Linux-2.6.12-rc2

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / arch / i386 / kernel / apic.c

/*
 *      Local APIC handling, local APIC timers
 *
 *      (c) 1999, 2000 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.
 *      Maciej W. Rozycki       :       Various updates and fixes.
 *      Mikael Pettersson       :       Power Management for UP-APIC.
 *      Pavel Machek and
 *      Mikael Pettersson       :       PM converted to driver model.
 */

#include <linux/config.h>
#include <linux/init.h>

#include <linux/mm.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/bootmem.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/mc146818rtc.h>
#include <linux/kernel_stat.h>
#include <linux/sysdev.h>

#include <asm/atomic.h>
#include <asm/smp.h>
#include <asm/mtrr.h>
#include <asm/mpspec.h>
#include <asm/desc.h>
#include <asm/arch_hooks.h>
#include <asm/hpet.h>

#include <mach_apic.h>

#include "io_ports.h"

/*
 * Debug level
 */
int apic_verbosity;


static void apic_pm_activate(void);

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves.
 */
void ack_bad_irq(unsigned int irq)
{
        printk("unexpected IRQ trap at vector %02x\n", irq);
        /*
         * Currently unexpected vectors happen only on SMP and APIC.
         * We _must_ ack these because every local APIC has only N
         * irq slots per priority level, and a 'hanging, unacked' IRQ
         * holds up an irq slot - in excessive cases (when multiple
         * unexpected vectors occur) that might lock up the APIC
         * completely.
         */
        ack_APIC_irq();
}

void __init apic_intr_init(void)
{
#ifdef CONFIG_SMP
        smp_intr_init();
#endif
        /* self generated IPI for local APIC timer */
        set_intr_gate(LOCAL_TIMER_VECTOR, apic_timer_interrupt);

        /* IPI vectors for APIC spurious and error interrupts */
        set_intr_gate(SPURIOUS_APIC_VECTOR, spurious_interrupt);
        set_intr_gate(ERROR_APIC_VECTOR, error_interrupt);

        /* thermal monitor LVT interrupt */
#ifdef CONFIG_X86_MCE_P4THERMAL
        set_intr_gate(THERMAL_APIC_VECTOR, thermal_interrupt);
#endif
}

/* Using APIC to generate smp_local_timer_interrupt? */
int using_apic_timer = 0;

static DEFINE_PER_CPU(int, prof_multiplier) = 1;
static DEFINE_PER_CPU(int, prof_old_multiplier) = 1;
static DEFINE_PER_CPU(int, prof_counter) = 1;

static int enabled_via_apicbase;

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

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

int get_physical_broadcast(void)
{
        unsigned int lvr, version;
        lvr = apic_read(APIC_LVR);
        version = GET_APIC_VERSION(lvr);
        if (!APIC_INTEGRATED(version) || version >= 0x14)
                return 0xff;
        else
                return 0xf;
}

int get_maxlvt(void)
{
        unsigned int v, ver, maxlvt;

        v = apic_read(APIC_LVR);
        ver = GET_APIC_VERSION(v);
        /* 82489DXs do not report # of LVT entries. */
        maxlvt = APIC_INTEGRATED(ver) ? GET_APIC_MAXLVT(v) : 2;
        return maxlvt;
}

void clear_local_APIC(void)
{
        int maxlvt;
        unsigned long v;

        maxlvt = get_maxlvt();

        /*
         * Masking an LVT entry on a P6 can trigger a local APIC error
         * if the vector is zero. Mask LVTERR first to prevent this.
         */
        if (maxlvt >= 3) {
                v = ERROR_APIC_VECTOR; /* any non-zero vector will do */
                apic_write_around(APIC_LVTERR, v | APIC_LVT_MASKED);
        }
        /*
         * Careful: we have to set masks only first to deassert
         * any level-triggered sources.
         */
        v = apic_read(APIC_LVTT);
        apic_write_around(APIC_LVTT, v | APIC_LVT_MASKED);
        v = apic_read(APIC_LVT0);
        apic_write_around(APIC_LVT0, v | APIC_LVT_MASKED);
        v = apic_read(APIC_LVT1);
        apic_write_around(APIC_LVT1, v | APIC_LVT_MASKED);
        if (maxlvt >= 4) {
                v = apic_read(APIC_LVTPC);
                apic_write_around(APIC_LVTPC, v | APIC_LVT_MASKED);
        }

/* lets not touch this if we didn't frob it */
#ifdef CONFIG_X86_MCE_P4THERMAL
        if (maxlvt >= 5) {
                v = apic_read(APIC_LVTTHMR);
                apic_write_around(APIC_LVTTHMR, v | APIC_LVT_MASKED);
        }
#endif
        /*
         * Clean APIC state for other OSs:
         */
        apic_write_around(APIC_LVTT, APIC_LVT_MASKED);
        apic_write_around(APIC_LVT0, APIC_LVT_MASKED);
        apic_write_around(APIC_LVT1, APIC_LVT_MASKED);
        if (maxlvt >= 3)
                apic_write_around(APIC_LVTERR, APIC_LVT_MASKED);
        if (maxlvt >= 4)
                apic_write_around(APIC_LVTPC, APIC_LVT_MASKED);

#ifdef CONFIG_X86_MCE_P4THERMAL
        if (maxlvt >= 5)
                apic_write_around(APIC_LVTTHMR, APIC_LVT_MASKED);
#endif
        v = GET_APIC_VERSION(apic_read(APIC_LVR));
        if (APIC_INTEGRATED(v)) {       /* !82489DX */
                if (maxlvt > 3)         /* Due to Pentium errata 3AP and 11AP. */
                        apic_write(APIC_ESR, 0);
                apic_read(APIC_ESR);
        }
}

void __init connect_bsp_APIC(void)
{
        if (pic_mode) {
                /*
                 * Do not trust the local APIC being empty at bootup.
                 */
                clear_local_APIC();
                /*
                 * PIC mode, enable APIC mode in the IMCR, i.e.
                 * connect BSP's local APIC to INT and NMI lines.
                 */
                apic_printk(APIC_VERBOSE, "leaving PIC mode, "
                                "enabling APIC mode.\n");
                outb(0x70, 0x22);
                outb(0x01, 0x23);
        }
        enable_apic_mode();
}

void disconnect_bsp_APIC(void)
{
        if (pic_mode) {
                /*
                 * Put the board back into PIC mode (has an effect
                 * only on certain older boards).  Note that APIC
                 * interrupts, including IPIs, won't work beyond
                 * this point!  The only exception are INIT IPIs.
                 */
                apic_printk(APIC_VERBOSE, "disabling APIC mode, "
                                "entering PIC mode.\n");
                outb(0x70, 0x22);
                outb(0x00, 0x23);
        }
}

void disable_local_APIC(void)
{
        unsigned long value;

        clear_local_APIC();

        /*
         * Disable APIC (implies clearing of registers
         * for 82489DX!).
         */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_SPIV_APIC_ENABLED;
        apic_write_around(APIC_SPIV, value);

        if (enabled_via_apicbase) {
                unsigned int l, h;
                rdmsr(MSR_IA32_APICBASE, l, h);
                l &= ~MSR_IA32_APICBASE_ENABLE;
                wrmsr(MSR_IA32_APICBASE, l, h);
        }
}

/*
 * This is to verify that we're looking at a real local APIC.
 * Check these against your board if the CPUs aren't getting
 * started for no apparent reason.
 */
int __init verify_local_APIC(void)
{
        unsigned int reg0, reg1;

        /*
         * The version register is read-only in a real APIC.
         */
        reg0 = apic_read(APIC_LVR);
        apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg0);
        apic_write(APIC_LVR, reg0 ^ APIC_LVR_MASK);
        reg1 = apic_read(APIC_LVR);
        apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg1);

        /*
         * The two version reads above should print the same
         * numbers.  If the second one is different, then we
         * poke at a non-APIC.
         */
        if (reg1 != reg0)
                return 0;

        /*
         * Check if the version looks reasonably.
         */
        reg1 = GET_APIC_VERSION(reg0);
        if (reg1 == 0x00 || reg1 == 0xff)
                return 0;
        reg1 = get_maxlvt();
        if (reg1 < 0x02 || reg1 == 0xff)
                return 0;

        /*
         * The ID register is read/write in a real APIC.
         */
        reg0 = apic_read(APIC_ID);
        apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg0);

        /*
         * The next two are just to see if we have sane values.
         * They're only really relevant if we're in Virtual Wire
         * compatibility mode, but most boxes are anymore.
         */
        reg0 = apic_read(APIC_LVT0);
        apic_printk(APIC_DEBUG, "Getting LVT0: %x\n", reg0);
        reg1 = apic_read(APIC_LVT1);
        apic_printk(APIC_DEBUG, "Getting LVT1: %x\n", reg1);

        return 1;
}

void __init sync_Arb_IDs(void)
{
        /* Unsupported on P4 - see Intel Dev. Manual Vol. 3, Ch. 8.6.1 */
        unsigned int ver = GET_APIC_VERSION(apic_read(APIC_LVR));
        if (ver >= 0x14)        /* P4 or higher */
                return;
        /*
         * Wait for idle.
         */
        apic_wait_icr_idle();

        apic_printk(APIC_DEBUG, "Synchronizing Arb IDs.\n");
        apic_write_around(APIC_ICR, APIC_DEST_ALLINC | APIC_INT_LEVELTRIG
                                | APIC_DM_INIT);
}

extern void __error_in_apic_c (void);

/*
 * An initial setup of the virtual wire mode.
 */
void __init init_bsp_APIC(void)
{
        unsigned long value, ver;

        /*
         * Don't do the setup now if we have a SMP BIOS as the
         * through-I/O-APIC virtual wire mode might be active.
         */
        if (smp_found_config || !cpu_has_apic)
                return;

        value = apic_read(APIC_LVR);
        ver = GET_APIC_VERSION(value);

        /*
         * Do not trust the local APIC being empty at bootup.
         */
        clear_local_APIC();

        /*
         * Enable APIC.
         */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_VECTOR_MASK;
        value |= APIC_SPIV_APIC_ENABLED;
        
        /* This bit is reserved on P4/Xeon and should be cleared */
        if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && (boot_cpu_data.x86 == 15))
                value &= ~APIC_SPIV_FOCUS_DISABLED;
        else
                value |= APIC_SPIV_FOCUS_DISABLED;
        value |= SPURIOUS_APIC_VECTOR;
        apic_write_around(APIC_SPIV, value);

        /*
         * Set up the virtual wire mode.
         */
        apic_write_around(APIC_LVT0, APIC_DM_EXTINT);
        value = APIC_DM_NMI;
        if (!APIC_INTEGRATED(ver))              /* 82489DX */
                value |= APIC_LVT_LEVEL_TRIGGER;
        apic_write_around(APIC_LVT1, value);
}

void __init setup_local_APIC (void)
{
        unsigned long oldvalue, value, ver, maxlvt;

        /* Pound the ESR really hard over the head with a big hammer - mbligh */
        if (esr_disable) {
                apic_write(APIC_ESR, 0);
                apic_write(APIC_ESR, 0);
                apic_write(APIC_ESR, 0);
                apic_write(APIC_ESR, 0);
        }

        value = apic_read(APIC_LVR);
        ver = GET_APIC_VERSION(value);

        if ((SPURIOUS_APIC_VECTOR & 0x0f) != 0x0f)
                __error_in_apic_c();

        /*
         * Double-check whether this APIC is really registered.
         */
        if (!apic_id_registered())
                BUG();

        /*
         * Intel recommends to set DFR, LDR and TPR before enabling
         * an APIC.  See e.g. "AP-388 82489DX User's Manual" (Intel
         * document number 292116).  So here it goes...
         */
        init_apic_ldr();

        /*
         * Set Task Priority to 'accept all'. We never change this
         * later on.
         */
        value = apic_read(APIC_TASKPRI);
        value &= ~APIC_TPRI_MASK;
        apic_write_around(APIC_TASKPRI, value);

        /*
         * Now that we are all set up, enable the APIC
         */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_VECTOR_MASK;
        /*
         * Enable APIC
         */
        value |= APIC_SPIV_APIC_ENABLED;

        /*
         * Some unknown Intel IO/APIC (or APIC) errata is biting us with
         * certain networking cards. If high frequency interrupts are
         * happening on a particular IOAPIC pin, plus the IOAPIC routing
         * entry is masked/unmasked at a high rate as well then sooner or
         * later IOAPIC line gets 'stuck', no more interrupts are received
         * from the device. If focus CPU is disabled then the hang goes
         * away, oh well :-(
         *
         * [ This bug can be reproduced easily with a level-triggered
         *   PCI Ne2000 networking cards and PII/PIII processors, dual
         *   BX chipset. ]
         */
        /*
         * Actually disabling the focus CPU check just makes the hang less
         * frequent as it makes the interrupt distributon model be more
         * like LRU than MRU (the short-term load is more even across CPUs).
         * See also the comment in end_level_ioapic_irq().  --macro
         */
#if 1
        /* Enable focus processor (bit==0) */
        value &= ~APIC_SPIV_FOCUS_DISABLED;
#else
        /* Disable focus processor (bit==1) */
        value |= APIC_SPIV_FOCUS_DISABLED;
#endif
        /*
         * Set spurious IRQ vector
         */
        value |= SPURIOUS_APIC_VECTOR;
        apic_write_around(APIC_SPIV, value);

        /*
         * Set up LVT0, LVT1:
         *
         * set up through-local-APIC on the BP's LINT0. This is not
         * strictly necessery in pure symmetric-IO mode, but sometimes
         * we delegate interrupts to the 8259A.
         */
        /*
         * TODO: set up through-local-APIC from through-I/O-APIC? --macro
         */
        value = apic_read(APIC_LVT0) & APIC_LVT_MASKED;
        if (!smp_processor_id() && (pic_mode || !value)) {
                value = APIC_DM_EXTINT;
                apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n",
                                smp_processor_id());
        } else {
                value = APIC_DM_EXTINT | APIC_LVT_MASKED;
                apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n",
                                smp_processor_id());
        }
        apic_write_around(APIC_LVT0, value);

        /*
         * only the BP should see the LINT1 NMI signal, obviously.
         */
        if (!smp_processor_id())
                value = APIC_DM_NMI;
        else
                value = APIC_DM_NMI | APIC_LVT_MASKED;
        if (!APIC_INTEGRATED(ver))              /* 82489DX */
                value |= APIC_LVT_LEVEL_TRIGGER;
        apic_write_around(APIC_LVT1, value);

        if (APIC_INTEGRATED(ver) && !esr_disable) {             /* !82489DX */
                maxlvt = get_maxlvt();
                if (maxlvt > 3)         /* Due to the Pentium erratum 3AP. */
                        apic_write(APIC_ESR, 0);
                oldvalue = apic_read(APIC_ESR);

                value = ERROR_APIC_VECTOR;      // enables sending errors
                apic_write_around(APIC_LVTERR, value);
                /*
                 * spec says clear errors after enabling vector.
                 */
                if (maxlvt > 3)
                        apic_write(APIC_ESR, 0);
                value = apic_read(APIC_ESR);
                if (value != oldvalue)
                        apic_printk(APIC_VERBOSE, "ESR value before enabling "
                                "vector: 0x%08lx  after: 0x%08lx\n",
                                oldvalue, value);
        } else {
                if (esr_disable)        
                        /* 
                         * Something untraceble is creating bad interrupts on 
                         * secondary quads ... for the moment, just leave the
                         * ESR disabled - we can't do anything useful with the
                         * errors anyway - mbligh
                         */
                        printk("Leaving ESR disabled.\n");
                else 
                        printk("No ESR for 82489DX.\n");
        }

        if (nmi_watchdog == NMI_LOCAL_APIC)
                setup_apic_nmi_watchdog();
        apic_pm_activate();
}

/*
 * If Linux enabled the LAPIC against the BIOS default
 * disable it down before re-entering the BIOS on shutdown.
 * Otherwise the BIOS may get confused and not power-off.
 */
void lapic_shutdown(void)
{
        if (!cpu_has_apic || !enabled_via_apicbase)
                return;

        local_irq_disable();
        disable_local_APIC();
        local_irq_enable();
}

#ifdef CONFIG_PM

static struct {
        int active;
        /* r/w apic fields */
        unsigned int apic_id;
        unsigned int apic_taskpri;
        unsigned int apic_ldr;
        unsigned int apic_dfr;
        unsigned int apic_spiv;
        unsigned int apic_lvtt;
        unsigned int apic_lvtpc;
        unsigned int apic_lvt0;
        unsigned int apic_lvt1;
        unsigned int apic_lvterr;
        unsigned int apic_tmict;
        unsigned int apic_tdcr;
        unsigned int apic_thmr;
} apic_pm_state;

static int lapic_suspend(struct sys_device *dev, u32 state)
{
        unsigned long flags;

        if (!apic_pm_state.active)
                return 0;

        apic_pm_state.apic_id = apic_read(APIC_ID);
        apic_pm_state.apic_taskpri = apic_read(APIC_TASKPRI);
        apic_pm_state.apic_ldr = apic_read(APIC_LDR);
        apic_pm_state.apic_dfr = apic_read(APIC_DFR);
        apic_pm_state.apic_spiv = apic_read(APIC_SPIV);
        apic_pm_state.apic_lvtt = apic_read(APIC_LVTT);
        apic_pm_state.apic_lvtpc = apic_read(APIC_LVTPC);
        apic_pm_state.apic_lvt0 = apic_read(APIC_LVT0);
        apic_pm_state.apic_lvt1 = apic_read(APIC_LVT1);
        apic_pm_state.apic_lvterr = apic_read(APIC_LVTERR);
        apic_pm_state.apic_tmict = apic_read(APIC_TMICT);
        apic_pm_state.apic_tdcr = apic_read(APIC_TDCR);
        apic_pm_state.apic_thmr = apic_read(APIC_LVTTHMR);
        
        local_irq_save(flags);
        disable_local_APIC();
        local_irq_restore(flags);
        return 0;
}

static int lapic_resume(struct sys_device *dev)
{
        unsigned int l, h;
        unsigned long flags;

        if (!apic_pm_state.active)
                return 0;

        local_irq_save(flags);

        /*
         * Make sure the APICBASE points to the right address
         *
         * FIXME! This will be wrong if we ever support suspend on
         * SMP! We'll need to do this as part of the CPU restore!
         */
        rdmsr(MSR_IA32_APICBASE, l, h);
        l &= ~MSR_IA32_APICBASE_BASE;
        l |= MSR_IA32_APICBASE_ENABLE | mp_lapic_addr;
        wrmsr(MSR_IA32_APICBASE, l, h);

        apic_write(APIC_LVTERR, ERROR_APIC_VECTOR | APIC_LVT_MASKED);
        apic_write(APIC_ID, apic_pm_state.apic_id);
        apic_write(APIC_DFR, apic_pm_state.apic_dfr);
        apic_write(APIC_LDR, apic_pm_state.apic_ldr);
        apic_write(APIC_TASKPRI, apic_pm_state.apic_taskpri);
        apic_write(APIC_SPIV, apic_pm_state.apic_spiv);
        apic_write(APIC_LVT0, apic_pm_state.apic_lvt0);
        apic_write(APIC_LVT1, apic_pm_state.apic_lvt1);
        apic_write(APIC_LVTTHMR, apic_pm_state.apic_thmr);
        apic_write(APIC_LVTPC, apic_pm_state.apic_lvtpc);
        apic_write(APIC_LVTT, apic_pm_state.apic_lvtt);
        apic_write(APIC_TDCR, apic_pm_state.apic_tdcr);
        apic_write(APIC_TMICT, apic_pm_state.apic_tmict);
        apic_write(APIC_ESR, 0);
        apic_read(APIC_ESR);
        apic_write(APIC_LVTERR, apic_pm_state.apic_lvterr);
        apic_write(APIC_ESR, 0);
        apic_read(APIC_ESR);
        local_irq_restore(flags);
        return 0;
}

/*
 * This device has no shutdown method - fully functioning local APICs
 * are needed on every CPU up until machine_halt/restart/poweroff.
 */

static struct sysdev_class lapic_sysclass = {
        set_kset_name("lapic"),
        .resume         = lapic_resume,
        .suspend        = lapic_suspend,
};

static struct sys_device device_lapic = {
        .id     = 0,
        .cls    = &lapic_sysclass,
};

static void __init apic_pm_activate(void)
{
        apic_pm_state.active = 1;
}

static int __init init_lapic_sysfs(void)
{
        int error;

        if (!cpu_has_apic)
                return 0;
        /* XXX: remove suspend/resume procs if !apic_pm_state.active? */

        error = sysdev_class_register(&lapic_sysclass);
        if (!error)
                error = sysdev_register(&device_lapic);
        return error;
}
device_initcall(init_lapic_sysfs);

#else   /* CONFIG_PM */

static void apic_pm_activate(void) { }

#endif  /* CONFIG_PM */

/*
 * Detect and enable local APICs on non-SMP boards.
 * Original code written by Keir Fraser.
 */

/*
 * Knob to control our willingness to enable the local APIC.
 */
int enable_local_apic __initdata = 0; /* -1=force-disable, +1=force-enable */

static int __init lapic_disable(char *str)
{
        enable_local_apic = -1;
        clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
        return 0;
}
__setup("nolapic", lapic_disable);

static int __init lapic_enable(char *str)
{
        enable_local_apic = 1;
        return 0;
}
__setup("lapic", lapic_enable);

static int __init apic_set_verbosity(char *str)
{
        if (strcmp("debug", str) == 0)
                apic_verbosity = APIC_DEBUG;
        else if (strcmp("verbose", str) == 0)
                apic_verbosity = APIC_VERBOSE;
        else
                printk(KERN_WARNING "APIC Verbosity level %s not recognised"
                                " use apic=verbose or apic=debug", str);

        return 0;
}

__setup("apic=", apic_set_verbosity);

static int __init detect_init_APIC (void)
{
        u32 h, l, features;
        extern void get_cpu_vendor(struct cpuinfo_x86*);

        /* Disabled by kernel option? */
        if (enable_local_apic < 0)
                return -1;

        /* Workaround for us being called before identify_cpu(). */
        get_cpu_vendor(&boot_cpu_data);

        switch (boot_cpu_data.x86_vendor) {
        case X86_VENDOR_AMD:
                if ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model > 1) ||
                    (boot_cpu_data.x86 == 15))      
                        break;
                goto no_apic;
        case X86_VENDOR_INTEL:
                if (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15 ||
                    (boot_cpu_data.x86 == 5 && cpu_has_apic))
                        break;
                goto no_apic;
        default:
                goto no_apic;
        }

        if (!cpu_has_apic) {
                /*
                 * Over-ride BIOS and try to enable the local
                 * APIC only if "lapic" specified.
                 */
                if (enable_local_apic <= 0) {
                        printk("Local APIC disabled by BIOS -- "
                               "you can enable it with \"lapic\"\n");
                        return -1;
                }
                /*
                 * Some BIOSes disable the local APIC in the
                 * APIC_BASE MSR. This can only be done in
                 * software for Intel P6 or later and AMD K7
                 * (Model > 1) or later.
                 */
                rdmsr(MSR_IA32_APICBASE, l, h);
                if (!(l & MSR_IA32_APICBASE_ENABLE)) {
                        printk("Local APIC disabled by BIOS -- reenabling.\n");
                        l &= ~MSR_IA32_APICBASE_BASE;
                        l |= MSR_IA32_APICBASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
                        wrmsr(MSR_IA32_APICBASE, l, h);
                        enabled_via_apicbase = 1;
                }
        }
        /*
         * The APIC feature bit should now be enabled
         * in `cpuid'
         */
        features = cpuid_edx(1);
        if (!(features & (1 << X86_FEATURE_APIC))) {
                printk("Could not enable APIC!\n");
                return -1;
        }
        set_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
        mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;

        /* The BIOS may have set up the APIC at some other address */
        rdmsr(MSR_IA32_APICBASE, l, h);
        if (l & MSR_IA32_APICBASE_ENABLE)
                mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;

        if (nmi_watchdog != NMI_NONE)
                nmi_watchdog = NMI_LOCAL_APIC;

        printk("Found and enabled local APIC!\n");

        apic_pm_activate();

        return 0;

no_apic:
        printk("No local APIC present or hardware disabled\n");
        return -1;
}

void __init init_apic_mappings(void)
{
        unsigned long apic_phys;

        /*
         * If no local APIC can be found then set up a fake all
         * zeroes page to simulate the local APIC and another
         * one for the IO-APIC.
         */
        if (!smp_found_config && detect_init_APIC()) {
                apic_phys = (unsigned long) alloc_bootmem_pages(PAGE_SIZE);
                apic_phys = __pa(apic_phys);
        } else
                apic_phys = mp_lapic_addr;

        set_fixmap_nocache(FIX_APIC_BASE, apic_phys);
        printk(KERN_DEBUG "mapped APIC to %08lx (%08lx)\n", APIC_BASE,
               apic_phys);

        /*
         * Fetch the APIC ID of the BSP in case we have a
         * default configuration (or the MP table is broken).
         */
        if (boot_cpu_physical_apicid == -1U)
                boot_cpu_physical_apicid = GET_APIC_ID(apic_read(APIC_ID));

#ifdef CONFIG_X86_IO_APIC
        {
                unsigned long ioapic_phys, idx = FIX_IO_APIC_BASE_0;
                int i;

                for (i = 0; i < nr_ioapics; i++) {
                        if (smp_found_config) {
                                ioapic_phys = mp_ioapics[i].mpc_apicaddr;
                                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;
                                }
                        } else {
fake_ioapic_page:
                                ioapic_phys = (unsigned long)
                                              alloc_bootmem_pages(PAGE_SIZE);
                                ioapic_phys = __pa(ioapic_phys);
                        }
                        set_fixmap_nocache(idx, ioapic_phys);
                        printk(KERN_DEBUG "mapped IOAPIC to %08lx (%08lx)\n",
                               __fix_to_virt(idx), ioapic_phys);
                        idx++;
                }
        }
#endif
}

/*
 * This part sets up the APIC 32 bit clock in LVTT1, with HZ interrupts
 * per second. We assume that the caller has already set up the local
 * APIC.
 *
 * The APIC timer is not exactly sync with the external timer chip, it
 * closely follows bus clocks.
 */

/*
 * The timer chip is already set up at HZ interrupts per second here,
 * but we do not accept timer interrupts yet. We only allow the BP
 * to calibrate.
 */
static unsigned int __init get_8254_timer_count(void)
{
        extern spinlock_t i8253_lock;
        unsigned long flags;

        unsigned int count;

        spin_lock_irqsave(&i8253_lock, flags);

        outb_p(0x00, PIT_MODE);
        count = inb_p(PIT_CH0);
        count |= inb_p(PIT_CH0) << 8;

        spin_unlock_irqrestore(&i8253_lock, flags);

        return count;
}

/* next tick in 8254 can be caught by catching timer wraparound */
static void __init wait_8254_wraparound(void)
{
        unsigned int curr_count, prev_count;

        curr_count = get_8254_timer_count();
        do {
                prev_count = curr_count;
                curr_count = get_8254_timer_count();

                /* workaround for broken Mercury/Neptune */
                if (prev_count >= curr_count + 0x100)
                        curr_count = get_8254_timer_count();

        } while (prev_count >= curr_count);
}

/*
 * Default initialization for 8254 timers. If we use other timers like HPET,
 * we override this later
 */
void (*wait_timer_tick)(void) __initdata = wait_8254_wraparound;

/*
 * This function sets up the local APIC timer, with a timeout of
 * 'clocks' APIC bus clock. During calibration we actually call
 * this function twice on the boot CPU, once with a bogus timeout
 * value, second time for real. The other (noncalibrating) CPUs
 * call this function only once, with the real, calibrated value.
 *
 * We do reads before writes even if unnecessary, to get around the
 * P5 APIC double write bug.
 */

#define APIC_DIVISOR 16

static void __setup_APIC_LVTT(unsigned int clocks)
{
        unsigned int lvtt_value, tmp_value, ver;

        ver = GET_APIC_VERSION(apic_read(APIC_LVR));
        lvtt_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
        if (!APIC_INTEGRATED(ver))
                lvtt_value |= SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV);
        apic_write_around(APIC_LVTT, lvtt_value);

        /*
         * Divide PICLK by 16
         */
        tmp_value = apic_read(APIC_TDCR);
        apic_write_around(APIC_TDCR, (tmp_value
                                & ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE))
                                | APIC_TDR_DIV_16);

        apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR);
}

static void __init setup_APIC_timer(unsigned int clocks)
{
        unsigned long flags;

        local_irq_save(flags);

        /*
         * Wait for IRQ0's slice:
         */
        wait_timer_tick();

        __setup_APIC_LVTT(clocks);

        local_irq_restore(flags);
}

/*
 * In this function we calibrate APIC bus clocks to the external
 * timer. Unfortunately we cannot use jiffies and the timer irq
 * to calibrate, since some later bootup code depends on getting
 * the first irq? Ugh.
 *
 * We want to do the calibration only once since we
 * want to have local timer irqs syncron. CPUs connected
 * by the same APIC bus have the very same bus frequency.
 * And we want to have irqs off anyways, no accidental
 * APIC irq that way.
 */

static int __init calibrate_APIC_clock(void)
{
        unsigned long long t1 = 0, t2 = 0;
        long tt1, tt2;
        long result;
        int i;
        const int LOOPS = HZ/10;

        apic_printk(APIC_VERBOSE, "calibrating APIC timer ...\n");

        /*
         * Put whatever arbitrary (but long enough) timeout
         * value into the APIC clock, we just want to get the
         * counter running for calibration.
         */
        __setup_APIC_LVTT(1000000000);

        /*
         * The timer chip counts down to zero. Let's wait
         * for a wraparound to start exact measurement:
         * (the current tick might have been already half done)
         */

        wait_timer_tick();

        /*
         * We wrapped around just now. Let's start:
         */
        if (cpu_has_tsc)
                rdtscll(t1);
        tt1 = apic_read(APIC_TMCCT);

        /*
         * Let's wait LOOPS wraprounds:
         */
        for (i = 0; i < LOOPS; i++)
                wait_timer_tick();

        tt2 = apic_read(APIC_TMCCT);
        if (cpu_has_tsc)
                rdtscll(t2);

        /*
         * The APIC bus clock counter is 32 bits only, it
         * might have overflown, but note that we use signed
         * longs, thus no extra care needed.
         *
         * underflown to be exact, as the timer counts down ;)
         */

        result = (tt1-tt2)*APIC_DIVISOR/LOOPS;

        if (cpu_has_tsc)
                apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
                        "%ld.%04ld MHz.\n",
                        ((long)(t2-t1)/LOOPS)/(1000000/HZ),
                        ((long)(t2-t1)/LOOPS)%(1000000/HZ));

        apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
                "%ld.%04ld MHz.\n",
                result/(1000000/HZ),
                result%(1000000/HZ));

        return result;
}

static unsigned int calibration_result;

void __init setup_boot_APIC_clock(void)
{
        apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n");
        using_apic_timer = 1;

        local_irq_disable();

        calibration_result = calibrate_APIC_clock();
        /*
         * Now set up the timer for real.
         */
        setup_APIC_timer(calibration_result);

        local_irq_enable();
}

void __init setup_secondary_APIC_clock(void)
{
        setup_APIC_timer(calibration_result);
}

void __init disable_APIC_timer(void)
{
        if (using_apic_timer) {
                unsigned long v;

                v = apic_read(APIC_LVTT);
                apic_write_around(APIC_LVTT, v | APIC_LVT_MASKED);
        }
}

void enable_APIC_timer(void)
{
        if (using_apic_timer) {
                unsigned long v;

                v = apic_read(APIC_LVTT);
                apic_write_around(APIC_LVTT, v & ~APIC_LVT_MASKED);
        }
}

/*
 * the frequency of the profiling timer can be changed
 * by writing a multiplier value into /proc/profile.
 */
int setup_profiling_timer(unsigned int multiplier)
{
        int i;

        /*
         * Sanity check. [at least 500 APIC cycles should be
         * between APIC interrupts as a rule of thumb, to avoid
         * irqs flooding us]
         */
        if ( (!multiplier) || (calibration_result/multiplier < 500))
                return -EINVAL;

        /* 
         * Set the new multiplier for each CPU. CPUs don't start using the
         * new values until the next timer interrupt in which they do process
         * accounting. At that time they also adjust their APIC timers
         * accordingly.
         */
        for (i = 0; i < NR_CPUS; ++i)
                per_cpu(prof_multiplier, i) = multiplier;

        return 0;
}

#undef APIC_DIVISOR

/*
 * Local timer interrupt handler. It does both profiling and
 * process statistics/rescheduling.
 *
 * We do profiling in every local tick, statistics/rescheduling
 * happen only every 'profiling multiplier' ticks. The default
 * multiplier is 1 and it can be changed by writing the new multiplier
 * value into /proc/profile.
 */

inline void smp_local_timer_interrupt(struct pt_regs * regs)
{
        int cpu = smp_processor_id();

        profile_tick(CPU_PROFILING, regs);
        if (--per_cpu(prof_counter, cpu) <= 0) {
                /*
                 * The multiplier may have changed since the last time we got
                 * to this point as a result of the user writing to
                 * /proc/profile. In this case we need to adjust the APIC
                 * timer accordingly.
                 *
                 * Interrupts are already masked off at this point.
                 */
                per_cpu(prof_counter, cpu) = per_cpu(prof_multiplier, cpu);
                if (per_cpu(prof_counter, cpu) !=
                                        per_cpu(prof_old_multiplier, cpu)) {
                        __setup_APIC_LVTT(
                                        calibration_result/
                                        per_cpu(prof_counter, cpu));
                        per_cpu(prof_old_multiplier, cpu) =
                                                per_cpu(prof_counter, cpu);
                }

#ifdef CONFIG_SMP
                update_process_times(user_mode(regs));
#endif
        }

        /*
         * We take the 'long' return path, and there every subsystem
         * grabs the apropriate locks (kernel lock/ irq lock).
         *
         * we might want to decouple profiling from the 'long path',
         * and do the profiling totally in assembly.
         *
         * Currently this isn't too much of an issue (performance wise),
         * we can take more than 100K local irqs per second on a 100 MHz P5.
         */
}

/*
 * Local APIC timer interrupt. This is the most natural way for doing
 * local interrupts, but local timer interrupts can be emulated by
 * broadcast interrupts too. [in case the hw doesn't support APIC timers]
 *
 * [ if a single-CPU system runs an SMP kernel then we call the local
 *   interrupt as well. Thus we cannot inline the local irq ... ]
 */

fastcall void smp_apic_timer_interrupt(struct pt_regs *regs)
{
        int cpu = smp_processor_id();

        /*
         * the NMI deadlock-detector uses this.
         */
        per_cpu(irq_stat, cpu).apic_timer_irqs++;

        /*
         * NOTE! We'd better ACK the irq immediately,
         * because timer handling can be slow.
         */
        ack_APIC_irq();
        /*
         * update_process_times() expects us to have done irq_enter().
         * Besides, if we don't timer interrupts ignore the global
         * interrupt lock, which is the WrongThing (tm) to do.
         */
        irq_enter();
        smp_local_timer_interrupt(regs);
        irq_exit();
}

/*
 * This interrupt should _never_ happen with our APIC/SMP architecture
 */
fastcall void smp_spurious_interrupt(struct pt_regs *regs)
{
        unsigned long v;

        irq_enter();
        /*
         * Check if this really is a spurious interrupt and ACK it
         * if it is a vectored one.  Just in case...
         * Spurious interrupts should not be ACKed.
         */
        v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));
        if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))
                ack_APIC_irq();

        /* see sw-dev-man vol 3, chapter 7.4.13.5 */
        printk(KERN_INFO "spurious APIC interrupt on CPU#%d, should never happen.\n",
                        smp_processor_id());
        irq_exit();
}

/*
 * This interrupt should never happen with our APIC/SMP architecture
 */

fastcall void smp_error_interrupt(struct pt_regs *regs)
{
        unsigned long v, v1;

        irq_enter();
        /* First tickle the hardware, only then report what went on. -- REW */
        v = apic_read(APIC_ESR);
        apic_write(APIC_ESR, 0);
        v1 = apic_read(APIC_ESR);
        ack_APIC_irq();
        atomic_inc(&irq_err_count);

        /* Here is what the APIC error bits mean:
           0: Send CS error
           1: Receive CS error
           2: Send accept error
           3: Receive accept error
           4: Reserved
           5: Send illegal vector
           6: Received illegal vector
           7: Illegal register address
        */
        printk (KERN_DEBUG "APIC error on CPU%d: %02lx(%02lx)\n",
                smp_processor_id(), v , v1);
        irq_exit();
}

/*
 * This initializes the IO-APIC and APIC hardware if this is
 * a UP kernel.
 */
int __init APIC_init_uniprocessor (void)
{
        if (enable_local_apic < 0)
                clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);

        if (!smp_found_config && !cpu_has_apic)
                return -1;

        /*
         * Complain if the BIOS pretends there is one.
         */
        if (!cpu_has_apic && APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
                printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
                        boot_cpu_physical_apicid);
                return -1;
        }

        verify_local_APIC();

        connect_bsp_APIC();

        phys_cpu_present_map = physid_mask_of_physid(boot_cpu_physical_apicid);

        setup_local_APIC();

        if (nmi_watchdog == NMI_LOCAL_APIC)
                check_nmi_watchdog();
#ifdef CONFIG_X86_IO_APIC
        if (smp_found_config)
                if (!skip_ioapic_setup && nr_ioapics)
                        setup_IO_APIC();
#endif
        setup_boot_APIC_clock();

        return 0;
}