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isa-irq.c

/*
 *  linux/arch/arm/mach-footbridge/irq.c
 *
 *  Copyright (C) 1996-2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  Changelog:
 *   22-Aug-1998 RMK    Restructured IRQ routines
 *   03-Sep-1998 PJB    Merged CATS support
 *   20-Jan-1998 RMK    Started merge of EBSA286, CATS and NetWinder
 *   26-Jan-1999 PJB    Don't use IACK on CATS
 *   16-Mar-1999 RMK    Added autodetect of ISA PICs
 */
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/init.h>

#include <asm/mach/irq.h>

#include <asm/hardware.h>
#include <asm/hardware/dec21285.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/mach-types.h>

static void isa_mask_pic_lo_irq(unsigned int irq)
{
      unsigned int mask = 1 << (irq & 7);

      outb(inb(PIC_MASK_LO) | mask, PIC_MASK_LO);
}

static void isa_ack_pic_lo_irq(unsigned int irq)
{
      unsigned int mask = 1 << (irq & 7);

      outb(inb(PIC_MASK_LO) | mask, PIC_MASK_LO);
      outb(0x20, PIC_LO);
}

static void isa_unmask_pic_lo_irq(unsigned int irq)
{
      unsigned int mask = 1 << (irq & 7);

      outb(inb(PIC_MASK_LO) & ~mask, PIC_MASK_LO);
}

static struct irqchip isa_lo_chip = {
      .ack  = isa_ack_pic_lo_irq,
      .mask = isa_mask_pic_lo_irq,
      .unmask = isa_unmask_pic_lo_irq,
};

static void isa_mask_pic_hi_irq(unsigned int irq)
{
      unsigned int mask = 1 << (irq & 7);

      outb(inb(PIC_MASK_HI) | mask, PIC_MASK_HI);
}

static void isa_ack_pic_hi_irq(unsigned int irq)
{
      unsigned int mask = 1 << (irq & 7);

      outb(inb(PIC_MASK_HI) | mask, PIC_MASK_HI);
      outb(0x62, PIC_LO);
      outb(0x20, PIC_HI);
}

static void isa_unmask_pic_hi_irq(unsigned int irq)
{
      unsigned int mask = 1 << (irq & 7);

      outb(inb(PIC_MASK_HI) & ~mask, PIC_MASK_HI);
}

static struct irqchip isa_hi_chip = {
      .ack  = isa_ack_pic_hi_irq,
      .mask = isa_mask_pic_hi_irq,
      .unmask = isa_unmask_pic_hi_irq,
};

static void
isa_irq_handler(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
{
      unsigned int isa_irq = *(unsigned char *)PCIIACK_BASE;

      if (isa_irq < _ISA_IRQ(0) || isa_irq >= _ISA_IRQ(16)) {
            do_bad_IRQ(isa_irq, desc, regs);
            return;
      }

      desc = irq_desc + isa_irq;
      desc_handle_irq(isa_irq, desc, regs);
}

static struct irqaction irq_cascade = {
      .handler = no_action,
      .name = "cascade",
};

static struct resource pic1_resource = {
      .name = "pic1",
      .start      = 0x20,
      .end  = 0x3f,
};

static struct resource pic2_resource = {
      .name = "pic2",
      .start      = 0xa0,
      .end  = 0xbf,
};

void __init isa_init_irq(unsigned int host_irq)
{
      unsigned int irq;

      /*
       * Setup, and then probe for an ISA PIC
       * If the PIC is not there, then we
       * ignore the PIC.
       */
      outb(0x11, PIC_LO);
      outb(_ISA_IRQ(0), PIC_MASK_LO);     /* IRQ number           */
      outb(0x04, PIC_MASK_LO);      /* Slave on Ch2         */
      outb(0x01, PIC_MASK_LO);      /* x86                  */
      outb(0xf5, PIC_MASK_LO);      /* pattern: 11110101    */

      outb(0x11, PIC_HI);
      outb(_ISA_IRQ(8), PIC_MASK_HI);     /* IRQ number           */
      outb(0x02, PIC_MASK_HI);      /* Slave on Ch1         */
      outb(0x01, PIC_MASK_HI);      /* x86                  */
      outb(0xfa, PIC_MASK_HI);      /* pattern: 11111010    */

      outb(0x0b, PIC_LO);
      outb(0x0b, PIC_HI);

      if (inb(PIC_MASK_LO) == 0xf5 && inb(PIC_MASK_HI) == 0xfa) {
            outb(0xff, PIC_MASK_LO);/* mask all IRQs  */
            outb(0xff, PIC_MASK_HI);/* mask all IRQs  */
      } else {
            printk(KERN_INFO "IRQ: ISA PIC not found\n");
            host_irq = (unsigned int)-1;
      }

      if (host_irq != (unsigned int)-1) {
            for (irq = _ISA_IRQ(0); irq < _ISA_IRQ(8); irq++) {
                  set_irq_chip(irq, &isa_lo_chip);
                  set_irq_handler(irq, do_level_IRQ);
                  set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
            }

            for (irq = _ISA_IRQ(8); irq < _ISA_IRQ(16); irq++) {
                  set_irq_chip(irq, &isa_hi_chip);
                  set_irq_handler(irq, do_level_IRQ);
                  set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
            }

            request_resource(&ioport_resource, &pic1_resource);
            request_resource(&ioport_resource, &pic2_resource);
            setup_irq(IRQ_ISA_CASCADE, &irq_cascade);

            set_irq_chained_handler(host_irq, isa_irq_handler);

            /*
             * On the NetWinder, don't automatically
             * enable ISA IRQ11 when it is requested.
             * There appears to be a missing pull-up
             * resistor on this line.
             */
            if (machine_is_netwinder())
                  set_irq_flags(_ISA_IRQ(11), IRQF_VALID |
                              IRQF_PROBE | IRQF_NOAUTOEN);
      }
}



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