Merge branch 'linus' into cpus4096

[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / io_apic_64.c

/*
 *      Intel IO-APIC support for multi-Pentium hosts.
 *
 *      Copyright (C) 1997, 1998, 1999, 2000 Ingo Molnar, Hajnalka Szabo
 *
 *      Many thanks to Stig Venaas for trying out countless experimental
 *      patches and reporting/debugging problems patiently!
 *
 *      (c) 1999, Multiple IO-APIC support, developed by
 *      Ken-ichi Yaku <yaku@css1.kbnes.nec.co.jp> and
 *      Hidemi Kishimoto <kisimoto@css1.kbnes.nec.co.jp>,
 *      further tested and cleaned up by Zach Brown <zab@redhat.com>
 *      and Ingo Molnar <mingo@redhat.com>
 *
 *      Fixes
 *      Maciej W. Rozycki       :       Bits for genuine 82489DX APICs;
 *                                      thanks to Eric Gilmore
 *                                      and Rolf G. Tews
 *                                      for testing these extensively
 *      Paul Diefenbaugh        :       Added full ACPI support
 */

#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/pci.h>
#include <linux/mc146818rtc.h>
#include <linux/acpi.h>
#include <linux/sysdev.h>
#include <linux/msi.h>
#include <linux/htirq.h>
#include <linux/dmar.h>
#include <linux/jiffies.h>
#ifdef CONFIG_ACPI
#include <acpi/acpi_bus.h>
#endif
#include <linux/bootmem.h>

#include <asm/idle.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/desc.h>
#include <asm/proto.h>
#include <asm/acpi.h>
#include <asm/dma.h>
#include <asm/nmi.h>
#include <asm/msidef.h>
#include <asm/hypertransport.h>

#include <mach_ipi.h>
#include <mach_apic.h>

struct irq_cfg {
        cpumask_t domain;
        cpumask_t old_domain;
        unsigned move_cleanup_count;
        u8 vector;
        u8 move_in_progress : 1;
};

/* irq_cfg is indexed by the sum of all RTEs in all I/O APICs. */
static struct irq_cfg irq_cfg[NR_IRQS] __read_mostly = {
        [0]  = { .domain = CPU_MASK_ALL, .vector = IRQ0_VECTOR,  },
        [1]  = { .domain = CPU_MASK_ALL, .vector = IRQ1_VECTOR,  },
        [2]  = { .domain = CPU_MASK_ALL, .vector = IRQ2_VECTOR,  },
        [3]  = { .domain = CPU_MASK_ALL, .vector = IRQ3_VECTOR,  },
        [4]  = { .domain = CPU_MASK_ALL, .vector = IRQ4_VECTOR,  },
        [5]  = { .domain = CPU_MASK_ALL, .vector = IRQ5_VECTOR,  },
        [6]  = { .domain = CPU_MASK_ALL, .vector = IRQ6_VECTOR,  },
        [7]  = { .domain = CPU_MASK_ALL, .vector = IRQ7_VECTOR,  },
        [8]  = { .domain = CPU_MASK_ALL, .vector = IRQ8_VECTOR,  },
        [9]  = { .domain = CPU_MASK_ALL, .vector = IRQ9_VECTOR,  },
        [10] = { .domain = CPU_MASK_ALL, .vector = IRQ10_VECTOR, },
        [11] = { .domain = CPU_MASK_ALL, .vector = IRQ11_VECTOR, },
        [12] = { .domain = CPU_MASK_ALL, .vector = IRQ12_VECTOR, },
        [13] = { .domain = CPU_MASK_ALL, .vector = IRQ13_VECTOR, },
        [14] = { .domain = CPU_MASK_ALL, .vector = IRQ14_VECTOR, },
        [15] = { .domain = CPU_MASK_ALL, .vector = IRQ15_VECTOR, },
};

static int assign_irq_vector(int irq, cpumask_t mask);

int first_system_vector = 0xfe;

char system_vectors[NR_VECTORS] = { [0 ... NR_VECTORS-1] = SYS_VECTOR_FREE};

#define __apicdebuginit  __init

int sis_apic_bug; /* not actually supported, dummy for compile */

static int no_timer_check;

static int disable_timer_pin_1 __initdata;

int timer_through_8259 __initdata;

/* Where if anywhere is the i8259 connect in external int mode */
static struct { int pin, apic; } ioapic_i8259 = { -1, -1 };

static DEFINE_SPINLOCK(ioapic_lock);
DEFINE_SPINLOCK(vector_lock);

/*
 * # of IRQ routing registers
 */
int nr_ioapic_registers[MAX_IO_APICS];

/* I/O APIC entries */
struct mp_config_ioapic mp_ioapics[MAX_IO_APICS];
int nr_ioapics;

/* MP IRQ source entries */
struct mp_config_intsrc mp_irqs[MAX_IRQ_SOURCES];

/* # of MP IRQ source entries */
int mp_irq_entries;

DECLARE_BITMAP(mp_bus_not_pci, MAX_MP_BUSSES);

/*
 * Rough estimation of how many shared IRQs there are, can
 * be changed anytime.
 */
#define MAX_PLUS_SHARED_IRQS NR_IRQS
#define PIN_MAP_SIZE (MAX_PLUS_SHARED_IRQS + NR_IRQS)

/*
 * This is performance-critical, we want to do it O(1)
 *
 * the indexing order of this array favors 1:1 mappings
 * between pins and IRQs.
 */

static struct irq_pin_list {
        short apic, pin, next;
} irq_2_pin[PIN_MAP_SIZE];

struct io_apic {
        unsigned int index;
        unsigned int unused[3];
        unsigned int data;
};

static __attribute_const__ struct io_apic __iomem *io_apic_base(int idx)
{
        return (void __iomem *) __fix_to_virt(FIX_IO_APIC_BASE_0 + idx)
                + (mp_ioapics[idx].mp_apicaddr & ~PAGE_MASK);
}

static inline unsigned int io_apic_read(unsigned int apic, unsigned int reg)
{
        struct io_apic __iomem *io_apic = io_apic_base(apic);
        writel(reg, &io_apic->index);
        return readl(&io_apic->data);
}

static inline void io_apic_write(unsigned int apic, unsigned int reg, unsigned int value)
{
        struct io_apic __iomem *io_apic = io_apic_base(apic);
        writel(reg, &io_apic->index);
        writel(value, &io_apic->data);
}

/*
 * Re-write a value: to be used for read-modify-write
 * cycles where the read already set up the index register.
 */
static inline void io_apic_modify(unsigned int apic, unsigned int value)
{
        struct io_apic __iomem *io_apic = io_apic_base(apic);
        writel(value, &io_apic->data);
}

static bool io_apic_level_ack_pending(unsigned int irq)
{
        struct irq_pin_list *entry;
        unsigned long flags;

        spin_lock_irqsave(&ioapic_lock, flags);
        entry = irq_2_pin + irq;
        for (;;) {
                unsigned int reg;
                int pin;

                pin = entry->pin;
                if (pin == -1)
                        break;
                reg = io_apic_read(entry->apic, 0x10 + pin*2);
                /* Is the remote IRR bit set? */
                if (reg & IO_APIC_REDIR_REMOTE_IRR) {
                        spin_unlock_irqrestore(&ioapic_lock, flags);
                        return true;
                }
                if (!entry->next)
                        break;
                entry = irq_2_pin + entry->next;
        }
        spin_unlock_irqrestore(&ioapic_lock, flags);

        return false;
}

/*
 * Synchronize the IO-APIC and the CPU by doing
 * a dummy read from the IO-APIC
 */
static inline void io_apic_sync(unsigned int apic)
{
        struct io_apic __iomem *io_apic = io_apic_base(apic);
        readl(&io_apic->data);
}

#define __DO_ACTION(R, ACTION, FINAL)                                   \
                                                                        \
{                                                                       \
        int pin;                                                        \
        struct irq_pin_list *entry = irq_2_pin + irq;                   \
                                                                        \
        BUG_ON(irq >= NR_IRQS);                                         \
        for (;;) {                                                      \
                unsigned int reg;                                       \
                pin = entry->pin;                                       \
                if (pin == -1)                                          \
                        break;                                          \
                reg = io_apic_read(entry->apic, 0x10 + R + pin*2);      \
                reg ACTION;                                             \
                io_apic_modify(entry->apic, reg);                       \
                FINAL;                                                  \
                if (!entry->next)                                       \
                        break;                                          \
                entry = irq_2_pin + entry->next;                        \
        }                                                               \
}

union entry_union {
        struct { u32 w1, w2; };
        struct IO_APIC_route_entry entry;
};

static struct IO_APIC_route_entry ioapic_read_entry(int apic, int pin)
{
        union entry_union eu;
        unsigned long flags;
        spin_lock_irqsave(&ioapic_lock, flags);
        eu.w1 = io_apic_read(apic, 0x10 + 2 * pin);
        eu.w2 = io_apic_read(apic, 0x11 + 2 * pin);
        spin_unlock_irqrestore(&ioapic_lock, flags);
        return eu.entry;
}

/*
 * When we write a new IO APIC routing entry, we need to write the high
 * word first! If the mask bit in the low word is clear, we will enable
 * the interrupt, and we need to make sure the entry is fully populated
 * before that happens.
 */
static void
__ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
{
        union entry_union eu;
        eu.entry = e;
        io_apic_write(apic, 0x11 + 2*pin, eu.w2);
        io_apic_write(apic, 0x10 + 2*pin, eu.w1);
}

static void ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
{
        unsigned long flags;
        spin_lock_irqsave(&ioapic_lock, flags);
        __ioapic_write_entry(apic, pin, e);
        spin_unlock_irqrestore(&ioapic_lock, flags);
}

/*
 * When we mask an IO APIC routing entry, we need to write the low
 * word first, in order to set the mask bit before we change the
 * high bits!
 */
static void ioapic_mask_entry(int apic, int pin)
{
        unsigned long flags;
        union entry_union eu = { .entry.mask = 1 };

        spin_lock_irqsave(&ioapic_lock, flags);
        io_apic_write(apic, 0x10 + 2*pin, eu.w1);
        io_apic_write(apic, 0x11 + 2*pin, eu.w2);
        spin_unlock_irqrestore(&ioapic_lock, flags);
}

#ifdef CONFIG_SMP
static void __target_IO_APIC_irq(unsigned int irq, unsigned int dest, u8 vector)
{
        int apic, pin;
        struct irq_pin_list *entry = irq_2_pin + irq;

        BUG_ON(irq >= NR_IRQS);
        for (;;) {
                unsigned int reg;
                apic = entry->apic;
                pin = entry->pin;
                if (pin == -1)
                        break;
                io_apic_write(apic, 0x11 + pin*2, dest);
                reg = io_apic_read(apic, 0x10 + pin*2);
                reg &= ~IO_APIC_REDIR_VECTOR_MASK;
                reg |= vector;
                io_apic_modify(apic, reg);
                if (!entry->next)
                        break;
                entry = irq_2_pin + entry->next;
        }
}

static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t mask)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        unsigned long flags;
        unsigned int dest;
        cpumask_t tmp;

        cpus_and(tmp, mask, cpu_online_map);
        if (cpus_empty(tmp))
                return;

        if (assign_irq_vector(irq, mask))
                return;

        cpus_and(tmp, cfg->domain, mask);
        dest = cpu_mask_to_apicid(tmp);

        /*
         * Only the high 8 bits are valid.
         */
        dest = SET_APIC_LOGICAL_ID(dest);

        spin_lock_irqsave(&ioapic_lock, flags);
        __target_IO_APIC_irq(irq, dest, cfg->vector);
        irq_desc[irq].affinity = mask;
        spin_unlock_irqrestore(&ioapic_lock, flags);
}
#endif

/*
 * The common case is 1:1 IRQ<->pin mappings. Sometimes there are
 * shared ISA-space IRQs, so we have to support them. We are super
 * fast in the common case, and fast for shared ISA-space IRQs.
 */
static void add_pin_to_irq(unsigned int irq, int apic, int pin)
{
        static int first_free_entry = NR_IRQS;
        struct irq_pin_list *entry = irq_2_pin + irq;

        BUG_ON(irq >= NR_IRQS);
        while (entry->next)
                entry = irq_2_pin + entry->next;

        if (entry->pin != -1) {
                entry->next = first_free_entry;
                entry = irq_2_pin + entry->next;
                if (++first_free_entry >= PIN_MAP_SIZE)
                        panic("io_apic.c: ran out of irq_2_pin entries!");
        }
        entry->apic = apic;
        entry->pin = pin;
}

/*
 * Reroute an IRQ to a different pin.
 */
static void __init replace_pin_at_irq(unsigned int irq,
                                      int oldapic, int oldpin,
                                      int newapic, int newpin)
{
        struct irq_pin_list *entry = irq_2_pin + irq;

        while (1) {
                if (entry->apic == oldapic && entry->pin == oldpin) {
                        entry->apic = newapic;
                        entry->pin = newpin;
                }
                if (!entry->next)
                        break;
                entry = irq_2_pin + entry->next;
        }
}


#define DO_ACTION(name,R,ACTION, FINAL)                                 \
                                                                        \
        static void name##_IO_APIC_irq (unsigned int irq)               \
        __DO_ACTION(R, ACTION, FINAL)

/* mask = 1 */
DO_ACTION(__mask,       0, |= IO_APIC_REDIR_MASKED, io_apic_sync(entry->apic))

/* mask = 0 */
DO_ACTION(__unmask,     0, &= ~IO_APIC_REDIR_MASKED, )

static void mask_IO_APIC_irq (unsigned int irq)
{
        unsigned long flags;

        spin_lock_irqsave(&ioapic_lock, flags);
        __mask_IO_APIC_irq(irq);
        spin_unlock_irqrestore(&ioapic_lock, flags);
}

static void unmask_IO_APIC_irq (unsigned int irq)
{
        unsigned long flags;

        spin_lock_irqsave(&ioapic_lock, flags);
        __unmask_IO_APIC_irq(irq);
        spin_unlock_irqrestore(&ioapic_lock, flags);
}

static void clear_IO_APIC_pin(unsigned int apic, unsigned int pin)
{
        struct IO_APIC_route_entry entry;

        /* Check delivery_mode to be sure we're not clearing an SMI pin */
        entry = ioapic_read_entry(apic, pin);
        if (entry.delivery_mode == dest_SMI)
                return;
        /*
         * Disable it in the IO-APIC irq-routing table:
         */
        ioapic_mask_entry(apic, pin);
}

static void clear_IO_APIC (void)
{
        int apic, pin;

        for (apic = 0; apic < nr_ioapics; apic++)
                for (pin = 0; pin < nr_ioapic_registers[apic]; pin++)
                        clear_IO_APIC_pin(apic, pin);
}

int skip_ioapic_setup;
int ioapic_force;

static int __init parse_noapic(char *str)
{
        disable_ioapic_setup();
        return 0;
}
early_param("noapic", parse_noapic);

/* Actually the next is obsolete, but keep it for paranoid reasons -AK */
static int __init disable_timer_pin_setup(char *arg)
{
        disable_timer_pin_1 = 1;
        return 1;
}
__setup("disable_timer_pin_1", disable_timer_pin_setup);


/*
 * Find the IRQ entry number of a certain pin.
 */
static int find_irq_entry(int apic, int pin, int type)
{
        int i;

        for (i = 0; i < mp_irq_entries; i++)
                if (mp_irqs[i].mp_irqtype == type &&
                    (mp_irqs[i].mp_dstapic == mp_ioapics[apic].mp_apicid ||
                     mp_irqs[i].mp_dstapic == MP_APIC_ALL) &&
                    mp_irqs[i].mp_dstirq == pin)
                        return i;

        return -1;
}

/*
 * Find the pin to which IRQ[irq] (ISA) is connected
 */
static int __init find_isa_irq_pin(int irq, int type)
{
        int i;

        for (i = 0; i < mp_irq_entries; i++) {
                int lbus = mp_irqs[i].mp_srcbus;

                if (test_bit(lbus, mp_bus_not_pci) &&
                    (mp_irqs[i].mp_irqtype == type) &&
                    (mp_irqs[i].mp_srcbusirq == irq))

                        return mp_irqs[i].mp_dstirq;
        }
        return -1;
}

static int __init find_isa_irq_apic(int irq, int type)
{
        int i;

        for (i = 0; i < mp_irq_entries; i++) {
                int lbus = mp_irqs[i].mp_srcbus;

                if (test_bit(lbus, mp_bus_not_pci) &&
                    (mp_irqs[i].mp_irqtype == type) &&
                    (mp_irqs[i].mp_srcbusirq == irq))
                        break;
        }
        if (i < mp_irq_entries) {
                int apic;
                for(apic = 0; apic < nr_ioapics; apic++) {
                        if (mp_ioapics[apic].mp_apicid == mp_irqs[i].mp_dstapic)
                                return apic;
                }
        }

        return -1;
}

/*
 * Find a specific PCI IRQ entry.
 * Not an __init, possibly needed by modules
 */
static int pin_2_irq(int idx, int apic, int pin);

int IO_APIC_get_PCI_irq_vector(int bus, int slot, int pin)
{
        int apic, i, best_guess = -1;

        apic_printk(APIC_DEBUG, "querying PCI -> IRQ mapping bus:%d, slot:%d, pin:%d.\n",
                bus, slot, pin);
        if (test_bit(bus, mp_bus_not_pci)) {
                apic_printk(APIC_VERBOSE, "PCI BIOS passed nonexistent PCI bus %d!\n", bus);
                return -1;
        }
        for (i = 0; i < mp_irq_entries; i++) {
                int lbus = mp_irqs[i].mp_srcbus;

                for (apic = 0; apic < nr_ioapics; apic++)
                        if (mp_ioapics[apic].mp_apicid == mp_irqs[i].mp_dstapic ||
                            mp_irqs[i].mp_dstapic == MP_APIC_ALL)
                                break;

                if (!test_bit(lbus, mp_bus_not_pci) &&
                    !mp_irqs[i].mp_irqtype &&
                    (bus == lbus) &&
                    (slot == ((mp_irqs[i].mp_srcbusirq >> 2) & 0x1f))) {
                        int irq = pin_2_irq(i,apic,mp_irqs[i].mp_dstirq);

                        if (!(apic || IO_APIC_IRQ(irq)))
                                continue;

                        if (pin == (mp_irqs[i].mp_srcbusirq & 3))
                                return irq;
                        /*
                         * Use the first all-but-pin matching entry as a
                         * best-guess fuzzy result for broken mptables.
                         */
                        if (best_guess < 0)
                                best_guess = irq;
                }
        }
        BUG_ON(best_guess >= NR_IRQS);
        return best_guess;
}

/* ISA interrupts are always polarity zero edge triggered,
 * when listed as conforming in the MP table. */

#define default_ISA_trigger(idx)        (0)
#define default_ISA_polarity(idx)       (0)

/* PCI interrupts are always polarity one level triggered,
 * when listed as conforming in the MP table. */

#define default_PCI_trigger(idx)        (1)
#define default_PCI_polarity(idx)       (1)

static int MPBIOS_polarity(int idx)
{
        int bus = mp_irqs[idx].mp_srcbus;
        int polarity;

        /*
         * Determine IRQ line polarity (high active or low active):
         */
        switch (mp_irqs[idx].mp_irqflag & 3)
        {
                case 0: /* conforms, ie. bus-type dependent polarity */
                        if (test_bit(bus, mp_bus_not_pci))
                                polarity = default_ISA_polarity(idx);
                        else
                                polarity = default_PCI_polarity(idx);
                        break;
                case 1: /* high active */
                {
                        polarity = 0;
                        break;
                }
                case 2: /* reserved */
                {
                        printk(KERN_WARNING "broken BIOS!!\n");
                        polarity = 1;
                        break;
                }
                case 3: /* low active */
                {
                        polarity = 1;
                        break;
                }
                default: /* invalid */
                {
                        printk(KERN_WARNING "broken BIOS!!\n");
                        polarity = 1;
                        break;
                }
        }
        return polarity;
}

static int MPBIOS_trigger(int idx)
{
        int bus = mp_irqs[idx].mp_srcbus;
        int trigger;

        /*
         * Determine IRQ trigger mode (edge or level sensitive):
         */
        switch ((mp_irqs[idx].mp_irqflag>>2) & 3)
        {
                case 0: /* conforms, ie. bus-type dependent */
                        if (test_bit(bus, mp_bus_not_pci))
                                trigger = default_ISA_trigger(idx);
                        else
                                trigger = default_PCI_trigger(idx);
                        break;
                case 1: /* edge */
                {
                        trigger = 0;
                        break;
                }
                case 2: /* reserved */
                {
                        printk(KERN_WARNING "broken BIOS!!\n");
                        trigger = 1;
                        break;
                }
                case 3: /* level */
                {
                        trigger = 1;
                        break;
                }
                default: /* invalid */
                {
                        printk(KERN_WARNING "broken BIOS!!\n");
                        trigger = 0;
                        break;
                }
        }
        return trigger;
}

static inline int irq_polarity(int idx)
{
        return MPBIOS_polarity(idx);
}

static inline int irq_trigger(int idx)
{
        return MPBIOS_trigger(idx);
}

static int pin_2_irq(int idx, int apic, int pin)
{
        int irq, i;
        int bus = mp_irqs[idx].mp_srcbus;

        /*
         * Debugging check, we are in big trouble if this message pops up!
         */
        if (mp_irqs[idx].mp_dstirq != pin)
                printk(KERN_ERR "broken BIOS or MPTABLE parser, ayiee!!\n");

        if (test_bit(bus, mp_bus_not_pci)) {
                irq = mp_irqs[idx].mp_srcbusirq;
        } else {
                /*
                 * PCI IRQs are mapped in order
                 */
                i = irq = 0;
                while (i < apic)
                        irq += nr_ioapic_registers[i++];
                irq += pin;
        }
        BUG_ON(irq >= NR_IRQS);
        return irq;
}

static int __assign_irq_vector(int irq, cpumask_t mask)
{
        /*
         * NOTE! The local APIC isn't very good at handling
         * multiple interrupts at the same interrupt level.
         * As the interrupt level is determined by taking the
         * vector number and shifting that right by 4, we
         * want to spread these out a bit so that they don't
         * all fall in the same interrupt level.
         *
         * Also, we've got to be careful not to trash gate
         * 0x80, because int 0x80 is hm, kind of importantish. ;)
         */
        static int current_vector = FIRST_DEVICE_VECTOR, current_offset = 0;
        unsigned int old_vector;
        int cpu;
        struct irq_cfg *cfg;

        BUG_ON((unsigned)irq >= NR_IRQS);
        cfg = &irq_cfg[irq];

        /* Only try and allocate irqs on cpus that are present */
        cpus_and(mask, mask, cpu_online_map);

        if ((cfg->move_in_progress) || cfg->move_cleanup_count)
                return -EBUSY;

        old_vector = cfg->vector;
        if (old_vector) {
                cpumask_t tmp;
                cpus_and(tmp, cfg->domain, mask);
                if (!cpus_empty(tmp))
                        return 0;
        }

        for_each_cpu_mask_nr(cpu, mask) {
                cpumask_t domain, new_mask;
                int new_cpu;
                int vector, offset;

                domain = vector_allocation_domain(cpu);
                cpus_and(new_mask, domain, cpu_online_map);

                vector = current_vector;
                offset = current_offset;
next:
                vector += 8;
                if (vector >= first_system_vector) {
                        /* If we run out of vectors on large boxen, must share them. */
                        offset = (offset + 1) % 8;
                        vector = FIRST_DEVICE_VECTOR + offset;
                }
                if (unlikely(current_vector == vector))
                        continue;
                if (vector == IA32_SYSCALL_VECTOR)
                        goto next;
                for_each_cpu_mask_nr(new_cpu, new_mask)
                        if (per_cpu(vector_irq, new_cpu)[vector] != -1)
                                goto next;
                /* Found one! */
                current_vector = vector;
                current_offset = offset;
                if (old_vector) {
                        cfg->move_in_progress = 1;
                        cfg->old_domain = cfg->domain;
                }
                for_each_cpu_mask_nr(new_cpu, new_mask)
                        per_cpu(vector_irq, new_cpu)[vector] = irq;
                cfg->vector = vector;
                cfg->domain = domain;
                return 0;
        }
        return -ENOSPC;
}

static int assign_irq_vector(int irq, cpumask_t mask)
{
        int err;
        unsigned long flags;

        spin_lock_irqsave(&vector_lock, flags);
        err = __assign_irq_vector(irq, mask);
        spin_unlock_irqrestore(&vector_lock, flags);
        return err;
}

static void __clear_irq_vector(int irq)
{
        struct irq_cfg *cfg;
        cpumask_t mask;
        int cpu, vector;

        BUG_ON((unsigned)irq >= NR_IRQS);
        cfg = &irq_cfg[irq];
        BUG_ON(!cfg->vector);

        vector = cfg->vector;
        cpus_and(mask, cfg->domain, cpu_online_map);
        for_each_cpu_mask_nr(cpu, mask)
                per_cpu(vector_irq, cpu)[vector] = -1;

        cfg->vector = 0;
        cpus_clear(cfg->domain);
}

static void __setup_vector_irq(int cpu)
{
        /* Initialize vector_irq on a new cpu */
        /* This function must be called with vector_lock held */
        int irq, vector;

        /* Mark the inuse vectors */
        for (irq = 0; irq < NR_IRQS; ++irq) {
                if (!cpu_isset(cpu, irq_cfg[irq].domain))
                        continue;
                vector = irq_cfg[irq].vector;
                per_cpu(vector_irq, cpu)[vector] = irq;
        }
        /* Mark the free vectors */
        for (vector = 0; vector < NR_VECTORS; ++vector) {
                irq = per_cpu(vector_irq, cpu)[vector];
                if (irq < 0)
                        continue;
                if (!cpu_isset(cpu, irq_cfg[irq].domain))
                        per_cpu(vector_irq, cpu)[vector] = -1;
        }
}

void setup_vector_irq(int cpu)
{
        spin_lock(&vector_lock);
        __setup_vector_irq(smp_processor_id());
        spin_unlock(&vector_lock);
}


static struct irq_chip ioapic_chip;

static void ioapic_register_intr(int irq, unsigned long trigger)
{
        if (trigger) {
                irq_desc[irq].status |= IRQ_LEVEL;
                set_irq_chip_and_handler_name(irq, &ioapic_chip,
                                              handle_fasteoi_irq, "fasteoi");
        } else {
                irq_desc[irq].status &= ~IRQ_LEVEL;
                set_irq_chip_and_handler_name(irq, &ioapic_chip,
                                              handle_edge_irq, "edge");
        }
}

static void setup_IO_APIC_irq(int apic, int pin, unsigned int irq,
                              int trigger, int polarity)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        struct IO_APIC_route_entry entry;
        cpumask_t mask;

        if (!IO_APIC_IRQ(irq))
                return;

        mask = TARGET_CPUS;
        if (assign_irq_vector(irq, mask))
                return;

        cpus_and(mask, cfg->domain, mask);

        apic_printk(APIC_VERBOSE,KERN_DEBUG
                    "IOAPIC[%d]: Set routing entry (%d-%d -> 0x%x -> "
                    "IRQ %d Mode:%i Active:%i)\n",
                    apic, mp_ioapics[apic].mp_apicid, pin, cfg->vector,
                    irq, trigger, polarity);

        /*
         * add it to the IO-APIC irq-routing table:
         */
        memset(&entry,0,sizeof(entry));

        entry.delivery_mode = INT_DELIVERY_MODE;
        entry.dest_mode = INT_DEST_MODE;
        entry.dest = cpu_mask_to_apicid(mask);
        entry.mask = 0;                         /* enable IRQ */
        entry.trigger = trigger;
        entry.polarity = polarity;
        entry.vector = cfg->vector;

        /* Mask level triggered irqs.
         * Use IRQ_DELAYED_DISABLE for edge triggered irqs.
         */
        if (trigger)
                entry.mask = 1;

        ioapic_register_intr(irq, trigger);
        if (irq < 16)
                disable_8259A_irq(irq);

        ioapic_write_entry(apic, pin, entry);
}

static void __init setup_IO_APIC_irqs(void)
{
        int apic, pin, idx, irq, first_notcon = 1;

        apic_printk(APIC_VERBOSE, KERN_DEBUG "init IO_APIC IRQs\n");

        for (apic = 0; apic < nr_ioapics; apic++) {
        for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {

                idx = find_irq_entry(apic,pin,mp_INT);
                if (idx == -1) {
                        if (first_notcon) {
                                apic_printk(APIC_VERBOSE, KERN_DEBUG " IO-APIC (apicid-pin) %d-%d", mp_ioapics[apic].mp_apicid, pin);
                                first_notcon = 0;
                        } else
                                apic_printk(APIC_VERBOSE, ", %d-%d", mp_ioapics[apic].mp_apicid, pin);
                        continue;
                }
                if (!first_notcon) {
                        apic_printk(APIC_VERBOSE, " not connected.\n");
                        first_notcon = 1;
                }

                irq = pin_2_irq(idx, apic, pin);
                add_pin_to_irq(irq, apic, pin);

                setup_IO_APIC_irq(apic, pin, irq,
                                  irq_trigger(idx), irq_polarity(idx));
        }
        }

        if (!first_notcon)
                apic_printk(APIC_VERBOSE, " not connected.\n");
}

/*
 * Set up the timer pin, possibly with the 8259A-master behind.
 */
static void __init setup_timer_IRQ0_pin(unsigned int apic, unsigned int pin,
                                        int vector)
{
        struct IO_APIC_route_entry entry;

        memset(&entry, 0, sizeof(entry));

        /*
         * We use logical delivery to get the timer IRQ
         * to the first CPU.
         */
        entry.dest_mode = INT_DEST_MODE;
        entry.mask = 1;                                 /* mask IRQ now */
        entry.dest = cpu_mask_to_apicid(TARGET_CPUS);
        entry.delivery_mode = INT_DELIVERY_MODE;
        entry.polarity = 0;
        entry.trigger = 0;
        entry.vector = vector;

        /*
         * The timer IRQ doesn't have to know that behind the
         * scene we may have a 8259A-master in AEOI mode ...
         */
        set_irq_chip_and_handler_name(0, &ioapic_chip, handle_edge_irq, "edge");

        /*
         * Add it to the IO-APIC irq-routing table:
         */
        ioapic_write_entry(apic, pin, entry);
}

void __apicdebuginit print_IO_APIC(void)
{
        int apic, i;
        union IO_APIC_reg_00 reg_00;
        union IO_APIC_reg_01 reg_01;
        union IO_APIC_reg_02 reg_02;
        unsigned long flags;

        if (apic_verbosity == APIC_QUIET)
                return;

        printk(KERN_DEBUG "number of MP IRQ sources: %d.\n", mp_irq_entries);
        for (i = 0; i < nr_ioapics; i++)
                printk(KERN_DEBUG "number of IO-APIC #%d registers: %d.\n",
                       mp_ioapics[i].mp_apicid, nr_ioapic_registers[i]);

        /*
         * We are a bit conservative about what we expect.  We have to
         * know about every hardware change ASAP.
         */
        printk(KERN_INFO "testing the IO APIC.......................\n");

        for (apic = 0; apic < nr_ioapics; apic++) {

        spin_lock_irqsave(&ioapic_lock, flags);
        reg_00.raw = io_apic_read(apic, 0);
        reg_01.raw = io_apic_read(apic, 1);
        if (reg_01.bits.version >= 0x10)
                reg_02.raw = io_apic_read(apic, 2);
        spin_unlock_irqrestore(&ioapic_lock, flags);

        printk("\n");
        printk(KERN_DEBUG "IO APIC #%d......\n", mp_ioapics[apic].mp_apicid);
        printk(KERN_DEBUG ".... register #00: %08X\n", reg_00.raw);
        printk(KERN_DEBUG ".......    : physical APIC id: %02X\n", reg_00.bits.ID);

        printk(KERN_DEBUG ".... register #01: %08X\n", *(int *)&reg_01);
        printk(KERN_DEBUG ".......     : max redirection entries: %04X\n", reg_01.bits.entries);

        printk(KERN_DEBUG ".......     : PRQ implemented: %X\n", reg_01.bits.PRQ);
        printk(KERN_DEBUG ".......     : IO APIC version: %04X\n", reg_01.bits.version);

        if (reg_01.bits.version >= 0x10) {
                printk(KERN_DEBUG ".... register #02: %08X\n", reg_02.raw);
                printk(KERN_DEBUG ".......     : arbitration: %02X\n", reg_02.bits.arbitration);
        }

        printk(KERN_DEBUG ".... IRQ redirection table:\n");

        printk(KERN_DEBUG " NR Dst Mask Trig IRR Pol"
                          " Stat Dmod Deli Vect:   \n");

        for (i = 0; i <= reg_01.bits.entries; i++) {
                struct IO_APIC_route_entry entry;

                entry = ioapic_read_entry(apic, i);

                printk(KERN_DEBUG " %02x %03X ",
                        i,
                        entry.dest
                );

                printk("%1d    %1d    %1d   %1d   %1d    %1d    %1d    %02X\n",
                        entry.mask,
                        entry.trigger,
                        entry.irr,
                        entry.polarity,
                        entry.delivery_status,
                        entry.dest_mode,
                        entry.delivery_mode,
                        entry.vector
                );
        }
        }
        printk(KERN_DEBUG "IRQ to pin mappings:\n");
        for (i = 0; i < NR_IRQS; i++) {
                struct irq_pin_list *entry = irq_2_pin + i;
                if (entry->pin < 0)
                        continue;
                printk(KERN_DEBUG "IRQ%d ", i);
                for (;;) {
                        printk("-> %d:%d", entry->apic, entry->pin);
                        if (!entry->next)
                                break;
                        entry = irq_2_pin + entry->next;
                }
                printk("\n");
        }

        printk(KERN_INFO ".................................... done.\n");

        return;
}

#if 0

static __apicdebuginit void print_APIC_bitfield (int base)
{
        unsigned int v;
        int i, j;

        if (apic_verbosity == APIC_QUIET)
                return;

        printk(KERN_DEBUG "0123456789abcdef0123456789abcdef\n" KERN_DEBUG);
        for (i = 0; i < 8; i++) {
                v = apic_read(base + i*0x10);
                for (j = 0; j < 32; j++) {
                        if (v & (1<<j))
                                printk("1");
                        else
                                printk("0");
                }
                printk("\n");
        }
}

void __apicdebuginit print_local_APIC(void * dummy)
{
        unsigned int v, ver, maxlvt;

        if (apic_verbosity == APIC_QUIET)
                return;

        printk("\n" KERN_DEBUG "printing local APIC contents on CPU#%d/%d:\n",
                smp_processor_id(), hard_smp_processor_id());
        v = apic_read(APIC_ID);
        printk(KERN_INFO "... APIC ID:      %08x (%01x)\n", v, GET_APIC_ID(read_apic_id()));
        v = apic_read(APIC_LVR);
        printk(KERN_INFO "... APIC VERSION: %08x\n", v);
        ver = GET_APIC_VERSION(v);
        maxlvt = lapic_get_maxlvt();

        v = apic_read(APIC_TASKPRI);
        printk(KERN_DEBUG "... APIC TASKPRI: %08x (%02x)\n", v, v & APIC_TPRI_MASK);

        v = apic_read(APIC_ARBPRI);
        printk(KERN_DEBUG "... APIC ARBPRI: %08x (%02x)\n", v,
                v & APIC_ARBPRI_MASK);
        v = apic_read(APIC_PROCPRI);
        printk(KERN_DEBUG "... APIC PROCPRI: %08x\n", v);

        v = apic_read(APIC_EOI);
        printk(KERN_DEBUG "... APIC EOI: %08x\n", v);
        v = apic_read(APIC_RRR);
        printk(KERN_DEBUG "... APIC RRR: %08x\n", v);
        v = apic_read(APIC_LDR);
        printk(KERN_DEBUG "... APIC LDR: %08x\n", v);
        v = apic_read(APIC_DFR);
        printk(KERN_DEBUG "... APIC DFR: %08x\n", v);
        v = apic_read(APIC_SPIV);
        printk(KERN_DEBUG "... APIC SPIV: %08x\n", v);

        printk(KERN_DEBUG "... APIC ISR field:\n");
        print_APIC_bitfield(APIC_ISR);
        printk(KERN_DEBUG "... APIC TMR field:\n");
        print_APIC_bitfield(APIC_TMR);
        printk(KERN_DEBUG "... APIC IRR field:\n");
        print_APIC_bitfield(APIC_IRR);

        v = apic_read(APIC_ESR);
        printk(KERN_DEBUG "... APIC ESR: %08x\n", v);

        v = apic_read(APIC_ICR);
        printk(KERN_DEBUG "... APIC ICR: %08x\n", v);
        v = apic_read(APIC_ICR2);
        printk(KERN_DEBUG "... APIC ICR2: %08x\n", v);

        v = apic_read(APIC_LVTT);
        printk(KERN_DEBUG "... APIC LVTT: %08x\n", v);

        if (maxlvt > 3) {                       /* PC is LVT#4. */
                v = apic_read(APIC_LVTPC);
                printk(KERN_DEBUG "... APIC LVTPC: %08x\n", v);
        }
        v = apic_read(APIC_LVT0);
        printk(KERN_DEBUG "... APIC LVT0: %08x\n", v);
        v = apic_read(APIC_LVT1);
        printk(KERN_DEBUG "... APIC LVT1: %08x\n", v);

        if (maxlvt > 2) {                       /* ERR is LVT#3. */
                v = apic_read(APIC_LVTERR);
                printk(KERN_DEBUG "... APIC LVTERR: %08x\n", v);
        }

        v = apic_read(APIC_TMICT);
        printk(KERN_DEBUG "... APIC TMICT: %08x\n", v);
        v = apic_read(APIC_TMCCT);
        printk(KERN_DEBUG "... APIC TMCCT: %08x\n", v);
        v = apic_read(APIC_TDCR);
        printk(KERN_DEBUG "... APIC TDCR: %08x\n", v);
        printk("\n");
}

void print_all_local_APICs (void)
{
        on_each_cpu(print_local_APIC, NULL, 1);
}

void __apicdebuginit print_PIC(void)
{
        unsigned int v;
        unsigned long flags;

        if (apic_verbosity == APIC_QUIET)
                return;

        printk(KERN_DEBUG "\nprinting PIC contents\n");

        spin_lock_irqsave(&i8259A_lock, flags);

        v = inb(0xa1) << 8 | inb(0x21);
        printk(KERN_DEBUG "... PIC  IMR: %04x\n", v);

        v = inb(0xa0) << 8 | inb(0x20);
        printk(KERN_DEBUG "... PIC  IRR: %04x\n", v);

        outb(0x0b,0xa0);
        outb(0x0b,0x20);
        v = inb(0xa0) << 8 | inb(0x20);
        outb(0x0a,0xa0);
        outb(0x0a,0x20);

        spin_unlock_irqrestore(&i8259A_lock, flags);

        printk(KERN_DEBUG "... PIC  ISR: %04x\n", v);

        v = inb(0x4d1) << 8 | inb(0x4d0);
        printk(KERN_DEBUG "... PIC ELCR: %04x\n", v);
}

#endif  /*  0  */

void __init enable_IO_APIC(void)
{
        union IO_APIC_reg_01 reg_01;
        int i8259_apic, i8259_pin;
        int i, apic;
        unsigned long flags;

        for (i = 0; i < PIN_MAP_SIZE; i++) {
                irq_2_pin[i].pin = -1;
                irq_2_pin[i].next = 0;
        }

        /*
         * The number of IO-APIC IRQ registers (== #pins):
         */
        for (apic = 0; apic < nr_ioapics; apic++) {
                spin_lock_irqsave(&ioapic_lock, flags);
                reg_01.raw = io_apic_read(apic, 1);
                spin_unlock_irqrestore(&ioapic_lock, flags);
                nr_ioapic_registers[apic] = reg_01.bits.entries+1;
        }
        for(apic = 0; apic < nr_ioapics; apic++) {
                int pin;
                /* See if any of the pins is in ExtINT mode */
                for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
                        struct IO_APIC_route_entry entry;
                        entry = ioapic_read_entry(apic, pin);

                        /* If the interrupt line is enabled and in ExtInt mode
                         * I have found the pin where the i8259 is connected.
                         */
                        if ((entry.mask == 0) && (entry.delivery_mode == dest_ExtINT)) {
                                ioapic_i8259.apic = apic;
                                ioapic_i8259.pin  = pin;
                                goto found_i8259;
                        }
                }
        }
 found_i8259:
        /* Look to see what if the MP table has reported the ExtINT */
        i8259_pin  = find_isa_irq_pin(0, mp_ExtINT);
        i8259_apic = find_isa_irq_apic(0, mp_ExtINT);
        /* Trust the MP table if nothing is setup in the hardware */
        if ((ioapic_i8259.pin == -1) && (i8259_pin >= 0)) {
                printk(KERN_WARNING "ExtINT not setup in hardware but reported by MP table\n");
                ioapic_i8259.pin  = i8259_pin;
                ioapic_i8259.apic = i8259_apic;
        }
        /* Complain if the MP table and the hardware disagree */
        if (((ioapic_i8259.apic != i8259_apic) || (ioapic_i8259.pin != i8259_pin)) &&
                (i8259_pin >= 0) && (ioapic_i8259.pin >= 0))
        {
                printk(KERN_WARNING "ExtINT in hardware and MP table differ\n");
        }

        /*
         * Do not trust the IO-APIC being empty at bootup
         */
        clear_IO_APIC();
}

/*
 * Not an __init, needed by the reboot code
 */
void disable_IO_APIC(void)
{
        /*
         * Clear the IO-APIC before rebooting:
         */
        clear_IO_APIC();

        /*
         * If the i8259 is routed through an IOAPIC
         * Put that IOAPIC in virtual wire mode
         * so legacy interrupts can be delivered.
         */
        if (ioapic_i8259.pin != -1) {
                struct IO_APIC_route_entry entry;

                memset(&entry, 0, sizeof(entry));
                entry.mask            = 0; /* Enabled */
                entry.trigger         = 0; /* Edge */
                entry.irr             = 0;
                entry.polarity        = 0; /* High */
                entry.delivery_status = 0;
                entry.dest_mode       = 0; /* Physical */
                entry.delivery_mode   = dest_ExtINT; /* ExtInt */
                entry.vector          = 0;
                entry.dest          = GET_APIC_ID(read_apic_id());

                /*
                 * Add it to the IO-APIC irq-routing table:
                 */
                ioapic_write_entry(ioapic_i8259.apic, ioapic_i8259.pin, entry);
        }

        disconnect_bsp_APIC(ioapic_i8259.pin != -1);
}

/*
 * There is a nasty bug in some older SMP boards, their mptable lies
 * about the timer IRQ. We do the following to work around the situation:
 *
 *      - timer IRQ defaults to IO-APIC IRQ
 *      - if this function detects that timer IRQs are defunct, then we fall
 *        back to ISA timer IRQs
 */
static int __init timer_irq_works(void)
{
        unsigned long t1 = jiffies;
        unsigned long flags;

        local_save_flags(flags);
        local_irq_enable();
        /* Let ten ticks pass... */
        mdelay((10 * 1000) / HZ);
        local_irq_restore(flags);

        /*
         * Expect a few ticks at least, to be sure some possible
         * glue logic does not lock up after one or two first
         * ticks in a non-ExtINT mode.  Also the local APIC
         * might have cached one ExtINT interrupt.  Finally, at
         * least one tick may be lost due to delays.
         */

        /* jiffies wrap? */
        if (time_after(jiffies, t1 + 4))
                return 1;
        return 0;
}

/*
 * In the SMP+IOAPIC case it might happen that there are an unspecified
 * number of pending IRQ events unhandled. These cases are very rare,
 * so we 'resend' these IRQs via IPIs, to the same CPU. It's much
 * better to do it this way as thus we do not have to be aware of
 * 'pending' interrupts in the IRQ path, except at this point.
 */
/*
 * Edge triggered needs to resend any interrupt
 * that was delayed but this is now handled in the device
 * independent code.
 */

/*
 * Starting up a edge-triggered IO-APIC interrupt is
 * nasty - we need to make sure that we get the edge.
 * If it is already asserted for some reason, we need
 * return 1 to indicate that is was pending.
 *
 * This is not complete - we should be able to fake
 * an edge even if it isn't on the 8259A...
 */

static unsigned int startup_ioapic_irq(unsigned int irq)
{
        int was_pending = 0;
        unsigned long flags;

        spin_lock_irqsave(&ioapic_lock, flags);
        if (irq < 16) {
                disable_8259A_irq(irq);
                if (i8259A_irq_pending(irq))
                        was_pending = 1;
        }
        __unmask_IO_APIC_irq(irq);
        spin_unlock_irqrestore(&ioapic_lock, flags);

        return was_pending;
}

static int ioapic_retrigger_irq(unsigned int irq)
{
        struct irq_cfg *cfg = &irq_cfg[irq];
        cpumask_t mask;
        unsigned long flags;

        spin_lock_irqsave(&vector_lock, flags);
        mask = cpumask_of_cpu(first_cpu(cfg->domain));
        send_IPI_mask(mask, cfg->vector);
        spin_unlock_irqrestore(&vector_lock, flags);

        return 1;
}

/*
 * Level and edge triggered IO-APIC interrupts need different handling,
 * so we use two separate IRQ descriptors. Edge triggered IRQs can be
 * handled with the level-triggered descriptor, but that one has slightly
 * more overhead. Level-triggered interrupts cannot be handled with the
 * edge-triggered handler, without risking IRQ storms and other ugly
 * races.
 */

#ifdef CONFIG_SMP
asmlinkage void smp_irq_move_cleanup_interrupt(void)
{
        unsigned vector, me;
        ack_APIC_irq();
        exit_idle();
        irq_enter();

        me = smp_processor_id();
        for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
                unsigned int irq;
                struct irq_desc *desc;
                struct irq_cfg *cfg;
                irq = __get_cpu_var(vector_irq)[vector];
                if (irq >= NR_IRQS)
                        continue;

                desc = irq_desc + irq;
                cfg = irq_cfg + irq;
                spin_lock(&desc->lock);
                if (!cfg->move_cleanup_count)
                        goto unlock;

                if ((vector == cfg->vector) && cpu_isset(me, cfg->domain))
                        goto unlock;

                __get_cpu_var(vector_irq)[vector] = -1;
                cfg->move_cleanup_count--;
unlock:
                spin_unlock(&desc->lock);
        }

        irq_exit();
}

static void irq_complete_move(unsigned int irq)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        unsigned vector, me;

        if (likely(!cfg->move_in_progress))
                return;

        vector = ~get_irq_regs()->orig_ax;
        me = smp_processor_id();
        if ((vector == cfg->vector) && cpu_isset(me, cfg->domain)) {
                cpumask_t cleanup_mask;

                cpus_and(cleanup_mask, cfg->old_domain, cpu_online_map);
                cfg->move_cleanup_count = cpus_weight(cleanup_mask);
                send_IPI_mask(cleanup_mask, IRQ_MOVE_CLEANUP_VECTOR);
                cfg->move_in_progress = 0;
        }
}
#else
static inline void irq_complete_move(unsigned int irq) {}
#endif

static void ack_apic_edge(unsigned int irq)
{
        irq_complete_move(irq);
        move_native_irq(irq);
        ack_APIC_irq();
}

static void ack_apic_level(unsigned int irq)
{
        int do_unmask_irq = 0;

        irq_complete_move(irq);
#ifdef CONFIG_GENERIC_PENDING_IRQ
        /* If we are moving the irq we need to mask it */
        if (unlikely(irq_desc[irq].status & IRQ_MOVE_PENDING)) {
                do_unmask_irq = 1;
                mask_IO_APIC_irq(irq);
        }
#endif

        /*
         * We must acknowledge the irq before we move it or the acknowledge will
         * not propagate properly.
         */
        ack_APIC_irq();

        /* Now we can move and renable the irq */
        if (unlikely(do_unmask_irq)) {
                /* Only migrate the irq if the ack has been received.
                 *
                 * On rare occasions the broadcast level triggered ack gets
                 * delayed going to ioapics, and if we reprogram the
                 * vector while Remote IRR is still set the irq will never
                 * fire again.
                 *
                 * To prevent this scenario we read the Remote IRR bit
                 * of the ioapic.  This has two effects.
                 * - On any sane system the read of the ioapic will
                 *   flush writes (and acks) going to the ioapic from
                 *   this cpu.
                 * - We get to see if the ACK has actually been delivered.
                 *
                 * Based on failed experiments of reprogramming the
                 * ioapic entry from outside of irq context starting
                 * with masking the ioapic entry and then polling until
                 * Remote IRR was clear before reprogramming the
                 * ioapic I don't trust the Remote IRR bit to be
                 * completey accurate.
                 *
                 * However there appears to be no other way to plug
                 * this race, so if the Remote IRR bit is not
                 * accurate and is causing problems then it is a hardware bug
                 * and you can go talk to the chipset vendor about it.
                 */
                if (!io_apic_level_ack_pending(irq))
                        move_masked_irq(irq);
                unmask_IO_APIC_irq(irq);
        }
}

static struct irq_chip ioapic_chip __read_mostly = {
        .name           = "IO-APIC",
        .startup        = startup_ioapic_irq,
        .mask           = mask_IO_APIC_irq,
        .unmask         = unmask_IO_APIC_irq,
        .ack            = ack_apic_edge,
        .eoi            = ack_apic_level,
#ifdef CONFIG_SMP
        .set_affinity   = set_ioapic_affinity_irq,
#endif
        .retrigger      = ioapic_retrigger_irq,
};

static inline void init_IO_APIC_traps(void)
{
        int irq;

        /*
         * NOTE! The local APIC isn't very good at handling
         * multiple interrupts at the same interrupt level.
         * As the interrupt level is determined by taking the
         * vector number and shifting that right by 4, we
         * want to spread these out a bit so that they don't
         * all fall in the same interrupt level.
         *
         * Also, we've got to be careful not to trash gate
         * 0x80, because int 0x80 is hm, kind of importantish. ;)
         */
        for (irq = 0; irq < NR_IRQS ; irq++) {
                if (IO_APIC_IRQ(irq) && !irq_cfg[irq].vector) {
                        /*
                         * Hmm.. We don't have an entry for this,
                         * so default to an old-fashioned 8259
                         * interrupt if we can..
                         */
                        if (irq < 16)
                                make_8259A_irq(irq);
                        else
                                /* Strange. Oh, well.. */
                                irq_desc[irq].chip = &no_irq_chip;
                }
        }
}

static void unmask_lapic_irq(unsigned int irq)
{
        unsigned long v;

        v = apic_read(APIC_LVT0);
        apic_write(APIC_LVT0, v & ~APIC_LVT_MASKED);
}

static void mask_lapic_irq(unsigned int irq)
{
        unsigned long v;

        v = apic_read(APIC_LVT0);
        apic_write(APIC_LVT0, v | APIC_LVT_MASKED);
}

static void ack_lapic_irq (unsigned int irq)
{
        ack_APIC_irq();
}

static struct irq_chip lapic_chip __read_mostly = {
        .name           = "local-APIC",
        .mask           = mask_lapic_irq,
        .unmask         = unmask_lapic_irq,
        .ack            = ack_lapic_irq,
};

static void lapic_register_intr(int irq)
{
        irq_desc[irq].status &= ~IRQ_LEVEL;
        set_irq_chip_and_handler_name(irq, &lapic_chip, handle_edge_irq,
                                      "edge");
}

static void __init setup_nmi(void)
{
        /*
         * Dirty trick to enable the NMI watchdog ...
         * We put the 8259A master into AEOI mode and
         * unmask on all local APICs LVT0 as NMI.
         *
         * The idea to use the 8259A in AEOI mode ('8259A Virtual Wire')
         * is from Maciej W. Rozycki - so we do not have to EOI from
         * the NMI handler or the timer interrupt.
         */ 
        printk(KERN_INFO "activating NMI Watchdog ...");

        enable_NMI_through_LVT0();

        printk(" done.\n");
}

/*
 * This looks a bit hackish but it's about the only one way of sending
 * a few INTA cycles to 8259As and any associated glue logic.  ICR does
 * not support the ExtINT mode, unfortunately.  We need to send these
 * cycles as some i82489DX-based boards have glue logic that keeps the
 * 8259A interrupt line asserted until INTA.  --macro
 */
static inline void __init unlock_ExtINT_logic(void)
{
        int apic, pin, i;
        struct IO_APIC_route_entry entry0, entry1;
        unsigned char save_control, save_freq_select;

        pin  = find_isa_irq_pin(8, mp_INT);
        apic = find_isa_irq_apic(8, mp_INT);
        if (pin == -1)
                return;

        entry0 = ioapic_read_entry(apic, pin);

        clear_IO_APIC_pin(apic, pin);

        memset(&entry1, 0, sizeof(entry1));

        entry1.dest_mode = 0;                   /* physical delivery */
        entry1.mask = 0;                        /* unmask IRQ now */
        entry1.dest = hard_smp_processor_id();
        entry1.delivery_mode = dest_ExtINT;
        entry1.polarity = entry0.polarity;
        entry1.trigger = 0;
        entry1.vector = 0;

        ioapic_write_entry(apic, pin, entry1);

        save_control = CMOS_READ(RTC_CONTROL);
        save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
        CMOS_WRITE((save_freq_select & ~RTC_RATE_SELECT) | 0x6,
                   RTC_FREQ_SELECT);
        CMOS_WRITE(save_control | RTC_PIE, RTC_CONTROL);

        i = 100;
        while (i-- > 0) {
                mdelay(10);
                if ((CMOS_READ(RTC_INTR_FLAGS) & RTC_PF) == RTC_PF)
                        i -= 10;
        }

        CMOS_WRITE(save_control, RTC_CONTROL);
        CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
        clear_IO_APIC_pin(apic, pin);

        ioapic_write_entry(apic, pin, entry0);
}

/*
 * This code may look a bit paranoid, but it's supposed to cooperate with
 * a wide range of boards and BIOS bugs.  Fortunately only the timer IRQ
 * is so screwy.  Thanks to Brian Perkins for testing/hacking this beast
 * fanatically on his truly buggy board.
 *
 * FIXME: really need to revamp this for modern platforms only.
 */
static inline void __init check_timer(void)
{
        struct irq_cfg *cfg = irq_cfg + 0;
        int apic1, pin1, apic2, pin2;
        unsigned long flags;
        int no_pin1 = 0;

        local_irq_save(flags);

        /*
         * get/set the timer IRQ vector:
         */
        disable_8259A_irq(0);
        assign_irq_vector(0, TARGET_CPUS);

        /*
         * As IRQ0 is to be enabled in the 8259A, the virtual
         * wire has to be disabled in the local APIC.
         */
        apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
        init_8259A(1);

        pin1  = find_isa_irq_pin(0, mp_INT);
        apic1 = find_isa_irq_apic(0, mp_INT);
        pin2  = ioapic_i8259.pin;
        apic2 = ioapic_i8259.apic;

        apic_printk(APIC_VERBOSE,KERN_INFO "..TIMER: vector=0x%02X apic1=%d pin1=%d apic2=%d pin2=%d\n",
                cfg->vector, apic1, pin1, apic2, pin2);

        /*
         * Some BIOS writers are clueless and report the ExtINTA
         * I/O APIC input from the cascaded 8259A as the timer
         * interrupt input.  So just in case, if only one pin
         * was found above, try it both directly and through the
         * 8259A.
         */
        if (pin1 == -1) {
                pin1 = pin2;
                apic1 = apic2;
                no_pin1 = 1;
        } else if (pin2 == -1) {
                pin2 = pin1;
                apic2 = apic1;
        }

        if (pin1 != -1) {
                /*
                 * Ok, does IRQ0 through the IOAPIC work?
                 */
                if (no_pin1) {
                        add_pin_to_irq(0, apic1, pin1);
                        setup_timer_IRQ0_pin(apic1, pin1, cfg->vector);
                }
                unmask_IO_APIC_irq(0);
                if (!no_timer_check && timer_irq_works()) {
                        if (nmi_watchdog == NMI_IO_APIC) {
                                setup_nmi();
                                enable_8259A_irq(0);
                        }
                        if (disable_timer_pin_1 > 0)
                                clear_IO_APIC_pin(0, pin1);
                        goto out;
                }
                clear_IO_APIC_pin(apic1, pin1);
                if (!no_pin1)
                        apic_printk(APIC_QUIET,KERN_ERR "..MP-BIOS bug: "
                                    "8254 timer not connected to IO-APIC\n");

                apic_printk(APIC_VERBOSE,KERN_INFO
                        "...trying to set up timer (IRQ0) "
                        "through the 8259A ... ");
                apic_printk(APIC_VERBOSE,"\n..... (found apic %d pin %d) ...",
                        apic2, pin2);
                /*
                 * legacy devices should be connected to IO APIC #0
                 */
                replace_pin_at_irq(0, apic1, pin1, apic2, pin2);
                setup_timer_IRQ0_pin(apic2, pin2, cfg->vector);
                unmask_IO_APIC_irq(0);
                enable_8259A_irq(0);
                if (timer_irq_works()) {
                        apic_printk(APIC_VERBOSE," works.\n");
                        timer_through_8259 = 1;
                        if (nmi_watchdog == NMI_IO_APIC) {
                                disable_8259A_irq(0);
                                setup_nmi();
                                enable_8259A_irq(0);
                        }
                        goto out;
                }
                /*
                 * Cleanup, just in case ...
                 */
                disable_8259A_irq(0);
                clear_IO_APIC_pin(apic2, pin2);
                apic_printk(APIC_VERBOSE," failed.\n");
        }

        if (nmi_watchdog == NMI_IO_APIC) {
                printk(KERN_WARNING "timer doesn't work through the IO-APIC - disabling NMI Watchdog!\n");
                nmi_watchdog = NMI_NONE;
        }

        apic_printk(APIC_VERBOSE, KERN_INFO "...trying to set up timer as Virtual Wire IRQ...");

        lapic_register_intr(0);
        apic_write(APIC_LVT0, APIC_DM_FIXED | cfg->vector);     /* Fixed mode */
        enable_8259A_irq(0);

        if (timer_irq_works()) {
                apic_printk(APIC_VERBOSE," works.\n");
                goto out;
        }
        disable_8259A_irq(0);
        apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_FIXED | cfg->vector);
        apic_printk(APIC_VERBOSE," failed.\n");

        apic_printk(APIC_VERBOSE, KERN_INFO "...trying to set up timer as ExtINT IRQ...");

        init_8259A(0);
        make_8259A_irq(0);
        apic_write(APIC_LVT0, APIC_DM_EXTINT);

        unlock_ExtINT_logic();

        if (timer_irq_works()) {
                apic_printk(APIC_VERBOSE," works.\n");
                goto out;
        }
        apic_printk(APIC_VERBOSE," failed :(.\n");
        panic("IO-APIC + timer doesn't work! Try using the 'noapic' kernel parameter\n");
out:
        local_irq_restore(flags);
}

static int __init notimercheck(char *s)
{
        no_timer_check = 1;
        return 1;
}
__setup("no_timer_check", notimercheck);

/*
 * Traditionally ISA IRQ2 is the cascade IRQ, and is not available
 * to devices.  However there may be an I/O APIC pin available for
 * this interrupt regardless.  The pin may be left unconnected, but
 * typically it will be reused as an ExtINT cascade interrupt for
 * the master 8259A.  In the MPS case such a pin will normally be
 * reported as an ExtINT interrupt in the MP table.  With ACPI
 * there is no provision for ExtINT interrupts, and in the absence
 * of an override it would be treated as an ordinary ISA I/O APIC
 * interrupt, that is edge-triggered and unmasked by default.  We
 * used to do this, but it caused problems on some systems because
 * of the NMI watchdog and sometimes IRQ0 of the 8254 timer using
 * the same ExtINT cascade interrupt to drive the local APIC of the
 * bootstrap processor.  Therefore we refrain from routing IRQ2 to
 * the I/O APIC in all cases now.  No actual device should request
 * it anyway.  --macro
 */
#define PIC_IRQS        (1<<2)

void __init setup_IO_APIC(void)
{

        /*
         * calling enable_IO_APIC() is moved to setup_local_APIC for BP
         */

        io_apic_irqs = ~PIC_IRQS;

        apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");

        sync_Arb_IDs();
        setup_IO_APIC_irqs();
        init_IO_APIC_traps();
        check_timer();
        if (!acpi_ioapic)
                print_IO_APIC();
}

struct sysfs_ioapic_data {
        struct sys_device dev;
        struct IO_APIC_route_entry entry[0];
};
static struct sysfs_ioapic_data * mp_ioapic_data[MAX_IO_APICS];

static int ioapic_suspend(struct sys_device *dev, pm_message_t state)
{
        struct IO_APIC_route_entry *entry;
        struct sysfs_ioapic_data *data;
        int i;

        data = container_of(dev, struct sysfs_ioapic_data, dev);
        entry = data->entry;
        for (i = 0; i < nr_ioapic_registers[dev->id]; i ++, entry ++ )
                *entry = ioapic_read_entry(dev->id, i);

        return 0;
}

static int ioapic_resume(struct sys_device *dev)
{
        struct IO_APIC_route_entry *entry;
        struct sysfs_ioapic_data *data;
        unsigned long flags;
        union IO_APIC_reg_00 reg_00;
        int i;

        data = container_of(dev, struct sysfs_ioapic_data, dev);
        entry = data->entry;

        spin_lock_irqsave(&ioapic_lock, flags);
        reg_00.raw = io_apic_read(dev->id, 0);
        if (reg_00.bits.ID != mp_ioapics[dev->id].mp_apicid) {
                reg_00.bits.ID = mp_ioapics[dev->id].mp_apicid;
                io_apic_write(dev->id, 0, reg_00.raw);
        }
        spin_unlock_irqrestore(&ioapic_lock, flags);
        for (i = 0; i < nr_ioapic_registers[dev->id]; i++)
                ioapic_write_entry(dev->id, i, entry[i]);

        return 0;
}

static struct sysdev_class ioapic_sysdev_class = {
        .name = "ioapic",
        .suspend = ioapic_suspend,
        .resume = ioapic_resume,
};

static int __init ioapic_init_sysfs(void)
{
        struct sys_device * dev;
        int i, size, error;

        error = sysdev_class_register(&ioapic_sysdev_class);
        if (error)
                return error;

        for (i = 0; i < nr_ioapics; i++ ) {
                size = sizeof(struct sys_device) + nr_ioapic_registers[i]
                        * sizeof(struct IO_APIC_route_entry);
                mp_ioapic_data[i] = kzalloc(size, GFP_KERNEL);
                if (!mp_ioapic_data[i]) {
                        printk(KERN_ERR "Can't suspend/resume IOAPIC %d\n", i);
                        continue;
                }
                dev = &mp_ioapic_data[i]->dev;
                dev->id = i;
                dev->cls = &ioapic_sysdev_class;
                error = sysdev_register(dev);
                if (error) {
                        kfree(mp_ioapic_data[i]);
                        mp_ioapic_data[i] = NULL;
                        printk(KERN_ERR "Can't suspend/resume IOAPIC %d\n", i);
                        continue;
                }
        }

        return 0;
}

device_initcall(ioapic_init_sysfs);

/*
 * Dynamic irq allocate and deallocation
 */
int create_irq(void)
{
        /* Allocate an unused irq */
        int irq;
        int new;
        unsigned long flags;

        irq = -ENOSPC;
        spin_lock_irqsave(&vector_lock, flags);
        for (new = (NR_IRQS - 1); new >= 0; new--) {
                if (platform_legacy_irq(new))
                        continue;
                if (irq_cfg[new].vector != 0)
                        continue;
                if (__assign_irq_vector(new, TARGET_CPUS) == 0)
                        irq = new;
                break;
        }
        spin_unlock_irqrestore(&vector_lock, flags);

        if (irq >= 0) {
                dynamic_irq_init(irq);
        }
        return irq;
}

void destroy_irq(unsigned int irq)
{
        unsigned long flags;

        dynamic_irq_cleanup(irq);

        spin_lock_irqsave(&vector_lock, flags);
        __clear_irq_vector(irq);
        spin_unlock_irqrestore(&vector_lock, flags);
}

/*
 * MSI message composition
 */
#ifdef CONFIG_PCI_MSI
static int msi_compose_msg(struct pci_dev *pdev, unsigned int irq, struct msi_msg *msg)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        int err;
        unsigned dest;
        cpumask_t tmp;

        tmp = TARGET_CPUS;
        err = assign_irq_vector(irq, tmp);
        if (!err) {
                cpus_and(tmp, cfg->domain, tmp);
                dest = cpu_mask_to_apicid(tmp);

                msg->address_hi = MSI_ADDR_BASE_HI;
                msg->address_lo =
                        MSI_ADDR_BASE_LO |
                        ((INT_DEST_MODE == 0) ?
                                MSI_ADDR_DEST_MODE_PHYSICAL:
                                MSI_ADDR_DEST_MODE_LOGICAL) |
                        ((INT_DELIVERY_MODE != dest_LowestPrio) ?
                                MSI_ADDR_REDIRECTION_CPU:
                                MSI_ADDR_REDIRECTION_LOWPRI) |
                        MSI_ADDR_DEST_ID(dest);

                msg->data =
                        MSI_DATA_TRIGGER_EDGE |
                        MSI_DATA_LEVEL_ASSERT |
                        ((INT_DELIVERY_MODE != dest_LowestPrio) ?
                                MSI_DATA_DELIVERY_FIXED:
                                MSI_DATA_DELIVERY_LOWPRI) |
                        MSI_DATA_VECTOR(cfg->vector);
        }
        return err;
}

#ifdef CONFIG_SMP
static void set_msi_irq_affinity(unsigned int irq, cpumask_t mask)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        struct msi_msg msg;
        unsigned int dest;
        cpumask_t tmp;

        cpus_and(tmp, mask, cpu_online_map);
        if (cpus_empty(tmp))
                return;

        if (assign_irq_vector(irq, mask))
                return;

        cpus_and(tmp, cfg->domain, mask);
        dest = cpu_mask_to_apicid(tmp);

        read_msi_msg(irq, &msg);

        msg.data &= ~MSI_DATA_VECTOR_MASK;
        msg.data |= MSI_DATA_VECTOR(cfg->vector);
        msg.address_lo &= ~MSI_ADDR_DEST_ID_MASK;
        msg.address_lo |= MSI_ADDR_DEST_ID(dest);

        write_msi_msg(irq, &msg);
        irq_desc[irq].affinity = mask;
}
#endif /* CONFIG_SMP */

/*
 * IRQ Chip for MSI PCI/PCI-X/PCI-Express Devices,
 * which implement the MSI or MSI-X Capability Structure.
 */
static struct irq_chip msi_chip = {
        .name           = "PCI-MSI",
        .unmask         = unmask_msi_irq,
        .mask           = mask_msi_irq,
        .ack            = ack_apic_edge,
#ifdef CONFIG_SMP
        .set_affinity   = set_msi_irq_affinity,
#endif
        .retrigger      = ioapic_retrigger_irq,
};

int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
{
        struct msi_msg msg;
        int irq, ret;
        irq = create_irq();
        if (irq < 0)
                return irq;

        ret = msi_compose_msg(dev, irq, &msg);
        if (ret < 0) {
                destroy_irq(irq);
                return ret;
        }

        set_irq_msi(irq, desc);
        write_msi_msg(irq, &msg);

        set_irq_chip_and_handler_name(irq, &msi_chip, handle_edge_irq, "edge");

        return 0;
}

void arch_teardown_msi_irq(unsigned int irq)
{
        destroy_irq(irq);
}

#ifdef CONFIG_DMAR
#ifdef CONFIG_SMP
static void dmar_msi_set_affinity(unsigned int irq, cpumask_t mask)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        struct msi_msg msg;
        unsigned int dest;
        cpumask_t tmp;

        cpus_and(tmp, mask, cpu_online_map);
        if (cpus_empty(tmp))
                return;

        if (assign_irq_vector(irq, mask))
                return;

        cpus_and(tmp, cfg->domain, mask);
        dest = cpu_mask_to_apicid(tmp);

        dmar_msi_read(irq, &msg);

        msg.data &= ~MSI_DATA_VECTOR_MASK;
        msg.data |= MSI_DATA_VECTOR(cfg->vector);
        msg.address_lo &= ~MSI_ADDR_DEST_ID_MASK;
        msg.address_lo |= MSI_ADDR_DEST_ID(dest);

        dmar_msi_write(irq, &msg);
        irq_desc[irq].affinity = mask;
}
#endif /* CONFIG_SMP */

struct irq_chip dmar_msi_type = {
        .name = "DMAR_MSI",
        .unmask = dmar_msi_unmask,
        .mask = dmar_msi_mask,
        .ack = ack_apic_edge,
#ifdef CONFIG_SMP
        .set_affinity = dmar_msi_set_affinity,
#endif
        .retrigger = ioapic_retrigger_irq,
};

int arch_setup_dmar_msi(unsigned int irq)
{
        int ret;
        struct msi_msg msg;

        ret = msi_compose_msg(NULL, irq, &msg);
        if (ret < 0)
                return ret;
        dmar_msi_write(irq, &msg);
        set_irq_chip_and_handler_name(irq, &dmar_msi_type, handle_edge_irq,
                "edge");
        return 0;
}
#endif

#endif /* CONFIG_PCI_MSI */
/*
 * Hypertransport interrupt support
 */
#ifdef CONFIG_HT_IRQ

#ifdef CONFIG_SMP

static void target_ht_irq(unsigned int irq, unsigned int dest, u8 vector)
{
        struct ht_irq_msg msg;
        fetch_ht_irq_msg(irq, &msg);

        msg.address_lo &= ~(HT_IRQ_LOW_VECTOR_MASK | HT_IRQ_LOW_DEST_ID_MASK);
        msg.address_hi &= ~(HT_IRQ_HIGH_DEST_ID_MASK);

        msg.address_lo |= HT_IRQ_LOW_VECTOR(vector) | HT_IRQ_LOW_DEST_ID(dest);
        msg.address_hi |= HT_IRQ_HIGH_DEST_ID(dest);

        write_ht_irq_msg(irq, &msg);
}

static void set_ht_irq_affinity(unsigned int irq, cpumask_t mask)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        unsigned int dest;
        cpumask_t tmp;

        cpus_and(tmp, mask, cpu_online_map);
        if (cpus_empty(tmp))
                return;

        if (assign_irq_vector(irq, mask))
                return;

        cpus_and(tmp, cfg->domain, mask);
        dest = cpu_mask_to_apicid(tmp);

        target_ht_irq(irq, dest, cfg->vector);
        irq_desc[irq].affinity = mask;
}
#endif

static struct irq_chip ht_irq_chip = {
        .name           = "PCI-HT",
        .mask           = mask_ht_irq,
        .unmask         = unmask_ht_irq,
        .ack            = ack_apic_edge,
#ifdef CONFIG_SMP
        .set_affinity   = set_ht_irq_affinity,
#endif
        .retrigger      = ioapic_retrigger_irq,
};

int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)
{
        struct irq_cfg *cfg = irq_cfg + irq;
        int err;
        cpumask_t tmp;

        tmp = TARGET_CPUS;
        err = assign_irq_vector(irq, tmp);
        if (!err) {
                struct ht_irq_msg msg;
                unsigned dest;

                cpus_and(tmp, cfg->domain, tmp);
                dest = cpu_mask_to_apicid(tmp);

                msg.address_hi = HT_IRQ_HIGH_DEST_ID(dest);

                msg.address_lo =
                        HT_IRQ_LOW_BASE |
                        HT_IRQ_LOW_DEST_ID(dest) |
                        HT_IRQ_LOW_VECTOR(cfg->vector) |
                        ((INT_DEST_MODE == 0) ?
                                HT_IRQ_LOW_DM_PHYSICAL :
                                HT_IRQ_LOW_DM_LOGICAL) |
                        HT_IRQ_LOW_RQEOI_EDGE |
                        ((INT_DELIVERY_MODE != dest_LowestPrio) ?
                                HT_IRQ_LOW_MT_FIXED :
                                HT_IRQ_LOW_MT_ARBITRATED) |
                        HT_IRQ_LOW_IRQ_MASKED;

                write_ht_irq_msg(irq, &msg);

                set_irq_chip_and_handler_name(irq, &ht_irq_chip,
                                              handle_edge_irq, "edge");
        }
        return err;
}
#endif /* CONFIG_HT_IRQ */

/* --------------------------------------------------------------------------
                          ACPI-based IOAPIC Configuration
   -------------------------------------------------------------------------- */

#ifdef CONFIG_ACPI

#define IO_APIC_MAX_ID          0xFE

int __init io_apic_get_redir_entries (int ioapic)
{
        union IO_APIC_reg_01    reg_01;
        unsigned long flags;

        spin_lock_irqsave(&ioapic_lock, flags);
        reg_01.raw = io_apic_read(ioapic, 1);
        spin_unlock_irqrestore(&ioapic_lock, flags);

        return reg_01.bits.entries;
}


int io_apic_set_pci_routing (int ioapic, int pin, int irq, int triggering, int polarity)
{
        if (!IO_APIC_IRQ(irq)) {
                apic_printk(APIC_QUIET,KERN_ERR "IOAPIC[%d]: Invalid reference to IRQ 0\n",
                        ioapic);
                return -EINVAL;
        }

        /*
         * IRQs < 16 are already in the irq_2_pin[] map
         */
        if (irq >= 16)
                add_pin_to_irq(irq, ioapic, pin);

        setup_IO_APIC_irq(ioapic, pin, irq, triggering, polarity);

        return 0;
}


int acpi_get_override_irq(int bus_irq, int *trigger, int *polarity)
{
        int i;

        if (skip_ioapic_setup)
                return -1;

        for (i = 0; i < mp_irq_entries; i++)
                if (mp_irqs[i].mp_irqtype == mp_INT &&
                    mp_irqs[i].mp_srcbusirq == bus_irq)
                        break;
        if (i >= mp_irq_entries)
                return -1;

        *trigger = irq_trigger(i);
        *polarity = irq_polarity(i);
        return 0;
}

#endif /* CONFIG_ACPI */

/*
 * This function currently is only a helper for the i386 smp boot process where
 * we need to reprogram the ioredtbls to cater for the cpus which have come online
 * so mask in all cases should simply be TARGET_CPUS
 */
#ifdef CONFIG_SMP
void __init setup_ioapic_dest(void)
{
        int pin, ioapic, irq, irq_entry;

        if (skip_ioapic_setup == 1)
                return;

        for (ioapic = 0; ioapic < nr_ioapics; ioapic++) {
                for (pin = 0; pin < nr_ioapic_registers[ioapic]; pin++) {
                        irq_entry = find_irq_entry(ioapic, pin, mp_INT);
                        if (irq_entry == -1)
                                continue;
                        irq = pin_2_irq(irq_entry, ioapic, pin);

                        /* setup_IO_APIC_irqs could fail to get vector for some device
                         * when you have too many devices, because at that time only boot
                         * cpu is online.
                         */
                        if (!irq_cfg[irq].vector)
                                setup_IO_APIC_irq(ioapic, pin, irq,
                                                  irq_trigger(irq_entry),
                                                  irq_polarity(irq_entry));
                        else
                                set_ioapic_affinity_irq(irq, TARGET_CPUS);
                }

        }
}
#endif

#define IOAPIC_RESOURCE_NAME_SIZE 11

static struct resource *ioapic_resources;

static struct resource * __init ioapic_setup_resources(void)
{
        unsigned long n;
        struct resource *res;
        char *mem;
        int i;

        if (nr_ioapics <= 0)
                return NULL;

        n = IOAPIC_RESOURCE_NAME_SIZE + sizeof(struct resource);
        n *= nr_ioapics;

        mem = alloc_bootmem(n);
        res = (void *)mem;

        if (mem != NULL) {
                mem += sizeof(struct resource) * nr_ioapics;

                for (i = 0; i < nr_ioapics; i++) {
                        res[i].name = mem;
                        res[i].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
                        sprintf(mem,  "IOAPIC %u", i);
                        mem += IOAPIC_RESOURCE_NAME_SIZE;
                }
        }

        ioapic_resources = res;

        return res;
}

void __init ioapic_init_mappings(void)
{
        unsigned long ioapic_phys, idx = FIX_IO_APIC_BASE_0;
        struct resource *ioapic_res;
        int i;

        ioapic_res = ioapic_setup_resources();
        for (i = 0; i < nr_ioapics; i++) {
                if (smp_found_config) {
                        ioapic_phys = mp_ioapics[i].mp_apicaddr;
                } else {
                        ioapic_phys = (unsigned long)
                                alloc_bootmem_pages(PAGE_SIZE);
                        ioapic_phys = __pa(ioapic_phys);
                }
                set_fixmap_nocache(idx, ioapic_phys);
                apic_printk(APIC_VERBOSE,
                            "mapped IOAPIC to %016lx (%016lx)\n",
                            __fix_to_virt(idx), ioapic_phys);
                idx++;

                if (ioapic_res != NULL) {
                        ioapic_res->start = ioapic_phys;
                        ioapic_res->end = ioapic_phys + (4 * 1024) - 1;
                        ioapic_res++;
                }
        }
}

static int __init ioapic_insert_resources(void)
{
        int i;
        struct resource *r = ioapic_resources;

        if (!r) {
                printk(KERN_ERR
                       "IO APIC resources could be not be allocated.\n");
                return -1;
        }

        for (i = 0; i < nr_ioapics; i++) {
                insert_resource(&iomem_resource, r);
                r++;
        }

        return 0;
}

/* Insert the IO APIC resources after PCI initialization has occured to handle
 * IO APICS that are mapped in on a BAR in PCI space. */
late_initcall(ioapic_insert_resources);