68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
|
/*
|
||
|
|
* 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 */
|