'\" te
.\"  Copyright (c) 2003, Sun Microsystems, Inc. All Rights Reserved
.TH ddi_add_event_handler 9F "62 Nov 2003" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
ddi_add_event_handler \- add an NDI event service callback handler
.SH SYNOPSIS
.LP
.nf
#include <sys/dditypes.h>
#include <sys/sunddi.h>

\fBint\fR \fBddi_add_event_handler\fR(\fBdev_info_t *\fR\fIdip\fR, \fBddi_eventcookie_t\fR \fIcookie\fR,
     \fBvoid (*\fR\fIhandler\fR)(dev_info_t *, ddi_eventcookie_t, void *, void *),
     \fBvoid *\fR\fIarg\fR, \fBddi_registration_id_t *\fR\fIid\fR);
.fi

.SH INTERFACE LEVEL
.sp
.LP
Solaris DDI specific (Solaris DDI).
.SH PARAMETERS
.sp
.ne 2
.mk
.na
\fB\fBdev_info_t *\fR\fIdip\fR\fR
.ad
.sp .6
.RS 4n
Device node registering the callback.
.RE

.sp
.ne 2
.mk
.na
\fB\fBddi_eventcookie_t\fR \fIcookie\fR\fR
.ad
.sp .6
.RS 4n
Cookie returned from call to \fBddi_get_eventcookie\fR(9F).
.RE

.sp
.ne 2
.mk
.na
\fB\fBvoid (*\fR\fIhandler\fR\fB)(dev_info_t *, ddi_eventcookie_t, void *, void *)\fR\fR
.ad
.sp .6
.RS 4n
Callback handler responsible for handling an NDI event service notification.
.RE

.sp
.ne 2
.mk
.na
\fB\fBvoid *\fR\fIarg\fR\fR
.ad
.sp .6
.RS 4n
Pointer to opaque data supplied by the caller. Typically, this would be a pointer to the driver's \fBsoftstate\fR structure.
.RE

.sp
.ne 2
.mk
.na
\fB\fBddi_registration_id_t *\fR\fIid\fR\fR
.ad
.sp .6
.RS 4n
Pointer to registration ID where a unique registration id will be returned. Registration ID must be saved and used when calling \fBddi_remove_event_handler\fR(9F) to unregister a callback.
.RE

.SH DESCRIPTION
.sp
.LP
The \fBddi_add_event_handler()\fR function adds a callback handler to be invoked in the face of the event specifed by \fIcookie\fR. The process of adding a callback handler is also known as subscribing to an event. Upon successful subscription, the handler will be invoked by the system when the event occurs. The handler can be unregistered by using \fBddi_remove_event_handler\fR(9F).
.sp
.LP
An instance of a driver can register multiple handlers for an event or a single handler for multiple events. Callback order is not defined and should assumed to be random.
.sp
.LP
The routine handler will be invoked with the following arguments:
.sp
.ne 2
.mk
.na
\fB\fBdev_info_t *\fR\fIdip\fR\fR
.ad
.RS 28n
.rt  
Device node requesting the notification.
.RE

.sp
.ne 2
.mk
.na
\fB\fBddi_eventcookie_t\fR \fIcookie\fR\fR
.ad
.RS 28n
.rt  
Structure describing event that occurred.
.RE

.sp
.ne 2
.mk
.na
\fB\fBvoid *\fR\fIarg\fR\fR
.ad
.RS 28n
.rt  
Opaque data pointer provided, by the driver, during callback registration.
.RE

.sp
.ne 2
.mk
.na
\fB\fBvoid *\fR\fIimpl_data\fR\fR
.ad
.RS 28n
.rt  
Pointer to event specific data defined by the framework which invokes the callback function.
.RE

.SH RETURN VALUES
.sp
.ne 2
.mk
.na
\fB\fBDDI_SUCCESS\fR\fR
.ad
.RS 15n
.rt  
Callback handler registered successfully.
.RE

.sp
.ne 2
.mk
.na
\fB\fBDDI_FAILURE\fR\fR
.ad
.RS 15n
.rt  
Failed to register callback handler. Possible reasons include lack of resources or a bad cookie.
.RE

.SH CONTEXT
.sp
.LP
The \fBddi_add_event_handler()\fR and \fBhandler()\fR function can be called from user and kernel contexts only.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for a description of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
\fBATTRIBUTE TYPE\fR\fBATTRIBUTE VALUE\fR
_
Stability LevelCommitted
.TE

.SH SEE ALSO
.sp
.LP
\fBattributes\fR(5), \fBddi_get_eventcookie\fR(9F), \fBddi_remove_event_handler\fR(9F)
.sp
.LP
\fIWriting Device Drivers for Oracle Solaris 11.2\fR 
.SH NOTES
.sp
.LP
Drivers must remove all registered callback handlers for a device instance by calling \fBddi_remove_event_handler\fR(9F) before detach completes.