.\"	$OpenBSD: pci_intr_map.9,v 1.13 2013/06/04 19:27:10 schwarze Exp $
.\"
.\" Copyright (c) 2005 Michael Shalayeff
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.Dd $Mdocdate: June 4 2013 $
.Dt PCI_INTR_MAP 9
.Os
.Sh NAME
.Nm pci_intr_map ,
.Nm pci_intr_map_msi ,
.Nm pci_intr_line ,
.Nm pci_intr_string ,
.Nm pci_intr_establish ,
.Nm pci_intr_disestablish
.Nd PCI interrupts
.Sh SYNOPSIS
.In alpha/pci/pci_machdep.h
.In i386/pci/pci_machdep.h
.In powerpc/pci/pci_machdep.h
.In sgi/pci/pci_machdep.h
.In machine/pci_machdep.h
.Ft int
.Fn pci_intr_map "struct pci_attach_args *paa" "pci_intr_handle_t *ih"
.Ft int
.Fn pci_intr_map_msi "struct pci_attach_args *paa" "pci_intr_handle_t *ih"
.Ft int
.Fn pci_intr_line "pci_intr_handle_t ih"
.Ft const char *
.Fn pci_intr_string "pci_chipset_tag_t pc" "pci_intr_handle_t ih"
.Ft void *
.Fn pci_intr_establish "pci_chipset_tag_t pc" "pci_intr_handle_t ih" \
"int level" "int (*func)(void *)" "void *arg" "const char *name"
.Ft void
.Fn pci_intr_disestablish "pci_chipset_tag_t pc" "void *v"
.Sh DESCRIPTION
These functions are provided by the machine-dependent implementation
for attaching handler functions to the interrupts of PCI devices.
.Pp
An architect type is provided by the machine-dependent
code
.Va pci_intr_handle_t ,
to be initialised by
.Fn pci_intr_map
or
.Fn pci_intr_map_msi .
.Pp
The
.Fn pci_intr_map
function should be called first to establish a mapping between a PCI
pin and the interrupt controller's interrupt vector.
This process may include resolving the mapping through
firmware-provided information.
For devices that support Message Signaled Interrupts (MSI) the
.Fn pci_intr_map_msi
function should be called instead.
This function can fail if the
system does not support MSI.
In that case
.Fn pci_intr_map
should be called to fall back on classic PCI interrupts.
.Pp
Having initialised the
.Va pci_intr_handle_t
in the previous step, an interrupt handler can be established using
.Fn pci_intr_establish
or converted into printable form using
.Fn pci_intr_string .
A handler established using
.Fn pci_intr_establish
is always called with the system interrupt priority level set equal to,
or higher than,
.Va level .
.Pp
.Fn pci_intr_line
provides the interrupt line extracted from the MD interrupt handle.
Upon device detachment,
.Fn pci_intr_disestablish
should be used to disassociate the handler from the interrupt.
.Pp
See
.Xr spl 9
for an explanation of the
.Va ipl
.Dq interrupt priority levels .
.Sh EXAMPLES
A typical code sequence for establishing a handler
for a device interrupt in the driver might be:
.Bd -literal -offset 3n
int
xxxattach(struct device *parent, struct device *self, void *aux)
{
	struct xxx_softc *sc = (struct xxx_softc *)self;
	struct pci_attach_args *pa = aux;
	pci_intr_handle_t ih;
	const char *intrstr;
	bus_size_t size;

	\&...

	if (pci_intr_map_msi(pa, &ih) && pci_intr_map(pa, &ih)) {
		printf(": can't map interrupt\en");
		bus_space_unmap(sc->iot, sc->ioh, size);
		return;
	}
	intrstr = pci_intr_string(pa->pa_pc, ih);
	sc->sc_ih = pci_intr_establish(pa->pa_pc, ih, IPL_NET,
	    xxx_intr, sc, sc->sc_dev.dv_xname);
	if (!sc->sc_ih) {
		printf(": can't establish interrupt");
		if (intrstr)
			printf(" at %s", intrstr);
		printf("\en");
		bus_space_unmap(sc->iot, sc->ioh, size);
		return;
	}

	printf(": %s\en", intrstr);

	\&...
}
.Ed
.Sh SEE ALSO
.Xr cardbus 4 ,
.Xr pci 4 ,
.Xr pcibios 4 ,
.Xr pci_conf_read 9 ,
.Xr spl 9
.Sh HISTORY
These functions first appeared in
.Ox 1.2 .
.\" .Sh AUTHORS