watchdog already installed\n");
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		return;
40 
	}
41 
	wd = watchdog = wdog;
42 
	if(wd)
43 
		wd->disable();
44 
}
45 
 
46 
static int
47 
wdallowed(void)
48 
{
49 
	return getconf("*nowatchdog") == nil;
50 
}
51 
 
52 
static void
53 
wdshutdown(void)
54 
{
55 
	if (wd) {
56 
		wd->disable();
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		watchdogon = 0;
58 
	}
59 
}
60 
 
61 
/* called from clock interrupt, so restart needs ilock internally */
62 
static void
63 
wdpet(void)
64 
{
65 
	/* watchdog could be paused; if so, don't restart */
66 
	if (wdautopet && watchdogon)
67 
		wd->restart();
68 
}
69 
 
70 
/*
71 
 * reassure the watchdog from the clock interrupt
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 * until the user takes control of it.
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 */
74 
static void
75 
wdautostart(void)
76 
{
77 
	if (wdautopet || !wd || !wdallowed())
78 
		return;
79 
	if (waserror()) {
80 
		print("watchdog: automatic enable failed\n");
81 
		return;
82 
	}
83 
	wd->enable();
84 
	poperror();
85 
 
86 
	wdautopet = watchdogon = 1;
87 
	if (!wdclock0called) {
88 
		addclock0link(wdpet, 200);
89 
		wdclock0called = 1;
90 
	}
91 
}
92 
 
93 
/*
94 
 * disable strokes from the clock interrupt.
95 
 * have to disable the watchdog to mark it `not in use'.
96 
 */
97 
static void
98 
wdautostop(void)
99 
{
100 
	if (!wdautopet)
101 
		return;
102 
	wdautopet = 0;
103 
	wdshutdown();
104 
}
105 
 
106 
/*
107 
 * user processes exist and up is non-nil when the
108 
 * device init routines are called.
109 
 */
110 
static void
111 
wdinit(void)
112 
{
113 
	wdautostart();
114 
}
115 
 
116 
static Chan*
117 
wdattach(char *spec)
118 
{
119 
	return devattach('w', spec);
120 
}
121 
 
122 
static Walkqid*
123 
wdwalk(Chan *c, Chan *nc, char **name, int nname)
124 
{
125 
	return devwalk(c, nc, name, nname, wddir, nelem(wddir), devgen);
126 
}
127 
 
128 
static int
129 
wdstat(Chan *c, uchar *dp, int n)
130 
{
131 
	return devstat(c, dp, n, wddir, nelem(wddir), devgen);
132 
}
133 
 
134 
static Chan*
135 
wdopen(Chan* c, int omode)
136 
{
137 
	wdautostop();
138 
	c = devopen(c, omode, wddir, nelem(wddir), devgen);
139 
	if (c->qid.path == Qwdctl)
140 
		incref(&refs);
141 
	return c;
142 
}
143 
 
144 
static void
145 
wdclose(Chan *c)
146 
{
147 
	if(c->qid.path == Qwdctl && c->flag&COPEN && decref(&refs) <= 0)
148 
		wdshutdown();
149 
}
150 
 
151 
static long
152 
wdread(Chan* c, void* a, long n, vlong off)
153 
{
154 
	ulong offset = off;
155 
	char *p;
156 
 
157 
	switch((ulong)c->qid.path){
158 
	case Qdir:
159 
		return devdirread(c, a, n, wddir, nelem(wddir), devgen);
160 
 
161 
	case Qwdctl:
162 
		if(wd == nil || wd->stat == nil)
163 
			return 0;
164 
 
165 
		p = malloc(READSTR);
166 
		if(p == nil)
167 
			error(Enomem);
168 
		if(waserror()){
169 
			free(p);
170 
			nexterror();
171 
		}
172 
 
173 
		wd->stat(p, p + READSTR);
174 
		n = readstr(offset, a, n, p);
175 
		free(p);
176 
		poperror();
177 
		return n;
178 
 
179 
	default:
180 
		error(Egreg);
181 
		break;
182 
	}
183 
	return 0;
184 
}
185 
 
186 
static long
187 
wdwrite(Chan* c, void* a, long n, vlong off)
188 
{
189 
	ulong offset = off;
190 
	char *p;
191 
 
192 
	switch((ulong)c->qid.path){
193 
	case Qdir:
194 
		error(Eperm);
195 
 
196 
	case Qwdctl:
197 
		if(wd == nil)
198 
			return n;
199 
 
200 
		if(offset || n >= READSTR)
201 
			error(Ebadarg);
202 
 
203 
		if((p = strchr(a, '\n')) != nil)
204 
			*p = 0;
205 
 
206 
		if(strncmp(a, "enable", n) == 0) {
207 
			if (waserror()) {
208 
				print("watchdog: enable failed\n");
209 
				nexterror();
210 
			}
211 
			wd->enable();
212 
			poperror();
213 
			watchdogon = 1;
214 
		} else if(strncmp(a, "disable", n) == 0)
215 
			wdshutdown();
216 
		else if(strncmp(a, "restart", n) == 0)
217 
			wd->restart();
218 
		else
219 
			error(Ebadarg);
220 
		return n;
221 
 
222 
	default:
223 
		error(Egreg);
224 
		break;
225 
	}
226 
 
227 
	return 0;
228 
}
229 
 
230 
Dev wddevtab = {
231 
	'w',
232 
	"watchdog",
233 
 
234 
	devreset,
235 
	wdinit,
236 
	wdshutdown,
237 
	wdattach,
238 
	wdwalk,
239 
	wdstat,
240 
	wdopen,
241 
	devcreate,
242 
	wdclose,
243 
	wdread,
244 
	devbread,
245 
	wdwrite,
246 
	devbwrite,
247 
	devremove,
248 
	devwstat,
249 
	devpower,
250 
};