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

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

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


#undef DEBUG_INTERRUPT_ROUTING
#undef OVERRIDE_DEBUG

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

static spinlock_t iosapic_lock = SPIN_LOCK_UNLOCKED;

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

static struct iosapic_intr_info {
	char		*addr;		/* base address of IOSAPIC */
	unsigned int	gsi_base;	/* first GSI assigned to this IOSAPIC */
	char		rte_index;	/* IOSAPIC RTE index (-1 => not an IOSAPIC interrupt) */
	unsigned char	dmode	: 3;	/* delivery mode (see iosapic.h) */
	unsigned char 	polarity: 1;	/* interrupt polarity (see iosapic.h) */
	unsigned char	trigger	: 1;	/* trigger mode (see iosapic.h) */
} iosapic_intr_info[IA64_NUM_VECTORS];

static struct iosapic {
	char		*addr;		/* base address of IOSAPIC */
	unsigned int 	gsi_base;	/* first GSI assigned to this IOSAPIC */
	unsigned short 	num_rte;	/* number of RTE in this IOSAPIC */
	unsigned char	pcat_compat;	/* 8259 compatibility flag */
} iosapic_lists[256] __devinitdata;

static int num_iosapic = 0;


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

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

	return -1;
}

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

	for (info = iosapic_intr_info; info < iosapic_intr_info + IA64_NUM_VECTORS; ++info)
		if (info->gsi_base + info->rte_index == gsi)
			return info - iosapic_intr_info;
	return -1;
}

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

int
gsi_to_irq (unsigned int gsi)
{
	/*
	 * XXX fix me: this assumes an identity mapping vetween IA-64 vector and Linux irq
	 * numbers...
	 */
	return _gsi_to_vector(gsi);
}

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

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

	rte_index = iosapic_intr_info[vector].rte_index;
	if (rte_index < 0)
		return;		/* not an IOSAPIC interrupt */

	addr    = iosapic_intr_info[vector].addr;
	pol     = iosapic_intr_info[vector].polarity;
	trigger = iosapic_intr_info[vector].trigger;
	dmode   = iosapic_intr_info[vector].dmode;

	redir = (dmode == IOSAPIC_LOWEST_PRIORITY) ? 1 : 0;
#ifdef CONFIG_SMP
	{
		unsigned int irq;

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

	low32 = ((pol << IOSAPIC_POLARITY_SHIFT) |
		 (trigger << IOSAPIC_TRIGGER_SHIFT) |
		 (dmode << IOSAPIC_DELIVERY_SHIFT) |
		 vector);

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

	writel(IOSAPIC_RTE_HIGH(rte_index), addr + IOSAPIC_REG_SELECT);
	writel(high32, addr + IOSAPIC_WINDOW);
	writel(IOSAPIC_RTE_LOW(rte_index), addr + IOSAPIC_REG_SELECT);
	writel(low32, addr + IOSAPIC_WINDOW);
}

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

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

	addr = iosapic_intr_info[vec].addr;
	rte_index = iosapic_intr_info[vec].rte_index;

	if (rte_index < 0)
		return;			/* not an IOSAPIC interrupt! */

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		writel(IOSAPIC_RTE_LOW(rte_index), addr + IOSAPIC_REG_SELECT);
		low32 = readl(addr + IOSAPIC_WINDOW);

		low32 |= (1 << IOSAPIC_MASK_SHIFT);    /* set only the mask bit */
		writel(low32, addr + IOSAPIC_WINDOW);
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);
}

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

	addr = iosapic_intr_info[vec].addr;
	rte_index = iosapic_intr_info[vec].rte_index;
	if (rte_index < 0)
		return;			/* not an IOSAPIC interrupt! */

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		writel(IOSAPIC_RTE_LOW(rte_index), addr + IOSAPIC_REG_SELECT);
		low32 = readl(addr + IOSAPIC_WINDOW);

		low32 &= ~(1 << IOSAPIC_MASK_SHIFT);    /* clear only the mask bit */
		writel(low32, addr + IOSAPIC_WINDOW);
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);
}


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

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

	mask &= cpu_online_map;

	if (!mask || vec >= IA64_NUM_VECTORS)
		return;

	dest = cpu_physical_id(ffz(~mask));

	rte_index = iosapic_intr_info[vec].rte_index;
	addr = iosapic_intr_info[vec].addr;

	if (rte_index < 0)
		return;			/* not an IOSAPIC interrupt */

	set_irq_affinity_info(irq, dest, redir);

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

	spin_lock_irqsave(&iosapic_lock, flags);
	{
		/* get current delivery mode by reading the low32 */
		writel(IOSAPIC_RTE_LOW(rte_index), addr + IOSAPIC_REG_SELECT);
		low32 = readl(addr + IOSAPIC_WINDOW);

		low32 &= ~(7 << IOSAPIC_DELIVERY_SHIFT);
		if (redir)
		        /* change delivery mode to lowest priority */
			low32 |= (IOSAPIC_LOWEST_PRIORITY << IOSAPIC_DELIVERY_SHIFT);
		else
		        /* change delivery mode to fixed */
			low32 |= (IOSAPIC_FIXED << IOSAPIC_DELIVERY_SHIFT);

		writel(IOSAPIC_RTE_HIGH(rte_index), addr + IOSAPIC_REG_SELECT);
		writel(high32, addr + IOSAPIC_WINDOW);
		writel(IOSAPIC_RTE_LOW(rte_index), addr + IOSAPIC_REG_SELECT);
		writel(low32, addr + IOSAPIC_WINDOW);
	}
	spin_unlock_irqrestore(&iosapic_lock, flags);
#endif
}

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

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

static void
iosapic_end_level_irq (unsigned int irq)
{
	ia64_vector vec = irq_to_vector(irq);

	writel(vec, iosapic_intr_info[vec].addr + IOSAPIC_EOI);
}

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

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

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

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

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

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

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

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

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

	if (iosapic_intr_info[vector].rte_index >= 0 || iosapic_intr_info[vector].addr
	    || iosapic_intr_info[vector].gsi_base || iosapic_intr_info[vector].dmode
	    || iosapic_intr_info[vector].polarity || iosapic_intr_info[vector].trigger)
	{
		new_vector = ia64_alloc_vector();
		printk("Reassigning vector %d to %d\n", vector, new_vector);
		memcpy(&iosapic_intr_info[new_vector], &iosapic_intr_info[vector],
		       sizeof(struct iosapic_intr_info));
		memset(&iosapic_intr_info[vector], 0, sizeof(struct iosapic_intr_info));
		iosapic_intr_info[vector].rte_index = -1;
	}
}

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

	rte_index = gsi - gsi_base;
	iosapic_intr_info[vector].rte_index = rte_index;
	iosapic_intr_info[vector].polarity = polarity ? IOSAPIC_POL_HIGH : IOSAPIC_POL_LOW;
	iosapic_intr_info[vector].dmode    = delivery;

	/*
	 * In override, it may not provide addr/gsi_base.  GSI is enough to
	 * locate iosapic addr, gsi_base and rte_index by examining
	 * gsi_base and num_rte of registered iosapics (tbd)
	 */
#ifndef	OVERRIDE_DEBUG
	if (iosapic_address) {
		iosapic_intr_info[vector].addr = iosapic_address;
		iosapic_intr_info[vector].gsi_base = gsi_base;
	}
#else
	if (iosapic_address) {
		if (iosapic_intr_info[vector].addr && (iosapic_intr_info[vector].addr != iosapic_address))
			printk("WARN: register_intr: diff IOSAPIC ADDRESS for GSI 0x%x, vector %d\n",
			       gsi, vector);
		iosapic_intr_info[vector].addr = iosapic_address;
		if (iosapic_intr_info[vector].gsi_base && (iosapic_intr_info[vector].gsi_base != gsi_base)) {
			printk("WARN: register_intr: diff GSI base 0x%x for GSI 0x%x, vector %d\n",
			       gsi_base, gsi, vector);
		}
		iosapic_intr_info[vector].gsi_base = gsi_base;
	} else if (!iosapic_intr_info[vector].addr)
		printk("WARN: register_intr: invalid override for GSI 0x%x, vector %d\n",
		       gsi, vector);
#endif
	if (edge_triggered) {
		iosapic_intr_info[vector].trigger = IOSAPIC_EDGE;
		irq_type = &irq_type_iosapic_edge;
	} else {
		iosapic_intr_info[vector].trigger = IOSAPIC_LEVEL;
		irq_type = &irq_type_iosapic_level;
	}

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

/*
 * ACPI can describe IOSAPIC interrupts via static tables and namespace
 * methods.  This provides an interface to register those interrupts and
 * program the IOSAPIC RTE.
 */
int
iosapic_register_intr (unsigned int gsi,
		       unsigned long polarity, unsigned long edge_triggered,
		       unsigned int gsi_base, char *iosapic_address)
{
	int vector;
	unsigned int dest = (ia64_get_lid() >> 16) & 0xffff;

	vector = gsi_to_vector(gsi);
	if (vector < 0)
		vector = ia64_alloc_vector();

	register_intr(gsi, vector, IOSAPIC_LOWEST_PRIORITY,
		      polarity, edge_triggered, gsi_base, iosapic_address);

	printk("GSI 0x%x(%s,%s) -> CPU 0x%04x vector %d\n",
	       gsi, (polarity ? "high" : "low"),
	       (edge_triggered ? "edge" : "level"), dest, vector);

	/* program the IOSAPIC routing table */
	set_rte(vector, dest);
	return vector;
}

/*
 * ACPI calls this when it finds an entry for a platform interrupt.
 * Note that the irq_base and IOSAPIC address must be set in iosapic_init().
 */
int
iosapic_register_platform_intr (u32 int_type, unsigned int gsi,
				int iosapic_vector, u16 eid, u16 id,
				unsigned long polarity, unsigned long edge_triggered,
				unsigned int gsi_base, char *iosapic_address)
{
	unsigned char delivery;
	int vector;
	unsigned int dest = ((id << 8) | eid) & 0xffff;

	switch (int_type) {
	      case ACPI_INTERRUPT_PMI:
		vector = iosapic_vector;
		/*
		 * since PMI vector is alloc'd by FW(ACPI) not by kernel,
		 * we need to make sure the vector is available
		 */
		iosapic_reassign_vector(vector);
		delivery = IOSAPIC_PMI;
		break;
	      case ACPI_INTERRUPT_INIT:
		vector = ia64_alloc_vector();
		delivery = IOSAPIC_INIT;
		break;
	      case ACPI_INTERRUPT_CPEI:
		vector = IA64_PCE_VECTOR;
		delivery = IOSAPIC_LOWEST_PRIORITY;
		break;
	      default:
		printk("iosapic_register_platform_irq(): invalid int type\n");
		return -1;
	}

	register_intr(gsi, vector, delivery, polarity,
		      edge_triggered, gsi_base, iosapic_address);

	printk("PLATFORM int 0x%x: GSI 0x%x(%s,%s) -> CPU 0x%04x vector %d\n",
	       int_type, gsi, (polarity ? "high" : "low"),
	       (edge_triggered ? "edge" : "level"), dest, vector);

	/* program the IOSAPIC routing table */
	set_rte(vector, dest);
	return vector;
}


/*
 * ACPI calls this when it finds an entry for a legacy ISA IRQ override.
 * Note that the gsi_base and IOSAPIC address must be set in iosapic_init().
 */
void
iosapic_override_isa_irq (unsigned int isa_irq, unsigned int gsi,
			  unsigned long polarity,
			  unsigned long edge_triggered)
{
	int index, vector;
	unsigned int gsi_base;
	char *addr;
	unsigned int dest = (ia64_get_lid() >> 16) & 0xffff;

	index = find_iosapic(gsi);

	if (index < 0) {
		printk("ISA: No corresponding IOSAPIC found : ISA IRQ %u -> GSI 0x%x\n",
		       isa_irq, gsi);
		return;
	}

	vector = isa_irq_to_vector(isa_irq);
	addr = iosapic_lists[index].addr;
	gsi_base = iosapic_lists[index].gsi_base;

	register_intr(gsi, vector, IOSAPIC_LOWEST_PRIORITY, polarity, edge_triggered,
		      gsi_base, addr);

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

	/* program the IOSAPIC routing table */
	set_rte(vector, dest);
}

void __devinit
iosapic_init (unsigned long phys_addr, unsigned int gsi_base, int pcat_compat)
{
	int num_rte, vector;
	unsigned int isa_irq, ver;
	char *addr;
	static int first_time = 1;

	if (first_time) {
		first_time = 0;
		for (vector = 0; vector < IA64_NUM_VECTORS; ++vector)
			iosapic_intr_info[vector].rte_index = -1;	/* mark as unused */
	}

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

	addr = ioremap(phys_addr, 0);
	ver = iosapic_version(addr);

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

	iosapic_lists[num_iosapic].addr = addr;
	iosapic_lists[num_iosapic].pcat_compat = pcat_compat;
	iosapic_lists[num_iosapic].gsi_base = gsi_base;
	iosapic_lists[num_iosapic].num_rte = num_rte;
	num_iosapic++;

	printk(KERN_INFO"  IOSAPIC v%x.%x, address 0x%lx, GSIs 0x%x-0x%x\n",
	       (ver & 0xf0) >> 4, (ver & 0x0f), phys_addr, gsi_base, gsi_base + num_rte - 1);

	if ((gsi_base == 0) && pcat_compat) {
		unsigned int dest = (ia64_get_lid() >> 16) & 0xffff;

		/*
		 * Map the legacy ISA devices into the IOSAPIC data.  Some of these may
		 * get reprogrammed later on with data from the ACPI Interrupt Source
		 * Override table.
		 */
		for (isa_irq = 0; isa_irq < 16; ++isa_irq) {
			vector = isa_irq_to_vector(isa_irq);

			register_intr(isa_irq, vector, IOSAPIC_LOWEST_PRIORITY,
				     /* IOSAPIC_POL_HIGH, IOSAPIC_EDGE */
				     1, 1, gsi_base, addr);

			DBG("ISA: IRQ %u -> GSI 0x%x (high,edge) -> CPU 0x%04x vector %d\n",
			    isa_irq, isa_irq, dest, vector);

			/* program the IOSAPIC routing table: */
			set_rte(vector, dest);
		}
	}
}

static void
fixup_vector (int vector, unsigned int gsi, const char *pci_id)
{
	struct hw_interrupt_type *irq_type = &irq_type_iosapic_level;
	irq_desc_t *idesc;
	unsigned int dest;

	idesc = irq_desc(vector);
	if (idesc->handler != irq_type) {
		if (idesc->handler != &no_irq_type)
			printk("IOSAPIC: changing vector %d from %s to %s\n",
			       vector, idesc->handler->typename, irq_type->typename);
		idesc->handler = irq_type;
	}
#ifdef CONFIG_SMP
	/*
	 * For platforms that do not support interrupt redirect via the XTP interface, we
	 * can round-robin the PCI device interrupts to the processors
	 */
	if (!(smp_int_redirect & SMP_IRQ_REDIRECTION)) {
		static int cpu_index = -1;

		do
			if (++cpu_index >= NR_CPUS)
				cpu_index = 0;
		while (!cpu_online(cpu_index));

		dest = cpu_physical_id(cpu_index) & 0xffff;
	} else {
		/*
		 * Direct the interrupt vector to the current cpu, platform redirection
		 * will distribute them.
		 */
		dest = (ia64_get_lid() >> 16) & 0xffff;
	}
#else
	/* direct the interrupt vector to the running cpu id */
	dest = (ia64_get_lid() >> 16) & 0xffff;
#endif
	set_rte(vector, dest);

	printk("IOSAPIC: %s -> GSI 0x%x -> CPU 0x%04x vector %d\n", pci_id, gsi, dest, vector);
}

void __init
iosapic_parse_prt (void)
{
	struct acpi_prt_entry *entry;
	struct list_head *node;
	unsigned int gsi, gsi_base;
	int index, vector, pcat_compat;
	char pci_id[16];
	char *addr;

	list_for_each(node, &acpi_prt.entries) {
		entry = list_entry(node, struct acpi_prt_entry, node);

		/* We're only interested in static (non-link) entries.  */
		if (entry->link.handle)
			continue;

		gsi = entry->link.index;

		vector = gsi_to_vector(gsi);
		if (vector < 0) {
			/* allocate a vector for this interrupt line */
			index = find_iosapic(gsi);

			if (index < 0) {
				printk(KERN_WARNING"IOSAPIC: GSI 0x%x has no IOSAPIC!\n", gsi);
				return;
			}
			addr = iosapic_lists[index].addr;
			gsi_base = iosapic_lists[index].gsi_base;
			pcat_compat = iosapic_lists[index].pcat_compat;

			if (pcat_compat && (gsi < 16))
				vector = isa_irq_to_vector(gsi);
			else
				/* new GSI; allocate a vector for it */
				vector = ia64_alloc_vector();

			register_intr(gsi, vector, IOSAPIC_LOWEST_PRIORITY, 0, 0, gsi_base, addr);
		}
		snprintf(pci_id, sizeof(pci_id), "%02x:%02x:%02x[%c]",
			 entry->id.segment, entry->id.bus, entry->id.device, 'A' + entry->pin);

		fixup_vector(vector, gsi, pci_id);
	}
}
