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irq.c

/*
 *  linux/arch/arm/kernel/irq.c
 *
 *  Copyright (C) 1992 Linus Torvalds
 *  Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
 *
 *  Support for Dynamic Tick Timer Copyright (C) 2004-2005 Nokia Corporation.
 *  Dynamic Tick Timer written by Tony Lindgren <tony@atomide.com> and
 *  Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.
 *
 * 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.
 *
 *  This file contains the code used by various IRQ handling routines:
 *  asking for different IRQ's should be done through these routines
 *  instead of just grabbing them. Thus setups with different IRQ numbers
 *  shouldn't result in any weird surprises, and installing new handlers
 *  should be easier.
 *
 *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
 *  Naturally it's not a 1:1 relation, but there are similarities.
 */
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/signal.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/kallsyms.h>
#include <linux/proc_fs.h>

#include <asm/system.h>
#include <asm/mach/time.h>

/*
 * No architecture-specific irq_finish function defined in arm/arch/irqs.h.
 */
#ifndef irq_finish
#define irq_finish(irq) do { } while (0)
#endif

void (*init_arch_irq)(void) __initdata = NULL;
unsigned long irq_err_count;

int show_interrupts(struct seq_file *p, void *v)
{
      int i = *(loff_t *) v, cpu;
      struct irqaction * action;
      unsigned long flags;

      if (i == 0) {
            char cpuname[12];

            seq_printf(p, "    ");
            for_each_present_cpu(cpu) {
                  sprintf(cpuname, "CPU%d", cpu);
                  seq_printf(p, " %10s", cpuname);
            }
            seq_putc(p, '\n');
      }

      if (i < NR_IRQS) {
            spin_lock_irqsave(&irq_desc[i].lock, flags);
            action = irq_desc[i].action;
            if (!action)
                  goto unlock;

            seq_printf(p, "%3d: ", i);
            for_each_present_cpu(cpu)
                  seq_printf(p, "%10u ", kstat_cpu(cpu).irqs[i]);
            seq_printf(p, " %10s", irq_desc[i].chip->name ? : "-");
            seq_printf(p, "  %s", action->name);
            for (action = action->next; action; action = action->next)
                  seq_printf(p, ", %s", action->name);

            seq_putc(p, '\n');
unlock:
            spin_unlock_irqrestore(&irq_desc[i].lock, flags);
      } else if (i == NR_IRQS) {
#ifdef CONFIG_ARCH_ACORN
            show_fiq_list(p, v);
#endif
#ifdef CONFIG_SMP
            show_ipi_list(p);
            show_local_irqs(p);
#endif
            seq_printf(p, "Err: %10lu\n", irq_err_count);
      }
      return 0;
}

/* Handle bad interrupts */
static struct irq_desc bad_irq_desc = {
      .handle_irq = handle_bad_irq,
      .lock = SPIN_LOCK_UNLOCKED
};

/*
 * do_IRQ handles all hardware IRQ's.  Decoded IRQs should not
 * come via this function.  Instead, they should provide their
 * own 'handler'
 */
asmlinkage void __exception asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
{
      struct pt_regs *old_regs = set_irq_regs(regs);
      struct irq_desc *desc = irq_desc + irq;

      /*
       * Some hardware gives randomly wrong interrupts.  Rather
       * than crashing, do something sensible.
       */
      if (irq >= NR_IRQS)
            desc = &bad_irq_desc;

      irq_enter();

      desc_handle_irq(irq, desc);

      /* AT91 specific workaround */
      irq_finish(irq);

      irq_exit();
      set_irq_regs(old_regs);
}

void set_irq_flags(unsigned int irq, unsigned int iflags)
{
      struct irq_desc *desc;
      unsigned long flags;

      if (irq >= NR_IRQS) {
            printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
            return;
      }

      desc = irq_desc + irq;
      spin_lock_irqsave(&desc->lock, flags);
      desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
      if (iflags & IRQF_VALID)
            desc->status &= ~IRQ_NOREQUEST;
      if (iflags & IRQF_PROBE)
            desc->status &= ~IRQ_NOPROBE;
      if (!(iflags & IRQF_NOAUTOEN))
            desc->status &= ~IRQ_NOAUTOEN;
      spin_unlock_irqrestore(&desc->lock, flags);
}

void __init init_IRQ(void)
{
      int irq;

      for (irq = 0; irq < NR_IRQS; irq++)
            irq_desc[irq].status |= IRQ_NOREQUEST | IRQ_NOPROBE;

#ifdef CONFIG_SMP
      bad_irq_desc.affinity = CPU_MASK_ALL;
      bad_irq_desc.cpu = smp_processor_id();
#endif
      init_arch_irq();
}

#ifdef CONFIG_HOTPLUG_CPU

static void route_irq(struct irq_desc *desc, unsigned int irq, unsigned int cpu)
{
      pr_debug("IRQ%u: moving from cpu%u to cpu%u\n", irq, desc->cpu, cpu);

      spin_lock_irq(&desc->lock);
      desc->chip->set_affinity(irq, cpumask_of_cpu(cpu));
      spin_unlock_irq(&desc->lock);
}

/*
 * The CPU has been marked offline.  Migrate IRQs off this CPU.  If
 * the affinity settings do not allow other CPUs, force them onto any
 * available CPU.
 */
void migrate_irqs(void)
{
      unsigned int i, cpu = smp_processor_id();

      for (i = 0; i < NR_IRQS; i++) {
            struct irq_desc *desc = irq_desc + i;

            if (desc->cpu == cpu) {
                  unsigned int newcpu = any_online_cpu(desc->affinity);

                  if (newcpu == NR_CPUS) {
                        if (printk_ratelimit())
                              printk(KERN_INFO "IRQ%u no longer affine to CPU%u\n",
                                     i, cpu);

                        cpus_setall(desc->affinity);
                        newcpu = any_online_cpu(desc->affinity);
                  }

                  route_irq(desc, i, newcpu);
            }
      }
}
#endif /* CONFIG_HOTPLUG_CPU */

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