DDI_PERIODIC_ADD(9F)DDI_PERIODIC_ADD(9F)NAME
ddi_periodic_add - request periodic function invocation
SYNOPSIS
#include <sys/dditypes.h>
#include <sys/sunddi.h>
ddi_periodic_t ddi_periodic_add(void (*func)(void *), void arg,
hrtime_t interval, int level);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)
PARAMETERS
func
The callback function to be invoked periodically in the
specified interval.
arg
The argument passed to the callback function.
interval
The periodic interval time in nanoseconds.
level
The callback function is invoked at this priority level.
If the value of level is zero, the callback function is
invoked in kernel context. If the value is greater than
zero, but less than or equal to ten, the callback function
is invoked in interrupt context at the specified interrupt
level, which may be used for real time applications.
This value must be in range of 0-10, which can be either an
integer literal, a pre-defined macro (DDI_IPL_0, ... ,
DDI_IPL_10), or the DDI_INTR_PRI macro with the interrupt
priority.
DESCRIPTION
The ddi_periodic_add() function schedules the specified function to be
periodically invoked in the nanosecond interval time.
As with timeout(9F), the exact time interval over which the function
takes effect cannot be guaranteed, but the value given is a close
approximation. If the callback function has not finished execution
when the next interval expires, the system will skip running the call‐
back for that interval.
RETURN VALUESddi_periodic_add() returns the non-zero opaque value (ddi_periodic_t),
which is later used to cancel the periodic request with ddi_peri‐
odic_delete(9F).
CONTEXT
The ddi_periodic_add() function may be called from user or kernel con‐
text.
EXAMPLES
Example 1 Using ddi_periodic_add() for a periodic callback function
In the following example, the device driver registers a periodic call‐
back function invoked in kernel context.
static void
my_periodic_func(void *arg)
{
/*
* This handler is invoked periodically.
*/
struct my_state *statep = (struct my_state *)arg;
mutex_enter(&statep->lock);
if (load_unbalanced(statep)) {
balance_tasks(statep);
}
mutex_exit(&statep->lock);
}
static void
start_periodic_timer(struct my_state *statep)
{
hrtime_t interval = CHECK_INTERVAL;
mutex_init(&statep->lock, NULL, MUTEX_DRIVER, DDI_IPL_0);
/*
* Register my_callback which is invoked periodically
* in CHECK_INTERVAL in kernel context.
*/
statep->periodic_id = ddi_periodic_add(my_periodic_func,
statep, interval, DDI_IPL_0);
In the following example, the device driver registers a callback func‐
tion invoked in interrupt context at level 7.
/*
* This handler is invoked periodically in interrupt context.
*/
static void
my_periodic_int7_func(void *arg)
{
struct my_state *statep = (struct my_state *)arg;
mutex_enter(&statep->lock);
monitor_device(statep);
mutex_exit(&statep->lock);
}
static void
start_monitor_device(struct my_state *statep)
{
hrtime_t interval = MONITOR_INTERVAL;
mutex_init(&statep->lock, NULL, MUTEX_DRIVER, DDI_IPL_7);
/*
* Register the callback function invoked periodically
* at interrupt level 7.
*/
statep->periodic_id = ddi_periodic_add(my_periodic_int7_func,
statep, interval, DDI_IPL_7);
}
SEE ALSOcv_timedwait(9F), ddi_intr_get_pri(9F), ddi_periodic_delete(9F),
ddi_intr_get_softint_pri(9F), qtimeout(9F), quntimeout(9F), time‐
out(9F), untimeout(9F)NOTES
The caller must specify interval as an even, non-zero multiple of 10ms.
No other values are supported at this time. The interval specified is a
lower bound on the interval between executions of the callback.
Jul 23, 2013 DDI_PERIODIC_ADD(9F)
