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irq.c

/*
 *  arch/s390/kernel/irq.c
 *
 *    Copyright IBM Corp. 2004,2007
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *           Thomas Spatzier (tspat@de.ibm.com)
 *
 * This file contains interrupt related functions.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <linux/cpu.h>
#include <linux/proc_fs.h>
#include <linux/profile.h>

/*
 * show_interrupts is needed by /proc/interrupts.
 */
int show_interrupts(struct seq_file *p, void *v)
{
      static const char *intrclass_names[] = { "EXT", "I/O", };
      int i = *(loff_t *) v, j;

      get_online_cpus();
      if (i == 0) {
            seq_puts(p, "           ");
            for_each_online_cpu(j)
                  seq_printf(p, "CPU%d       ",j);
            seq_putc(p, '\n');
      }

      if (i < NR_IRQS) {
            seq_printf(p, "%s: ", intrclass_names[i]);
#ifndef CONFIG_SMP
            seq_printf(p, "%10u ", kstat_irqs(i));
#else
            for_each_online_cpu(j)
                  seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
#endif
                seq_putc(p, '\n');

        }
      put_online_cpus();
        return 0;
}

/*
 * For compatibilty only. S/390 specific setup of interrupts et al. is done
 * much later in init_channel_subsystem().
 */
void __init
init_IRQ(void)
{
      /* nothing... */
}

/*
 * Switch to the asynchronous interrupt stack for softirq execution.
 */
asmlinkage void do_softirq(void)
{
      unsigned long flags, old, new;

      if (in_interrupt())
            return;

      local_irq_save(flags);

      if (local_softirq_pending()) {
            /* Get current stack pointer. */
            asm volatile("la %0,0(15)" : "=a" (old));
            /* Check against async. stack address range. */
            new = S390_lowcore.async_stack;
            if (((new - old) >> (PAGE_SHIFT + THREAD_ORDER)) != 0) {
                  /* Need to switch to the async. stack. */
                  new -= STACK_FRAME_OVERHEAD;
                  ((struct stack_frame *) new)->back_chain = old;

                  asm volatile("   la    15,0(%0)\n"
                             "   basr  14,%2\n"
                             "   la    15,0(%1)\n"
                             : : "a" (new), "a" (old),
                                 "a" (__do_softirq)
                             : "0", "1", "2", "3", "4", "5", "14",
                               "cc", "memory" );
            } else
                  /* We are already on the async stack. */
                  __do_softirq();
      }

      local_irq_restore(flags);
}

void init_irq_proc(void)
{
      struct proc_dir_entry *root_irq_dir;

      root_irq_dir = proc_mkdir("irq", NULL);
      create_prof_cpu_mask(root_irq_dir);
}

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