97 lines
2.5 KiB
C
97 lines
2.5 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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#include <irq.h>
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/* i8259A PIC registers */
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#define PIC_MASTER_CMD 0x20
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#define PIC_MASTER_IMR 0x21
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#define PIC_MASTER_ISR PIC_MASTER_CMD
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#define PIC_MASTER_POLL PIC_MASTER_ISR
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#define PIC_MASTER_OCW3 PIC_MASTER_ISR
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#define PIC_SLAVE_CMD 0xa0
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#define PIC_SLAVE_IMR 0xa1
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/* i8259A PIC related value */
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#define PIC_CASCADE_IR 2
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#define MASTER_ICW4_DEFAULT 0x01
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#define SLAVE_ICW4_DEFAULT 0x01
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#define PIC_ICW4_AEOI 2
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extern raw_spinlock_t i8259A_lock;
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extern void make_8259A_irq(unsigned int irq);
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extern void init_i8259_irqs(void);
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/**
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* i8159_set_poll() - Override the i8259 polling function
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* @poll: pointer to platform-specific polling function
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*
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* Call this to override the generic i8259 polling function, which directly
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* accesses i8259 registers, with a platform specific one which may be faster
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* in cases where hardware provides a more optimal means of polling for an
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* interrupt.
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*/
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extern void i8259_set_poll(int (*poll)(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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raw_spin_lock(&i8259A_lock);
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/* Perform an interrupt acknowledge cycle on controller 1. */
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outb(0x0C, PIC_MASTER_CMD); /* prepare for poll */
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irq = inb(PIC_MASTER_CMD) & 7;
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if (irq == PIC_CASCADE_IR) {
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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, PIC_SLAVE_CMD); /* prepare for poll */
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irq = (inb(PIC_SLAVE_CMD) & 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, PIC_MASTER_ISR); /* ISR register */
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if(~inb(PIC_MASTER_ISR) & 0x80)
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irq = -1;
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}
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raw_spin_unlock(&i8259A_lock);
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return likely(irq >= 0) ? irq + I8259A_IRQ_BASE : irq;
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}
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#endif /* _ASM_I8259_H */
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