diff --git a/share/man/man9/intr_event.9 b/share/man/man9/intr_event.9
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@@ -1,354 +1,430 @@
 .\" Copyright (c) 2001 John H. Baldwin <jhb@FreeBSD.org>
 .\"
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 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 .\"
 .\" $FreeBSD$
 .\"
 .Dd October 15, 2022
 .Dt INTR_EVENT 9
 .Os
 .Sh NAME
 .Nm intr_event_add_handler ,
 .Nm intr_event_create ,
 .Nm intr_event_destroy ,
 .Nm intr_event_remove_handler ,
 .Nm intr_priority
 .Nd "kernel interrupt handler and thread API"
 .Sh SYNOPSIS
 .In sys/param.h
 .In sys/bus.h
 .In sys/interrupt.h
 .Ft int
 .Fo intr_event_add_handler
 .Fa "struct intr_event *ie"
 .Fa "const char *name"
 .Fa "driver_filter_t filter"
 .Fa "driver_intr_t handler"
 .Fa "void *arg"
 .Fa "u_char pri"
 .Fa "enum intr_type flags"
 .Fa "void **cookiep"
 .Fc
 .Ft int
 .Fo intr_event_create
 .Fa "struct intr_event **event"
 .Fa "void *source"
 .Fa "int flags"
 .Fa "int irq"
 .Fa "void (*pre_ithread)(void *)"
 .Fa "void (*post_ithread)(void *)"
 .Fa "void (*post_filter)(void *)"
 .Fa "int (*assign_cpu)(void *, int)"
 .Fa "const char *fmt"
 .Fa "..."
 .Fc
 .Ft int
 .Fn intr_event_destroy "struct intr_event *ie"
 .Ft int
 .Fn intr_event_remove_handler "void *cookie"
 .Ft u_char
 .Fn intr_priority "enum intr_type flags"
 .Sh DESCRIPTION
 The interrupt event API provides methods to manage the registration and
 execution of interrupt handlers and their associated thread contexts.
 .Pp
 Each interrupt event in the system corresponds to a single hardware or software
 interrupt source.
 Each interrupt event maintains a list of interrupt handlers, sorted by
 priority, which will be invoked when handling the event.
 An interrupt event will typically, but not always, have an associated
 .Xr kthread 9 ,
 known as the interrupt thread.
 Finally, each event contains optional callback functions which will be
 invoked before and after the handler functions themselves.
 .Pp
 An interrupt handler contains two distinct handler functions:
 the
 .Em filter
 and the thread
 .Em handler .
 The
 .Em filter
 function is run from interrupt context and is intended to perform quick
 handling such as acknowledging or masking a hardware interrupt,
 and queueing work for the ensuing thread
 .Em handler .
 Both functions are optional; each interrupt handler may choose to register a
 filter, a thread handler, or both.
 Each interrupt handler also consists of a name,
 a set of flags,
 and an opaque argument which will be passed to both the
 .Em filter
 and
 .Em handler
 functions.
 .Ss Handler Constraints
 The
 .Em filter
 function is executed inside a
 .Xr critical 9
 section.
 Therefore, filters may not yield the CPU for any reason, and may only use spin
 locks to access shared data.
 Allocating memory within a filter is not permitted.
 .Pp
 The
 .Em handler
 function executes from the context of the associated interrupt kernel thread.
 Sleeping is not permitted, but the interrupt thread may be preempted by higher
 priority threads.
 Thus, threaded handler functions may obtain non-sleepable locks, as described
 in
 .Xr locking 9 .
 Any memory or zone allocations in an interrupt thread must specify the
 .Dv M_NOWAIT
 flag, and any allocation errors must be handled.
 .Pp
 The exception to these constraints is software interrupt threads, which are
 allowed to sleep but should be allocated and scheduled using the
 .Xr swi 9
 interface.
 .Ss Function Descriptions
 The
 .Fn intr_event_create
-function creates a new interrupt thread.
+function creates a new interrupt event.
 The
-.Fa source
+.Fa event
 argument points to a
-.Vt struct intr_event event
-pointer that will point to the newly created thread upon success.
+.Vt struct intr_event
+pointer that will reference the newly created event upon success.
+The
+.Fa source
+argument is an opaque pointer which will be passed to the
+.Fa pre_ithread ,
+.Fa post_ithread ,
+and
+.Fa post_filter
+callbacks.
 The
 .Fa flags
 argument is a mask of properties of this thread.
 The only valid flag currently for
 .Fn intr_event_create
 is
 .Dv IE_SOFT
 to specify that this interrupt thread is a software interrupt.
 The
 .Fa enable
 and
 .Fa disable
 arguments specify optional functions used to enable and disable this
 interrupt thread's interrupt source.
-The functions receive the vector corresponding to the thread's interrupt
-source as their only argument.
-The remaining arguments form a
+The
+.Fa irq
+argument is the unique interrupt vector number corresponding to the event.
+The
+.Fa pre_ithread ,
+.Fa post_ithread ,
+and
+.Fa post_filter
+arguments are callback functions that are invoked at different
+points while handling an interrupt.
+This is described in more detail in the
+.Sx Handler Callbacks
+section, below.
+They may be
+.Va NULL
+to specify no callback.
+The
+.Fa assign_cpu
+argument points to a callback function that will be invoked when binding
+an interrupt to a particular CPU.
+It may be
+.Va NULL
+if binding is unsupported.
+The
+remaining arguments form a
 .Xr printf 9
 argument list that is used to build the base name of the new interrupt thread.
 The full name of an interrupt thread is formed by concatenating the base
 name of the interrupt thread with the names of all of its interrupt handlers.
 .Pp
 The
 .Fn intr_event_destroy
-function destroys a previously created interrupt thread by releasing its
-resources and arranging for the backing kernel thread to terminate.
-An interrupt thread can only be destroyed if it has no handlers remaining.
+function destroys a previously created interrupt event by releasing its
+resources.
+.\" The following is not true (yet):
+.\"and arranging for the backing kernel thread to terminate.
+An interrupt event can only be destroyed if it has no handlers remaining.
 .Pp
 The
 .Fn intr_event_add_handler
-function adds a new handler to an existing interrupt thread specified by
-.Fa ithread .
+function adds a new handler to an existing interrupt event specified by
+.Fa ie .
 The
 .Fa name
 argument specifies a name for this handler.
 The
+.Fa filter
+argument provide the filter function to execute.
+The
 .Fa handler
-and
+argument provides the handler function to be executed from the
+event's interrupt thread.
+The
 .Fa arg
-arguments provide the function to execute for this handler and an argument
-to pass to it.
+argument will be passed to the
+.Fa filter
+and
+.Fa handler
+functions when they are invoked.
 The
 .Fa pri
-argument specifies the priority of this handler and is used both in sorting
-it in relation to the other handlers for this thread and to specify the
-priority of the backing kernel thread.
-The
+argument specifies the priority of this handler,
+corresponding to the values defined in
+.In sys/priority.h .
+It determines the order this handler is called relative to the other handlers
+for this event, as well as the scheduling priority of of the backing kernel
+thread.
 .Fa flags
 argument can be used to specify properties of this handler as defined in
 .In sys/bus.h .
 If
 .Fa cookiep
 is not
 .Dv NULL ,
 then it will be assigned a cookie that can be used later to remove this
 handler.
 .Pp
 The
 .Fn intr_event_remove_handler
-removes a handler from an interrupt thread.
+function removes an interrupt handler from the interrupt event specified by
+.Fa ie .
 The
 .Fa cookie
-argument specifies the handler to remove from its thread.
+argument, obtained from
+.Fn intr_event_add_handler ,
+identifies the handler to remove.
 .Pp
 The
 .Fn intr_priority
 function translates the
 .Dv INTR_TYPE_*
 interrupt flags into interrupt thread scheduling priorities.
 .Pp
 The interrupt flags not related to the type of a particular interrupt
 .Pq Dv INTR_TYPE_*
 can be used to specify additional properties of both hardware and software
 interrupt handlers.
 The
 .Dv INTR_EXCL
 flag specifies that this handler cannot share an interrupt thread with
 another handler.
 The
 .Dv INTR_MPSAFE
 flag specifies that this handler is MP safe in that it does not need the
 Giant mutex to be held while it is executed.
 The
 .Dv INTR_ENTROPY
 flag specifies that the interrupt source this handler is tied to is a good
 source of entropy, and thus that entropy should be gathered when an interrupt
 from the handler's source triggers.
 Presently, the
 .Dv INTR_ENTROPY
 flag is not valid for software interrupt handlers.
+.Ss Handler Callbacks
+Each
+.Vt struct intr_event
+is assigned three optional callback functions when it is created:
+.Fa pre_ithread ,
+.Fa post_ithread ,
+and
+.Fa post_filter .
+These callbacks are intended to be defined by the interrupt controller driver,
+to allow for actions such as masking and unmasking hardware interrupt signals.
+.Pp
+When an interrupt is triggered, all filters are run to determine if any
+threaded interrupt handlers should be scheduled for execution by the associated
+interrupt thread. If no threaded handlers are scheduled, the
+.Fa post_filter
+callback is invoked which should acknowledge the interrupt and permit it to
+trigger in the future.
+If any threaded handlers are scheduled, the
+.Fa pre_ithread
+callback is invoked instead.
+This handler should acknowledge the interrupt, but it should also ensure that
+the interrupt will not fire continuously until after the threaded handlers have
+executed.
+Typically this callback masks level-triggered interrupts in an interrupt
+controller while leaving edge-triggered interrupts alone.
+Once all threaded handlers have executed,
+the
+.Fa post_ithread
+callback is invoked from the interrupt thread to enable future interrupts.
+Typically this callback unmasks level-triggered interrupts in an interrupt
+controller.
 .Sh RETURN VALUES
 The
 .Fn intr_event_add_handler ,
 .Fn intr_event_create ,
 .Fn intr_event_destroy ,
 and
 .Fn intr_event_remove_handler
 functions return zero on success and non-zero on failure.
 The
 .Fn intr_priority
 function returns a process priority corresponding to the passed in interrupt
 flags.
 .Sh EXAMPLES
 The
 .Xr swi_add 9
 function demonstrates the use of
 .Fn intr_event_create
 and
 .Fn intr_event_add_handler .
 .Bd -literal -offset indent
 int
 swi_add(struct intr_event **eventp, const char *name, driver_intr_t handler,
     void *arg, int pri, enum intr_type flags, void **cookiep)
 {
 	struct intr_event *ie;
 	int error = 0;
 
 	if (flags & INTR_ENTROPY)
 		return (EINVAL);
 
 	ie = (eventp != NULL) ? *eventp : NULL;
 
 	if (ie != NULL) {
 		if (!(ie->ie_flags & IE_SOFT))
 			return (EINVAL);
 	} else {
 		error = intr_event_create(&ie, NULL, IE_SOFT, 0,
 		    NULL, NULL, NULL, swi_assign_cpu, "swi%d:", pri);
 		if (error)
 			return (error);
 		if (eventp != NULL)
 			*eventp = ie;
 	}
 	if (handler != NULL) {
 		error = intr_event_add_handler(ie, name, NULL, handler, arg,
 		    PI_SWI(pri), flags, cookiep);
 	}
 	return (error);
 }
 .Ed
 .Sh ERRORS
 The
 .Fn intr_event_add_handler
 function will fail if:
 .Bl -tag -width Er
 .It Bq Er EINVAL
 The
 .Fa ie
 or
 .Fa name
 arguments are
 .Dv NULL .
 .It Bq Er EINVAL
 The
 .Fa handler
 and
 .Fa filter
 arguments are both
 .Dv NULL .
 .It Bq Er EINVAL
 The
 .Dv IH_EXCLUSIVE
 flag is specified and the interrupt thread
 .Fa ie
 already has at least one handler, or the interrupt thread
 .Fa ie
 already has an exclusive handler.
 .El
 .Pp
 The
 .Fn intr_event_create
 function will fail if:
 .Bl -tag -width Er
 .It Bq Er EINVAL
 A flag other than
 .Dv IE_SOFT
 was specified in the
 .Fa flags
 parameter.
 .El
 .Pp
 The
 .Fn intr_event_destroy
 function will fail if:
 .Bl -tag -width Er
 .It Bq Er EINVAL
 The
 .Fa ie
 argument is
 .Dv NULL .
 .It Bq Er EBUSY
 The interrupt event pointed to by
 .Fa ie
 has at least one handler which has not been removed with
 .Fn intr_event_remove_handler .
 .El
 .Pp
 The
 .Fn intr_event_remove_handler
 function will fail if:
 .Bl -tag -width Er
 .It Bq Er EINVAL
 The
 .Fa cookie
 argument is
 .Dv NULL .
 .El
 .Sh SEE ALSO
 .Xr kthread 9 ,
 .Xr locking 9 ,
 .Xr malloc 9 ,
 .Xr swi 9 ,
 .Xr uma 9
 .Sh HISTORY
 Interrupt threads and their corresponding API first appeared in
 .Fx 5.0 .