Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
Copyright 1989 AT&T
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. 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 the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
#include <sys/types.h> #include <sys/conf.h> timeout_id_t timeout(void (* func)(void *), void *arg, clock_t ticks);
Architecture independent level 1 (DDI/DKI).
func
Kernel function to invoke when the time increment expires.
arg
Argument to the function.
ticks
Number of clock ticks to wait before the function is called. Use drv_usectohz(9F) to convert microseconds to clock ticks.
The timeout() function schedules the specified function to be called after a specified time interval. The exact time interval over which the timeout takes effect cannot be guaranteed, but the value given is a close approximation.
The function called by timeout() must adhere to the same restrictions as a driver soft interrupt handler.
The delay(9F) function calls timeout(). Because timeout() is subject to priority inversion, drivers waiting on behalf of processes with real-time constraints should use cv_timedwait(9F) rather than delay().
The timeout() function returns an opaque non-zero timeout identifier that can be passed to untimeout(9F) to cancel the request.
The timeout() function can be called from user, interrupt, or kernel context.
Example 1 Using timeout()
In the following example, the device driver has issued an IO request and is waiting for the device to respond. If the device does not respond within 5 seconds, the device driver will print out an error message to the console.
static void
xxtimeout_handler(void *arg)
{
struct xxstate *xsp = (struct xxstate *)arg;
mutex_enter(&xsp->lock);
cv_signal(&xsp->cv);
xsp->flags |= TIMED_OUT;
mutex_exit(&xsp->lock);
xsp->timeout_id = 0;
}
static uint_t
xxintr(caddr_t arg)
{
struct xxstate *xsp = (struct xxstate *)arg;
.
.
.
mutex_enter(&xsp->lock);
/* Service interrupt */
cv_signal(&xsp->cv);
mutex_exit(&xsp->lock);
if (xsp->timeout_id != 0) {
(void) untimeout(xsp->timeout_id);
xsp->timeout_id = 0;
}
return(DDI_INTR_CLAIMED);
}
static void
xxcheckcond(struct xxstate *xsp)
{
.
.
.
xsp->timeout_id = timeout(xxtimeout_handler,
xsp, (5 * drv_usectohz(1000000)));
mutex_enter(&xsp->lock);
while (/* Waiting for interrupt or timeout*/)
cv_wait(&xsp->cv, &xsp->lock);
if (xsp->flags & TIMED_OUT)
cmn_err(CE_WARN, "Device not responding");
.
.
.
mutex_exit(&xsp->lock);
.
.
.
}
bufcall(9F), cv_timedwait(9F), ddi_in_panic(9F), delay(9F), drv_usectohz(9F), untimeout(9F)
Writing Device Drivers