ddi_periodic_add(9F) Kernel Functions for Drivers ddi_periodic_add(9F)NAMEddi_periodic_add - issue nanosecond periodic timeout requests
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 is invoked periodically in the speci‐
fied interval. If the argument level is zero, the function
is invoked in kernel context. Otherwise, it's invoked in
interrupt context at the specified level.
arg The argument passed to the callback function.
interval Interval time in nanoseconds.
level Callback interrupt level. If the value is zero, the call‐
back function is invoked in kernel context. If the value is
more 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 applica‐
tions.
This value must be in range of 0-10, which can be either a
numeric number, 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.
RETURN VALUESddi_periodic_add()returns the non-zero opaque value (ddi_periodic_t),
which might be used for ddi_periodic_delete(9F) to specify the request.
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,
(void *)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,
(void *)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), delay(9F), drv_usectohz(9F), qtime‐
out(9F), quntimeout(9F), timeout(9F), untimeout(9F)NOTES
A caller can only specify an interval in an integral multiple of 10ms.
No other values are supported at this time. The interval specified is a
lower bound on the interval on which the callback occurs.
SunOS 5.10 13 Apr 2009 ddi_periodic_add(9F)
