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