BUG_ON conversion for fs/reiserfs

[linux-2.6/mini2440.git] / arch / i386 / kernel / io_apic.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/smp_lock.h>
#include <linux/mc146818rtc.h>
#include <linux/compiler.h>
#include <linux/acpi.h>
#include <linux/module.h>
#include <linux/sysdev.h>

#include <asm/io.h>
#include <asm/smp.h>
#include <asm/desc.h>
#include <asm/timer.h>
#include <asm/i8259.h>
#include <asm/nmi.h>

#include <mach_apic.h>
#include <mach_apicdef.h>

#include "io_ports.h"

int (*ioapic_renumber_irq)(int ioapic, int irq);
atomic_t irq_mis_count;

/* 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);
static DEFINE_SPINLOCK(vector_lock);

int timer_over_8254 __initdata = 1;

/*
 *      Is the SiS APIC rmw bug present ?
 *      -1 = don't know, 0 = no, 1 = yes
 */
int sis_apic_bug = -1;

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

static int disable_timer_pin_1 __initdata;

/*
 * 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 {
        int apic, pin, next;
} irq_2_pin[PIN_MAP_SIZE];

int vector_irq[NR_VECTORS] __read_mostly = { [0 ... NR_VECTORS - 1] = -1};
#ifdef CONFIG_PCI_MSI
#define vector_to_irq(vector)   \
        (platform_legacy_irq(vector) ? vector : vector_irq[vector])
#else
#define vector_to_irq(vector)   (vector)
#endif


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;
}

static void ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
{
        unsigned long flags;
        union entry_union eu;
        eu.entry = e;
        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);
}

/*
 * 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;

        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: whoops");
        }
        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;
        }
}

static void __modify_IO_APIC_irq (unsigned int irq, unsigned long enable, unsigned long disable)
{
        struct irq_pin_list *entry = irq_2_pin + irq;
        unsigned int pin, reg;

        for (;;) {
                pin = entry->pin;
                if (pin == -1)
                        break;
                reg = io_apic_read(entry->apic, 0x10 + pin*2);
                reg &= ~disable;
                reg |= enable;
                io_apic_modify(entry->apic, 0x10 + pin*2, reg);
                if (!entry->next)
                        break;
                entry = irq_2_pin + entry->next;
        }
}

/* mask = 1 */
static void __mask_IO_APIC_irq (unsigned int irq)
{
        __modify_IO_APIC_irq(irq, 0x00010000, 0);
}

/* mask = 0 */
static void __unmask_IO_APIC_irq (unsigned int irq)
{
        __modify_IO_APIC_irq(irq, 0, 0x00010000);
}

/* mask = 1, trigger = 0 */
static void __mask_and_edge_IO_APIC_irq (unsigned int irq)
{
        __modify_IO_APIC_irq(irq, 0x00010000, 0x00008000);
}

/* mask = 0, trigger = 1 */
static void __unmask_and_level_IO_APIC_irq (unsigned int irq)
{
        __modify_IO_APIC_irq(irq, 0x00008000, 0x00010000);
}

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:
         */
        memset(&entry, 0, sizeof(entry));
        entry.mask = 1;
        ioapic_write_entry(apic, pin, entry);
}

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);
}

#ifdef CONFIG_SMP
static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t cpumask)
{
        unsigned long flags;
        int pin;
        struct irq_pin_list *entry = irq_2_pin + irq;
        unsigned int apicid_value;
        cpumask_t tmp;
        
        cpus_and(tmp, cpumask, cpu_online_map);
        if (cpus_empty(tmp))
                tmp = TARGET_CPUS;

        cpus_and(cpumask, tmp, CPU_MASK_ALL);

        apicid_value = cpu_mask_to_apicid(cpumask);
        /* Prepare to do the io_apic_write */
        apicid_value = apicid_value << 24;
        spin_lock_irqsave(&ioapic_lock, flags);
        for (;;) {
                pin = entry->pin;
                if (pin == -1)
                        break;
                io_apic_write(entry->apic, 0x10 + 1 + pin*2, apicid_value);
                if (!entry->next)
                        break;
                entry = irq_2_pin + entry->next;
        }
        set_irq_info(irq, cpumask);
        spin_unlock_irqrestore(&ioapic_lock, flags);
}

#if defined(CONFIG_IRQBALANCE)
# include <asm/processor.h>     /* kernel_thread() */
# include <linux/kernel_stat.h> /* kstat */
# include <linux/slab.h>                /* kmalloc() */
# include <linux/timer.h>       /* time_after() */
 
#ifdef CONFIG_BALANCED_IRQ_DEBUG
#  define TDprintk(x...) do { printk("<%ld:%s:%d>: ", jiffies, __FILE__, __LINE__); printk(x); } while (0)
#  define Dprintk(x...) do { TDprintk(x); } while (0)
# else
#  define TDprintk(x...) 
#  define Dprintk(x...) 
# endif

#define IRQBALANCE_CHECK_ARCH -999
#define MAX_BALANCED_IRQ_INTERVAL       (5*HZ)
#define MIN_BALANCED_IRQ_INTERVAL       (HZ/2)
#define BALANCED_IRQ_MORE_DELTA         (HZ/10)
#define BALANCED_IRQ_LESS_DELTA         (HZ)

static int irqbalance_disabled __read_mostly = IRQBALANCE_CHECK_ARCH;
static int physical_balance __read_mostly;
static long balanced_irq_interval __read_mostly = MAX_BALANCED_IRQ_INTERVAL;

static struct irq_cpu_info {
        unsigned long * last_irq;
        unsigned long * irq_delta;
        unsigned long irq;
} irq_cpu_data[NR_CPUS];

#define CPU_IRQ(cpu)            (irq_cpu_data[cpu].irq)
#define LAST_CPU_IRQ(cpu,irq)   (irq_cpu_data[cpu].last_irq[irq])
#define IRQ_DELTA(cpu,irq)      (irq_cpu_data[cpu].irq_delta[irq])

#define IDLE_ENOUGH(cpu,now) \
        (idle_cpu(cpu) && ((now) - per_cpu(irq_stat, (cpu)).idle_timestamp > 1))

#define IRQ_ALLOWED(cpu, allowed_mask)  cpu_isset(cpu, allowed_mask)

#define CPU_TO_PACKAGEINDEX(i) (first_cpu(cpu_sibling_map[i]))

static cpumask_t balance_irq_affinity[NR_IRQS] = {
        [0 ... NR_IRQS-1] = CPU_MASK_ALL
};

void set_balance_irq_affinity(unsigned int irq, cpumask_t mask)
{
        balance_irq_affinity[irq] = mask;
}

static unsigned long move(int curr_cpu, cpumask_t allowed_mask,
                        unsigned long now, int direction)
{
        int search_idle = 1;
        int cpu = curr_cpu;

        goto inside;

        do {
                if (unlikely(cpu == curr_cpu))
                        search_idle = 0;
inside:
                if (direction == 1) {
                        cpu++;
                        if (cpu >= NR_CPUS)
                                cpu = 0;
                } else {
                        cpu--;
                        if (cpu == -1)
                                cpu = NR_CPUS-1;
                }
        } while (!cpu_online(cpu) || !IRQ_ALLOWED(cpu,allowed_mask) ||
                        (search_idle && !IDLE_ENOUGH(cpu,now)));

        return cpu;
}

static inline void balance_irq(int cpu, int irq)
{
        unsigned long now = jiffies;
        cpumask_t allowed_mask;
        unsigned int new_cpu;
                
        if (irqbalance_disabled)
                return; 

        cpus_and(allowed_mask, cpu_online_map, balance_irq_affinity[irq]);
        new_cpu = move(cpu, allowed_mask, now, 1);
        if (cpu != new_cpu) {
                set_pending_irq(irq, cpumask_of_cpu(new_cpu));
        }
}

static inline void rotate_irqs_among_cpus(unsigned long useful_load_threshold)
{
        int i, j;
        Dprintk("Rotating IRQs among CPUs.\n");
        for_each_online_cpu(i) {
                for (j = 0; j < NR_IRQS; j++) {
                        if (!irq_desc[j].action)
                                continue;
                        /* Is it a significant load ?  */
                        if (IRQ_DELTA(CPU_TO_PACKAGEINDEX(i),j) <
                                                useful_load_threshold)
                                continue;
                        balance_irq(i, j);
                }
        }
        balanced_irq_interval = max((long)MIN_BALANCED_IRQ_INTERVAL,
                balanced_irq_interval - BALANCED_IRQ_LESS_DELTA);       
        return;
}

static void do_irq_balance(void)
{
        int i, j;
        unsigned long max_cpu_irq = 0, min_cpu_irq = (~0);
        unsigned long move_this_load = 0;
        int max_loaded = 0, min_loaded = 0;
        int load;
        unsigned long useful_load_threshold = balanced_irq_interval + 10;
        int selected_irq;
        int tmp_loaded, first_attempt = 1;
        unsigned long tmp_cpu_irq;
        unsigned long imbalance = 0;
        cpumask_t allowed_mask, target_cpu_mask, tmp;

        for_each_possible_cpu(i) {
                int package_index;
                CPU_IRQ(i) = 0;
                if (!cpu_online(i))
                        continue;
                package_index = CPU_TO_PACKAGEINDEX(i);
                for (j = 0; j < NR_IRQS; j++) {
                        unsigned long value_now, delta;
                        /* Is this an active IRQ? */
                        if (!irq_desc[j].action)
                                continue;
                        if ( package_index == i )
                                IRQ_DELTA(package_index,j) = 0;
                        /* Determine the total count per processor per IRQ */
                        value_now = (unsigned long) kstat_cpu(i).irqs[j];

                        /* Determine the activity per processor per IRQ */
                        delta = value_now - LAST_CPU_IRQ(i,j);

                        /* Update last_cpu_irq[][] for the next time */
                        LAST_CPU_IRQ(i,j) = value_now;

                        /* Ignore IRQs whose rate is less than the clock */
                        if (delta < useful_load_threshold)
                                continue;
                        /* update the load for the processor or package total */
                        IRQ_DELTA(package_index,j) += delta;

                        /* Keep track of the higher numbered sibling as well */
                        if (i != package_index)
                                CPU_IRQ(i) += delta;
                        /*
                         * We have sibling A and sibling B in the package
                         *
                         * cpu_irq[A] = load for cpu A + load for cpu B
                         * cpu_irq[B] = load for cpu B
                         */
                        CPU_IRQ(package_index) += delta;
                }
        }
        /* Find the least loaded processor package */
        for_each_online_cpu(i) {
                if (i != CPU_TO_PACKAGEINDEX(i))
                        continue;
                if (min_cpu_irq > CPU_IRQ(i)) {
                        min_cpu_irq = CPU_IRQ(i);
                        min_loaded = i;
                }
        }
        max_cpu_irq = ULONG_MAX;

tryanothercpu:
        /* Look for heaviest loaded processor.
         * We may come back to get the next heaviest loaded processor.
         * Skip processors with trivial loads.
         */
        tmp_cpu_irq = 0;
        tmp_loaded = -1;
        for_each_online_cpu(i) {
                if (i != CPU_TO_PACKAGEINDEX(i))
                        continue;
                if (max_cpu_irq <= CPU_IRQ(i)) 
                        continue;
                if (tmp_cpu_irq < CPU_IRQ(i)) {
                        tmp_cpu_irq = CPU_IRQ(i);
                        tmp_loaded = i;
                }
        }

        if (tmp_loaded == -1) {
         /* In the case of small number of heavy interrupt sources, 
          * loading some of the cpus too much. We use Ingo's original 
          * approach to rotate them around.
          */
                if (!first_attempt && imbalance >= useful_load_threshold) {
                        rotate_irqs_among_cpus(useful_load_threshold);
                        return;
                }
                goto not_worth_the_effort;
        }
        
        first_attempt = 0;              /* heaviest search */
        max_cpu_irq = tmp_cpu_irq;      /* load */
        max_loaded = tmp_loaded;        /* processor */
        imbalance = (max_cpu_irq - min_cpu_irq) / 2;
        
        Dprintk("max_loaded cpu = %d\n", max_loaded);
        Dprintk("min_loaded cpu = %d\n", min_loaded);
        Dprintk("max_cpu_irq load = %ld\n", max_cpu_irq);
        Dprintk("min_cpu_irq load = %ld\n", min_cpu_irq);
        Dprintk("load imbalance = %lu\n", imbalance);

        /* if imbalance is less than approx 10% of max load, then
         * observe diminishing returns action. - quit
         */
        if (imbalance < (max_cpu_irq >> 3)) {
                Dprintk("Imbalance too trivial\n");
                goto not_worth_the_effort;
        }

tryanotherirq:
        /* if we select an IRQ to move that can't go where we want, then
         * see if there is another one to try.
         */
        move_this_load = 0;
        selected_irq = -1;
        for (j = 0; j < NR_IRQS; j++) {
                /* Is this an active IRQ? */
                if (!irq_desc[j].action)
                        continue;
                if (imbalance <= IRQ_DELTA(max_loaded,j))
                        continue;
                /* Try to find the IRQ that is closest to the imbalance
                 * without going over.
                 */
                if (move_this_load < IRQ_DELTA(max_loaded,j)) {
                        move_this_load = IRQ_DELTA(max_loaded,j);
                        selected_irq = j;
                }
        }
        if (selected_irq == -1) {
                goto tryanothercpu;
        }

        imbalance = move_this_load;
        
        /* For physical_balance case, we accumlated both load
         * values in the one of the siblings cpu_irq[],
         * to use the same code for physical and logical processors
         * as much as possible. 
         *
         * NOTE: the cpu_irq[] array holds the sum of the load for
         * sibling A and sibling B in the slot for the lowest numbered
         * sibling (A), _AND_ the load for sibling B in the slot for
         * the higher numbered sibling.
         *
         * We seek the least loaded sibling by making the comparison
         * (A+B)/2 vs B
         */
        load = CPU_IRQ(min_loaded) >> 1;
        for_each_cpu_mask(j, cpu_sibling_map[min_loaded]) {
                if (load > CPU_IRQ(j)) {
                        /* This won't change cpu_sibling_map[min_loaded] */
                        load = CPU_IRQ(j);
                        min_loaded = j;
                }
        }

        cpus_and(allowed_mask,
                cpu_online_map,
                balance_irq_affinity[selected_irq]);
        target_cpu_mask = cpumask_of_cpu(min_loaded);
        cpus_and(tmp, target_cpu_mask, allowed_mask);

        if (!cpus_empty(tmp)) {

                Dprintk("irq = %d moved to cpu = %d\n",
                                selected_irq, min_loaded);
                /* mark for change destination */
                set_pending_irq(selected_irq, cpumask_of_cpu(min_loaded));

                /* Since we made a change, come back sooner to 
                 * check for more variation.
                 */
                balanced_irq_interval = max((long)MIN_BALANCED_IRQ_INTERVAL,
                        balanced_irq_interval - BALANCED_IRQ_LESS_DELTA);       
                return;
        }
        goto tryanotherirq;

not_worth_the_effort:
        /*
         * if we did not find an IRQ to move, then adjust the time interval
         * upward
         */
        balanced_irq_interval = min((long)MAX_BALANCED_IRQ_INTERVAL,
                balanced_irq_interval + BALANCED_IRQ_MORE_DELTA);       
        Dprintk("IRQ worth rotating not found\n");
        return;
}

static int balanced_irq(void *unused)
{
        int i;
        unsigned long prev_balance_time = jiffies;
        long time_remaining = balanced_irq_interval;

        daemonize("kirqd");
        
        /* push everything to CPU 0 to give us a starting point.  */
        for (i = 0 ; i < NR_IRQS ; i++) {
                irq_desc[i].pending_mask = cpumask_of_cpu(0);
                set_pending_irq(i, cpumask_of_cpu(0));
        }

        for ( ; ; ) {
                time_remaining = schedule_timeout_interruptible(time_remaining);
                try_to_freeze();
                if (time_after(jiffies,
                                prev_balance_time+balanced_irq_interval)) {
                        preempt_disable();
                        do_irq_balance();
                        prev_balance_time = jiffies;
                        time_remaining = balanced_irq_interval;
                        preempt_enable();
                }
        }
        return 0;
}

static int __init balanced_irq_init(void)
{
        int i;
        struct cpuinfo_x86 *c;
        cpumask_t tmp;

        cpus_shift_right(tmp, cpu_online_map, 2);
        c = &boot_cpu_data;
        /* When not overwritten by the command line ask subarchitecture. */
        if (irqbalance_disabled == IRQBALANCE_CHECK_ARCH)
                irqbalance_disabled = NO_BALANCE_IRQ;
        if (irqbalance_disabled)
                return 0;
        
         /* disable irqbalance completely if there is only one processor online */
        if (num_online_cpus() < 2) {
                irqbalance_disabled = 1;
                return 0;
        }
        /*
         * Enable physical balance only if more than 1 physical processor
         * is present
         */
        if (smp_num_siblings > 1 && !cpus_empty(tmp))
                physical_balance = 1;

        for_each_online_cpu(i) {
                irq_cpu_data[i].irq_delta = kmalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
                irq_cpu_data[i].last_irq = kmalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
                if (irq_cpu_data[i].irq_delta == NULL || irq_cpu_data[i].last_irq == NULL) {
                        printk(KERN_ERR "balanced_irq_init: out of memory");
                        goto failed;
                }
                memset(irq_cpu_data[i].irq_delta,0,sizeof(unsigned long) * NR_IRQS);
                memset(irq_cpu_data[i].last_irq,0,sizeof(unsigned long) * NR_IRQS);
        }
        
        printk(KERN_INFO "Starting balanced_irq\n");
        if (kernel_thread(balanced_irq, NULL, CLONE_KERNEL) >= 0) 
                return 0;
        else 
                printk(KERN_ERR "balanced_irq_init: failed to spawn balanced_irq");
failed:
        for_each_possible_cpu(i) {
                kfree(irq_cpu_data[i].irq_delta);
                irq_cpu_data[i].irq_delta = NULL;
                kfree(irq_cpu_data[i].last_irq);
                irq_cpu_data[i].last_irq = NULL;
        }
        return 0;
}

int __init irqbalance_disable(char *str)
{
        irqbalance_disabled = 1;
        return 1;
}

__setup("noirqbalance", irqbalance_disable);

late_initcall(balanced_irq_init);
#endif /* CONFIG_IRQBALANCE */
#endif /* CONFIG_SMP */

#ifndef CONFIG_SMP
void fastcall send_IPI_self(int vector)
{
        unsigned int cfg;

        /*
         * Wait for idle.
         */
        apic_wait_icr_idle();
        cfg = APIC_DM_FIXED | APIC_DEST_SELF | vector | APIC_DEST_LOGICAL;
        /*
         * Send the IPI. The write to APIC_ICR fires this off.
         */
        apic_write_around(APIC_ICR, cfg);
}
#endif /* !CONFIG_SMP */


/*
 * support for broken MP BIOSs, enables hand-redirection of PIRQ0-7 to
 * specific CPU-side IRQs.
 */

#define MAX_PIRQS 8
static int pirq_entries [MAX_PIRQS];
static int pirqs_enabled;
int skip_ioapic_setup;

static int __init ioapic_setup(char *str)
{
        skip_ioapic_setup = 1;
        return 1;
}

__setup("noapic", ioapic_setup);

static int __init ioapic_pirq_setup(char *str)
{
        int i, max;
        int ints[MAX_PIRQS+1];

        get_options(str, ARRAY_SIZE(ints), ints);

        for (i = 0; i < MAX_PIRQS; i++)
                pirq_entries[i] = -1;

        pirqs_enabled = 1;
        apic_printk(APIC_VERBOSE, KERN_INFO
                        "PIRQ redirection, working around broken MP-BIOS.\n");
        max = MAX_PIRQS;
        if (ints[0] < MAX_PIRQS)
                max = ints[0];

        for (i = 0; i < max; i++) {
                apic_printk(APIC_VERBOSE, KERN_DEBUG
                                "... PIRQ%d -> IRQ %d\n", i, ints[i+1]);
                /*
                 * PIRQs are mapped upside down, usually.
                 */
                pirq_entries[MAX_PIRQS-i-1] = ints[i+1];
        }
        return 1;
}

__setup("pirq=", ioapic_pirq_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].mpc_irqtype == type &&
                    (mp_irqs[i].mpc_dstapic == mp_ioapics[apic].mpc_apicid ||
                     mp_irqs[i].mpc_dstapic == MP_APIC_ALL) &&
                    mp_irqs[i].mpc_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].mpc_srcbus;

                if ((mp_bus_id_to_type[lbus] == MP_BUS_ISA ||
                     mp_bus_id_to_type[lbus] == MP_BUS_EISA ||
                     mp_bus_id_to_type[lbus] == MP_BUS_MCA ||
                     mp_bus_id_to_type[lbus] == MP_BUS_NEC98
                    ) &&
                    (mp_irqs[i].mpc_irqtype == type) &&
                    (mp_irqs[i].mpc_srcbusirq == irq))

                        return mp_irqs[i].mpc_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].mpc_srcbus;

                if ((mp_bus_id_to_type[lbus] == MP_BUS_ISA ||
                     mp_bus_id_to_type[lbus] == MP_BUS_EISA ||
                     mp_bus_id_to_type[lbus] == MP_BUS_MCA ||
                     mp_bus_id_to_type[lbus] == MP_BUS_NEC98
                    ) &&
                    (mp_irqs[i].mpc_irqtype == type) &&
                    (mp_irqs[i].mpc_srcbusirq == irq))
                        break;
        }
        if (i < mp_irq_entries) {
                int apic;
                for(apic = 0; apic < nr_ioapics; apic++) {
                        if (mp_ioapics[apic].mpc_apicid == mp_irqs[i].mpc_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 (mp_bus_id_to_pci_bus[bus] == -1) {
                printk(KERN_WARNING "PCI BIOS passed nonexistent PCI bus %d!\n", bus);
                return -1;
        }
        for (i = 0; i < mp_irq_entries; i++) {
                int lbus = mp_irqs[i].mpc_srcbus;

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

                if ((mp_bus_id_to_type[lbus] == MP_BUS_PCI) &&
                    !mp_irqs[i].mpc_irqtype &&
                    (bus == lbus) &&
                    (slot == ((mp_irqs[i].mpc_srcbusirq >> 2) & 0x1f))) {
                        int irq = pin_2_irq(i,apic,mp_irqs[i].mpc_dstirq);

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

                        if (pin == (mp_irqs[i].mpc_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;
                }
        }
        return best_guess;
}
EXPORT_SYMBOL(IO_APIC_get_PCI_irq_vector);

/*
 * 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);
                        set_ioapic_affinity_irq(irq, TARGET_CPUS);
                }

        }
}
#endif

/*
 * EISA Edge/Level control register, ELCR
 */
static int EISA_ELCR(unsigned int irq)
{
        if (irq < 16) {
                unsigned int port = 0x4d0 + (irq >> 3);
                return (inb(port) >> (irq & 7)) & 1;
        }
        apic_printk(APIC_VERBOSE, KERN_INFO
                        "Broken MPtable reports ISA irq %d\n", irq);
        return 0;
}

/* EISA interrupts are always polarity zero and can be edge or level
 * trigger depending on the ELCR value.  If an interrupt is listed as
 * EISA conforming in the MP table, that means its trigger type must
 * be read in from the ELCR */

#define default_EISA_trigger(idx)       (EISA_ELCR(mp_irqs[idx].mpc_srcbusirq))
#define default_EISA_polarity(idx)      (0)

/* 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)

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

#define default_MCA_trigger(idx)        (1)
#define default_MCA_polarity(idx)       (0)

/* NEC98 interrupts are always polarity zero edge triggered,
 * when listed as conforming in the MP table. */

#define default_NEC98_trigger(idx)     (0)
#define default_NEC98_polarity(idx)    (0)

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

        /*
         * Determine IRQ line polarity (high active or low active):
         */
        switch (mp_irqs[idx].mpc_irqflag & 3)
        {
                case 0: /* conforms, ie. bus-type dependent polarity */
                {
                        switch (mp_bus_id_to_type[bus])
                        {
                                case MP_BUS_ISA: /* ISA pin */
                                {
                                        polarity = default_ISA_polarity(idx);
                                        break;
                                }
                                case MP_BUS_EISA: /* EISA pin */
                                {
                                        polarity = default_EISA_polarity(idx);
                                        break;
                                }
                                case MP_BUS_PCI: /* PCI pin */
                                {
                                        polarity = default_PCI_polarity(idx);
                                        break;
                                }
                                case MP_BUS_MCA: /* MCA pin */
                                {
                                        polarity = default_MCA_polarity(idx);
                                        break;
                                }
                                case MP_BUS_NEC98: /* NEC 98 pin */
                                {
                                        polarity = default_NEC98_polarity(idx);
                                        break;
                                }
                                default:
                                {
                                        printk(KERN_WARNING "broken BIOS!!\n");
                                        polarity = 1;
                                        break;
                                }
                        }
                        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].mpc_srcbus;
        int trigger;

        /*
         * Determine IRQ trigger mode (edge or level sensitive):
         */
        switch ((mp_irqs[idx].mpc_irqflag>>2) & 3)
        {
                case 0: /* conforms, ie. bus-type dependent */
                {
                        switch (mp_bus_id_to_type[bus])
                        {
                                case MP_BUS_ISA: /* ISA pin */
                                {
                                        trigger = default_ISA_trigger(idx);
                                        break;
                                }
                                case MP_BUS_EISA: /* EISA pin */
                                {
                                        trigger = default_EISA_trigger(idx);
                                        break;
                                }
                                case MP_BUS_PCI: /* PCI pin */
                                {
                                        trigger = default_PCI_trigger(idx);
                                        break;
                                }
                                case MP_BUS_MCA: /* MCA pin */
                                {
                                        trigger = default_MCA_trigger(idx);
                                        break;
                                }
                                case MP_BUS_NEC98: /* NEC 98 pin */
                                {
                                        trigger = default_NEC98_trigger(idx);
                                        break;
                                }
                                default:
                                {
                                        printk(KERN_WARNING "broken BIOS!!\n");
                                        trigger = 1;
                                        break;
                                }
                        }
                        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].mpc_srcbus;

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

        switch (mp_bus_id_to_type[bus])
        {
                case MP_BUS_ISA: /* ISA pin */
                case MP_BUS_EISA:
                case MP_BUS_MCA:
                case MP_BUS_NEC98:
                {
                        irq = mp_irqs[idx].mpc_srcbusirq;
                        break;
                }
                case MP_BUS_PCI: /* PCI pin */
                {
                        /*
                         * PCI IRQs are mapped in order
                         */
                        i = irq = 0;
                        while (i < apic)
                                irq += nr_ioapic_registers[i++];
                        irq += pin;

                        /*
                         * For MPS mode, so far only needed by ES7000 platform
                         */
                        if (ioapic_renumber_irq)
                                irq = ioapic_renumber_irq(apic, irq);

                        break;
                }
                default:
                {
                        printk(KERN_ERR "unknown bus type %d.\n",bus); 
                        irq = 0;
                        break;
                }
        }

        /*
         * PCI IRQ command line redirection. Yes, limits are hardcoded.
         */
        if ((pin >= 16) && (pin <= 23)) {
                if (pirq_entries[pin-16] != -1) {
                        if (!pirq_entries[pin-16]) {
                                apic_printk(APIC_VERBOSE, KERN_DEBUG
                                                "disabling PIRQ%d\n", pin-16);
                        } else {
                                irq = pirq_entries[pin-16];
                                apic_printk(APIC_VERBOSE, KERN_DEBUG
                                                "using PIRQ%d -> IRQ %d\n",
                                                pin-16, irq);
                        }
                }
        }
        return irq;
}

static inline int IO_APIC_irq_trigger(int irq)
{
        int apic, idx, pin;

        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) && (irq == pin_2_irq(idx,apic,pin)))
                                return irq_trigger(idx);
                }
        }
        /*
         * nonexistent IRQs are edge default
         */
        return 0;
}

/* irq_vectors is indexed by the sum of all RTEs in all I/O APICs. */
u8 irq_vector[NR_IRQ_VECTORS] __read_mostly = { FIRST_DEVICE_VECTOR , 0 };

int assign_irq_vector(int irq)
{
        static int current_vector = FIRST_DEVICE_VECTOR, offset = 0;
        unsigned long flags;
        int vector;

        BUG_ON(irq != AUTO_ASSIGN && (unsigned)irq >= NR_IRQ_VECTORS);

        spin_lock_irqsave(&vector_lock, flags);

        if (irq != AUTO_ASSIGN && IO_APIC_VECTOR(irq) > 0) {
                spin_unlock_irqrestore(&vector_lock, flags);
                return IO_APIC_VECTOR(irq);
        }
next:
        current_vector += 8;
        if (current_vector == SYSCALL_VECTOR)
                goto next;

        if (current_vector >= FIRST_SYSTEM_VECTOR) {
                offset++;
                if (!(offset%8)) {
                        spin_unlock_irqrestore(&vector_lock, flags);
                        return -ENOSPC;
                }
                current_vector = FIRST_DEVICE_VECTOR + offset;
        }

        vector = current_vector;
        vector_irq[vector] = irq;
        if (irq != AUTO_ASSIGN)
                IO_APIC_VECTOR(irq) = vector;

        spin_unlock_irqrestore(&vector_lock, flags);

        return vector;
}

static struct hw_interrupt_type ioapic_level_type;
static struct hw_interrupt_type ioapic_edge_type;

#define IOAPIC_AUTO     -1
#define IOAPIC_EDGE     0
#define IOAPIC_LEVEL    1

static void ioapic_register_intr(int irq, int vector, unsigned long trigger)
{
        unsigned idx;

        idx = use_pci_vector() && !platform_legacy_irq(irq) ? vector : irq;

        if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
                        trigger == IOAPIC_LEVEL)
                irq_desc[idx].chip = &ioapic_level_type;
        else
                irq_desc[idx].chip = &ioapic_edge_type;
        set_intr_gate(vector, interrupt[idx]);
}

static void __init setup_IO_APIC_irqs(void)
{
        struct IO_APIC_route_entry entry;
        int apic, pin, idx, irq, first_notcon = 1, vector;
        unsigned long flags;

        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++) {

                /*
                 * 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.mask = 0;                         /* enable IRQ */
                entry.dest.logical.logical_dest = 
                                        cpu_mask_to_apicid(TARGET_CPUS);

                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].mpc_apicid,
                                                pin);
                                first_notcon = 0;
                        } else
                                apic_printk(APIC_VERBOSE, ", %d-%d",
                                        mp_ioapics[apic].mpc_apicid, pin);
                        continue;
                }

                entry.trigger = irq_trigger(idx);
                entry.polarity = irq_polarity(idx);

                if (irq_trigger(idx)) {
                        entry.trigger = 1;
                        entry.mask = 1;
                }

                irq = pin_2_irq(idx, apic, pin);
                /*
                 * skip adding the timer int on secondary nodes, which causes
                 * a small but painful rift in the time-space continuum
                 */
                if (multi_timer_check(apic, irq))
                        continue;
                else
                        add_pin_to_irq(irq, apic, pin);

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

                if (IO_APIC_IRQ(irq)) {
                        vector = assign_irq_vector(irq);
                        entry.vector = vector;
                        ioapic_register_intr(irq, vector, IOAPIC_AUTO);
                
                        if (!apic && (irq < 16))
                                disable_8259A_irq(irq);
                }
                ioapic_write_entry(apic, pin, entry);
                spin_lock_irqsave(&ioapic_lock, flags);
                set_native_irq_info(irq, TARGET_CPUS);
                spin_unlock_irqrestore(&ioapic_lock, flags);
        }
        }

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

/*
 * Set up the 8259A-master output pin:
 */
static void __init setup_ExtINT_IRQ0_pin(unsigned int apic, unsigned int pin, int vector)
{
        struct IO_APIC_route_entry entry;

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

        disable_8259A_irq(0);

        /* mask LVT0 */
        apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);

        /*
         * We use logical delivery to get the timer IRQ
         * to the first CPU.
         */
        entry.dest_mode = INT_DEST_MODE;
        entry.mask = 0;                                 /* unmask IRQ now */
        entry.dest.logical.logical_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 have a 8259A-master in AEOI mode ...
         */
        irq_desc[0].chip = &ioapic_edge_type;

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

        enable_8259A_irq(0);
}

static inline void UNEXPECTED_IO_APIC(void)
{
}

void __init 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;
        union IO_APIC_reg_03 reg_03;
        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].mpc_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);
        if (reg_01.bits.version >= 0x20)
                reg_03.raw = io_apic_read(apic, 3);
        spin_unlock_irqrestore(&ioapic_lock, flags);

        printk(KERN_DEBUG "IO APIC #%d......\n", mp_ioapics[apic].mpc_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 ".......    : Delivery Type: %X\n", reg_00.bits.delivery_type);
        printk(KERN_DEBUG ".......    : LTS          : %X\n", reg_00.bits.LTS);
        if (reg_00.bits.ID >= get_physical_broadcast())
                UNEXPECTED_IO_APIC();
        if (reg_00.bits.__reserved_1 || reg_00.bits.__reserved_2)
                UNEXPECTED_IO_APIC();

        printk(KERN_DEBUG ".... register #01: %08X\n", reg_01.raw);
        printk(KERN_DEBUG ".......     : max redirection entries: %04X\n", reg_01.bits.entries);
        if (    (reg_01.bits.entries != 0x0f) && /* older (Neptune) boards */
                (reg_01.bits.entries != 0x17) && /* typical ISA+PCI boards */
                (reg_01.bits.entries != 0x1b) && /* Compaq Proliant boards */
                (reg_01.bits.entries != 0x1f) && /* dual Xeon boards */
                (reg_01.bits.entries != 0x22) && /* bigger Xeon boards */
                (reg_01.bits.entries != 0x2E) &&
                (reg_01.bits.entries != 0x3F)
        )
                UNEXPECTED_IO_APIC();

        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 != 0x01) && /* 82489DX IO-APICs */
                (reg_01.bits.version != 0x10) && /* oldest IO-APICs */
                (reg_01.bits.version != 0x11) && /* Pentium/Pro IO-APICs */
                (reg_01.bits.version != 0x13) && /* Xeon IO-APICs */
                (reg_01.bits.version != 0x20)    /* Intel P64H (82806 AA) */
        )
                UNEXPECTED_IO_APIC();
        if (reg_01.bits.__reserved_1 || reg_01.bits.__reserved_2)
                UNEXPECTED_IO_APIC();

        /*
         * Some Intel chipsets with IO APIC VERSION of 0x1? don't have reg_02,
         * but the value of reg_02 is read as the previous read register
         * value, so ignore it if reg_02 == reg_01.
         */
        if (reg_01.bits.version >= 0x10 && reg_02.raw != reg_01.raw) {
                printk(KERN_DEBUG ".... register #02: %08X\n", reg_02.raw);
                printk(KERN_DEBUG ".......     : arbitration: %02X\n", reg_02.bits.arbitration);
                if (reg_02.bits.__reserved_1 || reg_02.bits.__reserved_2)
                        UNEXPECTED_IO_APIC();
        }

        /*
         * Some Intel chipsets with IO APIC VERSION of 0x2? don't have reg_02
         * or reg_03, but the value of reg_0[23] is read as the previous read
         * register value, so ignore it if reg_03 == reg_0[12].
         */
        if (reg_01.bits.version >= 0x20 && reg_03.raw != reg_02.raw &&
            reg_03.raw != reg_01.raw) {
                printk(KERN_DEBUG ".... register #03: %08X\n", reg_03.raw);
                printk(KERN_DEBUG ".......     : Boot DT    : %X\n", reg_03.bits.boot_DT);
                if (reg_03.bits.__reserved_1)
                        UNEXPECTED_IO_APIC();
        }

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

        printk(KERN_DEBUG " NR Log Phy Mask Trig IRR Pol"
                          " Stat Dest 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 %02X  ",
                        i,
                        entry.dest.logical.logical_dest,
                        entry.dest.physical.physical_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
                );
        }
        }
        if (use_pci_vector())
                printk(KERN_INFO "Using vector-based indexing\n");
        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;
                if (use_pci_vector() && !platform_legacy_irq(i))
                        printk(KERN_DEBUG "IRQ%d ", IO_APIC_VECTOR(i));
                else
                        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 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 /*__init*/ 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(v));
        v = apic_read(APIC_LVR);
        printk(KERN_INFO "... APIC VERSION: %08x\n", v);
        ver = GET_APIC_VERSION(v);
        maxlvt = get_maxlvt();

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

        if (APIC_INTEGRATED(ver)) {                     /* !82489DX */
                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);

        if (APIC_INTEGRATED(ver)) {             /* !82489DX */
                if (maxlvt > 3)         /* Due to the Pentium erratum 3AP. */
                        apic_write(APIC_ESR, 0);
                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, 1);
}

void /*__init*/ 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  */

static 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;
        }
        if (!pirqs_enabled)
                for (i = 0; i < MAX_PIRQS; i++)
                        pirq_entries[i] = -1;

        /*
         * 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 */
        /* If we could not find the appropriate pin by looking at the ioapic
         * the i8259 probably is not connected the ioapic but give the
         * mptable a chance anyway.
         */
        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.physical.physical_dest =
                                        GET_APIC_ID(apic_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);
}

/*
 * function to set the IO-APIC physical IDs based on the
 * values stored in the MPC table.
 *
 * by Matt Domsch <Matt_Domsch@dell.com>  Tue Dec 21 12:25:05 CST 1999
 */

#ifndef CONFIG_X86_NUMAQ
static void __init setup_ioapic_ids_from_mpc(void)
{
        union IO_APIC_reg_00 reg_00;
        physid_mask_t phys_id_present_map;
        int apic;
        int i;
        unsigned char old_id;
        unsigned long flags;

        /*
         * Don't check I/O APIC IDs for xAPIC systems.  They have
         * no meaning without the serial APIC bus.
         */
        if (!(boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
                || APIC_XAPIC(apic_version[boot_cpu_physical_apicid]))
                return;
        /*
         * This is broken; anything with a real cpu count has to
         * circumvent this idiocy regardless.
         */
        phys_id_present_map = ioapic_phys_id_map(phys_cpu_present_map);

        /*
         * Set the IOAPIC ID to the value stored in the MPC table.
         */
        for (apic = 0; apic < nr_ioapics; apic++) {

                /* Read the register 0 value */
                spin_lock_irqsave(&ioapic_lock, flags);
                reg_00.raw = io_apic_read(apic, 0);
                spin_unlock_irqrestore(&ioapic_lock, flags);
                
                old_id = mp_ioapics[apic].mpc_apicid;

                if (mp_ioapics[apic].mpc_apicid >= get_physical_broadcast()) {
                        printk(KERN_ERR "BIOS bug, IO-APIC#%d ID is %d in the MPC table!...\n",
                                apic, mp_ioapics[apic].mpc_apicid);
                        printk(KERN_ERR "... fixing up to %d. (tell your hw vendor)\n",
                                reg_00.bits.ID);
                        mp_ioapics[apic].mpc_apicid = reg_00.bits.ID;
                }

                /*
                 * Sanity check, is the ID really free? Every APIC in a
                 * system must have a unique ID or we get lots of nice
                 * 'stuck on smp_invalidate_needed IPI wait' messages.
                 */
                if (check_apicid_used(phys_id_present_map,
                                        mp_ioapics[apic].mpc_apicid)) {
                        printk(KERN_ERR "BIOS bug, IO-APIC#%d ID %d is already used!...\n",
                                apic, mp_ioapics[apic].mpc_apicid);
                        for (i = 0; i < get_physical_broadcast(); i++)
                                if (!physid_isset(i, phys_id_present_map))
                                        break;
                        if (i >= get_physical_broadcast())
                                panic("Max APIC ID exceeded!\n");
                        printk(KERN_ERR "... fixing up to %d. (tell your hw vendor)\n",
                                i);
                        physid_set(i, phys_id_present_map);
                        mp_ioapics[apic].mpc_apicid = i;
                } else {
                        physid_mask_t tmp;
                        tmp = apicid_to_cpu_present(mp_ioapics[apic].mpc_apicid);
                        apic_printk(APIC_VERBOSE, "Setting %d in the "
                                        "phys_id_present_map\n",
                                        mp_ioapics[apic].mpc_apicid);
                        physids_or(phys_id_present_map, phys_id_present_map, tmp);
                }


                /*
                 * We need to adjust the IRQ routing table
                 * if the ID changed.
                 */
                if (old_id != mp_ioapics[apic].mpc_apicid)
                        for (i = 0; i < mp_irq_entries; i++)
                                if (mp_irqs[i].mpc_dstapic == old_id)
                                        mp_irqs[i].mpc_dstapic
                                                = mp_ioapics[apic].mpc_apicid;

                /*
                 * Read the right value from the MPC table and
                 * write it into the ID register.
                 */
                apic_printk(APIC_VERBOSE, KERN_INFO
                        "...changing IO-APIC physical APIC ID to %d ...",
                        mp_ioapics[apic].mpc_apicid);

                reg_00.bits.ID = mp_ioapics[apic].mpc_apicid;
                spin_lock_irqsave(&ioapic_lock, flags);
                io_apic_write(apic, 0, reg_00.raw);
                spin_unlock_irqrestore(&ioapic_lock, flags);

                /*
                 * Sanity check
                 */
                spin_lock_irqsave(&ioapic_lock, flags);
                reg_00.raw = io_apic_read(apic, 0);
                spin_unlock_irqrestore(&ioapic_lock, flags);
                if (reg_00.bits.ID != mp_ioapics[apic].mpc_apicid)
                        printk("could not set ID!\n");
                else
                        apic_printk(APIC_VERBOSE, " ok.\n");
        }
}
#else
static void __init setup_ioapic_ids_from_mpc(void) { }
#endif

/*
 * 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;

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

        /*
         * 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.
         */
        if (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_edge_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;
}

/*
 * Once we have recorded IRQ_PENDING already, we can mask the
 * interrupt for real. This prevents IRQ storms from unhandled
 * devices.
 */
static void ack_edge_ioapic_irq(unsigned int irq)
{
        move_irq(irq);
        if ((irq_desc[irq].status & (IRQ_PENDING | IRQ_DISABLED))
                                        == (IRQ_PENDING | IRQ_DISABLED))
                mask_IO_APIC_irq(irq);
        ack_APIC_irq();
}

/*
 * Level triggered interrupts can just be masked,
 * and shutting down and starting up the interrupt
 * is the same as enabling and disabling them -- except
 * with a startup need to return a "was pending" value.
 *
 * Level triggered interrupts are special because we
 * do not touch any IO-APIC register while handling
 * them. We ack the APIC in the end-IRQ handler, not
 * in the start-IRQ-handler. Protection against reentrance
 * from the same interrupt is still provided, both by the
 * generic IRQ layer and by the fact that an unacked local
 * APIC does not accept IRQs.
 */
static unsigned int startup_level_ioapic_irq (unsigned int irq)
{
        unmask_IO_APIC_irq(irq);

        return 0; /* don't check for pending */
}

static void end_level_ioapic_irq (unsigned int irq)
{
        unsigned long v;
        int i;

        move_irq(irq);
/*
 * It appears there is an erratum which affects at least version 0x11
 * of I/O APIC (that's the 82093AA and cores integrated into various
 * chipsets).  Under certain conditions a level-triggered interrupt is
 * erroneously delivered as edge-triggered one but the respective IRR
 * bit gets set nevertheless.  As a result the I/O unit expects an EOI
 * message but it will never arrive and further interrupts are blocked
 * from the source.  The exact reason is so far unknown, but the
 * phenomenon was observed when two consecutive interrupt requests
 * from a given source get delivered to the same CPU and the source is
 * temporarily disabled in between.
 *
 * A workaround is to simulate an EOI message manually.  We achieve it
 * by setting the trigger mode to edge and then to level when the edge
 * trigger mode gets detected in the TMR of a local APIC for a
 * level-triggered interrupt.  We mask the source for the time of the
 * operation to prevent an edge-triggered interrupt escaping meanwhile.
 * The idea is from Manfred Spraul.  --macro
 */
        i = IO_APIC_VECTOR(irq);

        v = apic_read(APIC_TMR + ((i & ~0x1f) >> 1));

        ack_APIC_irq();

        if (!(v & (1 << (i & 0x1f)))) {
                atomic_inc(&irq_mis_count);
                spin_lock(&ioapic_lock);
                __mask_and_edge_IO_APIC_irq(irq);
                __unmask_and_level_IO_APIC_irq(irq);
                spin_unlock(&ioapic_lock);
        }
}

#ifdef CONFIG_PCI_MSI
static unsigned int startup_edge_ioapic_vector(unsigned int vector)
{
        int irq = vector_to_irq(vector);

        return startup_edge_ioapic_irq(irq);
}

static void ack_edge_ioapic_vector(unsigned int vector)
{
        int irq = vector_to_irq(vector);

        move_native_irq(vector);
        ack_edge_ioapic_irq(irq);
}

static unsigned int startup_level_ioapic_vector (unsigned int vector)
{
        int irq = vector_to_irq(vector);

        return startup_level_ioapic_irq (irq);
}

static void end_level_ioapic_vector (unsigned int vector)
{
        int irq = vector_to_irq(vector);

        move_native_irq(vector);
        end_level_ioapic_irq(irq);
}

static void mask_IO_APIC_vector (unsigned int vector)
{
        int irq = vector_to_irq(vector);

        mask_IO_APIC_irq(irq);
}

static void unmask_IO_APIC_vector (unsigned int vector)
{
        int irq = vector_to_irq(vector);

        unmask_IO_APIC_irq(irq);
}

#ifdef CONFIG_SMP
static void set_ioapic_affinity_vector (unsigned int vector,
                                        cpumask_t cpu_mask)
{
        int irq = vector_to_irq(vector);

        set_native_irq_info(vector, cpu_mask);
        set_ioapic_affinity_irq(irq, cpu_mask);
}
#endif
#endif

static int ioapic_retrigger(unsigned int irq)
{
        send_IPI_self(IO_APIC_VECTOR(irq));

        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.
 */
static struct hw_interrupt_type ioapic_edge_type __read_mostly = {
        .typename       = "IO-APIC-edge",
        .startup        = startup_edge_ioapic,
        .shutdown       = shutdown_edge_ioapic,
        .enable         = enable_edge_ioapic,
        .disable        = disable_edge_ioapic,
        .ack            = ack_edge_ioapic,
        .end            = end_edge_ioapic,
#ifdef CONFIG_SMP
        .set_affinity   = set_ioapic_affinity,
#endif
        .retrigger      = ioapic_retrigger,
};

static struct hw_interrupt_type ioapic_level_type __read_mostly = {
        .typename       = "IO-APIC-level",
        .startup        = startup_level_ioapic,
        .shutdown       = shutdown_level_ioapic,
        .enable         = enable_level_ioapic,
        .disable        = disable_level_ioapic,
        .ack            = mask_and_ack_level_ioapic,
        .end            = end_level_ioapic,
#ifdef CONFIG_SMP
        .set_affinity   = set_ioapic_affinity,
#endif
        .retrigger      = ioapic_retrigger,
};

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++) {
                int tmp = irq;
                if (use_pci_vector()) {
                        if (!platform_legacy_irq(tmp))
                                if ((tmp = vector_to_irq(tmp)) == -1)
                                        continue;
                }
                if (IO_APIC_IRQ(tmp) && !IO_APIC_VECTOR(tmp)) {
                        /*
                         * 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_type;
                }
        }
}

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

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

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

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

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

static void end_lapic_irq (unsigned int i) { /* nothing */ }

static struct hw_interrupt_type lapic_irq_type __read_mostly = {
        .typename       = "local-APIC-edge",
        .startup        = NULL, /* startup_irq() not used for IRQ0 */
        .shutdown       = NULL, /* shutdown_irq() not used for IRQ0 */
        .enable         = enable_lapic_irq,
        .disable        = disable_lapic_irq,
        .ack            = ack_lapic_irq,
        .end            = end_lapic_irq
};

static void 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.
         */ 
        apic_printk(APIC_VERBOSE, KERN_INFO "activating NMI Watchdog ...");

        on_each_cpu(enable_NMI_through_LVT0, NULL, 1, 1);

        apic_printk(APIC_VERBOSE, " 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 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.physical.physical_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);
}

int timer_uses_ioapic_pin_0;

/*
 * 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.
 */
static inline void check_timer(void)
{
        int apic1, pin1, apic2, pin2;
        int vector;

        /*
         * get/set the timer IRQ vector:
         */
        disable_8259A_irq(0);
        vector = assign_irq_vector(0);
        set_intr_gate(vector, interrupt[0]);

        /*
         * Subtle, code in do_timer_interrupt() expects an AEOI
         * mode for the 8259A whenever interrupts are routed
         * through I/O APICs.  Also IRQ0 has to be enabled in
         * the 8259A which implies the virtual wire has to be
         * disabled in the local APIC.
         */
        apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
        init_8259A(1);
        timer_ack = 1;
        if (timer_over_8254 > 0)
                enable_8259A_irq(0);

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

        if (pin1 == 0)
                timer_uses_ioapic_pin_0 = 1;

        printk(KERN_INFO "..TIMER: vector=0x%02X apic1=%d pin1=%d apic2=%d pin2=%d\n",
                vector, apic1, pin1, apic2, pin2);

        if (pin1 != -1) {
                /*
                 * Ok, does IRQ0 through the IOAPIC work?
                 */
                unmask_IO_APIC_irq(0);
                if (timer_irq_works()) {
                        if (nmi_watchdog == NMI_IO_APIC) {
                                disable_8259A_irq(0);
                                setup_nmi();
                                enable_8259A_irq(0);
                        }
                        if (disable_timer_pin_1 > 0)
                                clear_IO_APIC_pin(0, pin1);
                        return;
                }
                clear_IO_APIC_pin(apic1, pin1);
                printk(KERN_ERR "..MP-BIOS bug: 8254 timer not connected to "
                                "IO-APIC\n");
        }

        printk(KERN_INFO "...trying to set up timer (IRQ0) through the 8259A ... ");
        if (pin2 != -1) {
                printk("\n..... (found pin %d) ...", pin2);
                /*
                 * legacy devices should be connected to IO APIC #0
                 */
                setup_ExtINT_IRQ0_pin(apic2, pin2, vector);
                if (timer_irq_works()) {
                        printk("works.\n");
                        if (pin1 != -1)
                                replace_pin_at_irq(0, apic1, pin1, apic2, pin2);
                        else
                                add_pin_to_irq(0, apic2, pin2);
                        if (nmi_watchdog == NMI_IO_APIC) {
                                setup_nmi();
                        }
                        return;
                }
                /*
                 * Cleanup, just in case ...
                 */
                clear_IO_APIC_pin(apic2, pin2);
        }
        printk(" 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 = 0;
        }

        printk(KERN_INFO "...trying to set up timer as Virtual Wire IRQ...");

        disable_8259A_irq(0);
        irq_desc[0].chip = &lapic_irq_type;
        apic_write_around(APIC_LVT0, APIC_DM_FIXED | vector);   /* Fixed mode */
        enable_8259A_irq(0);

        if (timer_irq_works()) {
                printk(" works.\n");
                return;
        }
        apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_FIXED | vector);
        printk(" failed.\n");

        printk(KERN_INFO "...trying to set up timer as ExtINT IRQ...");

        timer_ack = 0;
        init_8259A(0);
        make_8259A_irq(0);
        apic_write_around(APIC_LVT0, APIC_DM_EXTINT);

        unlock_ExtINT_logic();

        if (timer_irq_works()) {
                printk(" works.\n");
                return;
        }
        printk(" failed :(.\n");
        panic("IO-APIC + timer doesn't work!  Boot with apic=debug and send a "
                "report.  Then try booting with the 'noapic' option");
}

/*
 *
 * IRQ's that are handled by the PIC in the MPS IOAPIC case.
 * - IRQ2 is the cascade IRQ, and cannot be a io-apic IRQ.
 *   Linux doesn't really care, as it's not actually used
 *   for any interrupt handling anyway.
 */
#define PIC_IRQS        (1 << PIC_CASCADE_IR)

void __init setup_IO_APIC(void)
{
        enable_IO_APIC();

        if (acpi_ioapic)
                io_apic_irqs = ~0;      /* all IRQs go through IOAPIC */
        else
                io_apic_irqs = ~PIC_IRQS;

        printk("ENABLING IO-APIC IRQs\n");

        /*
         * Set up IO-APIC IRQ routing.
         */
        if (!acpi_ioapic)
                setup_ioapic_ids_from_mpc();
        sync_Arb_IDs();
        setup_IO_APIC_irqs();
        init_IO_APIC_traps();
        check_timer();
        if (!acpi_ioapic)
                print_IO_APIC();
}

static int __init setup_disable_8254_timer(char *s)
{
        timer_over_8254 = -1;
        return 1;
}
static int __init setup_enable_8254_timer(char *s)
{
        timer_over_8254 = 2;
        return 1;
}

__setup("disable_8254_timer", setup_disable_8254_timer);
__setup("enable_8254_timer", setup_enable_8254_timer);

/*
 *      Called after all the initialization is done. If we didnt find any
 *      APIC bugs then we can allow the modify fast path
 */
 
static int __init io_apic_bug_finalize(void)
{
        if(sis_apic_bug == -1)
                sis_apic_bug = 0;
        return 0;
}

late_initcall(io_apic_bug_finalize);

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[i] = 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].mpc_apicid) {
                reg_00.bits.ID = mp_ioapics[dev->id].mpc_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 = {
        set_kset_name("ioapic"),
        .suspend = ioapic_suspend,
        .resume = ioapic_resume,
};

static int __init ioapic_init_sysfs(void)
{
        struct sys_device * dev;
        int i, size, error = 0;

        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] = kmalloc(size, GFP_KERNEL);
                if (!mp_ioapic_data[i]) {
                        printk(KERN_ERR "Can't suspend/resume IOAPIC %d\n", i);
                        continue;
                }
                memset(mp_ioapic_data[i], 0, size);
                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);

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

#ifdef CONFIG_ACPI

int __init io_apic_get_unique_id (int ioapic, int apic_id)
{
        union IO_APIC_reg_00 reg_00;
        static physid_mask_t apic_id_map = PHYSID_MASK_NONE;
        physid_mask_t tmp;
        unsigned long flags;
        int i = 0;

        /*
         * The P4 platform supports up to 256 APIC IDs on two separate APIC 
         * buses (one for LAPICs, one for IOAPICs), where predecessors only 
         * supports up to 16 on one shared APIC bus.
         * 
         * TBD: Expand LAPIC/IOAPIC support on P4-class systems to take full
         *      advantage of new APIC bus architecture.
         */

        if (physids_empty(apic_id_map))
                apic_id_map = ioapic_phys_id_map(phys_cpu_present_map);

        spin_lock_irqsave(&ioapic_lock, flags);
        reg_00.raw = io_apic_read(ioapic, 0);
        spin_unlock_irqrestore(&ioapic_lock, flags);

        if (apic_id >= get_physical_broadcast()) {
                printk(KERN_WARNING "IOAPIC[%d]: Invalid apic_id %d, trying "
                        "%d\n", ioapic, apic_id, reg_00.bits.ID);
                apic_id = reg_00.bits.ID;
        }

        /*
         * Every APIC in a system must have a unique ID or we get lots of nice 
         * 'stuck on smp_invalidate_needed IPI wait' messages.
         */
        if (check_apicid_used(apic_id_map, apic_id)) {

                for (i = 0; i < get_physical_broadcast(); i++) {
                        if (!check_apicid_used(apic_id_map, i))
                                break;
                }

                if (i == get_physical_broadcast())
                        panic("Max apic_id exceeded!\n");

                printk(KERN_WARNING "IOAPIC[%d]: apic_id %d already used, "
                        "trying %d\n", ioapic, apic_id, i);

                apic_id = i;
        } 

        tmp = apicid_to_cpu_present(apic_id);
        physids_or(apic_id_map, apic_id_map, tmp);

        if (reg_00.bits.ID != apic_id) {
                reg_00.bits.ID = apic_id;

                spin_lock_irqsave(&ioapic_lock, flags);
                io_apic_write(ioapic, 0, reg_00.raw);
                reg_00.raw = io_apic_read(ioapic, 0);
                spin_unlock_irqrestore(&ioapic_lock, flags);

                /* Sanity check */
                if (reg_00.bits.ID != apic_id) {
                        printk("IOAPIC[%d]: Unable to change apic_id!\n", ioapic);
                        return -1;
                }
        }

        apic_printk(APIC_VERBOSE, KERN_INFO
                        "IOAPIC[%d]: Assigned apic_id %d\n", ioapic, apic_id);

        return apic_id;
}


int __init io_apic_get_version (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.version;
}


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 edge_level, int active_high_low)
{
        struct IO_APIC_route_entry entry;
        unsigned long flags;

        if (!IO_APIC_IRQ(irq)) {
                printk(KERN_ERR "IOAPIC[%d]: Invalid reference to IRQ 0\n",
                        ioapic);
                return -EINVAL;
        }

        /*
         * Generate a PCI IRQ routing entry and program the IOAPIC accordingly.
         * Note that we mask (disable) IRQs now -- these get enabled when the
         * corresponding device driver registers for this IRQ.
         */

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

        entry.delivery_mode = INT_DELIVERY_MODE;
        entry.dest_mode = INT_DEST_MODE;
        entry.dest.logical.logical_dest = cpu_mask_to_apicid(TARGET_CPUS);
        entry.trigger = edge_level;
        entry.polarity = active_high_low;
        entry.mask  = 1;

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

        entry.vector = assign_irq_vector(irq);

        apic_printk(APIC_DEBUG, KERN_DEBUG "IOAPIC[%d]: Set PCI routing entry "
                "(%d-%d -> 0x%x -> IRQ %d Mode:%i Active:%i)\n", ioapic,
                mp_ioapics[ioapic].mpc_apicid, pin, entry.vector, irq,
                edge_level, active_high_low);

        ioapic_register_intr(irq, entry.vector, edge_level);

        if (!ioapic && (irq < 16))
                disable_8259A_irq(irq);

        ioapic_write_entry(ioapic, pin, entry);
        spin_lock_irqsave(&ioapic_lock, flags);
        set_native_irq_info(use_pci_vector() ? entry.vector : irq, TARGET_CPUS);
        spin_unlock_irqrestore(&ioapic_lock, flags);

        return 0;
}

#endif /* CONFIG_ACPI */

static int __init parse_disable_timer_pin_1(char *arg)
{
        disable_timer_pin_1 = 1;
        return 0;
}
early_param("disable_timer_pin_1", parse_disable_timer_pin_1);

static int __init parse_enable_timer_pin_1(char *arg)
{
        disable_timer_pin_1 = -1;
        return 0;
}
early_param("enable_timer_pin_1", parse_enable_timer_pin_1);

static int __init parse_noapic(char *arg)
{
        /* disable IO-APIC */
        disable_ioapic_setup();
        return 0;
}
early_param("noapic", parse_noapic);