io_apic.c

/*
 *	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
 */

#include <linux/mm.h>
#include <linux/interrupt.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/module.h>
#include <linux/sysdev.h>
#include <linux/msi.h>
#include <linux/htirq.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/jiffies.h>	/* time_after() */
#ifdef CONFIG_ACPI
#include <acpi/acpi_bus.h>
#endif
#include <linux/bootmem.h>
#include <linux/dmar.h>
#include <linux/hpet.h>

#include <asm/idle.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/i8259.h>
#include <asm/nmi.h>
#include <asm/msidef.h>
#include <asm/hypertransport.h>
#include <asm/setup.h>
#include <asm/irq_remapping.h>
#include <asm/hpet.h>
#include <asm/uv/uv_hub.h>
#include <asm/uv/uv_irq.h>

#include <asm/apic.h>

#define __apicdebuginit(type) static type __init

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

static DEFINE_SPINLOCK(ioapic_lock);
static DEFINE_SPINLOCK(vector_lock);

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

/* I/O APIC entries */
struct mpc_ioapic mp_ioapics[MAX_IO_APICS];
int nr_ioapics;

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

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

#if defined (CONFIG_MCA) || defined (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;

void arch_disable_smp_support(void)
{
#ifdef CONFIG_PCI
	noioapicquirk = 1;
	noioapicreroute = -1;
#endif
	skip_ioapic_setup = 1;
}

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

struct irq_pin_list;

/*
 * This is performance-critical, we want to do it O(1)
 *
 * the indexing order of this array favors 1:1 mappings
 * between pins and IRQs.
 */

struct irq_pin_list {
	int apic, pin;
	struct irq_pin_list *next;
};

static struct irq_pin_list *get_one_free_irq_2_pin(int cpu)
{
	struct irq_pin_list *pin;
	int node;

	node = cpu_to_node(cpu);

	pin = kzalloc_node(sizeof(*pin), GFP_ATOMIC, node);

	return pin;
}

struct irq_cfg {
	struct irq_pin_list *irq_2_pin;
	cpumask_var_t domain;
	cpumask_var_t old_domain;
	unsigned move_cleanup_count;
	u8 vector;
	u8 move_in_progress : 1;
#ifdef CONFIG_NUMA_MIGRATE_IRQ_DESC
	u8 move_desc_pending : 1;
#endif
};

/* irq_cfg is indexed by the sum of all RTEs in all I/O APICs. */
#ifdef CONFIG_SPARSE_IRQ
static struct irq_cfg irq_cfgx[] = {
#else
static struct irq_cfg irq_cfgx[NR_IRQS] = {
#endif
	[0]  = { .vector = IRQ0_VECTOR,  },
	[1]  = { .vector = IRQ1_VECTOR,  },
	[2]  = { .vector = IRQ2_VECTOR,  },
	[3]  = { .vector = IRQ3_VECTOR,  },
	[4]  = { .vector = IRQ4_VECTOR,  },
	[5]  = { .vector = IRQ5_VECTOR,  },
	[6]  = { .vector = IRQ6_VECTOR,  },
	[7]  = { .vector = IRQ7_VECTOR,  },
	[8]  = { .vector = IRQ8_VECTOR,  },
	[9]  = { .vector = IRQ9_VECTOR,  },
	[10] = { .vector = IRQ10_VECTOR, },
	[11] = { .vector = IRQ11_VECTOR, },
	[12] = { .vector = IRQ12_VECTOR, },
	[13] = { .vector = IRQ13_VECTOR, },
	[14] = { .vector = IRQ14_VECTOR, },
	[15] = { .vector = IRQ15_VECTOR, },
};

int __init arch_early_irq_init(void)
{
	struct irq_cfg *cfg;
	struct irq_desc *desc;
	int count;
	int i;

	cfg = irq_cfgx;
	count = ARRAY_SIZE(irq_cfgx);

	for (i = 0; i < count; i++) {
		desc = irq_to_desc(i);
		desc->chip_data = &cfg[i];
		alloc_bootmem_cpumask_var(&cfg[i].domain);
		alloc_bootmem_cpumask_var(&cfg[i].old_domain);
		if (i < NR_IRQS_LEGACY)
			cpumask_setall(cfg[i].domain);
	}

	return 0;
}

#ifdef CONFIG_SPARSE_IRQ
static struct irq_cfg *irq_cfg(unsigned int irq)
{
	struct irq_cfg *cfg = NULL;
	struct irq_desc *desc;

	desc = irq_to_desc(irq);
	if (desc)
		cfg = desc->chip_data;

	return cfg;
}

static struct irq_cfg *get_one_free_irq_cfg(int cpu)
{
	struct irq_cfg *cfg;
	int node;

	node = cpu_to_node(cpu);

	cfg = kzalloc_node(sizeof(*cfg), GFP_ATOMIC, node);
	if (cfg) {
		if (!alloc_cpumask_var_node(&cfg->domain, GFP_ATOMIC, node)) {
			kfree(cfg);
			cfg = NULL;
		} else if (!alloc_cpumask_var_node(&cfg->old_domain,
							  GFP_ATOMIC, node)) {
			free_cpumask_var(cfg->domain);
			kfree(cfg);
			cfg = NULL;
		} else {
			cpumask_clear(cfg->domain);
			cpumask_clear(cfg->old_domain);
		}
	}

	return cfg;
}

int arch_init_chip_data(struct irq_desc *desc, int cpu)
{
	struct irq_cfg *cfg;

	cfg = desc->chip_data;
	if (!cfg) {
		desc->chip_data = get_one_free_irq_cfg(cpu);
		if (!desc->chip_data) {
			printk(KERN_ERR "can not alloc irq_cfg\n");
			BUG_ON(1);
		}
	}

	return 0;
}

#ifdef CONFIG_NUMA_MIGRATE_IRQ_DESC

static void
init_copy_irq_2_pin(struct irq_cfg *old_cfg, struct irq_cfg *cfg, int cpu)
{
	struct irq_pin_list *old_entry, *head, *tail, *entry;

	cfg->irq_2_pin = NULL;
	old_entry = old_cfg->irq_2_pin;
	if (!old_entry)
		return;

	entry = get_one_free_irq_2_pin(cpu);
	if (!entry)
		return;

	entry->apic	= old_entry->apic;
	entry->pin	= old_entry->pin;
	head		= entry;
	tail		= entry;
	old_entry	= old_entry->next;
	while (old_entry) {
		entry = get_one_free_irq_2_pin(cpu);
		if (!entry) {
			entry = head;
			while (entry) {
				head = entry->next;
				kfree(entry);
				entry = head;
			}
			/* still use the old one */
			return;
		}
		entry->apic	= old_entry->apic;
		entry->pin	= old_entry->pin;
		tail->next	= entry;
		tail		= entry;
		old_entry	= old_entry->next;
	}

	tail->next = NULL;
	cfg->irq_2_pin = head;
}

static void free_irq_2_pin(struct irq_cfg *old_cfg, struct irq_cfg *cfg)
{
	struct irq_pin_list *entry, *next;

	if (old_cfg->irq_2_pin == cfg->irq_2_pin)
		return;

	entry = old_cfg->irq_2_pin;

	while (entry) {
		next = entry->next;
		kfree(entry);
		entry = next;
	}
	old_cfg->irq_2_pin = NULL;
}

void arch_init_copy_chip_data(struct irq_desc *old_desc,
				 struct irq_desc *desc, int cpu)
{
	struct irq_cfg *cfg;
	struct irq_cfg *old_cfg;

	cfg = get_one_free_irq_cfg(cpu);

	if (!cfg)
		return;

	desc->chip_data = cfg;

	old_cfg = old_desc->chip_data;

	memcpy(cfg, old_cfg, sizeof(struct irq_cfg));

	init_copy_irq_2_pin(old_cfg, cfg, cpu);
}

static void free_irq_cfg(struct irq_cfg *old_cfg)
{
	kfree(old_cfg);
}

void arch_free_chip_data(struct irq_desc *old_desc, struct irq_desc *desc)
{
	struct irq_cfg *old_cfg, *cfg;

	old_cfg = old_desc->chip_data;
	cfg = desc->chip_data;

	if (old_cfg == cfg)
		return;

	if (old_cfg) {
		free_irq_2_pin(old_cfg, cfg);
		free_irq_cfg(old_cfg);
		old_desc->chip_data = NULL;
	}
}

static void
set_extra_move_desc(struct irq_desc *desc, const struct cpumask *mask)
{
	struct irq_cfg *cfg = desc->chip_data;

	if (!cfg->move_in_progress) {
		/* it means that domain is not changed */
		if (!cpumask_intersects(desc->affinity, mask))
			cfg->move_desc_pending = 1;
	}
}
#endif

#else
static struct irq_cfg *irq_cfg(unsigned int irq)
{
	return irq < nr_irqs ? irq_cfgx + irq : NULL;
}

#endif

#ifndef CONFIG_NUMA_MIGRATE_IRQ_DESC
static inline void
set_extra_move_desc(struct irq_desc *desc, const struct cpumask *mask)
{
}
#endif

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)
		+ (mp_ioapics[idx].apicaddr & ~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);
}

static inline unsigned int 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 inline 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);
}

/*
 * Re-write a value: to be used for read-modify-write
 * cycles where the read already set up the index register.
 *
 * Older SiS APIC requires we rewrite the index register
 */
static inline void io_apic_modify(unsigned int apic, unsigned int reg, unsigned int value)
{
	struct io_apic __iomem *io_apic = io_apic_base(apic);

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

static bool io_apic_level_ack_pending(struct irq_cfg *cfg)
{
	struct irq_pin_list *entry;
	unsigned long flags;

	spin_lock_irqsave(&ioapic_lock, flags);
	entry = cfg->irq_2_pin;
	for (;;) {
		unsigned int reg;
		int pin;

		if (!entry)
			break;
		pin = entry->pin;
		reg = io_apic_read(entry->apic, 0x10 + pin*2);
		/* Is the remote IRR bit set? */
		if (reg & IO_APIC_REDIR_REMOTE_IRR) {
			spin_unlock_irqrestore(&ioapic_lock, flags);
			return true;
		}
		if (!entry->next)
			break;
		entry = entry->next;
	}
	spin_unlock_irqrestore(&ioapic_lock, flags);

	return false;
}

union entry_union {
	struct { u32 w1, w2; };
	struct IO_APIC_route_entry entry;
};

static struct IO_APIC_route_entry ioapic_read_entry(int apic, int pin)
{
	union entry_union eu;
	unsigned long flags;
	spin_lock_irqsave(&ioapic_lock, flags);
	eu.w1 = io_apic_read(apic, 0x10 + 2 * pin);
	eu.w2 = io_apic_read(apic, 0x11 + 2 * pin);
	spin_unlock_irqrestore(&ioapic_lock, flags);
	return eu.entry;
}

/*
 * 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)
{
	union entry_union eu;
	eu.entry = e;
	io_apic_write(apic, 0x11 + 2*pin, eu.w2);
	io_apic_write(apic, 0x10 + 2*pin, eu.w1);
}

void ioapic_write_entry(int apic, int pin, struct IO_APIC_route_entry e)
{
	unsigned long flags;
	spin_lock_irqsave(&ioapic_lock, flags);
	__ioapic_write_entry(apic, pin, e);
	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)
{
	unsigned long flags;
	union entry_union eu = { .entry.mask = 1 };

	spin_lock_irqsave(&ioapic_lock, flags);
	io_apic_write(apic, 0x10 + 2*pin, eu.w1);
	io_apic_write(apic, 0x11 + 2*pin, eu.w2);
	spin_unlock_irqrestore(&ioapic_lock, flags);
}

#ifdef CONFIG_SMP
static void send_cleanup_vector(struct irq_cfg *cfg)
{
	cpumask_var_t cleanup_mask;

	if (unlikely(!alloc_cpumask_var(&cleanup_mask, GFP_ATOMIC))) {
		unsigned int i;
		cfg->move_cleanup_count = 0;
		for_each_cpu_and(i, cfg->old_domain, cpu_online_mask)
			cfg->move_cleanup_count++;
		for_each_cpu_and(i, cfg->old_domain, cpu_online_mask)
			apic->send_IPI_mask(cpumask_of(i), IRQ_MOVE_CLEANUP_VECTOR);
	} else {
		cpumask_and(cleanup_mask, cfg->old_domain, cpu_online_mask);
		cfg->move_cleanup_count = cpumask_weight(cleanup_mask);
		apic->send_IPI_mask(cleanup_mask, IRQ_MOVE_CLEANUP_VECTOR);
		free_cpumask_var(cleanup_mask);
	}
	cfg->move_in_progress = 0;
}

static void __target_IO_APIC_irq(unsigned int irq, unsigned int dest, struct irq_cfg *cfg)
{
	int apic, pin;
	struct irq_pin_list *entry;
	u8 vector = cfg->vector;

	entry = cfg->irq_2_pin;
	for (;;) {
		unsigned int reg;

		if (!entry)
			break;

		apic = entry->apic;
		pin = entry->pin;
		/*
		 * With interrupt-remapping, destination information comes
		 * from interrupt-remapping table entry.
		 */
		if (!irq_remapped(irq))
			io_apic_write(apic, 0x11 + pin*2, dest);
		reg = io_apic_read(apic, 0x10 + pin*2);
		reg &= ~IO_APIC_REDIR_VECTOR_MASK;
		reg |= vector;
		io_apic_modify(apic, 0x10 + pin*2, reg);
		if (!entry->next)
			break;
		entry = entry->next;
	}
}

static int
assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask);

/*
 * Either sets desc->affinity to a valid value, and returns
 * ->cpu_mask_to_apicid of that, or returns BAD_APICID and
 * leaves desc->affinity untouched.
 */
static unsigned int
set_desc_affinity(struct irq_desc *desc, const struct cpumask *mask)
{
	struct irq_cfg *cfg;
	unsigned int irq;

	if (!cpumask_intersects(mask, cpu_online_mask))
		return BAD_APICID;

	irq = desc->irq;
	cfg = desc->chip_data;
	if (assign_irq_vector(irq, cfg, mask))
		return BAD_APICID;

	cpumask_and(desc->affinity, cfg->domain, mask);
	set_extra_move_desc(desc, mask);

	return apic->cpu_mask_to_apicid_and(desc->affinity, cpu_online_mask);
}

static void
set_ioapic_affinity_irq_desc(struct irq_desc *desc, const struct cpumask *mask)
{
	struct irq_cfg *cfg;
	unsigned long flags;
	unsigned int dest;
	unsigned int irq;

	irq = desc->irq;
	cfg = desc->chip_data;

	spin_lock_irqsave(&ioapic_lock, flags);
	dest = set_desc_affinity(desc, mask);
	if (dest != BAD_APICID) {
		/* Only the high 8 bits are valid. */
		dest = SET_APIC_LOGICAL_ID(dest);
		__target_IO_APIC_irq(irq, dest, cfg);
	}
	spin_unlock_irqrestore(&ioapic_lock, flags);
}

static void
set_ioapic_affinity_irq(unsigned int irq, const struct cpumask *mask)
{
	struct irq_desc *desc;

	desc = irq_to_desc(irq);

	set_ioapic_affinity_irq_desc(desc, mask);
}
#endif /* CONFIG_SMP */

/*
 * The common case is 1:1 IRQ<->pin mappings. Sometimes there are
 * shared ISA-space IRQs, so we have to support them. We are super
 * fast in the common case, and fast for shared ISA-space IRQs.
 */
static void add_pin_to_irq_cpu(struct irq_cfg *cfg, int cpu, int apic, int pin)
{
	struct irq_pin_list *entry;

	entry = cfg->irq_2_pin;
	if (!entry) {
		entry = get_one_free_irq_2_pin(cpu);
		if (!entry) {
			printk(KERN_ERR "can not alloc irq_2_pin to add %d - %d\n",
					apic, pin);
			return;
		}
		cfg->irq_2_pin = entry;
		entry->apic = apic;
		entry->pin = pin;
		return;
	}

	while (entry->next) {
		/* not again, please */
		if (entry->apic == apic && entry->pin == pin)
			return;

		entry = entry->next;
	}

	entry->next = get_one_free_irq_2_pin(cpu);
	entry = entry->next;
	entry->apic = apic;
	entry->pin = pin;
}

/*
 * Reroute an IRQ to a different pin.
 */
static void __init replace_pin_at_irq_cpu(struct irq_cfg *cfg, int cpu,
				      int oldapic, int oldpin,
				      int newapic, int newpin)
{
	struct irq_pin_list *entry = cfg->irq_2_pin;
	int replaced = 0;

	while (entry) {
		if (entry->apic == oldapic && entry->pin == oldpin) {
			entry->apic = newapic;
			entry->pin = newpin;
			replaced = 1;
			/* every one is different, right? */
			break;
		}
		entry = entry->next;
	}

	/* why? call replace before add? */
	if (!replaced)
		add_pin_to_irq_cpu(cfg, cpu, newapic, newpin);
}

static inline void io_apic_modify_irq(struct irq_cfg *cfg,
				int mask_and, int mask_or,
				void (*final)(struct irq_pin_list *entry))
{
	int pin;
	struct irq_pin_list *entry;

	for (entry = cfg->irq_2_pin; entry != NULL; entry = entry->next) {
		unsigned int reg;
		pin = entry->pin;
		reg = io_apic_read(entry->apic, 0x10 + pin * 2);
		reg &= mask_and;
		reg |= mask_or;
		io_apic_modify(entry->apic, 0x10 + pin * 2, reg);
		if (final)
			final(entry);
	}
}

static void __unmask_IO_APIC_irq(struct irq_cfg *cfg)
{
	io_apic_modify_irq(cfg, ~IO_APIC_REDIR_MASKED, 0, NULL);
}

#ifdef CONFIG_X86_64
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_IO_APIC_irq(struct irq_cfg *cfg)
{
	io_apic_modify_irq(cfg, ~0, IO_APIC_REDIR_MASKED, &io_apic_sync);
}
#else /* CONFIG_X86_32 */
static void __mask_IO_APIC_irq(struct irq_cfg *cfg)
{
	io_apic_modify_irq(cfg, ~0, IO_APIC_REDIR_MASKED, NULL);
}

static void __mask_and_edge_IO_APIC_irq(struct irq_cfg *cfg)
{
	io_apic_modify_irq(cfg, ~IO_APIC_REDIR_LEVEL_TRIGGER,
			IO_APIC_REDIR_MASKED, NULL);
}

static void __unmask_and_level_IO_APIC_irq(struct irq_cfg *cfg)
{
	io_apic_modify_irq(cfg, ~IO_APIC_REDIR_MASKED,
			IO_APIC_REDIR_LEVEL_TRIGGER, NULL);
}
#endif /* CONFIG_X86_32 */

static void mask_IO_APIC_irq_desc(struct irq_desc *desc)
{
	struct irq_cfg *cfg = desc->chip_data;
	unsigned long flags;

	BUG_ON(!cfg);

	spin_lock_irqsave(&ioapic_lock, flags);
	__mask_IO_APIC_irq(cfg);
	spin_unlock_irqrestore(&ioapic_lock, flags);
}

static void unmask_IO_APIC_irq_desc(struct irq_desc *desc)
{
	struct irq_cfg *cfg = desc->chip_data;
	unsigned long flags;

	spin_lock_irqsave(&ioapic_lock, flags);
	__unmask_IO_APIC_irq(cfg);
	spin_unlock_irqrestore(&ioapic_lock, flags);
}

static void mask_IO_APIC_irq(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);

	mask_IO_APIC_irq_desc(desc);
}
static void unmask_IO_APIC_irq(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);

	unmask_IO_APIC_irq_desc(desc);
}

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

	/* Check delivery_mode to be sure we're not clearing an SMI pin */
	entry = ioapic_read_entry(apic, pin);
	if (entry.delivery_mode == dest_SMI)
		return;
	/*
	 * Disable it in the IO-APIC irq-routing table:
	 */
	ioapic_mask_entry(apic, pin);
}

static void clear_IO_APIC (void)
{
	int apic, pin;

	for (apic = 0; apic < nr_ioapics; apic++)
		for (pin = 0; pin < nr_ioapic_registers[apic]; pin++)
			clear_IO_APIC_pin(apic, pin);
}

#ifdef CONFIG_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 */

#ifdef CONFIG_INTR_REMAP
/* I/O APIC RTE contents at the OS boot up */
static struct IO_APIC_route_entry *early_ioapic_entries[MAX_IO_APICS];

/*
 * Saves and masks all the unmasked IO-APIC RTE's
 */
int save_mask_IO_APIC_setup(void)
{
	union IO_APIC_reg_01 reg_01;
	unsigned long flags;
	int apic, pin;

	/*
	 * The number of IO-APIC IRQ registers (== #pins):
	 */
	for (apic = 0; apic < nr_ioapics; apic++) {
		spin_lock_irqsave(&ioapic_lock, flags);
		reg_01.raw = io_apic_read(apic, 1);
		spin_unlock_irqrestore(&ioapic_lock, flags);
		nr_ioapic_registers[apic] = reg_01.bits.entries+1;
	}

	for (apic = 0; apic < nr_ioapics; apic++) {
		early_ioapic_entries[apic] =
			kzalloc(sizeof(struct IO_APIC_route_entry) *
				nr_ioapic_registers[apic], GFP_KERNEL);
		if (!early_ioapic_entries[apic])
			goto nomem;
	}

	for (apic = 0; apic < nr_ioapics; apic++)
		for (pin = 0; pin < nr_ioapic_registers[apic]; pin++) {
			struct IO_APIC_route_entry entry;

			entry = early_ioapic_entries[apic][pin] =
				ioapic_read_entry(apic, pin);
			if (!entry.mask) {
				entry.mask = 1;
				ioapic_write_entry(apic, pin, entry);
			}
		}

	return 0;

nomem:
	while (apic >= 0)
		kfree(early_ioapic_entries[apic--]);
	memset(early_ioapic_entries, 0,
		ARRAY_SIZE(early_ioapic_entries));

	return -ENOMEM;
}

void restore_IO_APIC_setup(void)
{
	int apic, pin;

	for (apic = 0; apic < nr_ioapics; apic++) {
		if (!early_ioapic_entries[apic])
			break;
		for (pin = 0; pin < nr_ioapic_registers[apic]; pin++)
			ioapic_write_entry(apic, pin,
					   early_ioapic_entries[apic][pin]);
		kfree(early_ioapic_entries[apic]);
		early_ioapic_entries[apic] = NULL;
	}
}

void reinit_intr_remapped_IO_APIC(int intr_remapping)
{
	/*
	 * for now plain restore of previous settings.
	 * TBD: In the case of OS enabling interrupt-remapping,
	 * IO-APIC RTE's need to be setup to point to interrupt-remapping
	 * table entries. for now, do a plain restore, and wait for
	 * the setup_IO_APIC_irqs() to do proper initialization.
	 */
	restore_IO_APIC_setup();
}
#endif

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

	for (i = 0; i < mp_irq_entries; i++)
		if (mp_irqs[i].irqtype == type &&
		    (mp_irqs[i].dstapic == mp_ioapics[apic].apicid ||
		     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 apic;
		for(apic = 0; apic < nr_ioapics; apic++) {
			if (mp_ioapics[apic].apicid == mp_irqs[i].dstapic)
				return apic;
		}
	}

	return -1;
}

/*
 * Find a specific PCI IRQ entry.
 * Not an __init, possibly needed by modules
 */
static int pin_2_irq(int idx, int apic, int pin);

int IO_APIC_get_PCI_irq_vector(int bus, int slot, int pin)
{
	int apic, i, best_guess = -1;