// 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>

#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);

int skip_ioapic_setup;

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

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_printk(APIC_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)
{
        struct IO_APIC_route_entry entry;
        unsigned long flags;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        entry = __ioapic_read_entry(apic, pin);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

        return entry;
}

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

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        __ioapic_write_entry(apic, pin, e);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
}

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

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

/*
 * The common case is 1:1 IRQ<->pin mappings. Sometimes there are
 * shared ISA-space IRQs, so we have to support them. We are super
 * fast in the common case, and fast for shared ISA-space IRQs.
 */
static int __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 0;

        entry = kzalloc_node(sizeof(struct irq_pin_list), GFP_ATOMIC, node);
        if (!entry) {
                pr_err("can not alloc irq_pin_list (%d,%d,%d)\n",
                       node, apic, pin);
                return -ENOMEM;
        }
        entry->apic = apic;
        entry->pin = pin;
        list_add_tail(&entry->list, &data->irq_2_pin);

        return 0;
}

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 add_pin_to_irq_node(struct mp_chip_data *data,
                                int node, int apic, int pin)
{
        if (__add_pin_to_irq_node(data, node, apic, pin))
                panic("IO-APIC: failed to add irq-pin. Can not proceed\n");
}

/*
 * Reroute an IRQ to a different pin.
 */
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;
                        /* every one is different, right? */
                        return;
                }
        }

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

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);
        }
}

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

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        io_apic_modify_irq(data, true, &io_apic_sync);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
}

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;
        unsigned long flags;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        __unmask_ioapic(data);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
}

/*
 * 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)
{
        unsigned long flags;
        struct irq_pin_list *entry;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        for_each_irq_pin(entry, data->irq_2_pin)
                __eoi_ioapic_pin(entry->apic, entry->pin, vector);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
}

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

        /* Check delivery_mode to be sure we're not clearing an SMI pin */
        entry = ioapic_read_entry(apic, pin);
        if (entry.delivery_mode == 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) {
                unsigned long flags;

                /*
                 * 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);
                }
                raw_spin_lock_irqsave(&ioapic_lock, flags);
                __eoi_ioapic_pin(apic, pin, entry.vector);
                raw_spin_unlock_irqrestore(&ioapic_lock, flags);
        }

        /*
         * 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;
        int ints[MAX_PIRQS+1];

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

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

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

__setup("pirq=", ioapic_pirq_setup);
#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 = 0x4d0 + (irq >> 3);
                return (inb(port) >> (irq & 7)) & 1;
        }
        apic_printk(APIC_VERBOSE, KERN_INFO
                        "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 (skip_ioapic_setup)
                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)
{
        bool legacy = false;
        int irq = -1;
        int type = ioapics[ioapic].irqdomain_cfg.type;

        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 mp_chip_data *data;
        struct irq_data *irq_data = irq_get_irq_data(irq);
        int node = ioapic_alloc_attr_node(info);

        /*
         * Legacy ISA IRQ has already been allocated, just add pin to
         * the pin list associated with this IRQ and program the IOAPIC
         * entry. 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)
{
        int irq;
        bool legacy = false;
        struct irq_alloc_info tmp;
        struct mp_chip_data *data;
        struct irq_domain *domain = mp_ioapic_irqdomain(ioapic);

        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;
        }

        mutex_lock(&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++;
                }
        }
        mutex_unlock(&ioapic_mutex);

        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_printk(APIC_VERBOSE, KERN_DEBUG
                                                "disabling PIRQ%d\n", pin-16);
                        } else {
                                int irq = pirq_entries[pin-16];
                                apic_printk(APIC_VERBOSE, KERN_DEBUG
                                                "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;

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

/*
 * 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_printk(APIC_DEBUG,
                    "querying PCI -> IRQ mapping bus:%d, slot:%d, pin:%d.\n",
                    bus, slot, pin);
        if (test_bit(bus, mp_bus_not_pci)) {
                apic_printk(APIC_VERBOSE,
                            "PCI BIOS passed nonexistent PCI bus %d!\n", bus);
                return -1;
        }

        for (i = 0; i < mp_irq_entries; i++) {
                int lbus = mp_irqs[i].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_printk(APIC_VERBOSE, KERN_DEBUG "init IO_APIC IRQs\n");

        for_each_ioapic_pin(ioapic, pin) {
                idx = find_irq_entry(ioapic, pin, mp_INT);
                if (idx < 0)
                        apic_printk(APIC_VERBOSE,
                                    KERN_DEBUG " 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;

        printk(KERN_DEBUG "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) {
                        printk(KERN_DEBUG "%s, remapped, I(%04X),  Z(%X)\n",
                               buf,
                               (entry.ir_index_15 << 15) | entry.ir_index_0_14,
                                entry.ir_zero);
                } else {
                        printk(KERN_DEBUG "%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;
        unsigned long flags;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        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);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

        printk(KERN_DEBUG "IO APIC #%d......\n", mpc_ioapic_id(ioapic_idx));
        printk(KERN_DEBUG ".... register #00: %08X\n", reg_00.raw);
        printk(KERN_DEBUG ".......    : physical APIC id: %02X\n", reg_00.bits.ID);
        printk(KERN_DEBUG ".......    : Delivery Type: %X\n", reg_00.bits.delivery_type);
        printk(KERN_DEBUG ".......    : LTS          : %X\n", reg_00.bits.LTS);

        printk(KERN_DEBUG ".... register #01: %08X\n", *(int *)&reg_01);
        printk(KERN_DEBUG ".......     : max redirection entries: %02X\n",
                reg_01.bits.entries);

        printk(KERN_DEBUG ".......     : PRQ implemented: %X\n", reg_01.bits.PRQ);
        printk(KERN_DEBUG ".......     : 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) {
                printk(KERN_DEBUG ".... register #02: %08X\n", reg_02.raw);
                printk(KERN_DEBUG ".......     : 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) {
                printk(KERN_DEBUG ".... register #03: %08X\n", reg_03.raw);
                printk(KERN_DEBUG ".......     : Boot DT    : %X\n", reg_03.bits.boot_DT);
        }

        printk(KERN_DEBUG ".... 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;

        printk(KERN_DEBUG "number of MP IRQ sources: %d.\n", mp_irq_entries);
        for_each_ioapic(ioapic_idx)
                printk(KERN_DEBUG "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);

        printk(KERN_DEBUG "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;

                printk(KERN_DEBUG "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;
        int apic, pin;

        if (skip_ioapic_setup)
                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;
                        goto found_i8259;
                }
        }
 found_i8259:
        /* Look to see what if the MP table has reported the ExtINT */
        /* If we could not find the appropriate pin by looking at the ioapic
         * the i8259 probably is not connected the ioapic but give the
         * mptable a chance anyway.
         */
        i8259_pin  = find_isa_irq_pin(0, mp_ExtINT);
        i8259_apic = find_isa_irq_apic(0, mp_ExtINT);
        /* Trust the MP table if nothing is setup in the hardware */
        if ((ioapic_i8259.pin == -1) && (i8259_pin >= 0)) {
                printk(KERN_WARNING "ExtINT not setup in hardware but reported by MP table\n");
                ioapic_i8259.pin  = i8259_pin;
                ioapic_i8259.apic = i8259_apic;
        }
        /* Complain if the MP table and the hardware disagree */
        if (((ioapic_i8259.apic != i8259_apic) || (ioapic_i8259.pin != i8259_pin)) &&
                (i8259_pin >= 0) && (ioapic_i8259.pin >= 0))
        {
                printk(KERN_WARNING "ExtINT in hardware and MP table differ\n");
        }

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

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
 */
void __init setup_ioapic_ids_from_mpc_nocheck(void)
{
        union IO_APIC_reg_00 reg_00;
        physid_mask_t phys_id_present_map;
        int ioapic_idx;
        int i;
        unsigned char old_id;
        unsigned long flags;

        /*
         * This is broken; anything with a real cpu count has to
         * circumvent this idiocy regardless.
         */
        apic->ioapic_phys_id_map(&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 */
                raw_spin_lock_irqsave(&ioapic_lock, flags);
                reg_00.raw = io_apic_read(ioapic_idx, 0);
                raw_spin_unlock_irqrestore(&ioapic_lock, flags);

                old_id = mpc_ioapic_id(ioapic_idx);

                if (mpc_ioapic_id(ioapic_idx) >= get_physical_broadcast()) {
                        printk(KERN_ERR "BIOS bug, IO-APIC#%d ID is %d in the MPC table!...\n",
                                ioapic_idx, mpc_ioapic_id(ioapic_idx));
                        printk(KERN_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 (apic->check_apicid_used(&phys_id_present_map,
                                            mpc_ioapic_id(ioapic_idx))) {
                        printk(KERN_ERR "BIOS bug, IO-APIC#%d ID %d is already used!...\n",
                                ioapic_idx, mpc_ioapic_id(ioapic_idx));
                        for (i = 0; i < get_physical_broadcast(); i++)
                                if (!physid_isset(i, phys_id_present_map))
                                        break;
                        if (i >= get_physical_broadcast())
                                panic("Max APIC ID exceeded!\n");
                        printk(KERN_ERR "... fixing up to %d. (tell your hw vendor)\n",
                                i);
                        physid_set(i, phys_id_present_map);
                        ioapics[ioapic_idx].mp_config.apicid = i;
                } else {
                        physid_mask_t tmp;
                        apic->apicid_to_cpu_present(mpc_ioapic_id(ioapic_idx),
                                                    &tmp);
                        apic_printk(APIC_VERBOSE, "Setting %d in the "
                                        "phys_id_present_map\n",
                                        mpc_ioapic_id(ioapic_idx));
                        physids_or(phys_id_present_map, phys_id_present_map, tmp);
                }

                /*
                 * We need to adjust the IRQ routing table
                 * if the ID changed.
                 */
                if (old_id != 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_printk(APIC_VERBOSE, KERN_INFO
                        "...changing IO-APIC physical APIC ID to %d ...",
                        mpc_ioapic_id(ioapic_idx));

                reg_00.bits.ID = mpc_ioapic_id(ioapic_idx);
                raw_spin_lock_irqsave(&ioapic_lock, flags);
                io_apic_write(ioapic_idx, 0, reg_00.raw);
                raw_spin_unlock_irqrestore(&ioapic_lock, flags);

                /*
                 * Sanity check
                 */
                raw_spin_lock_irqsave(&ioapic_lock, flags);
                reg_00.raw = io_apic_read(ioapic_idx, 0);
                raw_spin_unlock_irqrestore(&ioapic_lock, flags);
                if (reg_00.bits.ID != mpc_ioapic_id(ioapic_idx))
                        pr_cont("could not set ID!\n");
                else
                        apic_printk(APIC_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 {
                rep_nop();
                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;
        unsigned long flags;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        if (irq < nr_legacy_irqs()) {
                legacy_pic->mask(irq);
                if (legacy_pic->irq_pending(irq))
                        was_pending = 1;
        }
        __unmask_ioapic(data->chip_data);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

        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;
        unsigned long flags;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        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) {
                        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
                        return true;
                }
        }
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

        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.
         */
        ack_APIC_irq();

        /*
         * 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;
        unsigned long flags;
        int ret;

        ret = parent->chip->irq_set_affinity(parent, mask, force);
        raw_spin_lock_irqsave(&ioapic_lock, flags);
        if (ret >= 0 && ret != IRQ_SET_MASK_OK_DONE)
                ioapic_configure_entry(irq_data);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

        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;
        raw_spin_lock(&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;
                }
        }
        raw_spin_unlock(&ioapic_lock);
        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,
};

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,
};

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..
                         */
                        if (irq < nr_legacy_irqs())
                                legacy_pic->make_irq(irq);
                        else
                                /* Strange. Oh, well.. */
                                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;

        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;

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

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

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)
{
        int apic, pin, i;
        struct IO_APIC_route_entry entry0, entry1;
        unsigned char save_control, save_freq_select;
        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 = hard_smp_processor_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 mp_alloc_timer_irq(int ioapic, int pin)
{
        int irq = -1;
        struct irq_domain *domain = mp_ioapic_irqdomain(ioapic);

        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;
                mutex_lock(&ioapic_mutex);
                irq = alloc_isa_irq_from_domain(domain, 0, ioapic, pin, &info);
                mutex_unlock(&ioapic_mutex);
        }

        return irq;
}

/*
 * This code may look a bit paranoid, but it's supposed to cooperate with
 * a wide range of boards and BIOS bugs.  Fortunately only the timer IRQ
 * is so screwy.  Thanks to Brian Perkins for testing/hacking this beast
 * fanatically on his truly buggy board.
 *
 * FIXME: really need to revamp this for all platforms.
 */
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;

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

        /*
         * Some BIOS writers are clueless and report the ExtINTA
         * I/O APIC input from the cascaded 8259A as the timer
         * interrupt input.  So just in case, if only one pin
         * was found above, try it both directly and through the
         * 8259A.
         */
        if (pin1 == -1) {
                panic_if_irq_remap("BIOS 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)
                        apic_printk(APIC_QUIET, KERN_ERR "..MP-BIOS bug: "
                                    "8254 timer not connected to IO-APIC\n");

                apic_printk(APIC_QUIET, KERN_INFO "...trying to set up timer "
                            "(IRQ0) through the 8259A ...\n");
                apic_printk(APIC_QUIET, KERN_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()) {
                        apic_printk(APIC_QUIET, KERN_INFO "....... works.\n");
                        goto out;
                }
                /*
                 * Cleanup, just in case ...
                 */
                legacy_pic->mask(0);
                clear_IO_APIC_pin(apic2, pin2);
                apic_printk(APIC_QUIET, KERN_INFO "....... failed.\n");
        }

        apic_printk(APIC_QUIET, KERN_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()) {
                apic_printk(APIC_QUIET, KERN_INFO "..... works.\n");
                goto out;
        }
        legacy_pic->mask(0);
        apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_FIXED | cfg->vector);
        apic_printk(APIC_QUIET, KERN_INFO "..... failed.\n");

        apic_printk(APIC_QUIET, KERN_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()) {
                apic_printk(APIC_QUIET, KERN_INFO "..... works.\n");
                goto out;
        }
        apic_printk(APIC_QUIET, KERN_INFO "..... failed :(.\n");
        if (apic_is_x2apic_enabled())
                apic_printk(APIC_QUIET, KERN_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 irq_domain *parent;
        int hwirqs = mp_ioapic_pin_count(ioapic);
        struct ioapic *ip = &ioapics[ioapic];
        struct ioapic_domain_cfg *cfg = &ip->irqdomain_cfg;
        struct mp_ioapic_gsi *gsi_cfg = mp_ioapic_gsi_routing(ioapic);
        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_node_to_fwnode(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_ANY);
        if (!parent) {
                if (!cfg->dev)
                        irq_domain_free_fwnode(fn);
                return -ENODEV;
        }

        ip->irqdomain = irq_domain_create_linear(fn, hwirqs, 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;
        }

        ip->irqdomain->parent = parent;

        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 (skip_ioapic_setup || !nr_ioapics)
                return;

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

        apic_printk(APIC_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)
{
        unsigned long flags;
        union IO_APIC_reg_00 reg_00;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        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);
        }
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
}

static void ioapic_resume(void)
{
        int ioapic_idx;

        for_each_ioapic_reverse(ioapic_idx)
                resume_ioapic_id(ioapic_idx);

        restore_ioapic_entries();
}

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

static int __init ioapic_init_ops(void)
{
        register_syscore_ops(&ioapic_syscore_ops);

        return 0;
}

device_initcall(ioapic_init_ops);

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

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        reg_01.raw = io_apic_read(ioapic, 1);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

        /* 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)
{
        /*
         * dmar_alloc_hwirq() may be called before setup_IO_APIC(), so use
         * gsi_top if ioapic_dynirq_base hasn't been initialized yet.
         */
        if (!ioapic_initialized)
                return gsi_top;
        /*
         * For DT enabled machines ioapic_dynirq_base is irrelevant and not
         * updated. So simply return @from if ioapic_dynirq_base == 0.
         */
        return ioapic_dynirq_base ? : from;
}

#ifdef CONFIG_X86_32
static int io_apic_get_unique_id(int ioapic, int apic_id)
{
        union IO_APIC_reg_00 reg_00;
        static physid_mask_t apic_id_map = PHYSID_MASK_NONE;
        physid_mask_t tmp;
        unsigned long flags;
        int i = 0;

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

        if (physids_empty(apic_id_map))
                apic->ioapic_phys_id_map(&phys_cpu_present_map, &apic_id_map);

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        reg_00.raw = io_apic_read(ioapic, 0);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

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

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

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

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

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

                apic_id = i;
        }

        apic->apicid_to_cpu_present(apic_id, &tmp);
        physids_or(apic_id_map, apic_id_map, tmp);

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

                raw_spin_lock_irqsave(&ioapic_lock, flags);
                io_apic_write(ioapic, 0, reg_00.raw);
                reg_00.raw = io_apic_read(ioapic, 0);
                raw_spin_unlock_irqrestore(&ioapic_lock, flags);

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

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

        return apic_id;
}

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);
        else
                return id;
}
#else
static u8 io_apic_unique_id(int idx, u8 id)
{
        union IO_APIC_reg_00 reg_00;
        DECLARE_BITMAP(used, 256);
        unsigned long flags;
        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.
         */
        raw_spin_lock_irqsave(&ioapic_lock, flags);
        reg_00.raw = io_apic_read(idx, 0);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
        new_id = reg_00.bits.ID;
        if (!test_bit(new_id, used)) {
                apic_printk(APIC_VERBOSE, KERN_INFO
                        "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;
        raw_spin_lock_irqsave(&ioapic_lock, flags);
        io_apic_write(idx, 0, reg_00.raw);
        reg_00.raw = io_apic_read(idx, 0);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
        /* 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;
        unsigned long flags;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        reg_01.raw = io_apic_read(ioapic, 1);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);

        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)
{
        unsigned long n;
        struct resource *res;
        char *mem;
        int i;

        if (nr_ioapics == 0)
                return NULL;

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

        mem = memblock_alloc(n, SMP_CACHE_BYTES);
        if (!mem)
                panic("%s: Failed to allocate %lu bytes\n", __func__, n);
        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;
}

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) {
                                printk(KERN_ERR
                                       "WARNING: bogus zero IO-APIC "
                                       "address found in MPTABLE, "
                                       "disabling IO/APIC support!\n");
                                smp_found_config = 0;
                                skip_ioapic_setup = 1;
                                goto fake_ioapic_page;
                        }
#endif
                } else {
#ifdef CONFIG_X86_32
fake_ioapic_page:
#endif
                        ioapic_phys = (unsigned long)memblock_alloc(PAGE_SIZE,
                                                                    PAGE_SIZE);
                        if (!ioapic_phys)
                                panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
                                      __func__, PAGE_SIZE, PAGE_SIZE);
                        ioapic_phys = __pa(ioapic_phys);
                }
                set_fixmap_nocache(idx, ioapic_phys);
                apic_printk(APIC_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)
{
        int i;
        struct resource *r = ioapic_resources;

        if (!r) {
                if (nr_ioapics > 0)
                        printk(KERN_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;
        }

        printk(KERN_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)
{
        int idx;

        for (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;

        set_fixmap_nocache(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_find_mapping(domain, (irq_hw_number_t)pin) > 0)
                return -EEXIST;

        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, info);
        if (ret < 0) {
                kfree(data);
                return ret;
        }

        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);

        add_pin_to_irq_node(data, ioapic_alloc_attr_node(info), ioapic, pin);

        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_printk(APIC_VERBOSE, KERN_DEBUG
                    "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;
}

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)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&ioapic_lock, flags);
        ioapic_configure_entry(irq_data);
        raw_spin_unlock_irqrestore(&ioapic_lock, flags);
        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,
};