text: /*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Code to handle x86 style IRQs plus some generic interrupt stuff.
   *
   * Copyright (C) 1992 Linus Torvalds
   * Copyright (C) 1994 - 2000 Ralf Baechle
   */
  #include <linux/kernel.h>
  #include <linux/delay.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/kernel_stat.h>
  #include <linux/proc_fs.h>
  #include <linux/mm.h>
  #include <linux/random.h>
  #include <linux/sched.h>
  #include <linux/seq_file.h>
  #include <linux/kallsyms.h>
  #include <linux/kgdb.h>
  #include <linux/ftrace.h>
  
  #include <linux/atomic.h>
  #include <asm/uaccess.h>
  
  #ifdef CONFIG_KGDB
  int kgdb_early_setup;
  #endif
  
  static unsigned long irq_map[NR_IRQS / BITS_PER_LONG];
  
  int allocate_irqno(void)
  {
  	int irq;
  
  again:
  	irq = find_first_zero_bit(irq_map, NR_IRQS);
  
  	if (irq >= NR_IRQS)
  		return -ENOSPC;
  
  	if (test_and_set_bit(irq, irq_map))
  		goto again;
  
  	return irq;
  }
  
  /*
   * Allocate the 16 legacy interrupts for i8259 devices.	 This happens early
   * in the kernel initialization so treating allocation failure as BUG() is
   * ok.
   */
  void __init alloc_legacy_irqno(void)
  {
  	int i;
  
  	for (i = 0; i <= 16; i++)
  		BUG_ON(test_and_set_bit(i, irq_map));
  }
  
  void free_irqno(unsigned int irq)
  {
  	smp_mb__before_clear_bit();
  	clear_bit(irq, irq_map);
  	smp_mb__after_clear_bit();
  }
  
  /*
   * 'what should we do if we get a hw irq event on an illegal vector'.
   * each architecture has to answer this themselves.
   */
  void ack_bad_irq(unsigned int irq)
  {
  	smtc_im_ack_irq(irq);
  	printk("unexpected IRQ # %d\n", irq);
  }
  
  atomic_t irq_err_count;
  
  int arch_show_interrupts(struct seq_file *p, int prec)
  {
  	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
  	return 0;
  }
  
  asmlinkage void spurious_interrupt(void)
  {
  	atomic_inc(&irq_err_count);
  }
  
  void __init init_IRQ(void)
  {
  	int i;
  
  #ifdef CONFIG_KGDB
  	if (kgdb_early_setup)
  		return;
  #endif
  
  	for (i = 0; i < NR_IRQS; i++)
  		irq_set_noprobe(i);
  
  	arch_init_irq();
  
  #ifdef CONFIG_KGDB
  	if (!kgdb_early_setup)
  		kgdb_early_setup = 1;
  #endif
  }
  
  #ifdef DEBUG_STACKOVERFLOW
  static inline void check_stack_overflow(void)
  {
  	unsigned long sp;
  
  	__asm__ __volatile__("move %0, $sp" : "=r" (sp));
  	sp &= THREAD_MASK;
  
  	/*
  	 * Check for stack overflow: is there less than STACK_WARN free?
  	 * STACK_WARN is defined as 1/8 of THREAD_SIZE by default.
  	 */
  	if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
  		printk("do_IRQ: stack overflow: %ld\n",
  		       sp - sizeof(struct thread_info));
  		dump_stack();
  	}
  }
  #else
  static inline void check_stack_overflow(void) {}
  #endif
  
  
  /*
   * do_IRQ handles all normal device IRQ's (the special
   * SMP cross-CPU interrupts have their own specific
   * handlers).
   */
  void __irq_entry do_IRQ(unsigned int irq)
  {
  	irq_enter();
  	check_stack_overflow();
  	if (!smtc_handle_on_other_cpu(irq))
  		generic_handle_irq(irq);
  	irq_exit();
  }
  
  #ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
  /*
   * To avoid inefficient and in some cases pathological re-checking of
   * IRQ affinity, we have this variant that skips the affinity check.
   */
  
  void __irq_entry do_IRQ_no_affinity(unsigned int irq)
  {
  	irq_enter();
  	smtc_im_backstop(irq);
  	generic_handle_irq(irq);
  	irq_exit();
  }
  
  #endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */
  