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irq.c

/*
 * arch/arm/mach-ns9xxx/irq.c
 *
 * Copyright (C) 2006,2007 by Digi International Inc.
 * All rights reserved.
 *
 * 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.
 */
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <asm/io.h>
#include <asm/mach/irq.h>
#include <mach/regs-sys-common.h>
#include <mach/irqs.h>
#include <mach/board.h>

#include "generic.h"

/* simple interrupt prio table: prio(x) < prio(y) <=> x < y */
#define irq2prio(i) (i)
#define prio2irq(p) (p)

static void ns9xxx_mask_irq(unsigned int irq)
{
      /* XXX: better use cpp symbols */
      int prio = irq2prio(irq);
      u32 ic = __raw_readl(SYS_IC(prio / 4));
      ic &= ~(1 << (7 + 8 * (3 - (prio & 3))));
      __raw_writel(ic, SYS_IC(prio / 4));
}

static void ns9xxx_ack_irq(unsigned int irq)
{
      __raw_writel(0, SYS_ISRADDR);
}

static void ns9xxx_maskack_irq(unsigned int irq)
{
      ns9xxx_mask_irq(irq);
      ns9xxx_ack_irq(irq);
}

static void ns9xxx_unmask_irq(unsigned int irq)
{
      /* XXX: better use cpp symbols */
      int prio = irq2prio(irq);
      u32 ic = __raw_readl(SYS_IC(prio / 4));
      ic |= 1 << (7 + 8 * (3 - (prio & 3)));
      __raw_writel(ic, SYS_IC(prio / 4));
}

static struct irq_chip ns9xxx_chip = {
      .ack        = ns9xxx_ack_irq,
      .mask       = ns9xxx_mask_irq,
      .mask_ack   = ns9xxx_maskack_irq,
      .unmask           = ns9xxx_unmask_irq,
};

#if 0
#define handle_irq handle_level_irq
#else
static void handle_prio_irq(unsigned int irq, struct irq_desc *desc)
{
      unsigned int cpu = smp_processor_id();
      struct irqaction *action;
      irqreturn_t action_ret;

      spin_lock(&desc->lock);

      BUG_ON(desc->status & IRQ_INPROGRESS);

      desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
      kstat_cpu(cpu).irqs[irq]++;

      action = desc->action;
      if (unlikely(!action || (desc->status & IRQ_DISABLED)))
            goto out_mask;

      desc->status |= IRQ_INPROGRESS;
      spin_unlock(&desc->lock);

      action_ret = handle_IRQ_event(irq, action);

      /* XXX: There is no direct way to access noirqdebug, so check
       * unconditionally for spurious irqs...
       * Maybe this function should go to kernel/irq/chip.c? */
      note_interrupt(irq, desc, action_ret);

      spin_lock(&desc->lock);
      desc->status &= ~IRQ_INPROGRESS;

      if (desc->status & IRQ_DISABLED)
out_mask:
            desc->chip->mask(irq);

      /* ack unconditionally to unmask lower prio irqs */
      desc->chip->ack(irq);

      spin_unlock(&desc->lock);
}
#define handle_irq handle_prio_irq
#endif

void __init ns9xxx_init_irq(void)
{
      int i;

      /* disable all IRQs */
      for (i = 0; i < 8; ++i)
            __raw_writel(prio2irq(4 * i) << 24 |
                        prio2irq(4 * i + 1) << 16 |
                        prio2irq(4 * i + 2) << 8 |
                        prio2irq(4 * i + 3),
                        SYS_IC(i));

      for (i = 0; i < 32; ++i)
            __raw_writel(prio2irq(i), SYS_IVA(i));

      for (i = 0; i <= 31; ++i) {
            set_irq_chip(i, &ns9xxx_chip);
            set_irq_handler(i, handle_irq);
            set_irq_flags(i, IRQF_VALID);
      }
}

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