/*
 *	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
 */

#include <linux/mm.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/config.h>
#include <linux/smp_lock.h>
#include <linux/mc146818rtc.h>

#include <asm/io.h>
#include <asm/smp.h>
#include <asm/desc.h>

#undef APIC_LOCKUP_DEBUG

#define APIC_LOCKUP_DEBUG

static spinlock_t ioapic_lock = SPIN_LOCK_UNLOCKED;

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

/*
 * 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];

/*
 * 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 __init 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;
	}
}

#define __DO_ACTION(R, ACTION, FINAL)					\
									\
{									\
	int pin;							\
	struct irq_pin_list *entry = irq_2_pin + irq;			\
									\
	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);			\
		if (!entry->next)					\
			break;						\
		entry = irq_2_pin + entry->next;			\
	}								\
	FINAL;								\
}

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

DO_ACTION( __mask,             0, |= 0x00010000, io_apic_sync(entry->apic) )
						/* mask = 1 */
DO_ACTION( __unmask,           0, &= 0xfffeffff, )
						/* mask = 0 */
DO_ACTION( __mask_and_edge,    0, = (reg & 0xffff7fff) | 0x00010000, )
						/* mask = 1, trigger = 0 */
DO_ACTION( __unmask_and_level, 0, = (reg & 0xfffeffff) | 0x00008000, )
						/* mask = 0, trigger = 1 */

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);
}

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

	/*
	 * Disable it in the IO-APIC irq-routing table:
	 */
	memset(&entry, 0, sizeof(entry));
	entry.mask = 1;
	spin_lock_irqsave(&ioapic_lock, flags);
	io_apic_write(apic, 0x10 + 2 * pin, *(((int *)&entry) + 0));
	io_apic_write(apic, 0x11 + 2 * pin, *(((int *)&entry) + 1));
	spin_unlock_irqrestore(&ioapic_lock, flags);
}

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);
}

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

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

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

__setup("noapic", noioapic_setup);

static int __init ioapic_setup(char *str)
{
	skip_ioapic_setup = 0;
	return 1;
}

__setup("apic", 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;
	printk(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++) {
		printk(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 __init 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 ||
#ifndef CONFIG_PC9800
		     mp_bus_id_to_type[lbus] == MP_BUS_MCA
#else
		     mp_bus_id_to_type[lbus] == MP_BUS_NEC98
#endif
		    ) &&
		    (mp_irqs[i].mpc_irqtype == type) &&
		    (mp_irqs[i].mpc_srcbusirq == irq))

			return mp_irqs[i].mpc_dstirq;
	}
	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;

	Dprintk("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;
}

/*
 * EISA Edge/Level control register, ELCR
 */
static int __init EISA_ELCR(unsigned int irq)
{
	if (irq < 16) {
		unsigned int port = 0x4d0 + (irq >> 3);
		return (inb(port) >> (irq & 7)) & 1;
	}
	printk(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;
				}
#ifndef CONFIG_PC9800
				case MP_BUS_MCA: /* MCA pin */
				{
					polarity = default_MCA_polarity(idx);
					break;
				}
#else
				case MP_BUS_NEC98: /* NEC 98 pin */
				{
					polarity = default_NEC98_polarity(idx);
					break;
				}
#endif
				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 __init 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;
				}
#ifndef CONFIG_PC9800
				case MP_BUS_MCA: /* MCA pin */
				{
					trigger = default_MCA_trigger(idx);
					break;
				}
#else
				case MP_BUS_NEC98: /* NEC 98 pin */
				{
					trigger = default_NEC98_trigger(idx);
					break;
				}
#endif
				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:
#ifdef CONFIG_PC9800
		case MP_BUS_NEC98:
#endif /* CONFIG_PC9800 */
		{
			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;
			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]) {
				printk(KERN_DEBUG "disabling PIRQ%d\n", pin-16);
			} else {
				irq = pirq_entries[pin-16];
				printk(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;
}

int irq_vector[NR_IRQS] = { FIRST_DEVICE_VECTOR , 0 };

static int __init assign_irq_vector(int irq)
{
	static int current_vector = FIRST_DEVICE_VECTOR, offset = 0;
	if (IO_APIC_VECTOR(irq) > 0)
		return IO_APIC_VECTOR(irq);
next:
	current_vector += 8;
	if (current_vector == SYSCALL_VECTOR)
		goto next;

	if (current_vector > FIRST_SYSTEM_VECTOR) {
		offset++;
		current_vector = FIRST_DEVICE_VECTOR + offset;
	}

	if (current_vector == FIRST_SYSTEM_VECTOR)
		panic("ran out of interrupt sources!");

	IO_APIC_VECTOR(irq) = current_vector;
	return current_vector;
}

extern void (*interrupt[NR_IRQS])(void);
static struct hw_interrupt_type ioapic_level_irq_type;
static struct hw_interrupt_type ioapic_edge_irq_type;

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;

	printk(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 = dest_LowestPrio;
		entry.dest_mode = INT_DELIVERY_MODE;
		entry.mask = 0;				/* enable IRQ */
		entry.dest.logical.logical_dest = TARGET_CPUS;

		idx = find_irq_entry(apic,pin,mp_INT);
		if (idx == -1) {
			if (first_notcon) {
				printk(KERN_DEBUG " IO-APIC (apicid-pin) %d-%d", mp_ioapics[apic].mpc_apicid, pin);
				first_notcon = 0;
			} else
				printk(", %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;
			entry.dest.logical.logical_dest = TARGET_CPUS;
		}

		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 (clustered_apic_mode && (apic != 0) && (irq == 0))
			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;

			if (IO_APIC_irq_trigger(irq))
				irq_desc[irq].handler = &ioapic_level_irq_type;
			else
				irq_desc[irq].handler = &ioapic_edge_irq_type;

			set_intr_gate(vector, interrupt[irq]);
		
			if (!apic && (irq < 16))
				disable_8259A_irq(irq);
		}
		spin_lock_irqsave(&ioapic_lock, flags);
		io_apic_write(apic, 0x11+2*pin, *(((int *)&entry)+1));
		io_apic_write(apic, 0x10+2*pin, *(((int *)&entry)+0));
		spin_unlock_irqrestore(&ioapic_lock, flags);
	}
	}

	if (!first_notcon)
		printk(" not connected.\n");
}

/*
 * Set up the 8259A-master output pin as broadcast to all
 * CPUs.
 */
void __init setup_ExtINT_IRQ0_pin(unsigned int pin, int vector)
{
	struct IO_APIC_route_entry entry;
	unsigned long flags;

	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_DELIVERY_MODE;
	entry.mask = 0;					/* unmask IRQ now */
	entry.dest.logical.logical_dest = TARGET_CPUS;
	entry.delivery_mode = dest_LowestPrio;
	entry.polarity = 0;
	entry.trigger = 0;
	entry.vector = vector;

	/*
	 * The timer IRQ doesnt have to know that behind the
	 * scene we have a 8259A-master in AEOI mode ...
	 */
	irq_desc[0].handler = &ioapic_edge_irq_type;

	/*
	 * Add it to the IO-APIC irq-routing table:
	 */
	spin_lock_irqsave(&ioapic_lock, flags);
	io_apic_write(0, 0x11+2*pin, *(((int *)&entry)+1));
	io_apic_write(0, 0x10+2*pin, *(((int *)&entry)+0));
	spin_unlock_irqrestore(&ioapic_lock, flags);

	enable_8259A_irq(0);
}

void __init UNEXPECTED_IO_APIC(void)
{
	printk(KERN_WARNING " WARNING: unexpected IO-APIC, please mail\n");
	printk(KERN_WARNING "          to linux-smp@vger.kernel.org\n");
}

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

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

	printk("\n");
	printk(KERN_DEBUG "IO APIC #%d......\n", mp_ioapics[apic].mpc_apicid);
	printk(KERN_DEBUG ".... register #00: %08X\n", *(int *)&reg_00);
	printk(KERN_DEBUG ".......    : physical APIC id: %02X\n", reg_00.ID);
	if (reg_00.__reserved_1 || reg_00.__reserved_2)
		UNEXPECTED_IO_APIC();

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

	printk(KERN_DEBUG ".......     : PRQ implemented: %X\n", reg_01.PRQ);
	printk(KERN_DEBUG ".......     : IO APIC version: %04X\n", reg_01.version);
	if (	(reg_01.version != 0x01) && /* 82489DX IO-APICs */
		(reg_01.version != 0x10) && /* oldest IO-APICs */
		(reg_01.version != 0x11) && /* Pentium/Pro IO-APICs */
		(reg_01.version != 0x13) && /* Xeon IO-APICs */
		(reg_01.version != 0x20)    /* Intel P64H (82806 AA) */
	)
		UNEXPECTED_IO_APIC();
	if (reg_01.__reserved_1 || reg_01.__reserved_2)
		UNEXPECTED_IO_APIC();

	if (reg_01.version >= 0x10) {
		printk(KERN_DEBUG ".... register #02: %08X\n", *(int *)&reg_02);
		printk(KERN_DEBUG ".......     : arbitration: %02X\n", reg_02.arbitration);
		if (reg_02.__reserved_1 || reg_02.__reserved_2)
			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.entries; i++) {
		struct IO_APIC_route_entry entry;

		spin_lock_irqsave(&ioapic_lock, flags);
		*(((int *)&entry)+0) = io_apic_read(apic, 0x10+i*2);
		*(((int *)&entry)+1) = io_apic_read(apic, 0x11+i*2);
		spin_unlock_irqrestore(&ioapic_lock, flags);

		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
		);
	}
	}
	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;
}

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

	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;

	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)
{
	smp_call_function(print_local_APIC, NULL, 1, 1);
	print_local_APIC(NULL);
}

void /*__init*/ print_PIC(void)
{
	extern spinlock_t i8259A_lock;
	unsigned int v, flags;

	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);
}

static void __init enable_IO_APIC(void)
{
	struct IO_APIC_reg_01 reg_01;
	int i;
	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 (i = 0; i < nr_ioapics; i++) {
		spin_lock_irqsave(&ioapic_lock, flags);
		*(int *)&reg_01 = io_apic_read(i, 1);
		spin_unlock_irqrestore(&ioapic_lock, flags);
		nr_ioapic_registers[i] = reg_01.entries+1;
	}

	/*
	 * 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();

	disconnect_bsp_APIC();
}

/*
 * 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
 */

static void __init setup_ioapic_ids_from_mpc (void)
{
	struct IO_APIC_reg_00 reg_00;
	unsigned long phys_id_present_map = phys_cpu_present_map;
	int apic;
	int i;
	unsigned char old_id;
	unsigned long flags;

	if (clustered_apic_mode)
		/* We don't have a good way to do this yet - hack */
		phys_id_present_map = (u_long) 0xf;
	/*
	 * 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);
		*(int *)&reg_00 = io_apic_read(apic, 0);
		spin_unlock_irqrestore(&ioapic_lock, flags);
		
		old_id = mp_ioapics[apic].mpc_apicid;

		if (mp_ioapics[apic].mpc_apicid >= 0xf) {
			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.ID);
			mp_ioapics[apic].mpc_apicid = reg_00.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 (phys_id_present_map & (1 << 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 < 0xf; i++)
				if (!(phys_id_present_map & (1 << i)))
					break;
			if (i >= 0xf)
				panic("Max APIC ID exceeded!\n");
			printk(KERN_ERR "... fixing up to %d. (tell your hw vendor)\n",
				i);
			phys_id_present_map |= 1 << i;
			mp_ioapics[apic].mpc_apicid = i;
		} else {
			printk("Setting %d in the phys_id_present_map\n", mp_ioapics[apic].mpc_apicid);
			phys_id_present_map |= 1 << mp_ioapics[apic].mpc_apicid;
		}


		/*
		 * 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.
	 	 */
		printk(KERN_INFO "...changing IO-APIC physical APIC ID to %d ...",
					mp_ioapics[apic].mpc_apicid);

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

		/*
		 * Sanity check
		 */
		spin_lock_irqsave(&ioapic_lock, flags);
		*(int *)&reg_00 = io_apic_read(apic, 0);
		spin_unlock_irqrestore(&ioapic_lock, flags);
		if (reg_00.ID != mp_ioapics[apic].mpc_apicid)
			panic("could not set ID!\n");
		else
			printk(" ok.\n");
	}
}

/*
 * 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 int t1 = jiffies;

	sti();
	/* 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.
 */
#define enable_edge_ioapic_irq unmask_IO_APIC_irq

static void disable_edge_ioapic_irq (unsigned int irq) { /* nothing */ }

/*
 * 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;
}

#define shutdown_edge_ioapic_irq	disable_edge_ioapic_irq

/*
 * 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)
{
	if ((irq_desc[irq].status & (IRQ_PENDING | IRQ_DISABLED))
					== (IRQ_PENDING | IRQ_DISABLED))
		mask_IO_APIC_irq(irq);
	ack_APIC_irq();
}

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


/*
 * 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 */
}

#define shutdown_level_ioapic_irq	mask_IO_APIC_irq
#define enable_level_ioapic_irq		unmask_IO_APIC_irq
#define disable_level_ioapic_irq	mask_IO_APIC_irq

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

/*
 * 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)))) {
#ifdef APIC_LOCKUP_DEBUG
		struct irq_pin_list *entry;
#endif

#ifdef APIC_MISMATCH_DEBUG
		atomic_inc(&irq_mis_count);
#endif
		spin_lock(&ioapic_lock);
		__mask_and_edge_IO_APIC_irq(irq);
#ifdef APIC_LOCKUP_DEBUG
		for (entry = irq_2_pin + irq;;) {
			unsigned int reg;

			if (entry->pin == -1)
				break;
			reg = io_apic_read(entry->apic, 0x10 + entry->pin * 2);
			if (reg & 0x00004000)
				printk(KERN_CRIT "Aieee!!!  Remote IRR"
					" still set after unlock!\n");
			if (!entry->next)
				break;
			entry = irq_2_pin + entry->next;
		}
#endif
		__unmask_and_level_IO_APIC_irq(irq);
		spin_unlock(&ioapic_lock);
	}
}

static void mask_and_ack_level_ioapic_irq (unsigned int irq) { /* nothing */ }

static void set_ioapic_affinity (unsigned int irq, unsigned long mask)
{
	unsigned long flags;
	/*
	 * Only the first 8 bits are valid.
	 */
	mask = mask << 24;

	spin_lock_irqsave(&ioapic_lock, flags);
	__DO_ACTION(1, = mask, )
	spin_unlock_irqrestore(&ioapic_lock, flags);
}

/*
 * 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_irq_type = {
	"IO-APIC-edge",
	startup_edge_ioapic_irq,
	shutdown_edge_ioapic_irq,
	enable_edge_ioapic_irq,
	disable_edge_ioapic_irq,
	ack_edge_ioapic_irq,
	end_edge_ioapic_irq,
	set_ioapic_affinity,
};

static struct hw_interrupt_type ioapic_level_irq_type = {
	"IO-APIC-level",
	startup_level_ioapic_irq,
	shutdown_level_ioapic_irq,
	enable_level_ioapic_irq,
	disable_level_ioapic_irq,
	mask_and_ack_level_ioapic_irq,
	end_level_ioapic_irq,
	set_ioapic_affinity,
};

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) && !IO_APIC_VECTOR(irq)) {
			/*
			 * 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].handler = &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 = {
	"local-APIC-edge",
	NULL, /* startup_irq() not used for IRQ0 */
	NULL, /* shutdown_irq() not used for IRQ0 */
	enable_lapic_irq,
	disable_lapic_irq,
	ack_lapic_irq,
	end_lapic_irq
};

static void enable_NMI_through_LVT0 (void * dummy)
{
	unsigned int v, ver;

	ver = apic_read(APIC_LVR);
	ver = GET_APIC_VERSION(ver);
	v = APIC_DM_NMI;			/* unmask and set to NMI */
	if (!APIC_INTEGRATED(ver))		/* 82489DX */
		v |= APIC_LVT_LEVEL_TRIGGER;
	apic_write_around(APIC_LVT0, v);
}

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.
	 */ 
	printk(KERN_INFO "activating NMI Watchdog ...");

	smp_call_function(enable_NMI_through_LVT0, NULL, 1, 1);
	enable_NMI_through_LVT0(NULL);

	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 unlock_ExtINT_logic(void)
{
	int pin, i;
	struct IO_APIC_route_entry entry0, entry1;
	unsigned char save_control, save_freq_select;
	unsigned long flags;

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

	spin_lock_irqsave(&ioapic_lock, flags);
	*(((int *)&entry0) + 1) = io_apic_read(0, 0x11 + 2 * pin);
	*(((int *)&entry0) + 0) = io_apic_read(0, 0x10 + 2 * pin);
	spin_unlock_irqrestore(&ioapic_lock, flags);
	clear_IO_APIC_pin(0, 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;

	spin_lock_irqsave(&ioapic_lock, flags);
	io_apic_write(0, 0x11 + 2 * pin, *(((int *)&entry1) + 1));
	io_apic_write(0, 0x10 + 2 * pin, *(((int *)&entry1) + 0));
	spin_unlock_irqrestore(&ioapic_lock, flags);

	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(0, pin);

	spin_lock_irqsave(&ioapic_lock, flags);
	io_apic_write(0, 0x11 + 2 * pin, *(((int *)&entry0) + 1));
	io_apic_write(0, 0x10 + 2 * pin, *(((int *)&entry0) + 0));
	spin_unlock_irqrestore(&ioapic_lock, flags);
}

/*
 * 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)
{
	extern int timer_ack;
	int pin1, 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;
	enable_8259A_irq(0);

	pin1 = find_isa_irq_pin(0, mp_INT);
	pin2 = find_isa_irq_pin(0, mp_ExtINT);

	printk(KERN_INFO "..TIMER: vector=0x%02X pin1=%d pin2=%d\n", vector, pin1, 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);
				check_nmi_watchdog();
			}
			return;
		}
		clear_IO_APIC_pin(0, 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(pin2, vector);
		if (timer_irq_works()) {
			printk("works.\n");
			if (pin1 != -1)
				replace_pin_at_irq(0, 0, pin1, 0, pin2);
			else
				add_pin_to_irq(0, 0, pin2);
			if (nmi_watchdog == NMI_IO_APIC) {
				setup_nmi();
				check_nmi_watchdog();
			}
			return;
		}
		/*
		 * Cleanup, just in case ...
		 */
		clear_IO_APIC_pin(0, pin2);
	}
	printk(" failed.\n");

	if (nmi_watchdog) {
		printk(KERN_WARNING "timer doesnt 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].handler = &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...");

	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! pester mingo@redhat.com");
}

/*
 *
 * IRQ's that are handled by the old PIC in all cases:
 * - 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.
 * - There used to be IRQ13 here as well, but all
 *   MPS-compliant must not use it for FPU coupling and we
 *   want to use exception 16 anyway.  And there are
 *   systems who connect it to an I/O APIC for other uses.
 *   Thus we don't mark it special any longer.
 *
 * Additionally, something is definitely wrong with irq9
 * on PIIX4 boards.
 */
#ifndef CONFIG_PC9800
#define PIC_IRQS	(1<<2)
#else
/* PC-9800 uses IRQ7 for the cascade IRQ. */
#define PIC_IRQS	(1<<7)
#endif

void __init setup_IO_APIC(void)
{
	enable_IO_APIC();

	io_apic_irqs = ~PIC_IRQS;
	printk("ENABLING IO-APIC IRQs\n");

	/*
	 * Set up the IO-APIC IRQ routing table by parsing the MP-BIOS
	 * mptable:
	 */
	setup_ioapic_ids_from_mpc();
	sync_Arb_IDs();
	setup_IO_APIC_irqs();
	init_IO_APIC_traps();
	check_timer();
	print_IO_APIC();
}
