ddi_periodic_add(9f)

1ddi_periodic_add(9F)     Kernel Functions for Drivers     ddi_periodic_add(9F)
2
3
4

NAME

6       ddi_periodic_add - issue nanosecond periodic timeout requests
7

SYNOPSIS

9       #include <sys/dditypes.h>
10       #include <sys/sunddi.h>
11
12       ddi_periodic_t ddi_periodic_add(void (*func)(void *), void arg,
13            hrtime_t interval, int level);
14
15

INTERFACE LEVEL

17       Solaris DDI specific (Solaris DDI)
18

PARAMETERS

20       func        The callback function is invoked periodically in the speci‐
21                   fied interval. If the argument level is zero, the  function
22                   is  invoked  in  kernel context. Otherwise, it's invoked in
23                   interrupt context at the specified level.
24
25
26       arg         The argument passed to the callback function.
27
28
29       interval    Interval time in nanoseconds.
30
31
32       level       Callback interrupt level. If the value is zero,  the  call‐
33                   back function is invoked in kernel context. If the value is
34                   more than zero, but less than or equal to ten, the callback
35                   function  is  invoked in interrupt context at the specified
36                   interrupt level, which may be used for real  time  applica‐
37                   tions.
38
39                   This  value must be in range of 0-10, which can be either a
40                   numeric number,  a  pre-defined  macro  (DDI_IPL_0,  ...  ,
41                   DDI_IPL_10),  or  the DDI_INTR_PRI macro with the interrupt
42                   priority.
43
44

DESCRIPTION

46       The ddi_periodic_add() function schedules the specified function to  be
47       periodically invoked in the nanosecond interval time.
48
49
50       As  with  timeout(9F),  the exact time interval over which the function
51       takes effect cannot be guaranteed, but  the  value  given  is  a  close
52       approximation.
53

RETURN VALUES

55       ddi_periodic_add()returns  the  non-zero opaque value (ddi_periodic_t),
56       which might be used for ddi_periodic_delete(9F) to specify the request.
57

CONTEXT

59       The ddi_periodic_add() function may be called from user or kernel  con‐
60       text.
61

EXAMPLES

63       Example 1 Using ddi_periodic_add() for a periodic callback function
64
65
66       In  the following example, the device driver registers a periodic call‐
67       back function invoked in kernel context.
68
69
70         static void
71         my_periodic_func(void *arg)
72         {
73                  /*
74                   * This handler is invoked periodically.
75                   */
76                  struct my_state *statep = (struct my_state *)arg;
77
78                  mutex_enter(&statep->lock);
79                  if (load_unbalanced(statep)) {
80                      balance_tasks(statep);
81                  }
82                  mutex_exit(&statep->lock);
83         }
84
85         static void
86         start_periodic_timer(struct my_state *statep)
87         {
88                  hrtime_t interval = CHECK_INTERVAL;
89
90                  mutex_init(&statep->lock, NULL, MUTEX_DRIVER,
91                      (void *)DDI_IPL_0);
92
93                  /*
94                   * Register my_callback which is invoked periodically
95                   * in CHECK_INTERVAL in kernel context.
96                   */
97                   statep->periodic_id = ddi_periodic_add(my_periodic_func,
98                       statep, interval, DDI_IPL_0);
99
100
101
102       In the following example, the device driver registers a callback  func‐
103       tion invoked in interrupt context at level 7.
104
105         /*
106          * This handler is invoked periodically in interrupt context.
107          */
108          static void
109          my_periodic_int7_func(void *arg)
110          {
111                   struct my_state *statep = (struct my_state *)arg;
112                   mutex_enter(&statep->lock);
113                   monitor_device(statep);
114                   mutex_exit(&statep->lock);
115           }
116
117           static void
118           start_monitor_device(struct my_state *statep)
119           {
120                   hrtime_t interval = MONITOR_INTERVAL;
121
122                   mutex_init(&statep->lock, NULL, MUTEX_DRIVER,
123                       (void *)DDI_IPL_7);
124
125                   /*
126                    * Register the callback function invoked periodically
127                    * at interrupt level 7.
128                    */
129                   statep->periodic_id = ddi_periodic_add(my_periodic_int7_func,
130                       statep, interval, DDI_IPL_7);
131             }
132
133

NOTES

140       A  caller can only specify an interval in an integral multiple of 10ms.
141       No other values are supported at this time. The interval specified is a
142       lower bound on the interval on which the callback occurs.
143
144
145
146SunOS 5.11                        13 Apr 2009             ddi_periodic_add(9F)