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6 .TH DDI_PERIODIC_ADD 9F "Apr 13, 2009"
7 .SH NAME
8 ddi_periodic_add \- issue nanosecond periodic timeout requests
9 .SH SYNOPSIS
10 .LP
11 .nf
12 #include <sys/dditypes.h>
13 #include <sys/sunddi.h>
14
15 \fBddi_periodic_t\fR \fBddi_periodic_add\fR(\fBvoid (*\fR\fIfunc\fR)(\fBvoid *)\fR, \fBvoid\fR \fIarg\fR,
16 \fBhrtime_t\fR \fIinterval\fR, \fBint\fR \fIlevel\fR);
17 .fi
18
19 .SH INTERFACE LEVEL
20 .sp
21 .LP
22 Solaris DDI specific (Solaris DDI)
23 .SH PARAMETERS
24 .sp
25 .ne 2
26 .na
27 \fB\fIfunc\fR\fR
28 .ad
29 .RS 12n
30 The callback function is invoked periodically in the specified interval. If the
31 argument level is zero, the function is invoked in kernel context. Otherwise,
32 it's invoked in interrupt context at the specified level.
33 .RE
34
35 .sp
36 .ne 2
37 .na
38 \fB\fIarg\fR\fR
39 .ad
40 .RS 12n
41 The argument passed to the callback function.
42 .RE
43
44 .sp
45 .ne 2
46 .na
47 \fB\fIinterval\fR\fR
48 .ad
49 .RS 12n
50 Interval time in nanoseconds.
51 .RE
52
53 .sp
54 .ne 2
55 .na
56 \fB\fIlevel\fR\fR
57 .ad
58 .RS 12n
59 Callback interrupt level. If the value is zero, the callback function is
60 invoked in kernel context. If the value is more than zero, but less than or
61 equal to ten, the callback function is invoked in interrupt context at the
62 specified interrupt level, which may be used for real time applications.
63 .sp
64 This value must be in range of 0-10, which can be either a numeric number, a
65 pre-defined macro (\fBDDI_IPL_0\fR, ... , \fBDDI_IPL_10\fR), or the
66 \fBDDI_INTR_PRI\fR macro with the interrupt priority.
67 .RE
68
69 .SH DESCRIPTION
70 .sp
71 .LP
72 The \fBddi_periodic_add()\fR function schedules the specified function to be
73 periodically invoked in the nanosecond interval time.
74 .sp
75 .LP
76 As with \fBtimeout\fR(9F), the exact time interval over which the function
77 takes effect cannot be guaranteed, but the value given is a close
78 approximation.
79 .SH RETURN VALUES
80 .sp
81 .LP
82 \fBddi_periodic_add()\fRreturns the non-zero opaque value
83 (\fBddi_periodic_t\fR), which might be used for \fBddi_periodic_delete\fR(9F)
84 to specify the request.
85 .SH CONTEXT
86 .sp
87 .LP
88 The \fBddi_periodic_add()\fR function may be called from user or kernel
89 context.
90 .SH EXAMPLES
91 .LP
92 \fBExample 1 \fRUsing \fBddi_periodic_add()\fR for a periodic callback function
93 .sp
94 .LP
95 In the following example, the device driver registers a periodic callback
96 function invoked in kernel context.
97
98 .sp
99 .in +2
100 .nf
101 static void
102 my_periodic_func(void *arg)
103 {
104 /*
105 * This handler is invoked periodically.
106 */
107 struct my_state *statep = (struct my_state *)arg;
108
109 mutex_enter(&statep->lock);
110 if (load_unbalanced(statep)) {
111 balance_tasks(statep);
112 }
113 mutex_exit(&statep->lock);
114 }
115
116 static void
117 start_periodic_timer(struct my_state *statep)
118 {
119 hrtime_t interval = CHECK_INTERVAL;
120
121 mutex_init(&statep->lock, NULL, MUTEX_DRIVER,
122 (void *)DDI_IPL_0);
123
124 /*
125 * Register my_callback which is invoked periodically
126 * in CHECK_INTERVAL in kernel context.
127 */
128 statep->periodic_id = ddi_periodic_add(my_periodic_func,
129 statep, interval, DDI_IPL_0);
130 .fi
131 .in -2
132
133 .sp
134 .LP
135 In the following example, the device driver registers a callback function
136 invoked in interrupt context at level 7.
137 .sp
138 .in +2
139 .nf
140 /*
141 * This handler is invoked periodically in interrupt context.
142 */
143 static void
144 my_periodic_int7_func(void *arg)
145 {
146 struct my_state *statep = (struct my_state *)arg;
147 mutex_enter(&statep->lock);
148 monitor_device(statep);
149 mutex_exit(&statep->lock);
150 }
151
152 static void
153 start_monitor_device(struct my_state *statep)
154 {
155 hrtime_t interval = MONITOR_INTERVAL;
156
157 mutex_init(&statep->lock, NULL, MUTEX_DRIVER,
158 (void *)DDI_IPL_7);
159
160 /*
161 * Register the callback function invoked periodically
162 * at interrupt level 7.
163 */
164 statep->periodic_id = ddi_periodic_add(my_periodic_int7_func,
165 statep, interval, DDI_IPL_7);
166 }
167 .fi
168 .in -2
169
170 .SH SEE ALSO
171 .sp
172 .LP
173 \fBcv_timedwait\fR(9F), \fBddi_intr_get_pri\fR(9F),
174 \fBddi_periodic_delete\fR(9F), \fBddi_intr_get_softint_pri\fR(9F),
175 \fBdelay\fR(9F), \fBdrv_usectohz\fR(9F), \fBqtimeout\fR(9F),
176 \fBquntimeout\fR(9F), \fBtimeout\fR(9F), \fBuntimeout\fR(9F)
177 .SH NOTES
178 .sp
179 .LP
180 A caller can only specify an interval in an integral multiple of 10ms. No other
181 values are supported at this time. The interval specified is a lower bound on
182 the interval on which the callback occurs.