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s390_ext.c

/*
 *  arch/s390/kernel/s390_ext.c
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Holger Smolinski (Holger.Smolinski@de.ibm.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <asm/cpu.h>
#include <asm/lowcore.h>
#include <asm/s390_ext.h>
#include <asm/irq_regs.h>
#include <asm/irq.h>
#include "entry.h"

/*
 * ext_int_hash[index] is the start of the list for all external interrupts
 * that hash to this index. With the current set of external interrupts 
 * (0x1202 external call, 0x1004 cpu timer, 0x2401 hwc console, 0x4000
 * iucv and 0x2603 pfault) this is always the first element. 
 */
ext_int_info_t *ext_int_hash[256] = { NULL, };

static inline int ext_hash(__u16 code)
{
      return (code + (code >> 9)) & 0xff;
}

int register_external_interrupt(__u16 code, ext_int_handler_t handler)
{
        ext_int_info_t *p;
        int index;

      p = kmalloc(sizeof(ext_int_info_t), GFP_ATOMIC);
        if (p == NULL)
                return -ENOMEM;
        p->code = code;
        p->handler = handler;
      index = ext_hash(code);
        p->next = ext_int_hash[index];
        ext_int_hash[index] = p;
        return 0;
}

int register_early_external_interrupt(__u16 code, ext_int_handler_t handler,
                              ext_int_info_t *p)
{
        int index;

        if (p == NULL)
                return -EINVAL;
        p->code = code;
        p->handler = handler;
      index = ext_hash(code);
        p->next = ext_int_hash[index];
        ext_int_hash[index] = p;
        return 0;
}

int unregister_external_interrupt(__u16 code, ext_int_handler_t handler)
{
        ext_int_info_t *p, *q;
        int index;

      index = ext_hash(code);
        q = NULL;
        p = ext_int_hash[index];
        while (p != NULL) {
                if (p->code == code && p->handler == handler)
                        break;
                q = p;
                p = p->next;
        }
        if (p == NULL)
                return -ENOENT;
        if (q != NULL)
                q->next = p->next;
        else
                ext_int_hash[index] = p->next;
      kfree(p);
        return 0;
}

int unregister_early_external_interrupt(__u16 code, ext_int_handler_t handler,
                              ext_int_info_t *p)
{
      ext_int_info_t *q;
      int index;

      if (p == NULL || p->code != code || p->handler != handler)
            return -EINVAL;
      index = ext_hash(code);
      q = ext_int_hash[index];
      if (p != q) {
            while (q != NULL) {
                  if (q->next == p)
                        break;
                  q = q->next;
            }
            if (q == NULL)
                  return -ENOENT;
            q->next = p->next;
      } else
            ext_int_hash[index] = p->next;
      return 0;
}

void do_extint(struct pt_regs *regs, unsigned short code)
{
        ext_int_info_t *p;
        int index;
      struct pt_regs *old_regs;

      old_regs = set_irq_regs(regs);
      irq_enter();
      s390_idle_check();
      if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
            /* Serve timer interrupts first. */
            clock_comparator_work();
      kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
        index = ext_hash(code);
      for (p = ext_int_hash[index]; p; p = p->next) {
            if (likely(p->code == code))
                  p->handler(code);
      }
      irq_exit();
      set_irq_regs(old_regs);
}

EXPORT_SYMBOL(register_external_interrupt);
EXPORT_SYMBOL(unregister_external_interrupt);

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