// SPDX-License-Identifier: GPL-2.0
/*
 *	Intel IO-APIC support for multi-Pentium hosts.
 *
 *	Copyright (C) 1997, 1998, 1999, 2000, 2009 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
 *
 * Historical information which is worth to be preserved:
 *
 * - SiS APIC rmw bug:
 *
 *	We used to have a workaround for a bug in SiS chips which
 *	required to rewrite the index register for a read-modify-write
 *	operation as the chip lost the index information which was
 *	setup for the read already. We cache the data now, so that
 *	workaround has been removed.
 */

#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/pci.h>
#include <linux/mc146818rtc.h>
#include <linux/compiler.h>
#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/syscore_ops.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/jiffies.h>	/* time_after() */
#include <linux/slab.h>
#include <linux/memblock.h>
#include <linux/msi.h>

#include <asm/irqdomain.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/cpu.h>
#include <asm/desc.h>
#include <asm/proto.h>
#include <asm/acpi.h>
#include <asm/dma.h>
#include <asm/timer.h>
#include <asm/time.h>
#include <asm/i8259.h>
#include <asm/setup.h>
#include <asm/irq_remapping.h>
#include <asm/hw_irq.h>
#include <asm/apic.h>
#include <asm/pgtable.h>
#include <asm/x86_init.h>

#define	for_each_ioapic(idx)		\
	for ((idx) = 0; (idx) < nr_ioapics; (idx)++)
#define	for_each_ioapic_reverse(idx)	\
	for ((idx) = nr_ioapics - 1; (idx) >= 0; (idx)--)
#define	for_each_pin(idx, pin)		\
	for ((pin) = 0; (pin) < ioapics[(idx)].nr_registers; (pin)++)
#define	for_each_ioapic_pin(idx, pin)	\
	for_each_ioapic((idx))		\
		for_each_pin((idx), (pin))
#define for_each_irq_pin(entry, head) \
	list_for_each_entry(entry, &head, list)

static DEFINE_RAW_SPINLOCK(ioapic_lock);
static DEFINE_MUTEX(ioapic_mutex);
static unsigned int ioapic_dynirq_base;
static int ioapic_initialized;

struct irq_pin_list {
	struct list_head	list;
	int			apic, pin;
};

struct mp_chip_data {
	struct list_head		irq_2_pin;
	struct IO_APIC_route_entry	entry;
	bool				is_level;
	bool				active_low;
	bool				isa_irq;
	u32				count;
};

struct mp_ioapic_gsi {
	u32 gsi_base;
	u32 gsi_end;
};

static struct ioapic {
	/* # of IRQ routing registers */
	int				nr_registers;
	/* Saved state during suspend/resume, or while enabling intr-remap. */
	struct IO_APIC_route_entry	*saved_registers;
	/* I/O APIC config */
	struct mpc_ioapic		mp_config;
	/* IO APIC gsi routing info */
	struct mp_ioapic_gsi		gsi_config;
	struct ioapic_domain_cfg	irqdomain_cfg;
	struct irq_domain		*irqdomain;
	struct resource			*iomem_res;
} ioapics[MAX_IO_APICS];

#define mpc_ioapic_ver(ioapic_idx)	ioapics[ioapic_idx].mp_config.apicver

int mpc_ioapic_id(int ioapic_idx)
{
	return ioapics[ioapic_idx].mp_config.apicid;
}

unsigned int mpc_ioapic_addr(int ioapic_idx)
{
	return ioapics[ioapic_idx].mp_config.apicaddr;
}

static inline struct mp_ioapic_gsi *mp_ioapic_gsi_routing(int ioapic_idx)
{
	return &ioapics[ioapic_idx].gsi_config;
}

static inline int mp_ioapic_pin_count(int ioapic)
{
	struct mp_ioapic_gsi *gsi_cfg = mp_ioapic_gsi_routing(ioapic);

	return gsi_cfg->gsi_end - gsi_cfg->gsi_base + 1;
}

static inline u32 mp_pin_to_gsi(int ioapic, int pin)
{
	return mp_ioapic_gsi_routing(ioapic)->gsi_base + pin;
}

static inline bool mp_is_legacy_irq(int irq)
{
	return irq >= 0 && irq < nr_legacy_irqs();
}

static inline struct irq_domain *mp_ioapic_irqdomain(int ioapic)
{
	return ioapics[ioapic].irqdomain;
}

int nr_ioapics;

/* The one past the highest gsi number used */
u32 gsi_top;

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

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

#ifdef CONFIG_EISA
int mp_bus_id_to_type[MAX_MP_BUSSES];
#endif

DECLARE_BITMAP(mp_bus_not_pci, MAX_MP_BUSSES);

bool ioapic_is_disabled __ro_after_init;

/**
 * disable_ioapic_support() - disables ioapic support at runtime
 */
void disable_ioapic_support(void)
{
#ifdef CONFIG_PCI
	noioapicquirk = 1;
	noioapicreroute = -1;
#endif
	ioapic_is_disabled = true;
}

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

/* Will be called in mpparse/ACPI codes for saving IRQ info */
void mp_save_irq(struct mpc_intsrc *m)
{
	int i;

	apic_pr_verbose("Int: type %d, pol %d, trig %d, bus %02x, IRQ %02x, APIC ID %x, APIC INT %02x\n",
			m->irqtype, m->irqflag & 3, (m->irqflag >> 2) & 3, m->srcbus,
			m->srcbusirq, m->dstapic, m->dstirq);

	for (i = 0; i < mp_irq_entries; i++) {
		if (!memcmp(&mp_irqs[i], m, sizeof(*m)))
			return;
	}

	memcpy(&mp_irqs[mp_irq_entries], m, sizeof(*m));
	if (++mp_irq_entries == MAX_IRQ_SOURCES)
		panic("Max # of irq sources exceeded!!\n");
}

static void alloc_ioapic_saved_registers(int idx)
{
	size_t size;

	if (ioapics[idx].saved_registers)
		return;

	size = sizeof(struct IO_APIC_route_entry) * ioapics[idx].nr_registers;
	ioapics[idx].saved_registers = kzalloc(size, GFP_KERNEL);
	if (!ioapics[idx].saved_registers)
		pr_err("IOAPIC %d: suspend/resume impossible!\n", idx);
}

static void free_ioapic_saved_registers(int idx)
{
	kfree(ioapics[idx].saved_registers);
	ioapics[idx].saved_registers = NULL;
}

int __init arch_early_ioapic_init(void)
{
	int i;

	if (!nr_legacy_irqs())
		io_apic_irqs = ~0UL;

	for_each_ioapic(i)
		alloc_ioapic_saved_registers(i);

	return 0;
}

struct io_apic {
	unsigned int index;
	unsigned int unused[3];
	unsigned int data;
	unsigned int unused2[11];
	unsigned int eoi;
};

static __attribute_const__ struct io_apic __iomem *io_apic_base(int idx)
{
	return (void __iomem *) __fix_to_virt(FIX_IO_APIC_BASE_0 + idx)
		+ (mpc_ioapic_addr(idx) & ~PAGE_MASK);
}

static inline void io_apic_eoi(unsigned int apic, unsigned int vector)
{
	struct io_apic __iomem *io_apic = io_apic_base(apic);

	writel(vector, &io_apic->eoi);
}

unsigned int native_io_apic_read(unsigned int apic, unsigned int reg)
{
	struct io_apic __iomem *io_apic = io_apic_base(apic);

	writel(reg, &io_apic->index);
	return readl(&io_apic->data);
}

static void io_apic_write(unsigned int apic, unsigned int reg,
			  unsigned int value)
{
	struct io_apic __iomem *io_apic = io_apic_base(apic);

	writel(reg, &io_apic->index);
	writel(value, &io_apic->data);
}

static struct IO_APIC_route_entry __ioapic_read_entry(int apic, int pin)
{
	struct IO_APIC_route_entry entry;

	entry.w1 = io_apic_read(apic, 0x10 + 2 * pin);
	entry.w2 = io_apic_read(apic, 0x11 + 2 * pin);

	return entry;
}

static struct IO_APIC_route_entry ioapic_read_entry(int apic, int pin)
{
	guard(raw_spinlock_irqsave)(&ioapic_lock);
	return __ioapic_read_entry(apic, pin);
}

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

static void ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
{
	guard(raw_spinlock_irqsave)(&ioapic_lock);
	__ioapic_write_entry(apic, pin, e);
}

/*
 * When we mask an IO APIC routing entry, we need to write the low
 * word first, in order to set the mask bit before we change the
 * high bits!
 */
static void ioapic_mask_entry(int apic, int pin)
{
	struct IO_APIC_route_entry e = { .masked = true };

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	io_apic_write(apic, 0x10 + 2*pin, e.w1);
	io_apic_write(apic, 0x11 + 2*pin, e.w2);
}

/*
 * 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 bool add_pin_to_irq_node(struct mp_chip_data *data, int node, int apic, int pin)
{
	struct irq_pin_list *entry;

	/* Don't allow duplicates */
	for_each_irq_pin(entry, data->irq_2_pin) {
		if (entry->apic == apic && entry->pin == pin)
			return true;
	}

	entry = kzalloc_node(sizeof(struct irq_pin_list), GFP_ATOMIC, node);
	if (!entry) {
		pr_err("Cannot allocate irq_pin_list (%d,%d,%d)\n", node, apic, pin);
		return false;
	}

	entry->apic = apic;
	entry->pin = pin;
	list_add_tail(&entry->list, &data->irq_2_pin);
	return true;
}

static void __remove_pin_from_irq(struct mp_chip_data *data, int apic, int pin)
{
	struct irq_pin_list *tmp, *entry;

	list_for_each_entry_safe(entry, tmp, &data->irq_2_pin, list) {
		if (entry->apic == apic && entry->pin == pin) {
			list_del(&entry->list);
			kfree(entry);
			return;
		}
	}
}

static void io_apic_modify_irq(struct mp_chip_data *data, bool masked,
			       void (*final)(struct irq_pin_list *entry))
{
	struct irq_pin_list *entry;

	data->entry.masked = masked;

	for_each_irq_pin(entry, data->irq_2_pin) {
		io_apic_write(entry->apic, 0x10 + 2 * entry->pin, data->entry.w1);
		if (final)
			final(entry);
	}
}

/*
 * Synchronize the IO-APIC and the CPU by doing a dummy read from the
 * IO-APIC
 */
static void io_apic_sync(struct irq_pin_list *entry)
{
	struct io_apic __iomem *io_apic;

	io_apic = io_apic_base(entry->apic);
	readl(&io_apic->data);
}

static void mask_ioapic_irq(struct irq_data *irq_data)
{
	struct mp_chip_data *data = irq_data->chip_data;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	io_apic_modify_irq(data, true, &io_apic_sync);
}

static void __unmask_ioapic(struct mp_chip_data *data)
{
	io_apic_modify_irq(data, false, NULL);
}

static void unmask_ioapic_irq(struct irq_data *irq_data)
{
	struct mp_chip_data *data = irq_data->chip_data;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	__unmask_ioapic(data);
}

/*
 * IO-APIC versions below 0x20 don't support EOI register.
 * For the record, here is the information about various versions:
 *     0Xh     82489DX
 *     1Xh     I/OAPIC or I/O(x)APIC which are not PCI 2.2 Compliant
 *     2Xh     I/O(x)APIC which is PCI 2.2 Compliant
 *     30h-FFh Reserved
 *
 * Some of the Intel ICH Specs (ICH2 to ICH5) documents the io-apic
 * version as 0x2. This is an error with documentation and these ICH chips
 * use io-apic's of version 0x20.
 *
 * For IO-APIC's with EOI register, we use that to do an explicit EOI.
 * Otherwise, we simulate the EOI message manually by changing the trigger
 * mode to edge and then back to level, with RTE being masked during this.
 */
static void __eoi_ioapic_pin(int apic, int pin, int vector)
{
	if (mpc_ioapic_ver(apic) >= 0x20) {
		io_apic_eoi(apic, vector);
	} else {
		struct IO_APIC_route_entry entry, entry1;

		entry = entry1 = __ioapic_read_entry(apic, pin);

		/* Mask the entry and change the trigger mode to edge. */
		entry1.masked = true;
		entry1.is_level = false;

		__ioapic_write_entry(apic, pin, entry1);

		/* Restore the previous level triggered entry. */
		__ioapic_write_entry(apic, pin, entry);
	}
}

static void eoi_ioapic_pin(int vector, struct mp_chip_data *data)
{
	struct irq_pin_list *entry;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	for_each_irq_pin(entry, data->irq_2_pin)
		__eoi_ioapic_pin(entry->apic, entry->pin, vector);
}

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 == APIC_DELIVERY_MODE_SMI)
		return;

	/*
	 * Make sure the entry is masked and re-read the contents to check
	 * if it is a level triggered pin and if the remote-IRR is set.
	 */
	if (!entry.masked) {
		entry.masked = true;
		ioapic_write_entry(apic, pin, entry);
		entry = ioapic_read_entry(apic, pin);
	}

	if (entry.irr) {
		/*
		 * Make sure the trigger mode is set to level. Explicit EOI
		 * doesn't clear the remote-IRR if the trigger mode is not
		 * set to level.
		 */
		if (!entry.is_level) {
			entry.is_level = true;
			ioapic_write_entry(apic, pin, entry);
		}
		guard(raw_spinlock_irqsave)(&ioapic_lock);
		__eoi_ioapic_pin(apic, pin, entry.vector);
	}

	/*
	 * Clear the rest of the bits in the IO-APIC RTE except for the mask
	 * bit.
	 */
	ioapic_mask_entry(apic, pin);
	entry = ioapic_read_entry(apic, pin);
	if (entry.irr)
		pr_err("Unable to reset IRR for apic: %d, pin :%d\n",
		       mpc_ioapic_id(apic), pin);
}

void clear_IO_APIC (void)
{
	int apic, pin;

	for_each_ioapic_pin(apic, pin)
		clear_IO_APIC_pin(apic, pin);
}

#ifdef CONFIG_X86_32
/*
 * 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] = {
	[0 ... MAX_PIRQS - 1] = -1
};

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

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

	apic_pr_verbose("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_pr_verbose("... 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);
#endif /* CONFIG_X86_32 */

/*
 * Saves all the IO-APIC RTE's
 */
int save_ioapic_entries(void)
{
	int apic, pin;
	int err = 0;

	for_each_ioapic(apic) {
		if (!ioapics[apic].saved_registers) {
			err = -ENOMEM;
			continue;
		}

		for_each_pin(apic, pin)
			ioapics[apic].saved_registers[pin] = ioapic_read_entry(apic, pin);
	}

	return err;
}

/*
 * Mask all IO APIC entries.
 */
void mask_ioapic_entries(void)
{
	int apic, pin;

	for_each_ioapic(apic) {
		if (!ioapics[apic].saved_registers)
			continue;

		for_each_pin(apic, pin) {
			struct IO_APIC_route_entry entry;

			entry = ioapics[apic].saved_registers[pin];
			if (!entry.masked) {
				entry.masked = true;
				ioapic_write_entry(apic, pin, entry);
			}
		}
	}
}

/*
 * Restore IO APIC entries which was saved in the ioapic structure.
 */
int restore_ioapic_entries(void)
{
	int apic, pin;

	for_each_ioapic(apic) {
		if (!ioapics[apic].saved_registers)
			continue;

		for_each_pin(apic, pin)
			ioapic_write_entry(apic, pin, ioapics[apic].saved_registers[pin]);
	}
	return 0;
}

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

	for (i = 0; i < mp_irq_entries; i++) {
		if (mp_irqs[i].irqtype == type &&
		    (mp_irqs[i].dstapic == mpc_ioapic_id(ioapic_idx) ||
		     mp_irqs[i].dstapic == MP_APIC_ALL) &&
		    mp_irqs[i].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].srcbus;

		if (test_bit(lbus, mp_bus_not_pci) && (mp_irqs[i].irqtype == type) &&
		    (mp_irqs[i].srcbusirq == irq))
			return mp_irqs[i].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].srcbus;

		if (test_bit(lbus, mp_bus_not_pci) && (mp_irqs[i].irqtype == type) &&
		    (mp_irqs[i].srcbusirq == irq))
			break;
	}

	if (i < mp_irq_entries) {
		int ioapic_idx;

		for_each_ioapic(ioapic_idx) {
			if (mpc_ioapic_id(ioapic_idx) == mp_irqs[i].dstapic)
				return ioapic_idx;
		}
	}

	return -1;
}

static bool irq_active_low(int idx)
{
	int bus = mp_irqs[idx].srcbus;

	/*
	 * Determine IRQ line polarity (high active or low active):
	 */
	switch (mp_irqs[idx].irqflag & MP_IRQPOL_MASK) {
	case MP_IRQPOL_DEFAULT:
		/*
		 * Conforms to spec, ie. bus-type dependent polarity.  PCI
		 * defaults to low active. [E]ISA defaults to high active.
		 */
		return !test_bit(bus, mp_bus_not_pci);
	case MP_IRQPOL_ACTIVE_HIGH:
		return false;
	case MP_IRQPOL_RESERVED:
		pr_warn("IOAPIC: Invalid polarity: 2, defaulting to low\n");
		fallthrough;
	case MP_IRQPOL_ACTIVE_LOW:
	default: /* Pointless default required due to do gcc stupidity */
		return true;
	}
}

#ifdef CONFIG_EISA
/*
 * EISA Edge/Level control register, ELCR
 */
static bool EISA_ELCR(unsigned int irq)
{
	if (irq < nr_legacy_irqs()) {
		unsigned int port = PIC_ELCR1 + (irq >> 3);
		return (inb(port) >> (irq & 7)) & 1;
	}
	apic_pr_verbose("Broken MPtable reports ISA irq %d\n", irq);
	return false;
}

/*
 * EISA interrupts are always active high and can be edge or level
 * triggered 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.
 */
static bool eisa_irq_is_level(int idx, int bus, bool level)
{
	switch (mp_bus_id_to_type[bus]) {
	case MP_BUS_PCI:
	case MP_BUS_ISA:
		return level;
	case MP_BUS_EISA:
		return EISA_ELCR(mp_irqs[idx].srcbusirq);
	}
	pr_warn("IOAPIC: Invalid srcbus: %d defaulting to level\n", bus);
	return true;
}
#else
static inline int eisa_irq_is_level(int idx, int bus, bool level)
{
	return level;
}
#endif

static bool irq_is_level(int idx)
{
	int bus = mp_irqs[idx].srcbus;
	bool level;

	/*
	 * Determine IRQ trigger mode (edge or level sensitive):
	 */
	switch (mp_irqs[idx].irqflag & MP_IRQTRIG_MASK) {
	case MP_IRQTRIG_DEFAULT:
		/*
		 * Conforms to spec, ie. bus-type dependent trigger
		 * mode. PCI defaults to level, ISA to edge.
		 */
		level = !test_bit(bus, mp_bus_not_pci);
		/* Take EISA into account */
		return eisa_irq_is_level(idx, bus, level);
	case MP_IRQTRIG_EDGE:
		return false;
	case MP_IRQTRIG_RESERVED:
		pr_warn("IOAPIC: Invalid trigger mode 2 defaulting to level\n");
		fallthrough;
	case MP_IRQTRIG_LEVEL:
	default: /* Pointless default required due to do gcc stupidity */
		return true;
	}
}

static int __acpi_get_override_irq(u32 gsi, bool *trigger, bool *polarity)
{
	int ioapic, pin, idx;

	if (ioapic_is_disabled)
		return -1;

	ioapic = mp_find_ioapic(gsi);
	if (ioapic < 0)
		return -1;

	pin = mp_find_ioapic_pin(ioapic, gsi);
	if (pin < 0)
		return -1;

	idx = find_irq_entry(ioapic, pin, mp_INT);
	if (idx < 0)
		return -1;

	*trigger = irq_is_level(idx);
	*polarity = irq_active_low(idx);
	return 0;
}

#ifdef CONFIG_ACPI
int acpi_get_override_irq(u32 gsi, int *is_level, int *active_low)
{
	*is_level = *active_low = 0;
	return __acpi_get_override_irq(gsi, (bool *)is_level,
				       (bool *)active_low);
}
#endif

void ioapic_set_alloc_attr(struct irq_alloc_info *info, int node,
			   int trigger, int polarity)
{
	init_irq_alloc_info(info, NULL);
	info->type = X86_IRQ_ALLOC_TYPE_IOAPIC;
	info->ioapic.node = node;
	info->ioapic.is_level = trigger;
	info->ioapic.active_low = polarity;
	info->ioapic.valid = 1;
}

static void ioapic_copy_alloc_attr(struct irq_alloc_info *dst,
				   struct irq_alloc_info *src,
				   u32 gsi, int ioapic_idx, int pin)
{
	bool level, pol_low;

	copy_irq_alloc_info(dst, src);
	dst->type = X86_IRQ_ALLOC_TYPE_IOAPIC;
	dst->devid = mpc_ioapic_id(ioapic_idx);
	dst->ioapic.pin = pin;
	dst->ioapic.valid = 1;
	if (src && src->ioapic.valid) {
		dst->ioapic.node = src->ioapic.node;
		dst->ioapic.is_level = src->ioapic.is_level;
		dst->ioapic.active_low = src->ioapic.active_low;
	} else {
		dst->ioapic.node = NUMA_NO_NODE;
		if (__acpi_get_override_irq(gsi, &level, &pol_low) >= 0) {
			dst->ioapic.is_level = level;
			dst->ioapic.active_low = pol_low;
		} else {
			/*
			 * PCI interrupts are always active low level
			 * triggered.
			 */
			dst->ioapic.is_level = true;
			dst->ioapic.active_low = true;
		}
	}
}

static int ioapic_alloc_attr_node(struct irq_alloc_info *info)
{
	return (info && info->ioapic.valid) ? info->ioapic.node : NUMA_NO_NODE;
}

static void mp_register_handler(unsigned int irq, bool level)
{
	irq_flow_handler_t hdl;
	bool fasteoi;

	if (level) {
		irq_set_status_flags(irq, IRQ_LEVEL);
		fasteoi = true;
	} else {
		irq_clear_status_flags(irq, IRQ_LEVEL);
		fasteoi = false;
	}

	hdl = fasteoi ? handle_fasteoi_irq : handle_edge_irq;
	__irq_set_handler(irq, hdl, 0, fasteoi ? "fasteoi" : "edge");
}

static bool mp_check_pin_attr(int irq, struct irq_alloc_info *info)
{
	struct mp_chip_data *data = irq_get_chip_data(irq);

	/*
	 * setup_IO_APIC_irqs() programs all legacy IRQs with default trigger
	 * and polarity attributes. So allow the first user to reprogram the
	 * pin with real trigger and polarity attributes.
	 */
	if (irq < nr_legacy_irqs() && data->count == 1) {
		if (info->ioapic.is_level != data->is_level)
			mp_register_handler(irq, info->ioapic.is_level);
		data->entry.is_level = data->is_level = info->ioapic.is_level;
		data->entry.active_low = data->active_low = info->ioapic.active_low;
	}

	return data->is_level == info->ioapic.is_level &&
	       data->active_low == info->ioapic.active_low;
}

static int alloc_irq_from_domain(struct irq_domain *domain, int ioapic, u32 gsi,
				 struct irq_alloc_info *info)
{
	int type = ioapics[ioapic].irqdomain_cfg.type;
	bool legacy = false;
	int irq = -1;

	switch (type) {
	case IOAPIC_DOMAIN_LEGACY:
		/*
		 * Dynamically allocate IRQ number for non-ISA IRQs in the first
		 * 16 GSIs on some weird platforms.
		 */
		if (!ioapic_initialized || gsi >= nr_legacy_irqs())
			irq = gsi;
		legacy = mp_is_legacy_irq(irq);
		break;
	case IOAPIC_DOMAIN_STRICT:
		irq = gsi;
		break;
	case IOAPIC_DOMAIN_DYNAMIC:
		break;
	default:
		WARN(1, "ioapic: unknown irqdomain type %d\n", type);
		return -1;
	}

	return __irq_domain_alloc_irqs(domain, irq, 1, ioapic_alloc_attr_node(info),
				       info, legacy, NULL);
}

/*
 * Need special handling for ISA IRQs because there may be multiple IOAPIC pins
 * sharing the same ISA IRQ number and irqdomain only supports 1:1 mapping
 * between IOAPIC pin and IRQ number. A typical IOAPIC has 24 pins, pin 0-15 are
 * used for legacy IRQs and pin 16-23 are used for PCI IRQs (PIRQ A-H).
 * When ACPI is disabled, only legacy IRQ numbers (IRQ0-15) are available, and
 * some BIOSes may use MP Interrupt Source records to override IRQ numbers for
 * PIRQs instead of reprogramming the interrupt routing logic. Thus there may be
 * multiple pins sharing the same legacy IRQ number when ACPI is disabled.
 */
static int alloc_isa_irq_from_domain(struct irq_domain *domain, int irq, int ioapic, int pin,
				     struct irq_alloc_info *info)
{
	struct irq_data *irq_data = irq_get_irq_data(irq);
	int node = ioapic_alloc_attr_node(info);
	struct mp_chip_data *data;

	/*
	 * Legacy ISA IRQ has already been allocated, just add pin to
	 * the pin list associated with this IRQ and program the IOAPIC
	 * entry.
	 */
	if (irq_data && irq_data->parent_data) {
		if (!mp_check_pin_attr(irq, info))
			return -EBUSY;
		if (!add_pin_to_irq_node(irq_data->chip_data, node, ioapic, info->ioapic.pin))
			return -ENOMEM;
	} else {
		info->flags |= X86_IRQ_ALLOC_LEGACY;
		irq = __irq_domain_alloc_irqs(domain, irq, 1, node, info, true, NULL);
		if (irq >= 0) {
			irq_data = irq_domain_get_irq_data(domain, irq);
			data = irq_data->chip_data;
			data->isa_irq = true;
		}
	}

	return irq;
}

static int mp_map_pin_to_irq(u32 gsi, int idx, int ioapic, int pin,
			     unsigned int flags, struct irq_alloc_info *info)
{
	struct irq_domain *domain = mp_ioapic_irqdomain(ioapic);
	struct irq_alloc_info tmp;
	struct mp_chip_data *data;
	bool legacy = false;
	int irq;

	if (!domain)
		return -ENOSYS;

	if (idx >= 0 && test_bit(mp_irqs[idx].srcbus, mp_bus_not_pci)) {
		irq = mp_irqs[idx].srcbusirq;
		legacy = mp_is_legacy_irq(irq);
		/*
		 * IRQ2 is unusable for historical reasons on systems which
		 * have a legacy PIC. See the comment vs. IRQ2 further down.
		 *
		 * If this gets removed at some point then the related code
		 * in lapic_assign_system_vectors() needs to be adjusted as
		 * well.
		 */
		if (legacy && irq == PIC_CASCADE_IR)
			return -EINVAL;
	}

	guard(mutex)(&ioapic_mutex);
	if (!(flags & IOAPIC_MAP_ALLOC)) {
		if (!legacy) {
			irq = irq_find_mapping(domain, pin);
			if (irq == 0)
				irq = -ENOENT;
		}
	} else {
		ioapic_copy_alloc_attr(&tmp, info, gsi, ioapic, pin);
		if (legacy)
			irq = alloc_isa_irq_from_domain(domain, irq,
							ioapic, pin, &tmp);
		else if ((irq = irq_find_mapping(domain, pin)) == 0)
			irq = alloc_irq_from_domain(domain, ioapic, gsi, &tmp);
		else if (!mp_check_pin_attr(irq, &tmp))
			irq = -EBUSY;
		if (irq >= 0) {
			data = irq_get_chip_data(irq);
			data->count++;
		}
	}
	return irq;
}

static int pin_2_irq(int idx, int ioapic, int pin, unsigned int flags)
{
	u32 gsi = mp_pin_to_gsi(ioapic, pin);

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

#ifdef CONFIG_X86_32
	/* 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_pr_verbose("Disabling PIRQ%d\n", pin - 16);
			} else {
				int irq = pirq_entries[pin-16];

				apic_pr_verbose("Using PIRQ%d -> IRQ %d\n", pin - 16, irq);
				return irq;
			}
		}
	}
#endif

	return  mp_map_pin_to_irq(gsi, idx, ioapic, pin, flags, NULL);
}

int mp_map_gsi_to_irq(u32 gsi, unsigned int flags, struct irq_alloc_info *info)
{
	int ioapic, pin, idx;

	ioapic = mp_find_ioapic(gsi);
	if (ioapic < 0)
		return -ENODEV;

	pin = mp_find_ioapic_pin(ioapic, gsi);
	idx = find_irq_entry(ioapic, pin, mp_INT);
	if ((flags & IOAPIC_MAP_CHECK) && idx < 0)
		return -ENODEV;

	return mp_map_pin_to_irq(gsi, idx, ioapic, pin, flags, info);
}

void mp_unmap_irq(int irq)
{
	struct irq_data *irq_data = irq_get_irq_data(irq);
	struct mp_chip_data *data;

	if (!irq_data || !irq_data->domain)
		return;

	data = irq_data->chip_data;
	if (!data || data->isa_irq)
		return;

	guard(mutex)(&ioapic_mutex);
	if (--data->count == 0)
		irq_domain_free_irqs(irq, 1);
}

/*
 * Find a specific PCI IRQ entry.
 * Not an __init, possibly needed by modules
 */
int IO_APIC_get_PCI_irq_vector(int bus, int slot, int pin)
{
	int irq, i, best_ioapic = -1, best_idx = -1;

	apic_pr_debug("Querying PCI -> IRQ mapping bus:%d, slot:%d, pin:%d.\n",
		      bus, slot, pin);
	if (test_bit(bus, mp_bus_not_pci)) {
		apic_pr_verbose("PCI BIOS passed nonexistent PCI bus %d!\n", bus);
		return -1;
	}

	for (i = 0; i < mp_irq_entries; i++) {
		int lbus = mp_irqs[i].srcbus;
		int ioapic_idx, found = 0;

		if (bus != lbus || mp_irqs[i].irqtype != mp_INT ||
		    slot != ((mp_irqs[i].srcbusirq >> 2) & 0x1f))
			continue;

		for_each_ioapic(ioapic_idx)
			if (mpc_ioapic_id(ioapic_idx) == mp_irqs[i].dstapic ||
			    mp_irqs[i].dstapic == MP_APIC_ALL) {
				found = 1;
				break;
			}
		if (!found)
			continue;

		/* Skip ISA IRQs */
		irq = pin_2_irq(i, ioapic_idx, mp_irqs[i].dstirq, 0);
		if (irq > 0 && !IO_APIC_IRQ(irq))
			continue;

		if (pin == (mp_irqs[i].srcbusirq & 3)) {
			best_idx = i;
			best_ioapic = ioapic_idx;
			goto out;
		}

		/*
		 * Use the first all-but-pin matching entry as a
		 * best-guess fuzzy result for broken mptables.
		 */
		if (best_idx < 0) {
			best_idx = i;
			best_ioapic = ioapic_idx;
		}
	}
	if (best_idx < 0)
		return -1;

out:
	return pin_2_irq(best_idx, best_ioapic, mp_irqs[best_idx].dstirq, IOAPIC_MAP_ALLOC);
}
EXPORT_SYMBOL(IO_APIC_get_PCI_irq_vector);

static struct irq_chip ioapic_chip, ioapic_ir_chip;

static void __init setup_IO_APIC_irqs(void)
{
	unsigned int ioapic, pin;
	int idx;

	apic_pr_verbose("Init IO_APIC IRQs\n");

	for_each_ioapic_pin(ioapic, pin) {
		idx = find_irq_entry(ioapic, pin, mp_INT);
		if (idx < 0) {
			apic_pr_verbose("apic %d pin %d not connected\n",
					mpc_ioapic_id(ioapic), pin);
		} else {
			pin_2_irq(idx, ioapic, pin, ioapic ? 0 : IOAPIC_MAP_ALLOC);
		}
	}
}

void ioapic_zap_locks(void)
{
	raw_spin_lock_init(&ioapic_lock);
}

static void io_apic_print_entries(unsigned int apic, unsigned int nr_entries)
{
	struct IO_APIC_route_entry entry;
	char buf[256];
	int i;

	apic_dbg("IOAPIC %d:\n", apic);
	for (i = 0; i <= nr_entries; i++) {
		entry = ioapic_read_entry(apic, i);
		snprintf(buf, sizeof(buf), " pin%02x, %s, %s, %s, V(%02X), IRR(%1d), S(%1d)",
			 i, entry.masked ? "disabled" : "enabled ",
			 entry.is_level ? "level" : "edge ",
			 entry.active_low ? "low " : "high",
			 entry.vector, entry.irr, entry.delivery_status);
		if (entry.ir_format) {
			apic_dbg("%s, remapped, I(%04X),  Z(%X)\n", buf,
				 (entry.ir_index_15 << 15) | entry.ir_index_0_14, entry.ir_zero);
		} else {
			apic_dbg("%s, %s, D(%02X%02X), M(%1d)\n", buf,
				 entry.dest_mode_logical ? "logical " : "physical",
				 entry.virt_destid_8_14, entry.destid_0_7, entry.delivery_mode);
		}
	}
}

static void __init print_IO_APIC(int ioapic_idx)
{
	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;

	scoped_guard (raw_spinlock_irqsave, &ioapic_lock) {
		reg_00.raw = io_apic_read(ioapic_idx, 0);
		reg_01.raw = io_apic_read(ioapic_idx, 1);
		if (reg_01.bits.version >= 0x10)
			reg_02.raw = io_apic_read(ioapic_idx, 2);
		if (reg_01.bits.version >= 0x20)
			reg_03.raw = io_apic_read(ioapic_idx, 3);
	}

	apic_dbg("IO APIC #%d......\n", mpc_ioapic_id(ioapic_idx));
	apic_dbg(".... register #00: %08X\n", reg_00.raw);
	apic_dbg(".......    : physical APIC id: %02X\n", reg_00.bits.ID);
	apic_dbg(".......    : Delivery Type: %X\n", reg_00.bits.delivery_type);
	apic_dbg(".......    : LTS          : %X\n", reg_00.bits.LTS);
	apic_dbg(".... register #01: %08X\n", *(int *)&reg_01);
	apic_dbg(".......     : max redirection entries: %02X\n", reg_01.bits.entries);
	apic_dbg(".......     : PRQ implemented: %X\n", reg_01.bits.PRQ);
	apic_dbg(".......     : IO APIC version: %02X\n", reg_01.bits.version);

	/*
	 * 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) {
		apic_dbg(".... register #02: %08X\n", reg_02.raw);
		apic_dbg(".......     : arbitration: %02X\n", reg_02.bits.arbitration);
	}

	/*
	 * 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) {
		apic_dbg(".... register #03: %08X\n", reg_03.raw);
		apic_dbg(".......     : Boot DT    : %X\n", reg_03.bits.boot_DT);
	}

	apic_dbg(".... IRQ redirection table:\n");
	io_apic_print_entries(ioapic_idx, reg_01.bits.entries);
}

void __init print_IO_APICs(void)
{
	int ioapic_idx;
	unsigned int irq;

	apic_dbg("number of MP IRQ sources: %d.\n", mp_irq_entries);
	for_each_ioapic(ioapic_idx) {
		apic_dbg("number of IO-APIC #%d registers: %d.\n",
			 mpc_ioapic_id(ioapic_idx), ioapics[ioapic_idx].nr_registers);
	}

	/*
	 * 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_each_ioapic(ioapic_idx)
		print_IO_APIC(ioapic_idx);

	apic_dbg("IRQ to pin mappings:\n");
	for_each_active_irq(irq) {
		struct irq_pin_list *entry;
		struct irq_chip *chip;
		struct mp_chip_data *data;

		chip = irq_get_chip(irq);
		if (chip != &ioapic_chip && chip != &ioapic_ir_chip)
			continue;
		data = irq_get_chip_data(irq);
		if (!data)
			continue;
		if (list_empty(&data->irq_2_pin))
			continue;

		apic_dbg("IRQ%d ", irq);
		for_each_irq_pin(entry, data->irq_2_pin)
			pr_cont("-> %d:%d", entry->apic, entry->pin);
		pr_cont("\n");
	}

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

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

void __init enable_IO_APIC(void)
{
	int i8259_apic, i8259_pin, apic, pin;

	if (ioapic_is_disabled)
		nr_ioapics = 0;

	if (!nr_legacy_irqs() || !nr_ioapics)
		return;

	for_each_ioapic_pin(apic, pin) {
		/* See if any of the pins is in ExtINT mode */
		struct IO_APIC_route_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.masked && entry.delivery_mode == APIC_DELIVERY_MODE_EXTINT) {
			ioapic_i8259.apic = apic;
			ioapic_i8259.pin  = pin;
			break;
		}
	}

	/*
	 * 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)) {
		pr_warn("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))
		pr_warn("ExtINT in hardware and MP table differ\n");

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

void native_restore_boot_irq_mode(void)
{
	/*
	 * 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;
		u32 apic_id = read_apic_id();

		memset(&entry, 0, sizeof(entry));
		entry.masked		= false;
		entry.is_level		= false;
		entry.active_low	= false;
		entry.dest_mode_logical	= false;
		entry.delivery_mode	= APIC_DELIVERY_MODE_EXTINT;
		entry.destid_0_7	= apic_id & 0xFF;
		entry.virt_destid_8_14	= apic_id >> 8;

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

	if (boot_cpu_has(X86_FEATURE_APIC) || apic_from_smp_config())
		disconnect_bsp_APIC(ioapic_i8259.pin != -1);
}

void restore_boot_irq_mode(void)
{
	if (!nr_legacy_irqs())
		return;

	x86_apic_ops.restore();
}

#ifdef CONFIG_X86_32
/*
 * 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_nocheck(void)
{
	DECLARE_BITMAP(phys_id_present_map, MAX_LOCAL_APIC);
	const u32 broadcast_id = 0xF;
	union IO_APIC_reg_00 reg_00;
	unsigned char old_id;
	int ioapic_idx, i;

	/*
	 * This is broken; anything with a real cpu count has to
	 * circumvent this idiocy regardless.
	 */
	copy_phys_cpu_present_map(phys_id_present_map);

	/*
	 * Set the IOAPIC ID to the value stored in the MPC table.
	 */
	for_each_ioapic(ioapic_idx) {
		/* Read the register 0 value */
		scoped_guard (raw_spinlock_irqsave, &ioapic_lock)
			reg_00.raw = io_apic_read(ioapic_idx, 0);

		old_id = mpc_ioapic_id(ioapic_idx);

		if (mpc_ioapic_id(ioapic_idx) >= broadcast_id) {
			pr_err(FW_BUG "IO-APIC#%d ID is %d in the MPC table!...\n",
			       ioapic_idx, mpc_ioapic_id(ioapic_idx));
			pr_err("... fixing up to %d. (tell your hw vendor)\n", reg_00.bits.ID);
			ioapics[ioapic_idx].mp_config.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 (test_bit(mpc_ioapic_id(ioapic_idx), phys_id_present_map)) {
			pr_err(FW_BUG "IO-APIC#%d ID %d is already used!...\n",
			       ioapic_idx, mpc_ioapic_id(ioapic_idx));
			for (i = 0; i < broadcast_id; i++)
				if (!test_bit(i, phys_id_present_map))
					break;
			if (i >= broadcast_id)
				panic("Max APIC ID exceeded!\n");
			pr_err("... fixing up to %d. (tell your hw vendor)\n", i);
			set_bit(i, phys_id_present_map);
			ioapics[ioapic_idx].mp_config.apicid = i;
		} else {
			apic_pr_verbose("Setting %d in the phys_id_present_map\n",
					mpc_ioapic_id(ioapic_idx));
			set_bit(mpc_ioapic_id(ioapic_idx), phys_id_present_map);
		}

		/*
		 * We need to adjust the IRQ routing table if the ID
		 * changed.
		 */
		if (old_id != mpc_ioapic_id(ioapic_idx)) {
			for (i = 0; i < mp_irq_entries; i++) {
				if (mp_irqs[i].dstapic == old_id)
					mp_irqs[i].dstapic = mpc_ioapic_id(ioapic_idx);
			}
		}

		/*
		 * Update the ID register according to the right value from
		 * the MPC table if they are different.
		 */
		if (mpc_ioapic_id(ioapic_idx) == reg_00.bits.ID)
			continue;

		apic_pr_verbose("...changing IO-APIC physical APIC ID to %d ...",
				mpc_ioapic_id(ioapic_idx));

		reg_00.bits.ID = mpc_ioapic_id(ioapic_idx);
		scoped_guard (raw_spinlock_irqsave, &ioapic_lock) {
			io_apic_write(ioapic_idx, 0, reg_00.raw);
			reg_00.raw = io_apic_read(ioapic_idx, 0);
		}
		/* Sanity check */
		if (reg_00.bits.ID != mpc_ioapic_id(ioapic_idx))
			pr_cont("could not set ID!\n");
		else
			apic_pr_verbose(" ok.\n");
	}
}

void __init setup_ioapic_ids_from_mpc(void)
{

	if (acpi_ioapic)
		return;
	/*
	 * 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(boot_cpu_apic_version))
		return;
	setup_ioapic_ids_from_mpc_nocheck();
}
#endif

int no_timer_check __initdata;

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

static void __init delay_with_tsc(void)
{
	unsigned long long start, now;
	unsigned long end = jiffies + 4;

	start = rdtsc();

	/*
	 * We don't know the TSC frequency yet, but waiting for
	 * 40000000000/HZ TSC cycles is safe:
	 * 4 GHz == 10 jiffies
	 * 1 GHz == 40 jiffies
	 */
	do {
		native_pause();
		now = rdtsc();
	} while ((now - start) < 40000000000ULL / HZ &&	time_before_eq(jiffies, end));
}

static void __init delay_without_tsc(void)
{
	unsigned long end = jiffies + 4;
	int band = 1;

	/*
	 * We don't know any frequency yet, but waiting for
	 * 40940000000/HZ cycles is safe:
	 * 4 GHz == 10 jiffies
	 * 1 GHz == 40 jiffies
	 * 1 << 1 + 1 << 2 +...+ 1 << 11 = 4094
	 */
	do {
		__delay(((1U << band++) * 10000000UL) / HZ);
	} while (band < 12 && time_before_eq(jiffies, end));
}

/*
 * 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;

	if (no_timer_check)
		return 1;

	local_irq_enable();
	if (boot_cpu_has(X86_FEATURE_TSC))
		delay_with_tsc();
	else
		delay_without_tsc();

	/*
	 * 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.
	 */

	local_irq_disable();

	/* Did jiffies advance? */
	return time_after(jiffies, t1 + 4);
}

/*
 * In the SMP+IOAPIC case it might happen that there are an unspecified
 * number of pending IRQ events unhandled. These cases are very rare,
 * so we 'resend' these IRQs via IPIs, to the same CPU. It's much
 * better to do it this way as thus we do not have to be aware of
 * 'pending' interrupts in the IRQ path, except at this point.
 *
 *
 * Edge triggered needs to resend any interrupt that was delayed but this
 * is now handled in the device independent code.
 *
 * Starting up a edge-triggered IO-APIC interrupt is nasty - we need to
 * make sure that we get the edge.  If it is already asserted for some
 * reason, we need return 1 to indicate that is was pending.
 *
 * This is not complete - we should be able to fake an edge even if it
 * isn't on the 8259A...
 */
static unsigned int startup_ioapic_irq(struct irq_data *data)
{
	int was_pending = 0, irq = data->irq;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	if (irq < nr_legacy_irqs()) {
		legacy_pic->mask(irq);
		if (legacy_pic->irq_pending(irq))
			was_pending = 1;
	}
	__unmask_ioapic(data->chip_data);
	return was_pending;
}

atomic_t irq_mis_count;

#ifdef CONFIG_GENERIC_PENDING_IRQ
static bool io_apic_level_ack_pending(struct mp_chip_data *data)
{
	struct irq_pin_list *entry;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	for_each_irq_pin(entry, data->irq_2_pin) {
		struct IO_APIC_route_entry e;
		int pin;

		pin = entry->pin;
		e.w1 = io_apic_read(entry->apic, 0x10 + pin*2);
		/* Is the remote IRR bit set? */
		if (e.irr)
			return true;
	}
	return false;
}

static inline bool ioapic_prepare_move(struct irq_data *data)
{
	/* If we are moving the IRQ we need to mask it */
	if (unlikely(irqd_is_setaffinity_pending(data))) {
		if (!irqd_irq_masked(data))
			mask_ioapic_irq(data);
		return true;
	}
	return false;
}

static inline void ioapic_finish_move(struct irq_data *data, bool moveit)
{
	if (unlikely(moveit)) {
		/*
		 * Only migrate the irq if the ack has been received.
		 *
		 * On rare occasions the broadcast level triggered ack gets
		 * delayed going to ioapics, and if we reprogram the
		 * vector while Remote IRR is still set the irq will never
		 * fire again.
		 *
		 * To prevent this scenario we read the Remote IRR bit
		 * of the ioapic.  This has two effects.
		 * - On any sane system the read of the ioapic will
		 *   flush writes (and acks) going to the ioapic from
		 *   this cpu.
		 * - We get to see if the ACK has actually been delivered.
		 *
		 * Based on failed experiments of reprogramming the
		 * ioapic entry from outside of irq context starting
		 * with masking the ioapic entry and then polling until
		 * Remote IRR was clear before reprogramming the
		 * ioapic I don't trust the Remote IRR bit to be
		 * completely accurate.
		 *
		 * However there appears to be no other way to plug
		 * this race, so if the Remote IRR bit is not
		 * accurate and is causing problems then it is a hardware bug
		 * and you can go talk to the chipset vendor about it.
		 */
		if (!io_apic_level_ack_pending(data->chip_data))
			irq_move_masked_irq(data);
		/* If the IRQ is masked in the core, leave it: */
		if (!irqd_irq_masked(data))
			unmask_ioapic_irq(data);
	}
}
#else
static inline bool ioapic_prepare_move(struct irq_data *data)
{
	return false;
}
static inline void ioapic_finish_move(struct irq_data *data, bool moveit)
{
}
#endif

static void ioapic_ack_level(struct irq_data *irq_data)
{
	struct irq_cfg *cfg = irqd_cfg(irq_data);
	unsigned long v;
	bool moveit;
	int i;

	irq_complete_move(cfg);
	moveit = ioapic_prepare_move(irq_data);

	/*
	 * 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
	 *
	 * Also in the case when cpu goes offline, fixup_irqs() will forward
	 * any unhandled interrupt on the offlined cpu to the new cpu
	 * destination that is handling the corresponding interrupt. This
	 * interrupt forwarding is done via IPI's. Hence, in this case also
	 * level-triggered io-apic interrupt will be seen as an edge
	 * interrupt in the IRR. And we can't rely on the cpu's EOI
	 * to be broadcasted to the IO-APIC's which will clear the remoteIRR
	 * corresponding to the level-triggered interrupt. Hence on IO-APIC's
	 * supporting EOI register, we do an explicit EOI to clear the
	 * remote IRR and on IO-APIC's which don't have an EOI register,
	 * we use the above logic (mask+edge followed by unmask+level) from
	 * Manfred Spraul to clear the remote IRR.
	 */
	i = cfg->vector;
	v = apic_read(APIC_TMR + ((i & ~0x1f) >> 1));

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

	/*
	 * Tail end of clearing remote IRR bit (either by delivering the EOI
	 * message via io-apic EOI register write or simulating it using
	 * mask+edge followed by unmask+level logic) manually when the
	 * level triggered interrupt is seen as the edge triggered interrupt
	 * at the cpu.
	 */
	if (!(v & (1 << (i & 0x1f)))) {
		atomic_inc(&irq_mis_count);
		eoi_ioapic_pin(cfg->vector, irq_data->chip_data);
	}

	ioapic_finish_move(irq_data, moveit);
}

static void ioapic_ir_ack_level(struct irq_data *irq_data)
{
	struct mp_chip_data *data = irq_data->chip_data;

	/*
	 * Intr-remapping uses pin number as the virtual vector
	 * in the RTE. Actual vector is programmed in
	 * intr-remapping table entry. Hence for the io-apic
	 * EOI we use the pin number.
	 */
	apic_ack_irq(irq_data);
	eoi_ioapic_pin(data->entry.vector, data);
}

/*
 * The I/OAPIC is just a device for generating MSI messages from legacy
 * interrupt pins. Various fields of the RTE translate into bits of the
 * resulting MSI which had a historical meaning.
 *
 * With interrupt remapping, many of those bits have different meanings
 * in the underlying MSI, but the way that the I/OAPIC transforms them
 * from its RTE to the MSI message is the same. This function allows
 * the parent IRQ domain to compose the MSI message, then takes the
 * relevant bits to put them in the appropriate places in the RTE in
 * order to generate that message when the IRQ happens.
 *
 * The setup here relies on a preconfigured route entry (is_level,
 * active_low, masked) because the parent domain is merely composing the
 * generic message routing information which is used for the MSI.
 */
static void ioapic_setup_msg_from_msi(struct irq_data *irq_data,
				      struct IO_APIC_route_entry *entry)
{
	struct msi_msg msg;

	/* Let the parent domain compose the MSI message */
	irq_chip_compose_msi_msg(irq_data, &msg);

	/*
	 * - Real vector
	 * - DMAR/IR: 8bit subhandle (ioapic.pin)
	 * - AMD/IR:  8bit IRTE index
	 */
	entry->vector			= msg.arch_data.vector;
	/* Delivery mode (for DMAR/IR all 0) */
	entry->delivery_mode		= msg.arch_data.delivery_mode;
	/* Destination mode or DMAR/IR index bit 15 */
	entry->dest_mode_logical	= msg.arch_addr_lo.dest_mode_logical;
	/* DMAR/IR: 1, 0 for all other modes */
	entry->ir_format		= msg.arch_addr_lo.dmar_format;
	/*
	 * - DMAR/IR: index bit 0-14.
	 *
	 * - Virt: If the host supports x2apic without a virtualized IR
	 *	   unit then bit 0-6 of dmar_index_0_14 are providing bit
	 *	   8-14 of the destination id.
	 *
	 * All other modes have bit 0-6 of dmar_index_0_14 cleared and the
	 * topmost 8 bits are destination id bit 0-7 (entry::destid_0_7).
	 */
	entry->ir_index_0_14		= msg.arch_addr_lo.dmar_index_0_14;
}

static void ioapic_configure_entry(struct irq_data *irqd)
{
	struct mp_chip_data *mpd = irqd->chip_data;
	struct irq_pin_list *entry;

	ioapic_setup_msg_from_msi(irqd, &mpd->entry);

	for_each_irq_pin(entry, mpd->irq_2_pin)
		__ioapic_write_entry(entry->apic, entry->pin, mpd->entry);
}

static int ioapic_set_affinity(struct irq_data *irq_data, const struct cpumask *mask, bool force)
{
	struct irq_data *parent = irq_data->parent_data;
	int ret;

	ret = parent->chip->irq_set_affinity(parent, mask, force);

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	if (ret >= 0 && ret != IRQ_SET_MASK_OK_DONE)
		ioapic_configure_entry(irq_data);

	return ret;
}

/*
 * Interrupt shutdown masks the ioapic pin, but the interrupt might already
 * be in flight, but not yet serviced by the target CPU. That means
 * __synchronize_hardirq() would return and claim that everything is calmed
 * down. So free_irq() would proceed and deactivate the interrupt and free
 * resources.
 *
 * Once the target CPU comes around to service it it will find a cleared
 * vector and complain. While the spurious interrupt is harmless, the full
 * release of resources might prevent the interrupt from being acknowledged
 * which keeps the hardware in a weird state.
 *
 * Verify that the corresponding Remote-IRR bits are clear.
 */
static int ioapic_irq_get_chip_state(struct irq_data *irqd, enum irqchip_irq_state which,
				     bool *state)
{
	struct mp_chip_data *mcd = irqd->chip_data;
	struct IO_APIC_route_entry rentry;
	struct irq_pin_list *p;

	if (which != IRQCHIP_STATE_ACTIVE)
		return -EINVAL;

	*state = false;

	guard(raw_spinlock)(&ioapic_lock);
	for_each_irq_pin(p, mcd->irq_2_pin) {
		rentry = __ioapic_read_entry(p->apic, p->pin);
		/*
		 * The remote IRR is only valid in level trigger mode. It's
		 * meaning is undefined for edge triggered interrupts and
		 * irrelevant because the IO-APIC treats them as fire and
		 * forget.
		 */
		if (rentry.irr && rentry.is_level) {
			*state = true;
			break;
		}
	}
	return 0;
}

static struct irq_chip ioapic_chip __read_mostly = {
	.name			= "IO-APIC",
	.irq_startup		= startup_ioapic_irq,
	.irq_mask		= mask_ioapic_irq,
	.irq_unmask		= unmask_ioapic_irq,
	.irq_ack		= irq_chip_ack_parent,
	.irq_eoi		= ioapic_ack_level,
	.irq_set_affinity	= ioapic_set_affinity,
	.irq_retrigger		= irq_chip_retrigger_hierarchy,
	.irq_get_irqchip_state	= ioapic_irq_get_chip_state,
	.flags			= IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MOVE_DEFERRED |
				  IRQCHIP_AFFINITY_PRE_STARTUP,
};

static struct irq_chip ioapic_ir_chip __read_mostly = {
	.name			= "IR-IO-APIC",
	.irq_startup		= startup_ioapic_irq,
	.irq_mask		= mask_ioapic_irq,
	.irq_unmask		= unmask_ioapic_irq,
	.irq_ack		= irq_chip_ack_parent,
	.irq_eoi		= ioapic_ir_ack_level,
	.irq_set_affinity	= ioapic_set_affinity,
	.irq_retrigger		= irq_chip_retrigger_hierarchy,
	.irq_get_irqchip_state	= ioapic_irq_get_chip_state,
	.flags			= IRQCHIP_SKIP_SET_WAKE |
				  IRQCHIP_AFFINITY_PRE_STARTUP,
};

static inline void init_IO_APIC_traps(void)
{
	struct irq_cfg *cfg;
	unsigned int irq;

	for_each_active_irq(irq) {
		cfg = irq_cfg(irq);
		if (IO_APIC_IRQ(irq) && cfg && !cfg->vector) {
			/*
			 * Hmm.. We don't have an entry for this, so
			 * default to an old-fashioned 8259 interrupt if we
			 * can. Otherwise set the dummy interrupt chip.
			 */
			if (irq < nr_legacy_irqs())
				legacy_pic->make_irq(irq);
			else
				irq_set_chip(irq, &no_irq_chip);
		}
	}
}

/*
 * The local APIC irq-chip implementation:
 */
static void mask_lapic_irq(struct irq_data *data)
{
	unsigned long v = apic_read(APIC_LVT0);

	apic_write(APIC_LVT0, v | APIC_LVT_MASKED);
}

static void unmask_lapic_irq(struct irq_data *data)
{
	unsigned long v = apic_read(APIC_LVT0);

	apic_write(APIC_LVT0, v & ~APIC_LVT_MASKED);
}

static void ack_lapic_irq(struct irq_data *data)
{
	apic_eoi();
}

static struct irq_chip lapic_chip __read_mostly = {
	.name		= "local-APIC",
	.irq_mask	= mask_lapic_irq,
	.irq_unmask	= unmask_lapic_irq,
	.irq_ack	= ack_lapic_irq,
};

static void lapic_register_intr(int irq)
{
	irq_clear_status_flags(irq, IRQ_LEVEL);
	irq_set_chip_and_handler_name(irq, &lapic_chip, handle_edge_irq, "edge");
}

/*
 * This looks a bit hackish but it's about the only one way of sending
 * a few INTA cycles to 8259As and any associated glue logic.  ICR does
 * not support the ExtINT mode, unfortunately.  We need to send these
 * cycles as some i82489DX-based boards have glue logic that keeps the
 * 8259A interrupt line asserted until INTA.  --macro
 */
static inline void __init unlock_ExtINT_logic(void)
{
	unsigned char save_control, save_freq_select;
	struct IO_APIC_route_entry entry0, entry1;
	int apic, pin, i;
	u32 apic_id;

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

	entry0 = ioapic_read_entry(apic, pin);
	clear_IO_APIC_pin(apic, pin);

	apic_id = read_apic_id();
	memset(&entry1, 0, sizeof(entry1));

	entry1.dest_mode_logical	= true;
	entry1.masked			= false;
	entry1.destid_0_7		= apic_id & 0xFF;
	entry1.virt_destid_8_14		= apic_id >> 8;
	entry1.delivery_mode		= APIC_DELIVERY_MODE_EXTINT;
	entry1.active_low		= entry0.active_low;
	entry1.is_level			= false;
	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);
}

static int disable_timer_pin_1 __initdata;
/* Actually the next is obsolete, but keep it for paranoid reasons -AK */
static int __init disable_timer_pin_setup(char *arg)
{
	disable_timer_pin_1 = 1;
	return 0;
}
early_param("disable_timer_pin_1", disable_timer_pin_setup);

static int __init mp_alloc_timer_irq(int ioapic, int pin)
{
	struct irq_domain *domain = mp_ioapic_irqdomain(ioapic);
	int irq = -1;

	if (domain) {
		struct irq_alloc_info info;

		ioapic_set_alloc_attr(&info, NUMA_NO_NODE, 0, 0);
		info.devid = mpc_ioapic_id(ioapic);
		info.ioapic.pin = pin;
		guard(mutex)(&ioapic_mutex);
		irq = alloc_isa_irq_from_domain(domain, 0, ioapic, pin, &info);
	}

	return irq;
}

static void __init replace_pin_at_irq_node(struct mp_chip_data *data, int node,
					   int oldapic, int oldpin,
					   int newapic, int newpin)
{
	struct irq_pin_list *entry;

	for_each_irq_pin(entry, data->irq_2_pin) {
		if (entry->apic == oldapic && entry->pin == oldpin) {
			entry->apic = newapic;
			entry->pin = newpin;
			return;
		}
	}

	/* Old apic/pin didn't exist, so just add a new one */
	add_pin_to_irq_node(data, node, newapic, newpin);
}

/*
 * 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 __init check_timer(void)
{
	struct irq_data *irq_data = irq_get_irq_data(0);
	struct mp_chip_data *data = irq_data->chip_data;
	struct irq_cfg *cfg = irqd_cfg(irq_data);
	int node = cpu_to_node(0);
	int apic1, pin1, apic2, pin2;
	int no_pin1 = 0;

	if (!global_clock_event)
		return;

	local_irq_disable();

	/*
	 * get/set the timer IRQ vector:
	 */
	legacy_pic->mask(0);

	/*
	 * As IRQ0 is to be enabled in the 8259A, the virtual
	 * wire has to be disabled in the local APIC.  Also
	 * timer interrupts need to be acknowledged manually in
	 * the 8259A for the i82489DX when using the NMI
	 * watchdog as that APIC treats NMIs as level-triggered.
	 * The AEOI mode will finish them in the 8259A
	 * automatically.
	 */
	apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
	legacy_pic->init(1);

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

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

	/*
	 * Some BIOS writers are clueless and report the ExtINTA
	 * I/O APIC input from the cascaded 8259A as the timer
	 * interrupt input.  So just in case, if only one pin
	 * was found above, try it both directly and through the
	 * 8259A.
	 */
	if (pin1 == -1) {
		panic_if_irq_remap(FW_BUG "Timer not connected to IO-APIC");
		pin1 = pin2;
		apic1 = apic2;
		no_pin1 = 1;
	} else if (pin2 == -1) {
		pin2 = pin1;
		apic2 = apic1;
	}

	if (pin1 != -1) {
		/* Ok, does IRQ0 through the IOAPIC work? */
		if (no_pin1) {
			mp_alloc_timer_irq(apic1, pin1);
		} else {
			/*
			 * for edge trigger, it's already unmasked,
			 * so only need to unmask if it is level-trigger
			 * do we really have level trigger timer?
			 */
			int idx = find_irq_entry(apic1, pin1, mp_INT);

			if (idx != -1 && irq_is_level(idx))
				unmask_ioapic_irq(irq_get_irq_data(0));
		}
		irq_domain_deactivate_irq(irq_data);
		irq_domain_activate_irq(irq_data, false);
		if (timer_irq_works()) {
			if (disable_timer_pin_1 > 0)
				clear_IO_APIC_pin(0, pin1);
			goto out;
		}
		panic_if_irq_remap("timer doesn't work through Interrupt-remapped IO-APIC");
		clear_IO_APIC_pin(apic1, pin1);
		if (!no_pin1)
			pr_err("..MP-BIOS bug: 8254 timer not connected to IO-APIC\n");

		pr_info("...trying to set up timer (IRQ0) through the 8259A ...\n");
		pr_info("..... (found apic %d pin %d) ...\n", apic2, pin2);
		/*
		 * legacy devices should be connected to IO APIC #0
		 */
		replace_pin_at_irq_node(data, node, apic1, pin1, apic2, pin2);
		irq_domain_deactivate_irq(irq_data);
		irq_domain_activate_irq(irq_data, false);
		legacy_pic->unmask(0);
		if (timer_irq_works()) {
			pr_info("....... works.\n");
			goto out;
		}
		/*
		 * Cleanup, just in case ...
		 */
		legacy_pic->mask(0);
		clear_IO_APIC_pin(apic2, pin2);
		pr_info("....... failed.\n");
	}

	pr_info("...trying to set up timer as Virtual Wire IRQ...\n");

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

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

	pr_info("...trying to set up timer as ExtINT IRQ...\n");

	legacy_pic->init(0);
	legacy_pic->make_irq(0);
	apic_write(APIC_LVT0, APIC_DM_EXTINT);
	legacy_pic->unmask(0);

	unlock_ExtINT_logic();

	if (timer_irq_works()) {
		pr_info("..... works.\n");
		goto out;
	}

	pr_info("..... failed :\n");
	if (apic_is_x2apic_enabled()) {
		pr_info("Perhaps problem with the pre-enabled x2apic mode\n"
			"Try booting with x2apic and interrupt-remapping disabled in the bios.\n");
	}
	panic("IO-APIC + timer doesn't work!  Boot with apic=debug and send a "
		"report.  Then try booting with the 'noapic' option.\n");
out:
	local_irq_enable();
}

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

static int mp_irqdomain_create(int ioapic)
{
	struct mp_ioapic_gsi *gsi_cfg = mp_ioapic_gsi_routing(ioapic);
	int hwirqs = mp_ioapic_pin_count(ioapic);
	struct ioapic *ip = &ioapics[ioapic];
	struct ioapic_domain_cfg *cfg = &ip->irqdomain_cfg;
	struct irq_domain *parent;
	struct fwnode_handle *fn;
	struct irq_fwspec fwspec;

	if (cfg->type == IOAPIC_DOMAIN_INVALID)
		return 0;

	/* Handle device tree enumerated APICs proper */
	if (cfg->dev) {
		fn = of_fwnode_handle(cfg->dev);
	} else {
		fn = irq_domain_alloc_named_id_fwnode("IO-APIC", mpc_ioapic_id(ioapic));
		if (!fn)
			return -ENOMEM;
	}

	fwspec.fwnode = fn;
	fwspec.param_count = 1;
	fwspec.param[0] = mpc_ioapic_id(ioapic);

	parent = irq_find_matching_fwspec(&fwspec, DOMAIN_BUS_GENERIC_MSI);
	if (!parent) {
		if (!cfg->dev)
			irq_domain_free_fwnode(fn);
		return -ENODEV;
	}

	ip->irqdomain = irq_domain_create_hierarchy(parent, 0, hwirqs, fn, cfg->ops,
						    (void *)(long)ioapic);
	if (!ip->irqdomain) {
		/* Release fw handle if it was allocated above */
		if (!cfg->dev)
			irq_domain_free_fwnode(fn);
		return -ENOMEM;
	}

	if (cfg->type == IOAPIC_DOMAIN_LEGACY || cfg->type == IOAPIC_DOMAIN_STRICT)
		ioapic_dynirq_base = max(ioapic_dynirq_base, gsi_cfg->gsi_end + 1);

	return 0;
}

static void ioapic_destroy_irqdomain(int idx)
{
	struct ioapic_domain_cfg *cfg = &ioapics[idx].irqdomain_cfg;
	struct fwnode_handle *fn = ioapics[idx].irqdomain->fwnode;

	if (ioapics[idx].irqdomain) {
		irq_domain_remove(ioapics[idx].irqdomain);
		if (!cfg->dev)
			irq_domain_free_fwnode(fn);
		ioapics[idx].irqdomain = NULL;
	}
}

void __init setup_IO_APIC(void)
{
	int ioapic;

	if (ioapic_is_disabled || !nr_ioapics)
		return;

	io_apic_irqs = nr_legacy_irqs() ? ~PIC_IRQS : ~0UL;

	apic_pr_verbose("ENABLING IO-APIC IRQs\n");
	for_each_ioapic(ioapic)
		BUG_ON(mp_irqdomain_create(ioapic));

	/* Set up IO-APIC IRQ routing. */
	x86_init.mpparse.setup_ioapic_ids();

	sync_Arb_IDs();
	setup_IO_APIC_irqs();
	init_IO_APIC_traps();
	if (nr_legacy_irqs())
		check_timer();

	ioapic_initialized = 1;
}

static void resume_ioapic_id(int ioapic_idx)
{
	union IO_APIC_reg_00 reg_00;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	reg_00.raw = io_apic_read(ioapic_idx, 0);
	if (reg_00.bits.ID != mpc_ioapic_id(ioapic_idx)) {
		reg_00.bits.ID = mpc_ioapic_id(ioapic_idx);
		io_apic_write(ioapic_idx, 0, reg_00.raw);
	}
}

static int ioapic_suspend(void *data)
{
	return save_ioapic_entries();
}

static void ioapic_resume(void *data)
{
	int ioapic_idx;

	for_each_ioapic_reverse(ioapic_idx)
		resume_ioapic_id(ioapic_idx);

	restore_ioapic_entries();
}

static const struct syscore_ops ioapic_syscore_ops = {
	.suspend	= ioapic_suspend,
	.resume		= ioapic_resume,
};

static struct syscore ioapic_syscore = {
	.ops = &ioapic_syscore_ops,
};

static int __init ioapic_init_ops(void)
{
	register_syscore(&ioapic_syscore);

	return 0;
}

device_initcall(ioapic_init_ops);

static int io_apic_get_redir_entries(int ioapic)
{
	union IO_APIC_reg_01	reg_01;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	reg_01.raw = io_apic_read(ioapic, 1);

	/*
	 * The register returns the maximum index redir index supported,
	 * which is one less than the total number of redir entries.
	 */
	return reg_01.bits.entries + 1;
}

unsigned int arch_dynirq_lower_bound(unsigned int from)
{
	unsigned int ret;

	/*
	 * dmar_alloc_hwirq() may be called before setup_IO_APIC(), so use
	 * gsi_top if ioapic_dynirq_base hasn't been initialized yet.
	 */
	ret = ioapic_dynirq_base ? : gsi_top;

	/*
	 * For DT enabled machines ioapic_dynirq_base is irrelevant and
	 * always 0. gsi_top can be 0 if there is no IO/APIC registered.
	 * 0 is an invalid interrupt number for dynamic allocations. Return
	 * @from instead.
	 */
	return ret ? : from;
}

#ifdef CONFIG_X86_32
static int io_apic_get_unique_id(int ioapic, int apic_id)
{
	static DECLARE_BITMAP(apic_id_map, MAX_LOCAL_APIC);
	const u32 broadcast_id = 0xF;
	union IO_APIC_reg_00 reg_00;
	int i = 0;

	/* Initialize the ID map */
	if (bitmap_empty(apic_id_map, MAX_LOCAL_APIC))
		copy_phys_cpu_present_map(apic_id_map);

	scoped_guard (raw_spinlock_irqsave, &ioapic_lock)
		reg_00.raw = io_apic_read(ioapic, 0);

	if (apic_id >= broadcast_id) {
		pr_warn("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 */
	if (test_bit(apic_id, apic_id_map)) {
		for (i = 0; i < broadcast_id; i++) {
			if (!test_bit(i, apic_id_map))
				break;
		}

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

		pr_warn("IOAPIC[%d]: apic_id %d already used, trying %d\n", ioapic, apic_id, i);
		apic_id = i;
	}

	set_bit(apic_id, apic_id_map);

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

		scoped_guard (raw_spinlock_irqsave, &ioapic_lock) {
			io_apic_write(ioapic, 0, reg_00.raw);
			reg_00.raw = io_apic_read(ioapic, 0);
		}

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

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

	return apic_id;
}

static u8 io_apic_unique_id(int idx, u8 id)
{
	if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && !APIC_XAPIC(boot_cpu_apic_version))
		return io_apic_get_unique_id(idx, id);
	return id;
}
#else
static u8 io_apic_unique_id(int idx, u8 id)
{
	union IO_APIC_reg_00 reg_00;
	DECLARE_BITMAP(used, 256);
	u8 new_id;
	int i;

	bitmap_zero(used, 256);
	for_each_ioapic(i)
		__set_bit(mpc_ioapic_id(i), used);

	/* Hand out the requested id if available */
	if (!test_bit(id, used))
		return id;

	/*
	 * Read the current id from the ioapic and keep it if
	 * available.
	 */
	scoped_guard (raw_spinlock_irqsave, &ioapic_lock)
		reg_00.raw = io_apic_read(idx, 0);

	new_id = reg_00.bits.ID;
	if (!test_bit(new_id, used)) {
		apic_pr_verbose("IOAPIC[%d]: Using reg apic_id %d instead of %d\n",
				idx, new_id, id);
		return new_id;
	}

	/* Get the next free id and write it to the ioapic. */
	new_id = find_first_zero_bit(used, 256);
	reg_00.bits.ID = new_id;
	scoped_guard (raw_spinlock_irqsave, &ioapic_lock) {
		io_apic_write(idx, 0, reg_00.raw);
		reg_00.raw = io_apic_read(idx, 0);
	}
	/* Sanity check */
	BUG_ON(reg_00.bits.ID != new_id);

	return new_id;
}
#endif

static int io_apic_get_version(int ioapic)
{
	union IO_APIC_reg_01 reg_01;

	guard(raw_spinlock_irqsave)(&ioapic_lock);
	reg_01.raw = io_apic_read(ioapic, 1);

	return reg_01.bits.version;
}

/*
 * This function updates target affinity of IOAPIC interrupts to include
 * the CPUs which came online during SMP bringup.
 */
#define IOAPIC_RESOURCE_NAME_SIZE 11

static struct resource *ioapic_resources;

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

	if (nr_ioapics == 0)
		return NULL;

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

	mem = memblock_alloc_or_panic(n, SMP_CACHE_BYTES);
	res = (void *)mem;

	mem += sizeof(struct resource) * nr_ioapics;

	for_each_ioapic(i) {
		res[i].name = mem;
		res[i].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
		mem += IOAPIC_RESOURCE_NAME_SIZE;
		ioapics[i].iomem_res = &res[i];
	}

	ioapic_resources = res;

	return res;
}

static void io_apic_set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
{
	pgprot_t flags = FIXMAP_PAGE_NOCACHE;

	/*
	 * Ensure fixmaps for IO-APIC MMIO respect memory encryption pgprot
	 * bits, just like normal ioremap():
	 */
	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
		if (x86_platform.hyper.is_private_mmio(phys))
			flags = pgprot_encrypted(flags);
		else
			flags = pgprot_decrypted(flags);
	}

	__set_fixmap(idx, phys, flags);
}

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

	ioapic_res = ioapic_setup_resources();
	for_each_ioapic(i) {
		if (smp_found_config) {
			ioapic_phys = mpc_ioapic_addr(i);
#ifdef CONFIG_X86_32
			if (!ioapic_phys) {
				pr_err("WARNING: bogus zero IO-APIC address found in MPTABLE, "
				       "disabling IO/APIC support!\n");
				smp_found_config = 0;
				ioapic_is_disabled = true;
				goto fake_ioapic_page;
			}
#endif
		} else {
#ifdef CONFIG_X86_32
fake_ioapic_page:
#endif
			ioapic_phys = (unsigned long)memblock_alloc_or_panic(PAGE_SIZE,
								    PAGE_SIZE);
			ioapic_phys = __pa(ioapic_phys);
		}
		io_apic_set_fixmap(idx, ioapic_phys);
		apic_pr_verbose("mapped IOAPIC to %08lx (%08lx)\n",
				__fix_to_virt(idx) + (ioapic_phys & ~PAGE_MASK), ioapic_phys);
		idx++;

		ioapic_res->start = ioapic_phys;
		ioapic_res->end = ioapic_phys + IO_APIC_SLOT_SIZE - 1;
		ioapic_res++;
	}
}

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

	if (!r) {
		if (nr_ioapics > 0)
			pr_err("IO APIC resources couldn't be allocated.\n");
		return;
	}

	for_each_ioapic(i) {
		insert_resource(&iomem_resource, r);
		r++;
	}
}

int mp_find_ioapic(u32 gsi)
{
	int i;

	if (nr_ioapics == 0)
		return -1;

	/* Find the IOAPIC that manages this GSI. */
	for_each_ioapic(i) {
		struct mp_ioapic_gsi *gsi_cfg = mp_ioapic_gsi_routing(i);

		if (gsi >= gsi_cfg->gsi_base && gsi <= gsi_cfg->gsi_end)
			return i;
	}

	pr_err("ERROR: Unable to locate IOAPIC for GSI %d\n", gsi);
	return -1;
}

int mp_find_ioapic_pin(int ioapic, u32 gsi)
{
	struct mp_ioapic_gsi *gsi_cfg;

	if (WARN_ON(ioapic < 0))
		return -1;

	gsi_cfg = mp_ioapic_gsi_routing(ioapic);
	if (WARN_ON(gsi > gsi_cfg->gsi_end))
		return -1;

	return gsi - gsi_cfg->gsi_base;
}

static int bad_ioapic_register(int idx)
{
	union IO_APIC_reg_00 reg_00;
	union IO_APIC_reg_01 reg_01;
	union IO_APIC_reg_02 reg_02;

	reg_00.raw = io_apic_read(idx, 0);
	reg_01.raw = io_apic_read(idx, 1);
	reg_02.raw = io_apic_read(idx, 2);

	if (reg_00.raw == -1 && reg_01.raw == -1 && reg_02.raw == -1) {
		pr_warn("I/O APIC 0x%x registers return all ones, skipping!\n",
			mpc_ioapic_addr(idx));
		return 1;
	}

	return 0;
}

static int find_free_ioapic_entry(void)
{
	for (int idx = 0; idx < MAX_IO_APICS; idx++) {
		if (ioapics[idx].nr_registers == 0)
			return idx;
	}
	return MAX_IO_APICS;
}

/**
 * mp_register_ioapic - Register an IOAPIC device
 * @id:		hardware IOAPIC ID
 * @address:	physical address of IOAPIC register area
 * @gsi_base:	base of GSI associated with the IOAPIC
 * @cfg:	configuration information for the IOAPIC
 */
int mp_register_ioapic(int id, u32 address, u32 gsi_base, struct ioapic_domain_cfg *cfg)
{
	bool hotplug = !!ioapic_initialized;
	struct mp_ioapic_gsi *gsi_cfg;
	int idx, ioapic, entries;
	u32 gsi_end;

	if (!address) {
		pr_warn("Bogus (zero) I/O APIC address found, skipping!\n");
		return -EINVAL;
	}

	for_each_ioapic(ioapic) {
		if (ioapics[ioapic].mp_config.apicaddr == address) {
			pr_warn("address 0x%x conflicts with IOAPIC%d\n", address, ioapic);
			return -EEXIST;
		}
	}

	idx = find_free_ioapic_entry();
	if (idx >= MAX_IO_APICS) {
		pr_warn("Max # of I/O APICs (%d) exceeded (found %d), skipping\n",
			MAX_IO_APICS, idx);
		return -ENOSPC;
	}

	ioapics[idx].mp_config.type = MP_IOAPIC;
	ioapics[idx].mp_config.flags = MPC_APIC_USABLE;
	ioapics[idx].mp_config.apicaddr = address;

	io_apic_set_fixmap(FIX_IO_APIC_BASE_0 + idx, address);
	if (bad_ioapic_register(idx)) {
		clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
		return -ENODEV;
	}

	ioapics[idx].mp_config.apicid = io_apic_unique_id(idx, id);
	ioapics[idx].mp_config.apicver = io_apic_get_version(idx);

	/*
	 * Build basic GSI lookup table to facilitate gsi->io_apic lookups
	 * and to prevent reprogramming of IOAPIC pins (PCI GSIs).
	 */
	entries = io_apic_get_redir_entries(idx);
	gsi_end = gsi_base + entries - 1;
	for_each_ioapic(ioapic) {
		gsi_cfg = mp_ioapic_gsi_routing(ioapic);
		if ((gsi_base >= gsi_cfg->gsi_base &&
		     gsi_base <= gsi_cfg->gsi_end) ||
		    (gsi_end >= gsi_cfg->gsi_base &&
		     gsi_end <= gsi_cfg->gsi_end)) {
			pr_warn("GSI range [%u-%u] for new IOAPIC conflicts with GSI[%u-%u]\n",
				gsi_base, gsi_end, gsi_cfg->gsi_base, gsi_cfg->gsi_end);
			clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
			return -ENOSPC;
		}
	}
	gsi_cfg = mp_ioapic_gsi_routing(idx);
	gsi_cfg->gsi_base = gsi_base;
	gsi_cfg->gsi_end = gsi_end;

	ioapics[idx].irqdomain = NULL;
	ioapics[idx].irqdomain_cfg = *cfg;

	/*
	 * If mp_register_ioapic() is called during early boot stage when
	 * walking ACPI/DT tables, it's too early to create irqdomain,
	 * we are still using bootmem allocator. So delay it to setup_IO_APIC().
	 */
	if (hotplug) {
		if (mp_irqdomain_create(idx)) {
			clear_fixmap(FIX_IO_APIC_BASE_0 + idx);
			return -ENOMEM;
		}
		alloc_ioapic_saved_registers(idx);
	}

	if (gsi_cfg->gsi_end >= gsi_top)
		gsi_top = gsi_cfg->gsi_end + 1;
	if (nr_ioapics <= idx)
		nr_ioapics = idx + 1;

	/* Set nr_registers to mark entry present */
	ioapics[idx].nr_registers = entries;

	pr_info("IOAPIC[%d]: apic_id %d, version %d, address 0x%x, GSI %d-%d\n",
		idx, mpc_ioapic_id(idx), mpc_ioapic_ver(idx), mpc_ioapic_addr(idx),
		gsi_cfg->gsi_base, gsi_cfg->gsi_end);

	return 0;
}

int mp_unregister_ioapic(u32 gsi_base)
{
	int ioapic, pin;
	int found = 0;

	for_each_ioapic(ioapic) {
		if (ioapics[ioapic].gsi_config.gsi_base == gsi_base) {
			found = 1;
			break;
		}
	}

	if (!found) {
		pr_warn("can't find IOAPIC for GSI %d\n", gsi_base);
		return -ENODEV;
	}

	for_each_pin(ioapic, pin) {
		u32 gsi = mp_pin_to_gsi(ioapic, pin);
		int irq = mp_map_gsi_to_irq(gsi, 0, NULL);
		struct mp_chip_data *data;

		if (irq >= 0) {
			data = irq_get_chip_data(irq);
			if (data && data->count) {
				pr_warn("pin%d on IOAPIC%d is still in use.\n",	pin, ioapic);
				return -EBUSY;
			}
		}
	}

	/* Mark entry not present */
	ioapics[ioapic].nr_registers  = 0;
	ioapic_destroy_irqdomain(ioapic);
	free_ioapic_saved_registers(ioapic);
	if (ioapics[ioapic].iomem_res)
		release_resource(ioapics[ioapic].iomem_res);
	clear_fixmap(FIX_IO_APIC_BASE_0 + ioapic);
	memset(&ioapics[ioapic], 0, sizeof(ioapics[ioapic]));

	return 0;
}

int mp_ioapic_registered(u32 gsi_base)
{
	int ioapic;

	for_each_ioapic(ioapic)
		if (ioapics[ioapic].gsi_config.gsi_base == gsi_base)
			return 1;

	return 0;
}

static void mp_irqdomain_get_attr(u32 gsi, struct mp_chip_data *data,
				  struct irq_alloc_info *info)
{
	if (info && info->ioapic.valid) {
		data->is_level = info->ioapic.is_level;
		data->active_low = info->ioapic.active_low;
	} else if (__acpi_get_override_irq(gsi, &data->is_level, &data->active_low) < 0) {
		/* PCI interrupts are always active low level triggered. */
		data->is_level = true;
		data->active_low = true;
	}
}

/*
 * Configure the I/O-APIC specific fields in the routing entry.
 *
 * This is important to setup the I/O-APIC specific bits (is_level,
 * active_low, masked) because the underlying parent domain will only
 * provide the routing information and is oblivious of the I/O-APIC
 * specific bits.
 *
 * The entry is just preconfigured at this point and not written into the
 * RTE. This happens later during activation which will fill in the actual
 * routing information.
 */
static void mp_preconfigure_entry(struct mp_chip_data *data)
{
	struct IO_APIC_route_entry *entry = &data->entry;

	memset(entry, 0, sizeof(*entry));
	entry->is_level		 = data->is_level;
	entry->active_low	 = data->active_low;
	/*
	 * Mask level triggered irqs. Edge triggered irqs are masked
	 * by the irq core code in case they fire.
	 */
	entry->masked		= data->is_level;
}

int mp_irqdomain_alloc(struct irq_domain *domain, unsigned int virq,
		       unsigned int nr_irqs, void *arg)
{
	struct irq_alloc_info *info = arg;
	struct mp_chip_data *data;
	struct irq_data *irq_data;
	int ret, ioapic, pin;
	unsigned long flags;

	if (!info || nr_irqs > 1)
		return -EINVAL;
	irq_data = irq_domain_get_irq_data(domain, virq);
	if (!irq_data)
		return -EINVAL;

	ioapic = mp_irqdomain_ioapic_idx(domain);
	pin = info->ioapic.pin;
	if (irq_resolve_mapping(domain, (irq_hw_number_t)pin))
		return -EEXIST;

	data = kzalloc_obj(*data);
	if (!data)
		return -ENOMEM;

	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, info);
	if (ret < 0)
		goto free_data;

	INIT_LIST_HEAD(&data->irq_2_pin);
	irq_data->hwirq = info->ioapic.pin;
	irq_data->chip = (domain->parent == x86_vector_domain) ?
			  &ioapic_chip : &ioapic_ir_chip;
	irq_data->chip_data = data;
	mp_irqdomain_get_attr(mp_pin_to_gsi(ioapic, pin), data, info);

	if (!add_pin_to_irq_node(data, ioapic_alloc_attr_node(info), ioapic, pin)) {
		ret = -ENOMEM;
		goto free_irqs;
	}

	mp_preconfigure_entry(data);
	mp_register_handler(virq, data->is_level);

	local_irq_save(flags);
	if (virq < nr_legacy_irqs())
		legacy_pic->mask(virq);
	local_irq_restore(flags);

	apic_pr_verbose("IOAPIC[%d]: Preconfigured routing entry (%d-%d -> IRQ %d Level:%i ActiveLow:%i)\n",
			ioapic, mpc_ioapic_id(ioapic), pin, virq, data->is_level, data->active_low);
	return 0;

free_irqs:
	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
free_data:
	kfree(data);
	return ret;
}

void mp_irqdomain_free(struct irq_domain *domain, unsigned int virq,
		       unsigned int nr_irqs)
{
	struct irq_data *irq_data;
	struct mp_chip_data *data;

	BUG_ON(nr_irqs != 1);
	irq_data = irq_domain_get_irq_data(domain, virq);
	if (irq_data && irq_data->chip_data) {
		data = irq_data->chip_data;
		__remove_pin_from_irq(data, mp_irqdomain_ioapic_idx(domain), (int)irq_data->hwirq);
		WARN_ON(!list_empty(&data->irq_2_pin));
		kfree(irq_data->chip_data);
	}
	irq_domain_free_irqs_top(domain, virq, nr_irqs);
}

int mp_irqdomain_activate(struct irq_domain *domain, struct irq_data *irq_data, bool reserve)
{
	guard(raw_spinlock_irqsave)(&ioapic_lock);
	ioapic_configure_entry(irq_data);
	return 0;
}

void mp_irqdomain_deactivate(struct irq_domain *domain,
			     struct irq_data *irq_data)
{
	/* It won't be called for IRQ with multiple IOAPIC pins associated */
	ioapic_mask_entry(mp_irqdomain_ioapic_idx(domain), (int)irq_data->hwirq);
}

int mp_irqdomain_ioapic_idx(struct irq_domain *domain)
{
	return (int)(long)domain->host_data;
}

const struct irq_domain_ops mp_ioapic_irqdomain_ops = {
	.alloc		= mp_irqdomain_alloc,
	.free		= mp_irqdomain_free,
	.activate	= mp_irqdomain_activate,
	.deactivate	= mp_irqdomain_deactivate,
};
