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/*
* include/asm-mips/i8259.h
*
* i8259A interrupt definitions.
*
* Copyright (C) 2003 Maciej W. Rozycki
* Copyright (C) 2003 Ralf Baechle <ralf@linux-mips.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _ASM_I8259_H
#define _ASM_I8259_H
#include <linux/compiler.h>
#include <linux/spinlock.h>
#include <asm/io.h>
extern spinlock_t i8259A_lock;
extern void init_i8259_irqs(void);
/*
* Do the traditional i8259 interrupt polling thing. This is for the few
* cases where no better interrupt acknowledge method is available and we
* absolutely must touch the i8259.
*/
static inline int i8259_irq(void)
{
int irq;
spin_lock(&i8259A_lock);
/* Perform an interrupt acknowledge cycle on controller 1. */
outb(0x0C, 0x20); /* prepare for poll */
irq = inb(0x20) & 7;
if (irq == 2) {
/*
* Interrupt is cascaded so perform interrupt
* acknowledge on controller 2.
*/
outb(0x0C, 0xA0); /* prepare for poll */
irq = (inb(0xA0) & 7) + 8;
}
if (unlikely(irq == 7)) {
/*
* This may be a spurious interrupt.
*
* Read the interrupt status register (ISR). If the most
* significant bit is not set then there is no valid
* interrupt.
*/
outb(0x0B, 0x20); /* ISR register */
if(~inb(0x20) & 0x80)
irq = -1;
}
spin_unlock(&i8259A_lock);
return irq;
}
#endif /* _ASM_I8259_H */
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