215 lines
6.6 KiB
Groff
215 lines
6.6 KiB
Groff
.\" Copyright (c) 2000 Jeroen Ruigrok van der Werven
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd November 3, 2010
|
|
.Dt BUS_SETUP_INTR 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm BUS_SETUP_INTR ,
|
|
.Nm bus_setup_intr ,
|
|
.Nm BUS_TEARDOWN_INTR ,
|
|
.Nm bus_teardown_intr
|
|
.Nd create, attach and teardown an interrupt handler
|
|
.Sh SYNOPSIS
|
|
.In sys/param.h
|
|
.In sys/bus.h
|
|
.Ft int
|
|
.Fo BUS_SETUP_INTR
|
|
.Fa "device_t dev" "device_t child" "struct resource *irq" "int flags"
|
|
.Fa "driver_filter_t *filter" "driver_intr_t *ithread" "void *arg"
|
|
.Fa "void **cookiep"
|
|
.Fc
|
|
.Ft int
|
|
.Fo bus_setup_intr
|
|
.Fa "device_t dev" "struct resource *r" "int flags"
|
|
.Fa "driver_filter_t filter" "driver_intr_t ithread" "void *arg"
|
|
.Fa "void **cookiep"
|
|
.Fc
|
|
.Ft int
|
|
.Fo BUS_TEARDOWN_INTR
|
|
.Fa "device_t dev" "device_t child" "struct resource *irq" "void *cookiep"
|
|
.Fc
|
|
.Ft int
|
|
.Fn bus_teardown_intr "device_t dev" "struct resource *r" "void *cookiep"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn BUS_SETUP_INTR
|
|
method
|
|
will create and attach an interrupt handler to an interrupt
|
|
previously allocated by the resource manager's
|
|
.Xr BUS_ALLOC_RESOURCE 9
|
|
method.
|
|
The
|
|
.Fa flags
|
|
are found in
|
|
.In sys/bus.h ,
|
|
and give the broad category of interrupt.
|
|
The
|
|
.Fa flags
|
|
also tell the interrupt handlers about certain
|
|
device driver characteristics.
|
|
.Dv INTR_EXCL
|
|
marks the handler as being
|
|
an exclusive handler for this interrupt.
|
|
.Dv INTR_MPSAFE
|
|
tells the scheduler that the interrupt handler
|
|
is well behaved in a preemptive environment
|
|
(``SMP safe''),
|
|
and does not need
|
|
to be protected by the ``Giant Lock'' mutex.
|
|
.Dv INTR_ENTROPY
|
|
marks the interrupt as being a good source of entropy -
|
|
this may be used by the entropy device
|
|
.Pa /dev/random .
|
|
.Pp
|
|
To define a time-critical handler that will not execute any potentially
|
|
blocking operation, use the
|
|
.Fa filter
|
|
argument.
|
|
See the
|
|
.Sx "Filter Routines"
|
|
section below for information on writing a filter.
|
|
Otherwise, use the
|
|
.Fa ithread
|
|
argument.
|
|
The defined handler
|
|
will be called with the value
|
|
.Fa arg
|
|
as its only argument.
|
|
See the
|
|
.Sx "ithread Routines"
|
|
section below for more information on writing an interrupt handler.
|
|
.Pp
|
|
The
|
|
.Fa cookiep
|
|
argument is a pointer to a
|
|
.Vt "void *"
|
|
that
|
|
.Fn BUS_SETUP_INTR
|
|
will write a cookie for the parent bus' use to if it is successful in
|
|
establishing an interrupt.
|
|
Driver writers may assume that this cookie will be non-zero.
|
|
The nexus driver will write 0 on failure to
|
|
.Fa cookiep .
|
|
.Pp
|
|
The interrupt handler will be detached by
|
|
.Fn BUS_TEARDOWN_INTR .
|
|
The cookie needs to be passed to
|
|
.Fn BUS_TEARDOWN_INTR
|
|
in order to tear down the correct interrupt handler.
|
|
Once
|
|
.Fn BUS_TEARDOWN_INTR
|
|
returns, it is guaranteed that the interrupt function is not active and
|
|
will no longer be called.
|
|
.Pp
|
|
Mutexes are not allowed to be held across calls to these functions.
|
|
.Ss "Filter Routines"
|
|
A filter runs in primary interrupt context.
|
|
In this context, normal mutexes cannot be used.
|
|
Only the spin lock version of these can be used (specified by passing
|
|
.Dv MTX_SPIN
|
|
to
|
|
.Fn mtx_init
|
|
when initializing the mutex).
|
|
.Xr wakeup 9
|
|
and similar routines can be called.
|
|
Atomic operations from
|
|
.Pa machine/atomic
|
|
may be used.
|
|
Reads and writes to hardware through
|
|
.Xr bus_space 9
|
|
may be used.
|
|
PCI configuration registers may be read and written.
|
|
All other kernel interfaces cannot be used.
|
|
.Pp
|
|
In this restricted environment, care must be taken to account for all
|
|
races.
|
|
A careful analysis of races should be done as well.
|
|
It is generally cheaper to take an extra interrupt, for example, than
|
|
to protect variables with spinlocks.
|
|
Read, modify, write cycles of hardware registers need to be carefully
|
|
analyzed if other threads are accessing the same registers.
|
|
.Pp
|
|
Generally, a filter routine will use one of two strategies.
|
|
The first strategy is to simply mask the interrupt in hardware and
|
|
allow the
|
|
.Dv ithread
|
|
routine to read the state from the hardware and then reenable
|
|
interrupts.
|
|
The
|
|
.Dv ithread
|
|
also acknowledges the interrupt before re-enabling the interrupt
|
|
source in hardware.
|
|
Most PCI hardware can mask its interrupt source.
|
|
.Pp
|
|
The second common approach is to use a filter with multiple
|
|
.Xr taskqueue 9
|
|
tasks.
|
|
In this case, the filter acknowledges the interrupts and queues the
|
|
work to the appropriate taskqueue.
|
|
Where one has to multiplex different kinds of interrupt sources, like
|
|
a network card's transmit and receive paths, this can reduce lock
|
|
contention and increase performance.
|
|
.Pp
|
|
You should not
|
|
.Xr malloc 9
|
|
from inside a filter.
|
|
You may not call anything that uses a normal mutex.
|
|
Witness may complain about these.
|
|
.Ss "ithread Routines"
|
|
You can do whatever you want in an ithread routine, except sleep.
|
|
Care must be taken not to sleep in an ithread.
|
|
In addition, one should minimize lock contention in an ithread routine
|
|
because contested locks ripple over to all other ithread routines on
|
|
that interrupt.
|
|
.Ss "Sleeping"
|
|
Sleeping is voluntarily giving up control of your thread.
|
|
All the sleep routine found in
|
|
.Xr msleep 9
|
|
sleep.
|
|
Waiting for a condition variable described in
|
|
.Xr condvar 9
|
|
is sleeping.
|
|
Calling any function that does any of these things is sleeping.
|
|
.Sh RETURN VALUES
|
|
Zero is returned on success,
|
|
otherwise an appropriate error is returned.
|
|
.Sh SEE ALSO
|
|
.Xr random 4 ,
|
|
.Xr device 9 ,
|
|
.Xr driver 9 ,
|
|
.Xr locking 9
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
This manual page was written by
|
|
.An Jeroen Ruigrok van der Werven Aq Mt asmodai@FreeBSD.org
|
|
based on the manual pages for
|
|
.Fn BUS_CREATE_INTR
|
|
and
|
|
.Fn BUS_CONNECT_INTR
|
|
written by
|
|
.An Doug Rabson Aq Mt dfr@FreeBSD.org .
|