irq.c

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/*
 *  linux/arch/arm/mach-shark/irq.c
 *
 * by Alexander Schulz
 *
 * derived from linux/arch/ppc/kernel/i8259.c and:
 * arch/arm/mach-ebsa110/include/mach/irq.h
 * Copyright (C) 1996-1998 Russell King
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/io.h>

#include <asm/irq.h>
#include <asm/mach/irq.h>

/*
 * 8259A PIC functions to handle ISA devices:
 */

/*
 * This contains the irq mask for both 8259A irq controllers,
 * Let through the cascade-interrupt no. 2 (ff-(1<<2)==fb)
 */
static unsigned char cached_irq_mask[2] = { 0xfb, 0xff };

/*
 * These have to be protected by the irq controller spinlock
 * before being called.
 */
static void shark_disable_8259A_irq(struct irq_data *d)
{
    unsigned int mask;
    if (d->irq<8) {
      mask = 1 << d->irq;
      cached_irq_mask[0] |= mask;
      outb(cached_irq_mask[1],0xA1);
    } else {
      mask = 1 << (d->irq-8);
      cached_irq_mask[1] |= mask;
      outb(cached_irq_mask[0],0x21);
    }
}

static void shark_enable_8259A_irq(struct irq_data *d)
{
    unsigned int mask;
    if (d->irq<8) {
      mask = ~(1 << d->irq);
      cached_irq_mask[0] &= mask;
      outb(cached_irq_mask[0],0x21);
    } else {
      mask = ~(1 << (d->irq-8));
      cached_irq_mask[1] &= mask;
      outb(cached_irq_mask[1],0xA1);
    }
}

static void shark_ack_8259A_irq(struct irq_data *d){}

static irqreturn_t bogus_int(int irq, void *dev_id)
{
    printk("Got interrupt %i!\n",irq);
    return IRQ_NONE;
}

static struct irqaction cascade;

static struct irq_chip fb_chip = {
    .name       = "XT-PIC",
    .irq_ack    = shark_ack_8259A_irq,
    .irq_mask   = shark_disable_8259A_irq,
    .irq_unmask = shark_enable_8259A_irq,
};

void __init shark_init_irq(void)
{
    int irq;

    for (irq = 0; irq < NR_IRQS; irq++) {
        irq_set_chip_and_handler(irq, &fb_chip, handle_edge_irq);
        set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
    }

    /* init master interrupt controller */
    outb(0x11, 0x20); /* Start init sequence, edge triggered (level: 0x19)*/
    outb(0x00, 0x21); /* Vector base */
    outb(0x04, 0x21); /* Cascade (slave) on IRQ2 */
    outb(0x03, 0x21); /* Select 8086 mode , auto eoi*/
    outb(0x0A, 0x20);
    /* init slave interrupt controller */
    outb(0x11, 0xA0); /* Start init sequence, edge triggered */
    outb(0x08, 0xA1); /* Vector base */
    outb(0x02, 0xA1); /* Cascade (slave) on IRQ2 */
    outb(0x03, 0xA1); /* Select 8086 mode, auto eoi */
    outb(0x0A, 0xA0);
    outb(cached_irq_mask[1],0xA1);
    outb(cached_irq_mask[0],0x21);
    //request_region(0x20,0x2,"pic1");
    //request_region(0xA0,0x2,"pic2");

    cascade.handler = bogus_int;
    cascade.name = "cascade";
    setup_irq(2,&cascade);
}