NAME

pci_intr_map, pci_intr_map_msi, pci_intr_map_msix, pci_intr_line, pci_intr_string, pci_intr_establish, pci_intr_disestablish — PCI interrupts

SYNOPSIS

#include <alpha/pci/pci_machdep.h>
#include <i386/pci/pci_machdep.h>
#include <machine/pci_machdep.h>

int
pci_intr_map(struct pci_attach_args *paa, pci_intr_handle_t *ih);

int
pci_intr_map_msi(struct pci_attach_args *paa, pci_intr_handle_t *ih);

int
pci_intr_map_msix(struct pci_attach_args *paa, int vector, pci_intr_handle_t *ih);

int
pci_intr_line(pci_intr_handle_t ih);

const char *
pci_intr_string(pci_chipset_tag_t pc, pci_intr_handle_t ih);

void *
pci_intr_establish(pci_chipset_tag_t pc, pci_intr_handle_t ih, int level, int (*func)(void *), void *arg, const char *name);

void
pci_intr_disestablish(pci_chipset_tag_t pc, void *v);

DESCRIPTION

These functions are provided by the machine-dependent implementation for attaching handler functions to the interrupts of PCI devices.

An architect type is provided by the machine-dependent code pci_intr_handle_t, to be initialised by pci_intr_map(), pci_intr_map_msi(), or pci_intr_map_msix().

The 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 pci_intr_map_msi() function should be called instead. This function can fail if the system does not support MSI. In that case pci_intr_map() should be called to fall back on classic PCI interrupts.

For devices that support Extended Message Signaled Interrupts (MSI-X) the pci_intr_map_msix() function can be called instead. This function can fail if the system does not support MSI-X. In that case pci_intr_map_msi() or 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 pci_intr_map_msix() is made with the vector argument specifying which interrupt vector to map.

Having initialised the pci_intr_handle_t in the previous step, an interrupt handler can be established using pci_intr_establish(). An established interrupt handler is always called with the system interrupt priority level set equal to, or higher than, level.

A printable string representation of an initialised interrupt mapping can be generated with pci_intr_string().

pci_intr_line() provides the interrupt line extracted from the MD interrupt handle. Upon device detachment, pci_intr_disestablish() should be used to disassociate the handler from the interrupt.

See spl(9) for an explanation of the ipl “interrupt priority levels”.

EXAMPLES

A typical code sequence for establishing a handler for a device interrupt in the driver might be:

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\n");
		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("\n");
		bus_space_unmap(sc->iot, sc->ioh, size);
		return;
	}

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

	...
}

SEE ALSO

cardbus(4), pci(4), pcibios(4), pci_conf_read(9), spl(9)

HISTORY

These functions first appeared in OpenBSD 1.2.