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/*

 *  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/lowcore.h>

#include <asm/s390_ext.h>

#include <asm/irq_regs.h>

#include <asm/irq.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();

        asm volatile ("mc 0,0");

        if (S390_lowcore.int_clock >= S390_lowcore.jiffy_timer)

                /**

                 * Make sure that the i/o interrupt did not "overtake"

                 * the last HZ timer interrupt.

                 */

                account_ticks(S390_lowcore.int_clock);

        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);