arch/alpha/kernel/irq_i8259.c

Source file repositories/reference/linux-study-clean/arch/alpha/kernel/irq_i8259.c

File Facts

System
Linux kernel
Corpus path
arch/alpha/kernel/irq_i8259.c
Extension
.c
Size
3860 bytes
Lines
160
Domain
Architecture Layer
Bucket
arch/alpha
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 *      linux/arch/alpha/kernel/irq_i8259.c
 *
 * This is the 'legacy' 8259A Programmable Interrupt Controller,
 * present in the majority of PC/AT boxes.
 *
 * Started hacking from linux-2.3.30pre6/arch/i386/kernel/i8259.c.
 */

#include <linux/init.h>
#include <linux/cache.h>
#include <linux/sched.h>
#include <linux/irq.h>
#include <linux/interrupt.h>

#include <asm/io.h>

#include "proto.h"
#include "irq_impl.h"


/* Note mask bit is true for DISABLED irqs.  */
static unsigned int cached_irq_mask = 0xffff;
static DEFINE_SPINLOCK(i8259_irq_lock);

static inline void
i8259_update_irq_hw(unsigned int irq, unsigned long mask)
{
	int port = 0x21;
	if (irq & 8) mask >>= 8;
	if (irq & 8) port = 0xA1;
	outb(mask, port);
}

inline void
i8259a_enable_irq(struct irq_data *d)
{
	spin_lock(&i8259_irq_lock);
	i8259_update_irq_hw(d->irq, cached_irq_mask &= ~(1 << d->irq));
	spin_unlock(&i8259_irq_lock);
}

static inline void
__i8259a_disable_irq(unsigned int irq)
{
	i8259_update_irq_hw(irq, cached_irq_mask |= 1 << irq);
}

void
i8259a_disable_irq(struct irq_data *d)
{
	spin_lock(&i8259_irq_lock);
	__i8259a_disable_irq(d->irq);
	spin_unlock(&i8259_irq_lock);
}

void
i8259a_mask_and_ack_irq(struct irq_data *d)
{
	unsigned int irq = d->irq;

	spin_lock(&i8259_irq_lock);
	__i8259a_disable_irq(irq);

	/* Ack the interrupt making it the lowest priority.  */
	if (irq >= 8) {
		outb(0xE0 | (irq - 8), 0xa0);   /* ack the slave */
		irq = 2;
	}
	outb(0xE0 | irq, 0x20);			/* ack the master */
	spin_unlock(&i8259_irq_lock);
}

struct irq_chip i8259a_irq_type = {
	.name		= "XT-PIC",
	.irq_unmask	= i8259a_enable_irq,
	.irq_mask	= i8259a_disable_irq,
	.irq_mask_ack	= i8259a_mask_and_ack_irq,
};

void __init
init_i8259a_irqs(void)
{
	long i;

	outb(0xff, 0x21);	/* mask all of 8259A-1 */
	outb(0xff, 0xA1);	/* mask all of 8259A-2 */

	for (i = 0; i < 16; i++) {

Annotation

Implementation Notes