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/*
* linux/arch/alpha/kernel/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 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(unsigned int irq)
{
i8259_update_irq_hw(irq, cached_irq_mask &= ~(1 << irq));
}
inline void
i8259a_disable_irq(unsigned int irq)
{
i8259_update_irq_hw(irq, cached_irq_mask |= 1 << irq);
}
void
i8259a_mask_and_ack_irq(unsigned int irq)
{
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 */
}
unsigned int
i8259a_startup_irq(unsigned int irq)
{
i8259a_enable_irq(irq);
return 0; /* never anything pending */
}
struct hw_interrupt_type i8259a_irq_type = {
typename: "XT-PIC",
startup: i8259a_startup_irq,
shutdown: i8259a_disable_irq,
enable: i8259a_enable_irq,
disable: i8259a_disable_irq,
ack: i8259a_mask_and_ack_irq,
end: i8259a_enable_irq,
};
void __init
init_i8259a_irqs(void)
{
static struct irqaction cascade = {
handler: no_action,
name: "cascade",
};
long i;
outb(0xff, 0x21); /* mask all of 8259A-1 */
outb(0xff, 0xA1); /* mask all of 8259A-2 */
for (i = 0; i < 16; i++) {
irq_desc[i].status = IRQ_DISABLED;
irq_desc[i].handler = &i8259a_irq_type;
}
setup_irq(2, &cascade);
}
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