.\"	$OpenBSD: pci_intr_map.9,v 1.18 2021/05/01 16:11:10 visa Exp $
.\"
.\" Copyright (c) 2005 Michael Shalayeff
.\" All rights reserved.
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: May 1 2021 $
.Dt PCI_INTR_MAP 9
.Os
.Sh NAME
.Nm pci_intr_map ,
.Nm pci_intr_map_msi ,
.Nm pci_intr_map_msix ,
.Nm pci_intr_line ,
.Nm pci_intr_string ,
.Nm pci_intr_establish ,
.\" .Nm pci_intr_establish_cpu ,
.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 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
.Fo pci_intr_map_msix
.Fa "struct pci_attach_args *paa"
.Fa "int vector"
.Fa "pci_intr_handle_t *ih"
.Fc
.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 *
.Fo pci_intr_establish
.Fa "pci_chipset_tag_t pc"
.Fa "pci_intr_handle_t ih"
.Fa "int level"
.Fa "int (*func)(void *)"
.Fa "void *arg"
.Fa "const char *name"
.Fc
.\" .Ft void *
.\" .Fo pci_intr_establish_cpu
.\" .Fa "pci_chipset_tag_t pc"
.\" .Fa "pci_intr_handle_t ih"
.\" .Fa "int level"
.\" .Fa "struct cpu_info *ci"
.\" .Fa "int (*func)(void *)"
.\" .Fa "void *arg"
.\" .Fa "const char *name"
.\" .Fc
.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 ,
.Fn pci_intr_map_msi ,
or
.Fn pci_intr_map_msix .
.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.
.Pp
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
For devices that support Extended Message Signaled Interrupts (MSI-X) the
.Fn pci_intr_map_msix
function can be called instead.
This function can fail if the system does not support MSI-X.
In that case
.Fn pci_intr_map_msi
or
.Fn pci_intr_map
can be called to fall back on Message Signalled Interrupts or classic
PCI interrupts respectively.
MSI-X can provide multiple interrupt vectors per device.
For each vector, a separate call to
.Fn pci_intr_map_msix
is made with the
.Fa vector
argument specifying which interrupt vector to map.
.Pp
Having initialised the
.Fa pci_intr_handle_t
in the previous step, an interrupt handler can be established using
.Fn pci_intr_establish .
.\" or
.\" .Fn pci_intr_establish_cpu .
.\" .Fn pci_intr_establish_cpu
.\" establishes an interrupt on the CPU specified in the
.\" .Fa ci
.\" argument, while
.\" .Fn pci_intr_establish
.\" uses a system selected CPU.
An established interrupt handler is always called with the system
interrupt priority level set equal to, or higher than,
.Fa level .
.Pp
A printable string representation of an initialised interrupt mapping
can be generated with
.Fn pci_intr_string .
.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