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OS-2366 ddi_periodic_add(9F) is entirely rubbish
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--- old/usr/src/man/man9f/ddi_periodic_add.9f
+++ new/usr/src/man/man9f/ddi_periodic_add.9f
1 1 '\" te
2 2 .\" Copyright (c) 2009, Sun Microsystems, Inc. All Rights Reserved
3 +.\" Copyright 2013, Joyent, Inc. All Rights Reserved.
3 4 .\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License. You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.
4 5 .\" See the License for the specific language governing permissions and limitations under the License. When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with
5 6 .\" the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
6 -.TH DDI_PERIODIC_ADD 9F "Apr 13, 2009"
7 +.TH DDI_PERIODIC_ADD 9F "Jul 23, 2013"
7 8 .SH NAME
8 -ddi_periodic_add \- issue nanosecond periodic timeout requests
9 +ddi_periodic_add \- request periodic function invocation
9 10 .SH SYNOPSIS
10 11 .LP
11 12 .nf
12 13 #include <sys/dditypes.h>
13 14 #include <sys/sunddi.h>
14 15
15 16 \fBddi_periodic_t\fR \fBddi_periodic_add\fR(\fBvoid (*\fR\fIfunc\fR)(\fBvoid *)\fR, \fBvoid\fR \fIarg\fR,
16 17 \fBhrtime_t\fR \fIinterval\fR, \fBint\fR \fIlevel\fR);
17 18 .fi
18 19
19 20 .SH INTERFACE LEVEL
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20 21 .sp
21 22 .LP
22 23 Solaris DDI specific (Solaris DDI)
23 24 .SH PARAMETERS
24 25 .sp
25 26 .ne 2
26 27 .na
27 28 \fB\fIfunc\fR\fR
28 29 .ad
29 30 .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.
31 +The callback function to be invoked periodically in the specified interval.
33 32 .RE
34 33
35 34 .sp
36 35 .ne 2
37 36 .na
38 37 \fB\fIarg\fR\fR
39 38 .ad
40 39 .RS 12n
41 40 The argument passed to the callback function.
42 41 .RE
43 42
44 43 .sp
45 44 .ne 2
46 45 .na
47 46 \fB\fIinterval\fR\fR
48 47 .ad
49 48 .RS 12n
50 -Interval time in nanoseconds.
49 +The periodic interval time in nanoseconds.
51 50 .RE
52 51
53 52 .sp
54 53 .ne 2
55 54 .na
56 55 \fB\fIlevel\fR\fR
57 56 .ad
58 57 .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.
58 +The callback function is invoked at this priority level. If the value of
59 +\fIlevel\fR is zero, the callback function is invoked in kernel context.
60 +If the value is greater than zero, but less than or equal to ten, the callback
61 +function is invoked in interrupt context at the specified interrupt level,
62 +which may be used for real time applications.
63 63 .sp
64 -This value must be in range of 0-10, which can be either a numeric number, a
64 +This value must be in range of 0-10, which can be either an integer literal, a
65 65 pre-defined macro (\fBDDI_IPL_0\fR, ... , \fBDDI_IPL_10\fR), or the
66 66 \fBDDI_INTR_PRI\fR macro with the interrupt priority.
67 67 .RE
68 68
69 69 .SH DESCRIPTION
70 70 .sp
71 71 .LP
72 72 The \fBddi_periodic_add()\fR function schedules the specified function to be
73 73 periodically invoked in the nanosecond interval time.
74 74 .sp
75 75 .LP
76 76 As with \fBtimeout\fR(9F), the exact time interval over which the function
77 77 takes effect cannot be guaranteed, but the value given is a close
78 -approximation.
78 +approximation. If the callback function has not finished execution when the
79 +next interval expires, the system will skip running the callback for that
80 +interval.
79 81 .SH RETURN VALUES
80 82 .sp
81 83 .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.
84 +\fBddi_periodic_add()\fR returns the non-zero opaque value
85 +(\fBddi_periodic_t\fR), which is later used to cancel the periodic request
86 +with \fBddi_periodic_delete\fR(9F).
85 87 .SH CONTEXT
86 88 .sp
87 89 .LP
88 90 The \fBddi_periodic_add()\fR function may be called from user or kernel
89 91 context.
90 92 .SH EXAMPLES
91 93 .LP
92 94 \fBExample 1 \fRUsing \fBddi_periodic_add()\fR for a periodic callback function
93 95 .sp
94 96 .LP
95 97 In the following example, the device driver registers a periodic callback
96 98 function invoked in kernel context.
97 99
98 100 .sp
99 101 .in +2
100 102 .nf
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101 103 static void
102 104 my_periodic_func(void *arg)
103 105 {
104 106 /*
105 107 * This handler is invoked periodically.
106 108 */
107 109 struct my_state *statep = (struct my_state *)arg;
108 110
109 111 mutex_enter(&statep->lock);
110 112 if (load_unbalanced(statep)) {
111 - balance_tasks(statep);
113 + balance_tasks(statep);
112 114 }
113 115 mutex_exit(&statep->lock);
114 116 }
115 117
116 118 static void
117 119 start_periodic_timer(struct my_state *statep)
118 120 {
119 121 hrtime_t interval = CHECK_INTERVAL;
120 122
121 - mutex_init(&statep->lock, NULL, MUTEX_DRIVER,
122 - (void *)DDI_IPL_0);
123 + mutex_init(&statep->lock, NULL, MUTEX_DRIVER, DDI_IPL_0);
123 124
124 125 /*
125 126 * Register my_callback which is invoked periodically
126 127 * in CHECK_INTERVAL in kernel context.
127 128 */
128 129 statep->periodic_id = ddi_periodic_add(my_periodic_func,
129 130 statep, interval, DDI_IPL_0);
130 131 .fi
131 132 .in -2
132 133
133 134 .sp
134 135 .LP
135 136 In the following example, the device driver registers a callback function
136 137 invoked in interrupt context at level 7.
137 138 .sp
138 139 .in +2
139 140 .nf
140 141 /*
141 142 * This handler is invoked periodically in interrupt context.
142 143 */
143 144 static void
144 145 my_periodic_int7_func(void *arg)
145 146 {
146 147 struct my_state *statep = (struct my_state *)arg;
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147 148 mutex_enter(&statep->lock);
148 149 monitor_device(statep);
149 150 mutex_exit(&statep->lock);
150 151 }
151 152
152 153 static void
153 154 start_monitor_device(struct my_state *statep)
154 155 {
155 156 hrtime_t interval = MONITOR_INTERVAL;
156 157
157 - mutex_init(&statep->lock, NULL, MUTEX_DRIVER,
158 - (void *)DDI_IPL_7);
158 + mutex_init(&statep->lock, NULL, MUTEX_DRIVER, DDI_IPL_7);
159 159
160 160 /*
161 161 * Register the callback function invoked periodically
162 162 * at interrupt level 7.
163 163 */
164 164 statep->periodic_id = ddi_periodic_add(my_periodic_int7_func,
165 165 statep, interval, DDI_IPL_7);
166 166 }
167 167 .fi
168 168 .in -2
169 169
170 170 .SH SEE ALSO
171 171 .sp
172 172 .LP
173 173 \fBcv_timedwait\fR(9F), \fBddi_intr_get_pri\fR(9F),
174 174 \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)
175 +\fBqtimeout\fR(9F), \fBquntimeout\fR(9F), \fBtimeout\fR(9F), \fBuntimeout\fR(9F)
177 176 .SH NOTES
178 177 .sp
179 178 .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.
179 +The caller must specify \fIinterval\fR as an even, non-zero multiple of 10ms.
180 +No other values are supported at this time. The interval specified is a lower
181 +bound on the interval between executions of the callback.
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