[IA64] Use per iosapic lock for indirect iosapic register access

[linux-2.6.git] / 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
 * describeinterrupts.  Now we use "IRQ" only for Linux IRQ's.  ISA IRQ
 * (isa_irq) is the only exception in this source code.
 */

#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/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.
 */
static struct iosapic {
        char __iomem    *addr;          /* base address of IOSAPIC */
        unsigned int    gsi_base;       /* GSI base */
        unsigned short  num_rte;        /* # of RTEs on this IOSAPIC */
        int             rtes_inuse;     /* # of RTEs in use on this IOSAPIC */
#ifdef CONFIG_NUMA
        unsigned short  node;           /* numa node association via pxm */
#endif
        spinlock_t      lock;           /* lock for indirect reg access */
} iosapic_lists[NR_IOSAPICS];

struct iosapic_rte_info {
        struct list_head rte_list;      /* RTEs sharing the same vector */
        char            rte_index;      /* IOSAPIC RTE index */
        int             refcnt;         /* reference counter */
        unsigned int    flags;          /* flags */
        struct iosapic  *iosapic;
} ____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 unsigned char pcat_compat __devinitdata; /* 8259 compatibility flag */

static int iosapic_kmalloc_ok;
static LIST_HEAD(free_rte_list);

static inline void
iosapic_write(struct iosapic *iosapic, unsigned int reg, u32 val)
{
        unsigned long flags;

        spin_lock_irqsave(&iosapic->lock, flags);
        __iosapic_write(iosapic->addr, reg, val);
        spin_unlock_irqrestore(&iosapic->lock, flags);
}

/*
 * 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->iosapic->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 between 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->iosapic->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;
        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;
        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(rte->iosapic, IOSAPIC_RTE_HIGH(rte_index), high32);
        iosapic_write(rte->iosapic, IOSAPIC_RTE_LOW(rte_index), low32);
        iosapic_intr_info[vector].low32 = low32;
        iosapic_intr_info[vector].dest = dest;
}

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


#ifdef CONFIG_KEXEC
void
kexec_disable_iosapic(void)
{
        struct iosapic_intr_info *info;
        struct iosapic_rte_info *rte;
        u8 vec = 0;
        for (info = iosapic_intr_info; info <
                        iosapic_intr_info + IA64_NUM_VECTORS; ++info, ++vec) {
                list_for_each_entry(rte, &info->rtes,
                                rte_list) {
                        iosapic_write(rte->iosapic,
                                        IOSAPIC_RTE_LOW(rte->rte_index),
                                        IOSAPIC_MASK|vec);
                        iosapic_eoi(rte->iosapic->addr, vec);
                }
        }
}
#endif

static void
mask_irq (unsigned int irq)
{
        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! */

        /* 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) {
                rte_index = rte->rte_index;
                iosapic_write(rte->iosapic, IOSAPIC_RTE_LOW(rte_index), low32);
        }
}

static void
unmask_irq (unsigned int irq)
{
        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! */

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


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

        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;

        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) {
                iosapic = rte->iosapic;
                rte_index = rte->rte_index;
                iosapic_write(iosapic, IOSAPIC_RTE_HIGH(rte_index), high32);
                iosapic_write(iosapic, IOSAPIC_RTE_LOW(rte_index), low32);
        }
#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_native_irq(irq);
        list_for_each_entry(rte, &iosapic_intr_info[vec].rtes, rte_list)
                iosapic_eoi(rte->iosapic->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 irq_chip irq_type_iosapic_level = {
        .name =         "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,
        .mask =         mask_irq,
        .unmask =       unmask_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_desc + irq;

        move_native_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 irq_chip irq_type_iosapic_edge = {
        .name =         "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,
        .mask =         mask_irq,
        .unmask =       unmask_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 = -ENOSPC, min_count = -1;
        struct iosapic_intr_info *info;

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

        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 int
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 index;
        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 -ENODEV;
        }

        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 -ENOMEM;
                }

                rte->iosapic    = &iosapic_lists[index];
                rte->rte_index  = gsi - rte->iosapic->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 -EINVAL;
                }
        }

        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_desc + vector;
        if (idesc->chip != irq_type) {
                if (idesc->chip != &no_irq_type)
                        printk(KERN_WARNING
                               "%s: changing vector %d from %s to %s\n",
                               __FUNCTION__, vector,
                               idesc->chip->name, irq_type->name);
                idesc->chip = irq_type;
        }
        return 0;
}

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

        /*
         * 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_ACPI
        if (cpe_vector > 0 && vector == IA64_CPEP_VECTOR)
                return get_cpei_target_cpu();
#endif

#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 assignment 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  /* CONFIG_SMP */
        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, err;
        unsigned int dest;
        unsigned long flags;
        struct iosapic_rte_info *rte;
        u32 low32;

        /*
         * 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++;
                goto unlock_iosapic_lock;
        }

        /* 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)
                        goto unlock_iosapic_lock;
        }

        spin_lock(&irq_desc[vector].lock);
        dest = get_target_cpu(gsi, vector);
        err = register_intr(gsi, vector, IOSAPIC_LOWEST_PRIORITY,
                            polarity, trigger);
        if (err < 0) {
                vector = err;
                goto unlock_all;
        }

        /*
         * 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);

        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);
 unlock_all:
        spin_unlock(&irq_desc[vector].lock);
 unlock_iosapic_lock:
        spin_unlock_irqrestore(&iosapic_lock, flags);
        return vector;
}

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);

        spin_lock_irqsave(&iosapic_lock, flags);
        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;

        /* Remove the rte entry from the list */
        idesc = irq_desc + irq;
        spin_lock(&idesc->lock);
        list_del(&rte->rte_list);
        spin_unlock(&idesc->lock);

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

        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->chip = &no_irq_type;

#ifdef CONFIG_SMP
                /* Clear affinity */
                cpus_setall(idesc->affinity);
#endif

                /* 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_irqrestore(&iosapic_lock, flags);
}

/*
 * ACPI calls this when it finds an entry for a platform interrupt.
 */
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 "%s: invalid int type 0x%x\n", __FUNCTION__,
                       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.
 */
void __devinit
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;
                /* mark as unused */
                INIT_LIST_HEAD(&iosapic_intr_info[vector].rtes);
        }

        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_end < base || end < gsi_base)
                        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);
        index = find_iosapic(gsi_base);
        if (index >= 0) {
                spin_unlock_irqrestore(&iosapic_lock, flags);
                return -EBUSY;
        }

        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_lock_init(&iosapic_lists[index].lock);
        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);