NAME

ddi_intr_hilevel − indicate interrupt handler type

SYNOPSIS

#include <sys/ddi.h>
#include <sys/sunddi.h>
int ddi_intr_hilevel(dev_info_t ∗dip, u_int inumber);

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI). 

ARGUMENTS

dip Pointer to dev_info structure. 

inumber Interrupt number. 

DESCRIPTION

ddi_intr_hilevel() returns non-zero if the specified interrupt is a "high level" interrupt. 

High level interrupts must be handled without using system services that manipulate thread or process states, because these interrupts are not blocked by the scheduler. 

In addition, high level interrupt handlers must take care to do a minimum of work because they are not preemptable. 

A typical high level interrupt handler would put data into a circular buffer and schedule a soft interrupt by calling ddi_trigger_softintr().  The circular buffer could be protected by using a mutex that was properly initialized for the interrupt handler. 

ddi_intr_hilevel() can be used before calling ddi_add_intr() to decide which type of interrupt handler should be used.  Most device drivers are designed with the knowledge that the devices they support will always generate low level interrupts, however some devices, for example those using SBus or VME bus level 6 or 7 interrupts must use this test because on some machines those interrupts are high level (above the scheduler level) and on other machines they are not. 

RETURN VALUES

non-zero indicates a high-level interrupt. 

CONTEXT

These functions can be called from user or interrupt context. 

SEE ALSO

ddi_add_intr(9F), mutex(9F)

Writing Device Drivers

SunOS 5.5/SPARC  —  Last change: 7 Jan 1992