i_eoi Kernel Service

Purpose

Issues an End of Interrupt (EOI) for a given handler.

Syntax

int i_eoi(struct intr   *handler)

Description

The i_eoi kernel service allows a device driver to issue an End of Interrupt (EOI) for its device explicitly. For level-triggered interrupts, after the second level interrupt handler (SLIH) has completed, the kernel issues an EOI on behalf of the device driver. For ISA (8259) edge-triggered interrupts, the kernel issues the EOI on behalf of the device driver before calling the SLIH. However, in the case of some edge-triggered interrupts (for example, PCI and PCI-E style edge-triggered interrupt), it is desirable that the device driver checks for pending work before the EOI is issued, and the driver is required to check for any additional work after the EOI is issued. The i_eoi kernel service facilitates such operations and issues an EOI for an edge-triggered interrupt source. The i_eoi kernel service fails if called for a level-triggered interrupt source.

Parameters

Item	Description
handler	Pointer to the interrupt handler

Execution Environment

The i_eoi kernel service can be called from process or interrupt environment.

Return Values

INTR_SUCC if successful

INTR_FAIL if unsuccessful (the INTR_EDGE flag was not set on i_init()).

Virtual device drivers' interrupt services are similar to the PCI interrupt services. Interrupts are registered with a bus_type of BUS_BID. The primary difference is that the edge flag should be set for vdevices. For example:

Parent  CuDv  "bus_id"		VDEVICE bus BID
Device  CuAt  "bus_intr_lvl"	Adapter interrupt level

intr.flags	|= INTR_EDGE
intr.bus_type	= BUS_BID
intr.bid	= Parent_CuDv.bus_id
intr.level	= Device_CuAt.bus_intr_lvl

PCI-E interrupts are Message Signalled Interrupts, and hence, they are edge-triggered. Therefore, INTR_EDGE flag should be specified.