linux/arch/ia64/kernel/iosapic.c

/*
 * I/O SAPIC support.
 *
 * Copyright (C) 1999 Intel Corp.
 * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
 * Copyright (C) 2000-2002 J.I. Lee <jung-ik.lee@intel.com>
 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co.
 *	David Mosberger-Tang <davidm@hpl.hp.com>
 * Copyright (C) 1999 VA Linux Systems
 * Copyright (C) 1999,2000 Walt Drummond <drummond@valinux.com>
 *
 * 00/04/19	D. Mosberger	Rewritten to mirror more closely the x86 I/O APIC code.
 *				In particular, we now have separate handlers for edge
 *				and level triggered interrupts.
 * 00/10/27	Asit Mallick, Goutham Rao <goutham.rao@intel.com> IRQ vector allocation
 *				PCI to vector mapping, shared PCI interrupts.
 * 00/10/27	D. Mosberger	Document things a bit more to make them more understandable.
 *				Clean up much of the old IOSAPIC cruft.
 * 01/07/27	J.I. Lee	PCI irq routing, Platform/Legacy interrupts and fixes for
 *				ACPI S5(SoftOff) support.
 * 02/01/23	J.I. Lee	iosapic pgm fixes for PCI irq routing from _PRT
 * 02/01/07     E. Focht        <efocht@ess.nec.de> Redirectable interrupt vectors in
 *                              iosapic_set_affinity(), initializations for
 *                              /proc/irq/#/smp_affinity
 * 02/04/02	P. Diefenbaugh	Cleaned up ACPI PCI IRQ routing.
 * 02/04/18	J.I. Lee	bug fix in iosapic_init_pci_irq
 * 02/04/30	J.I. Lee	bug fix in find_iosapic to fix ACPI PCI IRQ to IOSAPIC mapping
 *				error
 * 02/07/29	T. Kochi	Allocate interrupt vectors dynamically
 * 02/08/04	T. Kochi	Cleaned up terminology (irq, global system interrupt, vector, etc.)
 * 02/09/20	D. Mosberger	Simplified by taking advantage of ACPI's pci_irq code.
 * 03/02/19	B. Helgaas	Make pcat_compat system-wide, not per-IOSAPIC.
 *				Remove iosapic_address & gsi_base from external interfaces.
 *				Rationalize __init/__devinit attributes.
 * 04/12/04 Ashok Raj	<ashok.raj@intel.com> Intel Corporation 2004
 *				Updated to work with irq migration necessary for CPU Hotplug
 */
/*
 * Here is what the interrupt logic between a PCI device and the kernel looks like:
 *
 * (1) A PCI device raises one of the four interrupt pins (INTA, INTB, INTC, INTD).  The
 *     device is uniquely identified by its bus--, and slot-number (the function
 *     number does not matter here because all functions share the same interrupt
 *     lines).
 *
 * (2) The motherboard routes the interrupt line to a pin on a IOSAPIC controller.
 *     Multiple interrupt lines may have to share the same IOSAPIC pin (if they're level
 *     triggered and use the same polarity).  Each interrupt line has a unique Global
 *     System Interrupt (GSI) number which can be calculated as the sum of the controller's
 *     base GSI number and the IOSAPIC pin number to which the line connects.
 *
 * (3) The IOSAPIC uses an internal routing table entries (RTEs) to map the IOSAPIC pin
 *     into the IA-64 interrupt vector.  This interrupt vector is then sent to the CPU.
 *
 * (4) The kernel recognizes an interrupt as an IRQ.  The IRQ interface is used as
 *     architecture-independent interrupt handling mechanism in Linux.  As an
 *     IRQ is a number, we have to have IA-64 interrupt vector number <-> IRQ number
 *     mapping.  On smaller systems, we use one-to-one mapping between IA-64 vector and
 *     IRQ.  A platform can implement platform_irq_to_vector(irq) and
 *     platform_local_vector_to_irq(vector) APIs to differentiate the mapping.
 *     Please see also include/asm-ia64/hw_irq.h for those APIs.
 *
 * To sum up, there are three levels of mappings involved:
 *
 *	PCI pin -> global system interrupt (GSI) -> IA-64 vector <-> IRQ
 *
 * Note: The term "IRQ" is loosely used everywhere in Linux kernel to describe interrupts.
 * Now we use "IRQ" only for Linux IRQ's.  ISA IRQ (isa_irq) is the only exception in this
 * source code.
 */
#include <linux/config.h>

#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/string.h>
#include <linux/bootmem.h>

#include <asm/delay.h>
#include <asm/hw_irq.h>
#include <asm/io.h>
#include <asm/iosapic.h>
#include <asm/machvec.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/system.h>


#undef DEBUG_INTERRUPT_ROUTING

#ifdef DEBUG_INTERRUPT_ROUTING
#define DBG(fmt...)	printk(fmt)
#else
#define DBG(fmt...)
#endif

#define NR_PREALLOCATE_RTE_ENTRIES	(PAGE_SIZE / sizeof(struct iosapic_rte_info))
#define RTE_PREALLOCATED	(1)

static DEFINE_SPINLOCK(iosapic_lock);

/* These tables map IA-64 vectors to the IOSAPIC pin that generates this vector. */

struct iosapic_rte_info {
	struct list_head rte_list;	/* node in list of RTEs sharing the same vector */
	char __iomem	*addr;		/* base address of IOSAPIC */
	unsigned int	gsi_base;	/* first GSI assigned to this IOSAPIC */
	char		rte_index;	/* IOSAPIC RTE index */
	int		refcnt;		/* reference counter */
	unsigned int	flags;		/* flags */
} ____cacheline_aligned;

static struct iosapic_intr_info {
	struct list_head rtes;		/* RTEs using this vector (empty => not an IOSAPIC interrupt) */
	int		count;		/* # of RTEs that shares this vector */
	u32		low32;		/* current value of low word of Redirection table entry */
	unsigned int	dest;		/* destination CPU physical ID */
	unsigned char	dmode	: 3;	/* delivery mode (see iosapic.h) */
	unsigned char 	polarity: 1;	/* interrupt polarity (see iosapic.h) */
	unsigned char	trigger	: 1;	/* trigger mode (see iosapic.h) */
} iosapic_intr_info[IA64_NUM_VECTORS];

static struct iosapic {
	char __iomem	*addr;		/* base address of IOSAPIC */
	unsigned int 	gsi_base;	/* first GSI assigned to this IOSAPIC */
	unsigned short 	num_rte;	/* number of RTE in this IOSAPIC */
	int		rtes_inuse;	/* # of RTEs in use on this IOSAPIC */
#ifdef CONFIG_NUMA
	unsigned short	node;		/* numa node association via pxm */
#endif
} iosapic_lists[NR_IOSAPICS];

static unsigned char pcat_compat __devinitdata;	/* 8259 compatibility flag */

static int iosapic_kmalloc_ok;
static LIST_HEAD(free_rte_list);

/*
 * Find an IOSAPIC associated with a GSI
 */
static inline int
find_iosapic (unsigned int gsi)
{
	int i;

	for (i = 0; i < NR_IOSAPICS; i++) {
		if ((unsigned) (gsi - iosapic_lists[i].gsi_base) < iosapic_lists[i].num_rte)
			return i;
	}

	return -1;
}

static inline int
_gsi_to_vector (unsigned int gsi)
{
	struct iosapic_intr_info *info;
	struct iosapic_rte_info *rte;

	for (info = iosapic_intr_info; info < iosapic_intr_info + IA64_NUM_VECTORS; ++info)
		list_for_each_entry(rte, &info->rtes, rte_list)
			if (rte->gsi_base + rte->rte_index == gsi)
				return info - iosapic_intr_info;
	return -1;
}

/*
 * Translate GSI number to the corresponding IA-64 interrupt vector.  If no
 * entry exists, return -1.
 */
inline int
gsi_to_vector (unsigned int gsi)
{
	return _gsi_to_vector(gsi);
}

int
gsi_to_irq (unsigned int gsi)
{
	unsigned long flags;
	int irq;
	/*
	 * XXX fix me: this assumes an identity mapping vetween IA-64 vector and Linux irq
	 * numbers...
	 */
	spin_lock_irqsave(&iosapic_lock, flags);
	{
		irq = _gsi_to_vector(gsi);
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);

	return irq;
}

static struct iosapic_rte_info *gsi_vector_to_rte(unsigned int gsi, unsigned int vec)
{
	struct iosapic_rte_info *rte;

	list_for_each_entry(rte, &iosapic_intr_info[vec].rtes, rte_list)
		if (rte->gsi_base + rte->rte_index == gsi)
			return rte;
	return NULL;
}

static void
set_rte (unsigned int gsi, unsigned int vector, unsigned int dest, int mask)
{
	unsigned long pol, trigger, dmode;
	u32 low32, high32;
	char __iomem *addr;
	int rte_index;
	char redir;
	struct iosapic_rte_info *rte;

	DBG(KERN_DEBUG"IOSAPIC: routing vector %d to 0x%x\n", vector, dest);

	rte = gsi_vector_to_rte(gsi, vector);
	if (!rte)
		return;		/* not an IOSAPIC interrupt */

	rte_index = rte->rte_index;
	addr	= rte->addr;
	pol     = iosapic_intr_info[vector].polarity;
	trigger = iosapic_intr_info[vector].trigger;
	dmode   = iosapic_intr_info[vector].dmode;

	redir = (dmode == IOSAPIC_LOWEST_PRIORITY) ? 1 : 0;

#ifdef CONFIG_SMP
	{
		unsigned int irq;

		for (irq = 0; irq < NR_IRQS; ++irq)
			if (irq_to_vector(irq) == vector) {
				set_irq_affinity_info(irq, (int)(dest & 0xffff), redir);
				break;
			}
	}
#endif

	low32 = ((pol << IOSAPIC_POLARITY_SHIFT) |
		 (trigger << IOSAPIC_TRIGGER_SHIFT) |
		 (dmode << IOSAPIC_DELIVERY_SHIFT) |
		 ((mask ? 1 : 0) << IOSAPIC_MASK_SHIFT) |
		 vector);

	/* dest contains both id and eid */
	high32 = (dest << IOSAPIC_DEST_SHIFT);

	iosapic_write(addr, IOSAPIC_RTE_HIGH(rte_index), high32);
	iosapic_write(addr, IOSAPIC_RTE_LOW(rte_index), low32);
	iosapic_intr_info[vector].low32 = low32;
	iosapic_intr_info[vector].dest = dest;
}

static void
nop (unsigned int vector)
{
	/* do nothing... */
}

static void
mask_irq (unsigned int irq)
{
	unsigned long flags;
	char __iomem *addr;
	u32 low32;
	int rte_index;
	ia64_vector vec = irq_to_vector(irq);
	struct iosapic_rte_info *rte;

	if (list_empty(&iosapic_intr_info[vec].rtes))
		return;			/* not an IOSAPIC interrupt! */

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		/* set only the mask bit */
		low32 = iosapic_intr_info[vec].low32 |= IOSAPIC_MASK;
		list_for_each_entry(rte, &iosapic_intr_info[vec].rtes, rte_list) {
			addr = rte->addr;
			rte_index = rte->rte_index;
			iosapic_write(addr, IOSAPIC_RTE_LOW(rte_index), low32);
		}
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);
}

static void
unmask_irq (unsigned int irq)
{
	unsigned long flags;
	char __iomem *addr;
	u32 low32;
	int rte_index;
	ia64_vector vec = irq_to_vector(irq);
	struct iosapic_rte_info *rte;

	if (list_empty(&iosapic_intr_info[vec].rtes))
		return;			/* not an IOSAPIC interrupt! */

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		low32 = iosapic_intr_info[vec].low32 &= ~IOSAPIC_MASK;
		list_for_each_entry(rte, &iosapic_intr_info[vec].rtes, rte_list) {
			addr = rte->addr;
			rte_index = rte->rte_index;
			iosapic_write(addr, IOSAPIC_RTE_LOW(rte_index), low32);
		}
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);
}


static void
iosapic_set_affinity (unsigned int irq, cpumask_t mask)
{
#ifdef CONFIG_SMP
	unsigned long flags;
	u32 high32, low32;
	int dest, rte_index;
	char __iomem *addr;
	int redir = (irq & IA64_IRQ_REDIRECTED) ? 1 : 0;
	ia64_vector vec;
	struct iosapic_rte_info *rte;

	irq &= (~IA64_IRQ_REDIRECTED);
	vec = irq_to_vector(irq);

	if (cpus_empty(mask))
		return;

	dest = cpu_physical_id(first_cpu(mask));

	if (list_empty(&iosapic_intr_info[vec].rtes))
		return;			/* not an IOSAPIC interrupt */

	set_irq_affinity_info(irq, dest, redir);

	/* dest contains both id and eid */
	high32 = dest << IOSAPIC_DEST_SHIFT;

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		low32 = iosapic_intr_info[vec].low32 & ~(7 << IOSAPIC_DELIVERY_SHIFT);

		if (redir)
		        /* change delivery mode to lowest priority */
			low32 |= (IOSAPIC_LOWEST_PRIORITY << IOSAPIC_DELIVERY_SHIFT);
		else
		        /* change delivery mode to fixed */
			low32 |= (IOSAPIC_FIXED << IOSAPIC_DELIVERY_SHIFT);

		iosapic_intr_info[vec].low32 = low32;
		iosapic_intr_info[vec].dest = dest;
		list_for_each_entry(rte, &iosapic_intr_info[vec].rtes, rte_list) {
			addr = rte->addr;
			rte_index = rte->rte_index;
			iosapic_write(addr, IOSAPIC_RTE_HIGH(rte_index), high32);
			iosapic_write(addr, IOSAPIC_RTE_LOW(rte_index), low32);
		}
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);
#endif
}

/*
 * Handlers for level-triggered interrupts.
 */

static unsigned int
iosapic_startup_level_irq (unsigned int irq)
{
	unmask_irq(irq);
	return 0;
}

static void
iosapic_end_level_irq (unsigned int irq)
{
	ia64_vector vec = irq_to_vector(irq);
	struct iosapic_rte_info *rte;

	move_irq(irq);
	list_for_each_entry(rte, &iosapic_intr_info[vec].rtes, rte_list)
		iosapic_eoi(rte->addr, vec);
}

#define iosapic_shutdown_level_irq	mask_irq
#define iosapic_enable_level_irq	unmask_irq
#define iosapic_disable_level_irq	mask_irq
#define iosapic_ack_level_irq		nop

struct hw_interrupt_type irq_type_iosapic_level = {
	.typename =	"IO-SAPIC-level",
	.startup =	iosapic_startup_level_irq,
	.shutdown =	iosapic_shutdown_level_irq,
	.enable =	iosapic_enable_level_irq,
	.disable =	iosapic_disable_level_irq,
	.ack =		iosapic_ack_level_irq,
	.end =		iosapic_end_level_irq,
	.set_affinity =	iosapic_set_affinity
};

/*
 * Handlers for edge-triggered interrupts.
 */

static unsigned int
iosapic_startup_edge_irq (unsigned int irq)
{
	unmask_irq(irq);
	/*
	 * IOSAPIC simply drops interrupts pended while the
	 * corresponding pin was masked, so we can't know if an
	 * interrupt is pending already.  Let's hope not...
	 */
	return 0;
}

static void
iosapic_ack_edge_irq (unsigned int irq)
{
	irq_desc_t *idesc = irq_descp(irq);

	move_irq(irq);
	/*
	 * Once we have recorded IRQ_PENDING already, we can mask the
	 * interrupt for real. This prevents IRQ storms from unhandled
	 * devices.
	 */
	if ((idesc->status & (IRQ_PENDING|IRQ_DISABLED)) == (IRQ_PENDING|IRQ_DISABLED))
		mask_irq(irq);
}

#define iosapic_enable_edge_irq		unmask_irq
#define iosapic_disable_edge_irq	nop
#define iosapic_end_edge_irq		nop

struct hw_interrupt_type irq_type_iosapic_edge = {
	.typename =	"IO-SAPIC-edge",
	.startup =	iosapic_startup_edge_irq,
	.shutdown =	iosapic_disable_edge_irq,
	.enable =	iosapic_enable_edge_irq,
	.disable =	iosapic_disable_edge_irq,
	.ack =		iosapic_ack_edge_irq,
	.end =		iosapic_end_edge_irq,
	.set_affinity =	iosapic_set_affinity
};

unsigned int
iosapic_version (char __iomem *addr)
{
	/*
	 * IOSAPIC Version Register return 32 bit structure like:
	 * {
	 *	unsigned int version   : 8;
	 *	unsigned int reserved1 : 8;
	 *	unsigned int max_redir : 8;
	 *	unsigned int reserved2 : 8;
	 * }
	 */
	return iosapic_read(addr, IOSAPIC_VERSION);
}

static int iosapic_find_sharable_vector (unsigned long trigger, unsigned long pol)
{
	int i, vector = -1, min_count = -1;
	struct iosapic_intr_info *info;

	/*
	 * shared vectors for edge-triggered interrupts are not
	 * supported yet
	 */
	if (trigger == IOSAPIC_EDGE)
		return -1;

	for (i = IA64_FIRST_DEVICE_VECTOR; i <= IA64_LAST_DEVICE_VECTOR; i++) {
		info = &iosapic_intr_info[i];
		if (info->trigger == trigger && info->polarity == pol &&
		    (info->dmode == IOSAPIC_FIXED || info->dmode == IOSAPIC_LOWEST_PRIORITY)) {
			if (min_count == -1 || info->count < min_count) {
				vector = i;
				min_count = info->count;
			}
		}
	}

	return vector;
}

/*
 * if the given vector is already owned by other,
 *  assign a new vector for the other and make the vector available
 */
static void __init
iosapic_reassign_vector (int vector)
{
	int new_vector;

	if (!list_empty(&iosapic_intr_info[vector].rtes)) {
		new_vector = assign_irq_vector(AUTO_ASSIGN);
		if (new_vector < 0)
			panic("%s: out of interrupt vectors!\n", __FUNCTION__);
		printk(KERN_INFO "Reassigning vector %d to %d\n", vector, new_vector);
		memcpy(&iosapic_intr_info[new_vector], &iosapic_intr_info[vector],
		       sizeof(struct iosapic_intr_info));
		INIT_LIST_HEAD(&iosapic_intr_info[new_vector].rtes);
		list_move(iosapic_intr_info[vector].rtes.next, &iosapic_intr_info[new_vector].rtes);
		memset(&iosapic_intr_info[vector], 0, sizeof(struct iosapic_intr_info));
		iosapic_intr_info[vector].low32 = IOSAPIC_MASK;
		INIT_LIST_HEAD(&iosapic_intr_info[vector].rtes);
	}
}

static struct iosapic_rte_info *iosapic_alloc_rte (void)
{
	int i;
	struct iosapic_rte_info *rte;
	int preallocated = 0;

	if (!iosapic_kmalloc_ok && list_empty(&free_rte_list)) {
		rte = alloc_bootmem(sizeof(struct iosapic_rte_info) * NR_PREALLOCATE_RTE_ENTRIES);
		if (!rte)
			return NULL;
		for (i = 0; i < NR_PREALLOCATE_RTE_ENTRIES; i++, rte++)
			list_add(&rte->rte_list, &free_rte_list);
	}

	if (!list_empty(&free_rte_list)) {
		rte = list_entry(free_rte_list.next, struct iosapic_rte_info, rte_list);
		list_del(&rte->rte_list);
		preallocated++;
	} else {
		rte = kmalloc(sizeof(struct iosapic_rte_info), GFP_ATOMIC);
		if (!rte)
			return NULL;
	}

	memset(rte, 0, sizeof(struct iosapic_rte_info));
	if (preallocated)
		rte->flags |= RTE_PREALLOCATED;

	return rte;
}

static void iosapic_free_rte (struct iosapic_rte_info *rte)
{
	if (rte->flags & RTE_PREALLOCATED)
		list_add_tail(&rte->rte_list, &free_rte_list);
	else
		kfree(rte);
}

static inline int vector_is_shared (int vector)
{
	return (iosapic_intr_info[vector].count > 1);
}

static void
register_intr (unsigned int gsi, int vector, unsigned char delivery,
	       unsigned long polarity, unsigned long trigger)
{
	irq_desc_t *idesc;
	struct hw_interrupt_type *irq_type;
	int rte_index;
	int index;
	unsigned long gsi_base;
	void __iomem *iosapic_address;
	struct iosapic_rte_info *rte;

	index = find_iosapic(gsi);
	if (index < 0) {
		printk(KERN_WARNING "%s: No IOSAPIC for GSI %u\n", __FUNCTION__, gsi);
		return;
	}

	iosapic_address = iosapic_lists[index].addr;
	gsi_base = iosapic_lists[index].gsi_base;

	rte = gsi_vector_to_rte(gsi, vector);
	if (!rte) {
		rte = iosapic_alloc_rte();
		if (!rte) {
			printk(KERN_WARNING "%s: cannot allocate memory\n", __FUNCTION__);
			return;
		}

		rte_index = gsi - gsi_base;
		rte->rte_index	= rte_index;
		rte->addr	= iosapic_address;
		rte->gsi_base	= gsi_base;
		rte->refcnt++;
		list_add_tail(&rte->rte_list, &iosapic_intr_info[vector].rtes);
		iosapic_intr_info[vector].count++;
		iosapic_lists[index].rtes_inuse++;
	}
	else if (vector_is_shared(vector)) {
		struct iosapic_intr_info *info = &iosapic_intr_info[vector];
		if (info->trigger != trigger || info->polarity != polarity) {
			printk (KERN_WARNING "%s: cannot override the interrupt\n", __FUNCTION__);
			return;
		}
	}

	iosapic_intr_info[vector].polarity = polarity;
	iosapic_intr_info[vector].dmode    = delivery;
	iosapic_intr_info[vector].trigger  = trigger;

	if (trigger == IOSAPIC_EDGE)
		irq_type = &irq_type_iosapic_edge;
	else
		irq_type = &irq_type_iosapic_level;

	idesc = irq_descp(vector);
	if (idesc->handler != irq_type) {
		if (idesc->handler != &no_irq_type)
			printk(KERN_WARNING "%s: changing vector %d from %s to %s\n",
			       __FUNCTION__, vector, idesc->handler->typename, irq_type->typename);
		idesc->handler = irq_type;
	}
}

static unsigned int
get_target_cpu (unsigned int gsi, int vector)
{
#ifdef CONFIG_SMP
	static int cpu = -1;

	/*
	 * In case of vector shared by multiple RTEs, all RTEs that
	 * share the vector need to use the same destination CPU.
	 */
	if (!list_empty(&iosapic_intr_info[vector].rtes))
		return iosapic_intr_info[vector].dest;

	/*
	 * If the platform supports redirection via XTP, let it
	 * distribute interrupts.
	 */
	if (smp_int_redirect & SMP_IRQ_REDIRECTION)
		return cpu_physical_id(smp_processor_id());

	/*
	 * Some interrupts (ACPI SCI, for instance) are registered
	 * before the BSP is marked as online.
	 */
	if (!cpu_online(smp_processor_id()))
		return cpu_physical_id(smp_processor_id());

#ifdef CONFIG_NUMA
	{
		int num_cpus, cpu_index, iosapic_index, numa_cpu, i = 0;
		cpumask_t cpu_mask;

		iosapic_index = find_iosapic(gsi);
		if (iosapic_index < 0 ||
		    iosapic_lists[iosapic_index].node == MAX_NUMNODES)
			goto skip_numa_setup;

		cpu_mask = node_to_cpumask(iosapic_lists[iosapic_index].node);

		for_each_cpu_mask(numa_cpu, cpu_mask) {
			if (!cpu_online(numa_cpu))
				cpu_clear(numa_cpu, cpu_mask);
		}

		num_cpus = cpus_weight(cpu_mask);

		if (!num_cpus)
			goto skip_numa_setup;

		/* Use vector assigment to distribute across cpus in node */
		cpu_index = vector % num_cpus;

		for (numa_cpu = first_cpu(cpu_mask) ; i < cpu_index ; i++)
			numa_cpu = next_cpu(numa_cpu, cpu_mask);

		if (numa_cpu != NR_CPUS)
			return cpu_physical_id(numa_cpu);
	}
skip_numa_setup:
#endif
	/*
	 * Otherwise, round-robin interrupt vectors across all the
	 * processors.  (It'd be nice if we could be smarter in the
	 * case of NUMA.)
	 */
	do {
		if (++cpu >= NR_CPUS)
			cpu = 0;
	} while (!cpu_online(cpu));

	return cpu_physical_id(cpu);
#else
	return cpu_physical_id(smp_processor_id());
#endif
}

/*
 * ACPI can describe IOSAPIC interrupts via static tables and namespace
 * methods.  This provides an interface to register those interrupts and
 * program the IOSAPIC RTE.
 */
int
iosapic_register_intr (unsigned int gsi,
		       unsigned long polarity, unsigned long trigger)
{
	int vector, mask = 1;
	unsigned int dest;
	unsigned long flags;
	struct iosapic_rte_info *rte;
	u32 low32;
again:
	/*
	 * If this GSI has already been registered (i.e., it's a
	 * shared interrupt, or we lost a race to register it),
	 * don't touch the RTE.
	 */
	spin_lock_irqsave(&iosapic_lock, flags);
	{
		vector = gsi_to_vector(gsi);
		if (vector > 0) {
			rte = gsi_vector_to_rte(gsi, vector);
			rte->refcnt++;
			spin_unlock_irqrestore(&iosapic_lock, flags);
			return vector;
		}
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);

	/* If vector is running out, we try to find a sharable vector */
	vector = assign_irq_vector(AUTO_ASSIGN);
	if (vector < 0) {
		vector = iosapic_find_sharable_vector(trigger, polarity);
		if (vector < 0)
			panic("%s: out of interrupt vectors!\n", __FUNCTION__);
	}

	spin_lock_irqsave(&irq_descp(vector)->lock, flags);
	spin_lock(&iosapic_lock);
	{
		if (gsi_to_vector(gsi) > 0) {
			if (list_empty(&iosapic_intr_info[vector].rtes))
				free_irq_vector(vector);
			spin_unlock(&iosapic_lock);
			spin_unlock_irqrestore(&irq_descp(vector)->lock, flags);
			goto again;
		}

		dest = get_target_cpu(gsi, vector);
		register_intr(gsi, vector, IOSAPIC_LOWEST_PRIORITY,
			      polarity, trigger);

		/*
		 * If the vector is shared and already unmasked for
		 * other interrupt sources, don't mask it.
		 */
		low32 = iosapic_intr_info[vector].low32;
		if (vector_is_shared(vector) && !(low32 & IOSAPIC_MASK))
			mask = 0;
		set_rte(gsi, vector, dest, mask);
	}
	spin_unlock(&iosapic_lock);
	spin_unlock_irqrestore(&irq_descp(vector)->lock, flags);

	printk(KERN_INFO "GSI %u (%s, %s) -> CPU %d (0x%04x) vector %d\n",
	       gsi, (trigger == IOSAPIC_EDGE ? "edge" : "level"),
	       (polarity == IOSAPIC_POL_HIGH ? "high" : "low"),
	       cpu_logical_id(dest), dest, vector);

	return vector;
}

#ifdef CONFIG_ACPI_DEALLOCATE_IRQ
void
iosapic_unregister_intr (unsigned int gsi)
{
	unsigned long flags;
	int irq, vector, index;
	irq_desc_t *idesc;
	u32 low32;
	unsigned long trigger, polarity;
	unsigned int dest;
	struct iosapic_rte_info *rte;

	/*
	 * If the irq associated with the gsi is not found,
	 * iosapic_unregister_intr() is unbalanced. We need to check
	 * this again after getting locks.
	 */
	irq = gsi_to_irq(gsi);
	if (irq < 0) {
		printk(KERN_ERR "iosapic_unregister_intr(%u) unbalanced\n", gsi);
		WARN_ON(1);
		return;
	}
	vector = irq_to_vector(irq);

	idesc = irq_descp(irq);
	spin_lock_irqsave(&idesc->lock, flags);
	spin_lock(&iosapic_lock);
	{
		if ((rte = gsi_vector_to_rte(gsi, vector)) == NULL) {
			printk(KERN_ERR "iosapic_unregister_intr(%u) unbalanced\n", gsi);
			WARN_ON(1);
			goto out;
		}

		if (--rte->refcnt > 0)
			goto out;

		/* Mask the interrupt */
		low32 = iosapic_intr_info[vector].low32 | IOSAPIC_MASK;
		iosapic_write(rte->addr, IOSAPIC_RTE_LOW(rte->rte_index), low32);

		/* Remove the rte entry from the list */
		list_del(&rte->rte_list);
		iosapic_intr_info[vector].count--;
		iosapic_free_rte(rte);
		index = find_iosapic(gsi);
		iosapic_lists[index].rtes_inuse--;
		WARN_ON(iosapic_lists[index].rtes_inuse < 0);

		trigger	 = iosapic_intr_info[vector].trigger;
		polarity = iosapic_intr_info[vector].polarity;
		dest     = iosapic_intr_info[vector].dest;
		printk(KERN_INFO "GSI %u (%s, %s) -> CPU %d (0x%04x) vector %d unregistered\n",
		       gsi, (trigger == IOSAPIC_EDGE ? "edge" : "level"),
		       (polarity == IOSAPIC_POL_HIGH ? "high" : "low"),
		       cpu_logical_id(dest), dest, vector);

		if (list_empty(&iosapic_intr_info[vector].rtes)) {
			/* Sanity check */
			BUG_ON(iosapic_intr_info[vector].count);

			/* Clear the interrupt controller descriptor */
			idesc->handler = &no_irq_type;

			/* Clear the interrupt information */
			memset(&iosapic_intr_info[vector], 0, sizeof(struct iosapic_intr_info));
			iosapic_intr_info[vector].low32 |= IOSAPIC_MASK;
			INIT_LIST_HEAD(&iosapic_intr_info[vector].rtes);

			if (idesc->action) {
				printk(KERN_ERR "interrupt handlers still exist on IRQ %u\n", irq);
				WARN_ON(1);
			}

			/* Free the interrupt vector */
			free_irq_vector(vector);
		}
	}
 out:
	spin_unlock(&iosapic_lock);
	spin_unlock_irqrestore(&idesc->lock, flags);
}
#endif /* CONFIG_ACPI_DEALLOCATE_IRQ */

/*
 * ACPI calls this when it finds an entry for a platform interrupt.
 * Note that the irq_base and IOSAPIC address must be set in iosapic_init().
 */
int __init
iosapic_register_platform_intr (u32 int_type, unsigned int gsi,
				int iosapic_vector, u16 eid, u16 id,
				unsigned long polarity, unsigned long trigger)
{
	static const char * const name[] = {"unknown", "PMI", "INIT", "CPEI"};
	unsigned char delivery;
	int vector, mask = 0;
	unsigned int dest = ((id << 8) | eid) & 0xffff;

	switch (int_type) {
	      case ACPI_INTERRUPT_PMI:
		vector = iosapic_vector;
		/*
		 * since PMI vector is alloc'd by FW(ACPI) not by kernel,
		 * we need to make sure the vector is available
		 */
		iosapic_reassign_vector(vector);
		delivery = IOSAPIC_PMI;
		break;
	      case ACPI_INTERRUPT_INIT:
		vector = assign_irq_vector(AUTO_ASSIGN);
		if (vector < 0)
			panic("%s: out of interrupt vectors!\n", __FUNCTION__);
		delivery = IOSAPIC_INIT;
		break;
	      case ACPI_INTERRUPT_CPEI:
		vector = IA64_CPE_VECTOR;
		delivery = IOSAPIC_LOWEST_PRIORITY;
		mask = 1;
		break;
	      default:
		printk(KERN_ERR "iosapic_register_platform_irq(): invalid int type 0x%x\n", int_type);
		return -1;
	}

	register_intr(gsi, vector, delivery, polarity, trigger);

	printk(KERN_INFO "PLATFORM int %s (0x%x): GSI %u (%s, %s) -> CPU %d (0x%04x) vector %d\n",
	       int_type < ARRAY_SIZE(name) ? name[int_type] : "unknown",
	       int_type, gsi, (trigger == IOSAPIC_EDGE ? "edge" : "level"),
	       (polarity == IOSAPIC_POL_HIGH ? "high" : "low"),
	       cpu_logical_id(dest), dest, vector);

	set_rte(gsi, vector, dest, mask);
	return vector;
}


/*
 * ACPI calls this when it finds an entry for a legacy ISA IRQ override.
 * Note that the gsi_base and IOSAPIC address must be set in iosapic_init().
 */
void __init
iosapic_override_isa_irq (unsigned int isa_irq, unsigned int gsi,
			  unsigned long polarity,
			  unsigned long trigger)
{
	int vector;
	unsigned int dest = cpu_physical_id(smp_processor_id());

	vector = isa_irq_to_vector(isa_irq);

	register_intr(gsi, vector, IOSAPIC_LOWEST_PRIORITY, polarity, trigger);

	DBG("ISA: IRQ %u -> GSI %u (%s,%s) -> CPU %d (0x%04x) vector %d\n",
	    isa_irq, gsi, trigger == IOSAPIC_EDGE ? "edge" : "level",
	    polarity == IOSAPIC_POL_HIGH ? "high" : "low",
	    cpu_logical_id(dest), dest, vector);

	set_rte(gsi, vector, dest, 1);
}

void __init
iosapic_system_init (int system_pcat_compat)
{
	int vector;

	for (vector = 0; vector < IA64_NUM_VECTORS; ++vector) {
		iosapic_intr_info[vector].low32 = IOSAPIC_MASK;
		INIT_LIST_HEAD(&iosapic_intr_info[vector].rtes);	/* mark as unused */
	}

	pcat_compat = system_pcat_compat;
	if (pcat_compat) {
		/*
		 * Disable the compatibility mode interrupts (8259 style), needs IN/OUT support
		 * enabled.
		 */
		printk(KERN_INFO "%s: Disabling PC-AT compatible 8259 interrupts\n", __FUNCTION__);
		outb(0xff, 0xA1);
		outb(0xff, 0x21);
	}
}

static inline int
iosapic_alloc (void)
{
	int index;

	for (index = 0; index < NR_IOSAPICS; index++)
		if (!iosapic_lists[index].addr)
			return index;

	printk(KERN_WARNING "%s: failed to allocate iosapic\n", __FUNCTION__);
	return -1;
}

static inline void
iosapic_free (int index)
{
	memset(&iosapic_lists[index], 0, sizeof(iosapic_lists[0]));
}

static inline int
iosapic_check_gsi_range (unsigned int gsi_base, unsigned int ver)
{
	int index;
	unsigned int gsi_end, base, end;

	/* check gsi range */
	gsi_end = gsi_base + ((ver >> 16) & 0xff);
	for (index = 0; index < NR_IOSAPICS; index++) {
		if (!iosapic_lists[index].addr)
			continue;

		base = iosapic_lists[index].gsi_base;
		end  = base + iosapic_lists[index].num_rte - 1;

		if (gsi_base < base && gsi_end < base)
			continue;/* OK */

		if (gsi_base > end && gsi_end > end)
			continue; /* OK */

		return -EBUSY;
	}
	return 0;
}

int __devinit
iosapic_init (unsigned long phys_addr, unsigned int gsi_base)
{
	int num_rte, err, index;
	unsigned int isa_irq, ver;
	char __iomem *addr;
	unsigned long flags;

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		addr = ioremap(phys_addr, 0);
		ver = iosapic_version(addr);

		if ((err = iosapic_check_gsi_range(gsi_base, ver))) {
			iounmap(addr);
			spin_unlock_irqrestore(&iosapic_lock, flags);
			return err;
		}

		/*
		 * The MAX_REDIR register holds the highest input pin
		 * number (starting from 0).
		 * We add 1 so that we can use it for number of pins (= RTEs)
		 */
		num_rte = ((ver >> 16) & 0xff) + 1;

		index = iosapic_alloc();
		iosapic_lists[index].addr = addr;
		iosapic_lists[index].gsi_base = gsi_base;
		iosapic_lists[index].num_rte = num_rte;
#ifdef CONFIG_NUMA
		iosapic_lists[index].node = MAX_NUMNODES;
#endif
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);

	if ((gsi_base == 0) && pcat_compat) {
		/*
		 * Map the legacy ISA devices into the IOSAPIC data.  Some of these may
		 * get reprogrammed later on with data from the ACPI Interrupt Source
		 * Override table.
		 */
		for (isa_irq = 0; isa_irq < 16; ++isa_irq)
			iosapic_override_isa_irq(isa_irq, isa_irq, IOSAPIC_POL_HIGH, IOSAPIC_EDGE);
	}
	return 0;
}

#ifdef CONFIG_HOTPLUG
int
iosapic_remove (unsigned int gsi_base)
{
	int index, err = 0;
	unsigned long flags;

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		index = find_iosapic(gsi_base);
		if (index < 0) {
			printk(KERN_WARNING "%s: No IOSAPIC for GSI base %u\n",
			       __FUNCTION__, gsi_base);
			goto out;
		}

		if (iosapic_lists[index].rtes_inuse) {
			err = -EBUSY;
			printk(KERN_WARNING "%s: IOSAPIC for GSI base %u is busy\n",
			       __FUNCTION__, gsi_base);
			goto out;
		}

		iounmap(iosapic_lists[index].addr);
		iosapic_free(index);
	}
 out:
	spin_unlock_irqrestore(&iosapic_lock, flags);
	return err;
}
#endif /* CONFIG_HOTPLUG */

#ifdef CONFIG_NUMA
void __devinit
map_iosapic_to_node(unsigned int gsi_base, int node)
{
	int index;

	index = find_iosapic(gsi_base);
	if (index < 0) {
		printk(KERN_WARNING "%s: No IOSAPIC for GSI %u\n",
		       __FUNCTION__, gsi_base);
		return;
	}
	iosapic_lists[index].node = node;
	return;
}
#endif

static int __init iosapic_enable_kmalloc (void)
{
	iosapic_kmalloc_ok = 1;
	return 0;
}
core_initcall (iosapic_enable_kmalloc);