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irqchip.c

/*
 * Copyright 2005-2009 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later
 */

#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <asm/trace.h>
#include <asm/pda.h>

static atomic_t irq_err_count;
void ack_bad_irq(unsigned int irq)
{
      atomic_inc(&irq_err_count);
      printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
}

static struct irq_desc bad_irq_desc = {
      .handle_irq = handle_bad_irq,
      .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
};

#ifdef CONFIG_CPUMASK_OFFSTACK
/* We are not allocating a variable-sized bad_irq_desc.affinity */
#error "Blackfin architecture does not support CONFIG_CPUMASK_OFFSTACK."
#endif

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

      if (i < NR_IRQS) {
            spin_lock_irqsave(&irq_desc[i].lock, flags);
            action = irq_desc[i].action;
            if (!action)
                  goto skip;
            seq_printf(p, "%3d: ", i);
            for_each_online_cpu(j)
                  seq_printf(p, "%10u ", kstat_irqs_cpu(i, j));
            seq_printf(p, " %8s", 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');
 skip:
            spin_unlock_irqrestore(&irq_desc[i].lock, flags);
      } else if (i == NR_IRQS) {
            seq_printf(p, "NMI: ");
            for_each_online_cpu(j)
                  seq_printf(p, "%10u ", cpu_pda[j].__nmi_count);
            seq_printf(p, "     CORE  Non Maskable Interrupt\n");
            seq_printf(p, "Err: %10u\n",  atomic_read(&irq_err_count));
      }
      return 0;
}
#endif

#ifdef CONFIG_DEBUG_STACKOVERFLOW
static void check_stack_overflow(int irq)
{
      /* Debugging check for stack overflow: is there less than STACK_WARN free? */
      long sp = __get_SP() & (THREAD_SIZE - 1);

      if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
            dump_stack();
            pr_emerg("irq%i: possible stack overflow only %ld bytes free\n",
                  irq, sp - sizeof(struct thread_info));
      }
}
#else
static inline void check_stack_overflow(int irq) { }
#endif

#ifndef CONFIG_IPIPE
static void maybe_lower_to_irq14(void)
{
      unsigned short pending, other_ints;

      /*
       * If we're the only interrupt running (ignoring IRQ15 which
       * is for syscalls), lower our priority to IRQ14 so that
       * softirqs run at that level.  If there's another,
       * lower-level interrupt, irq_exit will defer softirqs to
       * that. If the interrupt pipeline is enabled, we are already
       * running at IRQ14 priority, so we don't need this code.
       */
      CSYNC();
      pending = bfin_read_IPEND() & ~0x8000;
      other_ints = pending & (pending - 1);
      if (other_ints == 0)
            lower_to_irq14();
}
#else
static inline void maybe_lower_to_irq14(void) { }
#endif

/*
 * do_IRQ handles all hardware IRQs.  Decoded IRQs should not
 * come via this function.  Instead, they should provide their
 * own 'handler'
 */
#ifdef CONFIG_DO_IRQ_L1
__attribute__((l1_text))
#endif
asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
{
      struct pt_regs *old_regs = set_irq_regs(regs);

      irq_enter();

      check_stack_overflow(irq);

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

      maybe_lower_to_irq14();

      irq_exit();

      set_irq_regs(old_regs);
}

void __init init_IRQ(void)
{
      init_arch_irq();

#ifdef CONFIG_DEBUG_BFIN_HWTRACE_EXPAND
      /* Now that evt_ivhw is set up, turn this on */
      trace_buff_offset = 0;
      bfin_write_TBUFCTL(BFIN_TRACE_ON);
      printk(KERN_INFO "Hardware Trace expanded to %ik\n",
        1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN);
#endif
}

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