arch/parisc/kernel/irq.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Code to handle x86 style IRQs plus some generic interrupt stuff.
  *
  * Copyright (C) 1992 Linus Torvalds
  * Copyright (C) 1994, 1995, 1996, 1997, 1998 Ralf Baechle
  * Copyright (C) 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
  * Copyright (C) 1999-2000 Grant Grundler
  * Copyright (c) 2005 Matthew Wilcox
  *
  *    This program is free software; you can redistribute it and/or modify
  *    it under the terms of the GNU General Public License as published by
  *    the Free Software Foundation; either version 2, or (at your option)
  *    any later version.
  *
  *    This program is distributed in the hope that it will be useful,
  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *    GNU General Public License for more details.
  *
  *    You should have received a copy of the GNU General Public License
  *    along with this program; if not, write to the Free Software
  *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 #include <linux/bitops.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
 #include <linux/seq_file.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <asm/io.h>

 #include <asm/smp.h>

 #undef PARISC_IRQ_CR16_COUNTS

 extern irqreturn_t timer_interrupt(int, void *);
 extern irqreturn_t ipi_interrupt(int, void *);

 #define EIEM_MASK(irq)       (1UL<<(CPU_IRQ_MAX - irq))

 /* Bits in EIEM correlate with cpu_irq_action[].
 ** Numbered *Big Endian*! (ie bit 0 is MSB)
 */
 static volatile unsigned long cpu_eiem = 0;

 /*
 ** local ACK bitmap ... habitually set to 1, but reset to zero
 ** between ->ack() and ->end() of the interrupt to prevent
 ** re-interruption of a processing interrupt.
 */
 static DEFINE_PER_CPU(unsigned long, local_ack_eiem) = ~0UL;

 static void cpu_mask_irq(struct irq_data *d)
 {
 	unsigned long eirr_bit = EIEM_MASK(d->irq);

 	cpu_eiem &= ~eirr_bit;
 	/* Do nothing on the other CPUs.  If they get this interrupt,
 	 * The & cpu_eiem in the do_cpu_irq_mask() ensures they won't
 	 * handle it, and the set_eiem() at the bottom will ensure it
 	 * then gets disabled */
 }

 static void __cpu_unmask_irq(unsigned int irq)
 {
 	unsigned long eirr_bit = EIEM_MASK(irq);

 	cpu_eiem |= eirr_bit;

 	/* This is just a simple NOP IPI.  But what it does is cause
 	 * all the other CPUs to do a set_eiem(cpu_eiem) at the end
 	 * of the interrupt handler */
 	smp_send_all_nop();
 }

 static void cpu_unmask_irq(struct irq_data *d)
 {
 	__cpu_unmask_irq(d->irq);
 }

 void cpu_ack_irq(struct irq_data *d)
 {
 	unsigned long mask = EIEM_MASK(d->irq);
 	int cpu = smp_processor_id();

 	/* Clear in EIEM so we can no longer process */
 	per_cpu(local_ack_eiem, cpu) &= ~mask;

 	/* disable the interrupt */
 	set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));

 	/* and now ack it */
 	mtctl(mask, 23);
 }

 void cpu_eoi_irq(struct irq_data *d)
 {
 	unsigned long mask = EIEM_MASK(d->irq);
 	int cpu = smp_processor_id();

 	/* set it in the eiems---it's no longer in process */
 	per_cpu(local_ack_eiem, cpu) |= mask;

 	/* enable the interrupt */
 	set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
 }

 #ifdef CONFIG_SMP
 int cpu_check_affinity(struct irq_data *d, const struct cpumask *dest)
 {
 	int cpu_dest;

 	/* timer and ipi have to always be received on all CPUs */
 	if (irqd_is_per_cpu(d))
 		return -EINVAL;

 	/* whatever mask they set, we just allow one CPU */
 	cpu_dest = first_cpu(*dest);

 	return cpu_dest;
 }

 static int cpu_set_affinity_irq(struct irq_data *d, const struct cpumask *dest,
 				bool force)
 {
 	int cpu_dest;

 	cpu_dest = cpu_check_affinity(d, dest);
 	if (cpu_dest < 0)
 		return -1;

 	cpumask_copy(d->affinity, dest);

 	return 0;
 }
 #endif

 static struct irq_chip cpu_interrupt_type = {
 	.name			= "CPU",
 	.irq_mask		= cpu_mask_irq,
 	.irq_unmask		= cpu_unmask_irq,
 	.irq_ack		= cpu_ack_irq,
 	.irq_eoi		= cpu_eoi_irq,
 #ifdef CONFIG_SMP
 	.irq_set_affinity	= cpu_set_affinity_irq,
 #endif
 	/* XXX: Needs to be written.  We managed without it so far, but
 	 * we really ought to write it.
 	 */
 	.irq_retrigger	= NULL,
 };

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

 	if (i == 0) {
 		seq_puts(p, "    ");
 		for_each_online_cpu(j)
 			seq_printf(p, "       CPU%d", j);

 #ifdef PARISC_IRQ_CR16_COUNTS
 		seq_printf(p, " [min/avg/max] (CPU cycle counts)");
 #endif
 		seq_putc(p, '\n');
 	}

 	if (i < NR_IRQS) {
 		struct irq_desc *desc = irq_to_desc(i);
 		struct irqaction *action;

 		raw_spin_lock_irqsave(&desc->lock, flags);
 		action = desc->action;
 		if (!action)
 			goto skip;
 		seq_printf(p, "%3d: ", i);
 #ifdef CONFIG_SMP
 		for_each_online_cpu(j)
 			seq_printf(p, "%10u ", kstat_irqs_cpu(i, j));
 #else
 		seq_printf(p, "%10u ", kstat_irqs(i));
 #endif

 		seq_printf(p, " %14s", irq_desc_get_chip(desc)->name);
 #ifndef PARISC_IRQ_CR16_COUNTS
 		seq_printf(p, "  %s", action->name);

 		while ((action = action->next))
 			seq_printf(p, ", %s", action->name);
 #else
 		for ( ;action; action = action->next) {
 			unsigned int k, avg, min, max;

 			min = max = action->cr16_hist[0];

 			for (avg = k = 0; k < PARISC_CR16_HIST_SIZE; k++) {
 				int hist = action->cr16_hist[k];

 				if (hist) {
 					avg += hist;
 				} else
 					break;

 				if (hist > max) max = hist;
 				if (hist < min) min = hist;
 			}

 			avg /= k;
 			seq_printf(p, " %s[%d/%d/%d]", action->name,
 					min,avg,max);
 		}
 #endif

 		seq_putc(p, '\n');
  skip:
 		raw_spin_unlock_irqrestore(&desc->lock, flags);
 	}

 	return 0;
 }


 /*
 ** The following form a "set": Virtual IRQ, Transaction Address, Trans Data.
 ** Respectively, these map to IRQ region+EIRR, Processor HPA, EIRR bit.
 **
 ** To use txn_XXX() interfaces, get a Virtual IRQ first.
 ** Then use that to get the Transaction address and data.
 */

 int cpu_claim_irq(unsigned int irq, struct irq_chip *type, void *data)
 {
 	if (irq_has_action(irq))
 		return -EBUSY;
 	if (irq_get_chip(irq) != &cpu_interrupt_type)
 		return -EBUSY;

 	/* for iosapic interrupts */
 	if (type) {
 		irq_set_chip_and_handler(irq, type, handle_percpu_irq);
 		irq_set_chip_data(irq, data);
 		__cpu_unmask_irq(irq);
 	}
 	return 0;
 }

 int txn_claim_irq(int irq)
 {
 	return cpu_claim_irq(irq, NULL, NULL) ? -1 : irq;
 }

 /*
  * The bits_wide parameter accommodates the limitations of the HW/SW which
  * use these bits:
  * Legacy PA I/O (GSC/NIO): 5 bits (architected EIM register)
  * V-class (EPIC):          6 bits
  * N/L/A-class (iosapic):   8 bits
  * PCI 2.2 MSI:            16 bits
  * Some PCI devices:       32 bits (Symbios SCSI/ATM/HyperFabric)
  *
  * On the service provider side:
  * o PA 1.1 (and PA2.0 narrow mode)     5-bits (width of EIR register)
  * o PA 2.0 wide mode                   6-bits (per processor)
  * o IA64                               8-bits (0-256 total)
  *
  * So a Legacy PA I/O device on a PA 2.0 box can't use all the bits supported
  * by the processor...and the N/L-class I/O subsystem supports more bits than
  * PA2.0 has. The first case is the problem.
  */
 int txn_alloc_irq(unsigned int bits_wide)
 {
 	int irq;

 	/* never return irq 0 cause that's the interval timer */
 	for (irq = CPU_IRQ_BASE + 1; irq <= CPU_IRQ_MAX; irq++) {
 		if (cpu_claim_irq(irq, NULL, NULL) < 0)
 			continue;
 		if ((irq - CPU_IRQ_BASE) >= (1 << bits_wide))
 			continue;
 		return irq;
 	}

 	/* unlikely, but be prepared */
 	return -1;
 }


 unsigned long txn_affinity_addr(unsigned int irq, int cpu)
 {
 #ifdef CONFIG_SMP
 	struct irq_data *d = irq_get_irq_data(irq);
 	cpumask_copy(d->affinity, cpumask_of(cpu));
 #endif

 	return per_cpu(cpu_data, cpu).txn_addr;
 }


 unsigned long txn_alloc_addr(unsigned int virt_irq)
 {
 	static int next_cpu = -1;

 	next_cpu++; /* assign to "next" CPU we want this bugger on */

 	/* validate entry */
 	while ((next_cpu < nr_cpu_ids) &&
 		(!per_cpu(cpu_data, next_cpu).txn_addr ||
 		 !cpu_online(next_cpu)))
 		next_cpu++;

 	if (next_cpu >= nr_cpu_ids)
 		next_cpu = 0;	/* nothing else, assign monarch */

 	return txn_affinity_addr(virt_irq, next_cpu);
 }


 unsigned int txn_alloc_data(unsigned int virt_irq)
 {
 	return virt_irq - CPU_IRQ_BASE;
 }

 static inline int eirr_to_irq(unsigned long eirr)
 {
 	int bit = fls_long(eirr);
 	return (BITS_PER_LONG - bit) + TIMER_IRQ;
 }

 /* ONLY called from entry.S:intr_extint() */
 void do_cpu_irq_mask(struct pt_regs *regs)
 {
 	struct pt_regs *old_regs;
 	unsigned long eirr_val;
 	int irq, cpu = smp_processor_id();
 #ifdef CONFIG_SMP
 	struct irq_desc *desc;
 	cpumask_t dest;
 #endif

 	old_regs = set_irq_regs(regs);
 	local_irq_disable();
 	irq_enter();

 	eirr_val = mfctl(23) & cpu_eiem & per_cpu(local_ack_eiem, cpu);
 	if (!eirr_val)
 		goto set_out;
 	irq = eirr_to_irq(eirr_val);

 #ifdef CONFIG_SMP
 	desc = irq_to_desc(irq);
 	cpumask_copy(&dest, desc->irq_data.affinity);
 	if (irqd_is_per_cpu(&desc->irq_data) &&
 	    !cpu_isset(smp_processor_id(), dest)) {
 		int cpu = first_cpu(dest);

 		printk(KERN_DEBUG "redirecting irq %d from CPU %d to %d\n",
 		       irq, smp_processor_id(), cpu);
 		gsc_writel(irq + CPU_IRQ_BASE,
 			   per_cpu(cpu_data, cpu).hpa);
 		goto set_out;
 	}
 #endif
 	generic_handle_irq(irq);

  out:
 	irq_exit();
 	set_irq_regs(old_regs);
 	return;

  set_out:
 	set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
 	goto out;
 }

 static struct irqaction timer_action = {
 	.handler = timer_interrupt,
 	.name = "timer",
 	.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_PERCPU | IRQF_IRQPOLL,
 };

 #ifdef CONFIG_SMP
 static struct irqaction ipi_action = {
 	.handler = ipi_interrupt,
 	.name = "IPI",
 	.flags = IRQF_DISABLED | IRQF_PERCPU,
 };
 #endif

 static void claim_cpu_irqs(void)
 {
 	int i;
 	for (i = CPU_IRQ_BASE; i <= CPU_IRQ_MAX; i++) {
 		irq_set_chip_and_handler(i, &cpu_interrupt_type,
 					 handle_percpu_irq);
 	}

 	irq_set_handler(TIMER_IRQ, handle_percpu_irq);
 	setup_irq(TIMER_IRQ, &timer_action);
 #ifdef CONFIG_SMP
 	irq_set_handler(IPI_IRQ, handle_percpu_irq);
 	setup_irq(IPI_IRQ, &ipi_action);
 #endif
 }

 void __init init_IRQ(void)
 {
 	local_irq_disable();	/* PARANOID - should already be disabled */
 	mtctl(~0UL, 23);	/* EIRR : clear all pending external intr */
 	claim_cpu_irqs();
 #ifdef CONFIG_SMP
 	if (!cpu_eiem)
 		cpu_eiem = EIEM_MASK(IPI_IRQ) | EIEM_MASK(TIMER_IRQ);
 #else
 	cpu_eiem = EIEM_MASK(TIMER_IRQ);
 #endif
         set_eiem(cpu_eiem);	/* EIEM : enable all external intr */

 }
	/*
	* Code to handle x86 style IRQs plus some generic interrupt stuff.
	*
	* Copyright (C) 1992 Linus Torvalds
	* Copyright (C) 1994, 1995, 1996, 1997, 1998 Ralf Baechle
	* Copyright (C) 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
	* Copyright (C) 1999-2000 Grant Grundler
	* Copyright (c) 2005 Matthew Wilcox
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2, or (at your option)
	* any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/
	#include <linux/bitops.h>
	#include <linux/errno.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/kernel_stat.h>
	#include <linux/seq_file.h>
	#include <linux/spinlock.h>
	#include <linux/types.h>
	#include <asm/io.h>

	#include <asm/smp.h>

	#undef PARISC_IRQ_CR16_COUNTS

	extern irqreturn_t timer_interrupt(int, void *);
	extern irqreturn_t ipi_interrupt(int, void *);

	#define EIEM_MASK(irq) (1UL<<(CPU_IRQ_MAX - irq))

	/* Bits in EIEM correlate with cpu_irq_action[].
	** Numbered Big Endian! (ie bit 0 is MSB)
	*/
	static volatile unsigned long cpu_eiem = 0;

	/*
	** local ACK bitmap ... habitually set to 1, but reset to zero
	** between ->ack() and ->end() of the interrupt to prevent
	** re-interruption of a processing interrupt.
	*/
	static DEFINE_PER_CPU(unsigned long, local_ack_eiem) = ~0UL;

	static void cpu_mask_irq(struct irq_data *d)
	{
	unsigned long eirr_bit = EIEM_MASK(d->irq);

	cpu_eiem &= ~eirr_bit;
	/* Do nothing on the other CPUs. If they get this interrupt,
	* The & cpu_eiem in the do_cpu_irq_mask() ensures they won't
	* handle it, and the set_eiem() at the bottom will ensure it
	* then gets disabled */
	}

	static void __cpu_unmask_irq(unsigned int irq)
	{
	unsigned long eirr_bit = EIEM_MASK(irq);

	cpu_eiem \|= eirr_bit;

	/* This is just a simple NOP IPI. But what it does is cause
	* all the other CPUs to do a set_eiem(cpu_eiem) at the end
	* of the interrupt handler */
	smp_send_all_nop();
	}

	static void cpu_unmask_irq(struct irq_data *d)
	{
	__cpu_unmask_irq(d->irq);
	}

	void cpu_ack_irq(struct irq_data *d)
	{
	unsigned long mask = EIEM_MASK(d->irq);
	int cpu = smp_processor_id();

	/* Clear in EIEM so we can no longer process */
	per_cpu(local_ack_eiem, cpu) &= ~mask;

	/* disable the interrupt */
	set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));

	/* and now ack it */
	mtctl(mask, 23);
	}

	void cpu_eoi_irq(struct irq_data *d)
	{
	unsigned long mask = EIEM_MASK(d->irq);
	int cpu = smp_processor_id();

	/* set it in the eiems---it's no longer in process */
	per_cpu(local_ack_eiem, cpu) \|= mask;

	/* enable the interrupt */
	set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
	}

	#ifdef CONFIG_SMP
	int cpu_check_affinity(struct irq_data d, const struct cpumask dest)
	{
	int cpu_dest;

	/* timer and ipi have to always be received on all CPUs */
	if (irqd_is_per_cpu(d))
	return -EINVAL;

	/* whatever mask they set, we just allow one CPU */
	cpu_dest = first_cpu(*dest);

	return cpu_dest;
	}

	static int cpu_set_affinity_irq(struct irq_data d, const struct cpumask dest,
	bool force)
	{
	int cpu_dest;

	cpu_dest = cpu_check_affinity(d, dest);
	if (cpu_dest < 0)
	return -1;

	cpumask_copy(d->affinity, dest);

	return 0;
	}
	#endif

	static struct irq_chip cpu_interrupt_type = {
	.name = "CPU",
	.irq_mask = cpu_mask_irq,
	.irq_unmask = cpu_unmask_irq,
	.irq_ack = cpu_ack_irq,
	.irq_eoi = cpu_eoi_irq,
	#ifdef CONFIG_SMP
	.irq_set_affinity = cpu_set_affinity_irq,
	#endif
	/* XXX: Needs to be written. We managed without it so far, but
	* we really ought to write it.
	*/
	.irq_retrigger = NULL,
	};

	int show_interrupts(struct seq_file p, void v)
	{
	int i = (loff_t ) v, j;
	unsigned long flags;

	if (i == 0) {
	seq_puts(p, " ");
	for_each_online_cpu(j)
	seq_printf(p, " CPU%d", j);

	#ifdef PARISC_IRQ_CR16_COUNTS
	seq_printf(p, " [min/avg/max] (CPU cycle counts)");
	#endif
	seq_putc(p, '\n');
	}

	if (i < NR_IRQS) {
	struct irq_desc *desc = irq_to_desc(i);
	struct irqaction *action;

	raw_spin_lock_irqsave(&desc->lock, flags);
	action = desc->action;
	if (!action)
	goto skip;
	seq_printf(p, "%3d: ", i);
	#ifdef CONFIG_SMP
	for_each_online_cpu(j)
	seq_printf(p, "%10u ", kstat_irqs_cpu(i, j));
	#else
	seq_printf(p, "%10u ", kstat_irqs(i));
	#endif

	seq_printf(p, " %14s", irq_desc_get_chip(desc)->name);
	#ifndef PARISC_IRQ_CR16_COUNTS
	seq_printf(p, " %s", action->name);

	while ((action = action->next))
	seq_printf(p, ", %s", action->name);
	#else
	for ( ;action; action = action->next) {
	unsigned int k, avg, min, max;

	min = max = action->cr16_hist[0];

	for (avg = k = 0; k < PARISC_CR16_HIST_SIZE; k++) {
	int hist = action->cr16_hist[k];

	if (hist) {
	avg += hist;
	} else
	break;

	if (hist > max) max = hist;
	if (hist < min) min = hist;
	}

	avg /= k;
	seq_printf(p, " %s[%d/%d/%d]", action->name,
	min,avg,max);
	}
	#endif

	seq_putc(p, '\n');
	skip:
	raw_spin_unlock_irqrestore(&desc->lock, flags);
	}

	return 0;
	}



	/*
	** The following form a "set": Virtual IRQ, Transaction Address, Trans Data.
	** Respectively, these map to IRQ region+EIRR, Processor HPA, EIRR bit.
	**
	** To use txn_XXX() interfaces, get a Virtual IRQ first.
	** Then use that to get the Transaction address and data.
	*/

	int cpu_claim_irq(unsigned int irq, struct irq_chip type, void data)
	{
	if (irq_has_action(irq))
	return -EBUSY;
	if (irq_get_chip(irq) != &cpu_interrupt_type)
	return -EBUSY;

	/* for iosapic interrupts */
	if (type) {
	irq_set_chip_and_handler(irq, type, handle_percpu_irq);
	irq_set_chip_data(irq, data);
	__cpu_unmask_irq(irq);
	}
	return 0;
	}

	int txn_claim_irq(int irq)
	{
	return cpu_claim_irq(irq, NULL, NULL) ? -1 : irq;
	}

	/*
	* The bits_wide parameter accommodates the limitations of the HW/SW which
	* use these bits:
	* Legacy PA I/O (GSC/NIO): 5 bits (architected EIM register)
	* V-class (EPIC): 6 bits
	* N/L/A-class (iosapic): 8 bits
	* PCI 2.2 MSI: 16 bits
	* Some PCI devices: 32 bits (Symbios SCSI/ATM/HyperFabric)
	*
	* On the service provider side:
	* o PA 1.1 (and PA2.0 narrow mode) 5-bits (width of EIR register)
	* o PA 2.0 wide mode 6-bits (per processor)
	* o IA64 8-bits (0-256 total)
	*
	* So a Legacy PA I/O device on a PA 2.0 box can't use all the bits supported
	* by the processor...and the N/L-class I/O subsystem supports more bits than
	* PA2.0 has. The first case is the problem.
	*/
	int txn_alloc_irq(unsigned int bits_wide)
	{
	int irq;

	/* never return irq 0 cause that's the interval timer */
	for (irq = CPU_IRQ_BASE + 1; irq <= CPU_IRQ_MAX; irq++) {
	if (cpu_claim_irq(irq, NULL, NULL) < 0)
	continue;
	if ((irq - CPU_IRQ_BASE) >= (1 << bits_wide))
	continue;
	return irq;
	}

	/* unlikely, but be prepared */
	return -1;
	}


	unsigned long txn_affinity_addr(unsigned int irq, int cpu)
	{
	#ifdef CONFIG_SMP
	struct irq_data *d = irq_get_irq_data(irq);
	cpumask_copy(d->affinity, cpumask_of(cpu));
	#endif

	return per_cpu(cpu_data, cpu).txn_addr;
	}


	unsigned long txn_alloc_addr(unsigned int virt_irq)
	{
	static int next_cpu = -1;

	next_cpu++; /* assign to "next" CPU we want this bugger on */

	/* validate entry */
	while ((next_cpu < nr_cpu_ids) &&
	(!per_cpu(cpu_data, next_cpu).txn_addr \|\|
	!cpu_online(next_cpu)))
	next_cpu++;

	if (next_cpu >= nr_cpu_ids)
	next_cpu = 0; /* nothing else, assign monarch */

	return txn_affinity_addr(virt_irq, next_cpu);
	}


	unsigned int txn_alloc_data(unsigned int virt_irq)
	{
	return virt_irq - CPU_IRQ_BASE;
	}

	static inline int eirr_to_irq(unsigned long eirr)
	{
	int bit = fls_long(eirr);
	return (BITS_PER_LONG - bit) + TIMER_IRQ;
	}

	/* ONLY called from entry.S:intr_extint() */
	void do_cpu_irq_mask(struct pt_regs *regs)
	{
	struct pt_regs *old_regs;
	unsigned long eirr_val;
	int irq, cpu = smp_processor_id();
	#ifdef CONFIG_SMP
	struct irq_desc *desc;
	cpumask_t dest;
	#endif

	old_regs = set_irq_regs(regs);
	local_irq_disable();
	irq_enter();

	eirr_val = mfctl(23) & cpu_eiem & per_cpu(local_ack_eiem, cpu);
	if (!eirr_val)
	goto set_out;
	irq = eirr_to_irq(eirr_val);

	#ifdef CONFIG_SMP
	desc = irq_to_desc(irq);
	cpumask_copy(&dest, desc->irq_data.affinity);
	if (irqd_is_per_cpu(&desc->irq_data) &&
	!cpu_isset(smp_processor_id(), dest)) {
	int cpu = first_cpu(dest);

	printk(KERN_DEBUG "redirecting irq %d from CPU %d to %d\n",
	irq, smp_processor_id(), cpu);
	gsc_writel(irq + CPU_IRQ_BASE,
	per_cpu(cpu_data, cpu).hpa);
	goto set_out;
	}
	#endif
	generic_handle_irq(irq);

	out:
	irq_exit();
	set_irq_regs(old_regs);
	return;

	set_out:
	set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
	goto out;
	}

	static struct irqaction timer_action = {
	.handler = timer_interrupt,
	.name = "timer",
	.flags = IRQF_DISABLED \| IRQF_TIMER \| IRQF_PERCPU \| IRQF_IRQPOLL,
	};

	#ifdef CONFIG_SMP
	static struct irqaction ipi_action = {
	.handler = ipi_interrupt,
	.name = "IPI",
	.flags = IRQF_DISABLED \| IRQF_PERCPU,
	};
	#endif

	static void claim_cpu_irqs(void)
	{
	int i;
	for (i = CPU_IRQ_BASE; i <= CPU_IRQ_MAX; i++) {
	irq_set_chip_and_handler(i, &cpu_interrupt_type,
	handle_percpu_irq);
	}

	irq_set_handler(TIMER_IRQ, handle_percpu_irq);
	setup_irq(TIMER_IRQ, &timer_action);
	#ifdef CONFIG_SMP
	irq_set_handler(IPI_IRQ, handle_percpu_irq);
	setup_irq(IPI_IRQ, &ipi_action);
	#endif
	}

	void __init init_IRQ(void)
	{
	local_irq_disable(); /* PARANOID - should already be disabled */
	mtctl(~0UL, 23); /* EIRR : clear all pending external intr */
	claim_cpu_irqs();
	#ifdef CONFIG_SMP
	if (!cpu_eiem)
	cpu_eiem = EIEM_MASK(IPI_IRQ) \| EIEM_MASK(TIMER_IRQ);
	#else
	cpu_eiem = EIEM_MASK(TIMER_IRQ);
	#endif
	set_eiem(cpu_eiem); /* EIEM : enable all external intr */

	}