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scoutos / prex-0.9.0 / bsp / hal / ppc / prep / interrupt.c @ 03e9c04a

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/*-
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 * Copyright (c) 2009, Kohsuke Ohtani
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the author nor the names of any co-contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 */
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/*
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 * interrupt.c - interrupt management routines for intel 8259 chip
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 */
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#include <kernel.h>
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#include <hal.h>
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#include <irq.h>
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#include <io.h>
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#include <cpufunc.h>
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#include <context.h>
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#include <trap.h>
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#include <clock.h>
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#include <locore.h>
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#include <sys/ipl.h>
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/* Number of IRQ lines */
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#define NIRQS                16
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/* I/O address for master/slave programmable interrupt controller */
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#define PIC_M           0x20
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#define PIC_S           0xa0
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/* Edge/level control register */
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#define ELCR            0x4d0
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/*
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 * Interrupt priority level
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 *
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 * Each interrupt has its logical priority level, with 0 being
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 * the highest priority. While some ISR is running, all lower
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 * priority interrupts are masked off.
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 */
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static volatile int irq_level;
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/*
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 * Interrupt mapping table
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 */
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static int        ipl_table[NIRQS];        /* Vector -> level */
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static u_int        mask_table[NIPLS];        /* Level -> mask */
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/*
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 * Set mask for current ipl
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 */
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static void
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update_mask(void)
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{
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        u_int mask = mask_table[irq_level];
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        outb(PIC_M + 1, mask & 0xff);
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        outb(PIC_S + 1, mask >> 8);
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}
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/*
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 * Unmask interrupt in PIC for specified irq.
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 * The interrupt mask table is also updated.
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 * Assumed CPU interrupt is disabled in caller.
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 */
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void
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interrupt_unmask(int vector, int level)
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{
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        u_int unmask = (u_int)~(1 << vector);
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        int i, s;
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        s = splhigh();
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        ipl_table[vector] = level;
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        /*
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         * Unmask target interrupt for all
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         * lower interrupt levels.
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         */
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        for (i = 0; i < level; i++)
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                mask_table[i] &= unmask;
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        update_mask();
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        splx(s);
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}
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/*
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 * Mask interrupt in PIC for specified irq.
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 * Interrupt must be disabled when this routine is called.
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 */
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void
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interrupt_mask(int vector)
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{
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        u_int mask = (u_int)(1 << vector);
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        int i, level, s;
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        s = splhigh();
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        level = ipl_table[vector];
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        for (i = 0; i < level; i++)
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                mask_table[i] |= mask;
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        ipl_table[vector] = IPL_NONE;
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        update_mask();
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        splx(s);
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}
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/*
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 * Setup interrupt mode.
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 * Select whether an interrupt trigger is edge or level.
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 */
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void
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interrupt_setup(int vector, int mode)
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{
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        int port, s;
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        u_int bit;
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        u_char val;
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        s = splhigh();
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        port = vector < 8 ? ELCR : ELCR + 1;
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        bit = (u_int)(1 << (vector & 7));
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        val = inb(port);
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        if (mode == IMODE_LEVEL)
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                val |= bit;
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        else
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                val &= ~bit;
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        outb(port, val);
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        splx(s);
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}
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/*
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 * Get interrupt source.
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 */
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static int
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interrupt_lookup(void)
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{
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        int irq;
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        outb(PIC_M, 0x0c);        /* poll and ack */
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        irq = inb(PIC_M) & 7;
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        if (irq == 2) {
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                outb(PIC_S, 0x0c);
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                irq = (inb(PIC_M) & 7) + 8;
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        }
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        return irq;
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}
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/*
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 * Common interrupt handler.
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 *
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 * This routine is called from the low level interrupt routine
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 * written in assemble code. The interrupt flag is automatically
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 * disabled by h/w in CPU when the interrupt is occurred. The
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 * target interrupt will be masked in ICU while the irq handler
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 * is called.
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 */
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void
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interrupt_handler(struct cpu_regs *regs)
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{
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        int vector;
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        int old_ipl, new_ipl;
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        /* Handle decrementer interrupt */
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        if (regs->trap_no == TRAP_DECREMENTER) {
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                clock_isr(NULL);
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                return;
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        }
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        /* Find pending interrupt */
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        vector = interrupt_lookup();
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        /* Adjust interrupt level */
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        old_ipl = irq_level;
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        new_ipl = ipl_table[vector];
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        if (new_ipl > old_ipl)                /* Ignore spurious interrupt */
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                irq_level = new_ipl;
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        update_mask();
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        /* Dispatch interrupt */
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        splon();
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        irq_handler(vector);
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        sploff();
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        /* Restore interrupt level */
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        irq_level = old_ipl;
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        update_mask();
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}
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/*
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 * Initialize 8259 interrupt controllers.
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 * All interrupts will be masked off in ICU.
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 */
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void
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interrupt_init(void)
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{
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        int i;
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        irq_level = IPL_NONE;
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        for (i = 0; i < NIRQS; i++)
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                ipl_table[i] = IPL_NONE;
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        for (i = 0; i < NIPLS; i++)
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                mask_table[i] = 0xfffb;
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        outb(PIC_M, 0x11);        /* Start initialization edge, master */
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        outb(PIC_M + 1, 0x00);        /* Set h/w vector = 0x0 */
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        outb(PIC_M + 1, 0x04);        /* Chain to slave (IRQ2) */
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        outb(PIC_M + 1, 0x01);        /* 8086 mode */
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        outb(PIC_S, 0x11);        /* Start initialization edge, master */
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        outb(PIC_S + 1, 0x08);        /* Set h/w vector = 0x8 */
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        outb(PIC_S + 1, 0x02);        /* Slave (cascade) */
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        outb(PIC_S + 1, 0x01);        /* 8086 mode */
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        outb(PIC_S, 0x0b);        /* Read ISR by default */
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        outb(PIC_M, 0x0b);        /* Read ISR by default */
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        outb(PIC_S + 1, 0xff);        /* Mask all */
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        outb(PIC_M + 1, 0xfb);        /* Mask all except IRQ2 (cascade) */
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}