[safe/jmp/linux-2.6] / arch / x86_64 / 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/init.h>

#include <linux/mm.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 <linux/module.h>

#include <asm/atomic.h>
#include <asm/smp.h>
#include <asm/mtrr.h>
#include <asm/mpspec.h>
#include <asm/pgalloc.h>
#include <asm/mach_apic.h>
#include <asm/nmi.h>
#include <asm/idle.h>
#include <asm/proto.h>
#include <asm/timex.h>

int apic_verbosity;
int apic_runs_main_timer;
int apic_calibrate_pmtmr __initdata;

int disable_apic_timer __initdata;

/*
 * cpu_mask that denotes the CPUs that needs timer interrupt coming in as
 * IPIs in place of local APIC timers
 */
static cpumask_t timer_interrupt_broadcast_ipi_mask;

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

static void apic_pm_activate(void);

void enable_NMI_through_LVT0 (void * dummy)
{
        unsigned int v;
        
        v = APIC_DM_NMI;                        /* unmask and set to NMI */
        apic_write(APIC_LVT0, v);
}

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

        v = apic_read(APIC_LVR);
        maxlvt = GET_APIC_MAXLVT(v);
        return maxlvt;
}

/*
 * '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.
         * But don't ack when the APIC is disabled. -AK
         */
        if (!disable_apic)
                ack_APIC_irq();
}

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

        maxlvt = get_maxlvt();

        /*
         * Masking an LVT entry 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(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(APIC_LVTT, v | APIC_LVT_MASKED);
        v = apic_read(APIC_LVT0);
        apic_write(APIC_LVT0, v | APIC_LVT_MASKED);
        v = apic_read(APIC_LVT1);
        apic_write(APIC_LVT1, v | APIC_LVT_MASKED);
        if (maxlvt >= 4) {
                v = apic_read(APIC_LVTPC);
                apic_write(APIC_LVTPC, v | APIC_LVT_MASKED);
        }

        /*
         * Clean APIC state for other OSs:
         */
        apic_write(APIC_LVTT, APIC_LVT_MASKED);
        apic_write(APIC_LVT0, APIC_LVT_MASKED);
        apic_write(APIC_LVT1, APIC_LVT_MASKED);
        if (maxlvt >= 3)
                apic_write(APIC_LVTERR, APIC_LVT_MASKED);
        if (maxlvt >= 4)
                apic_write(APIC_LVTPC, APIC_LVT_MASKED);
        v = GET_APIC_VERSION(apic_read(APIC_LVR));
        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);
        }
}

void disconnect_bsp_APIC(int virt_wire_setup)
{
        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_QUIET, "disabling APIC mode, entering PIC mode.\n");
                outb(0x70, 0x22);
                outb(0x00, 0x23);
        }
        else {
                /* Go back to Virtual Wire compatibility mode */
                unsigned long value;

                /* For the spurious interrupt use vector F, and enable it */
                value = apic_read(APIC_SPIV);
                value &= ~APIC_VECTOR_MASK;
                value |= APIC_SPIV_APIC_ENABLED;
                value |= 0xf;
                apic_write(APIC_SPIV, value);

                if (!virt_wire_setup) {
                        /* For LVT0 make it edge triggered, active high, external and enabled */
                        value = apic_read(APIC_LVT0);
                        value &= ~(APIC_MODE_MASK | APIC_SEND_PENDING |
                                APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
                                APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED );
                        value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
                        value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_EXTINT);
                        apic_write(APIC_LVT0, value);
                }
                else {
                        /* Disable LVT0 */
                        apic_write(APIC_LVT0, APIC_LVT_MASKED);
                }

                /* For LVT1 make it edge triggered, active high, nmi and enabled */
                value = apic_read(APIC_LVT1);
                value &= ~(
                        APIC_MODE_MASK | APIC_SEND_PENDING |
                        APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
                        APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
                value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
                value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_NMI);
                apic_write(APIC_LVT1, value);
        }
}

void disable_local_APIC(void)
{
        unsigned int value;

        clear_local_APIC();

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

/*
 * 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);
        apic_write(APIC_ID, reg0 ^ APIC_ID_MASK);
        reg1 = apic_read(APIC_ID);
        apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg1);
        apic_write(APIC_ID, reg0);
        if (reg1 != (reg0 ^ APIC_ID_MASK))
                return 0;

        /*
         * 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(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 int value;

        /*
         * 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);

        /*
         * 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;
        value |= APIC_SPIV_FOCUS_DISABLED;
        value |= SPURIOUS_APIC_VECTOR;
        apic_write(APIC_SPIV, value);

        /*
         * Set up the virtual wire mode.
         */
        apic_write(APIC_LVT0, APIC_DM_EXTINT);
        value = APIC_DM_NMI;
        apic_write(APIC_LVT1, value);
}

void __cpuinit setup_local_APIC (void)
{
        unsigned int value, maxlvt;
        int i, j;

        value = apic_read(APIC_LVR);

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

        /*
         * Double-check whether this APIC is really registered.
         * This is meaningless in clustered apic mode, so we skip it.
         */
        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(APIC_TASKPRI, value);

        /*
         * After a crash, we no longer service the interrupts and a pending
         * interrupt from previous kernel might still have ISR bit set.
         *
         * Most probably by now CPU has serviced that pending interrupt and
         * it might not have done the ack_APIC_irq() because it thought,
         * interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
         * does not clear the ISR bit and cpu thinks it has already serivced
         * the interrupt. Hence a vector might get locked. It was noticed
         * for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
         */
        for (i = APIC_ISR_NR - 1; i >= 0; i--) {
                value = apic_read(APIC_ISR + i*0x10);
                for (j = 31; j >= 0; j--) {
                        if (value & (1<<j))
                                ack_APIC_irq();
                }
        }

        /*
         * 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 are 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(APIC_SPIV, value);

        /*
         * Set up LVT0, LVT1:
         *
         * set up through-local-APIC on the BP's LINT0. This is not
         * strictly necessary 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(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;
        apic_write(APIC_LVT1, value);

        {
                unsigned oldvalue;
                maxlvt = get_maxlvt();
                oldvalue = apic_read(APIC_ESR);
                value = ERROR_APIC_VECTOR;      // enables sending errors
                apic_write(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 after enabling vector: %08x, after %08x\n",
                        oldvalue, value);
        }

        nmi_watchdog_default();
        setup_apic_nmi_watchdog(NULL);
        apic_pm_activate();
}

#ifdef CONFIG_PM

static struct {
        /* 'active' is true if the local APIC was enabled by us and
           not the BIOS; this signifies that we are also responsible
           for disabling it before entering apm/acpi suspend */
        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, pm_message_t 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_save_flags(flags);
        local_irq_disable();
        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);
        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;
}

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 __cpuinit 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 */

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 1;
}

__setup("apic=", apic_set_verbosity);

/*
 * Detect and enable local APICs on non-SMP boards.
 * Original code written by Keir Fraser.
 * On AMD64 we trust the BIOS - if it says no APIC it is likely
 * not correctly set up (usually the APIC timer won't work etc.) 
 */

static int __init detect_init_APIC (void)
{
        if (!cpu_has_apic) {
                printk(KERN_INFO "No local APIC present\n");
                return -1;
        }

        mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
        boot_cpu_id = 0;
        return 0;
}

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);
        apic_printk(APIC_VERBOSE,"mapped APIC to %16lx (%16lx)\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).
         */
        boot_cpu_id = GET_APIC_ID(apic_read(APIC_ID));

        {
                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;
                        } else {
                                ioapic_phys = (unsigned long) alloc_bootmem_pages(PAGE_SIZE);
                                ioapic_phys = __pa(ioapic_phys);
                        }
                        set_fixmap_nocache(idx, ioapic_phys);
                        apic_printk(APIC_VERBOSE,"mapped IOAPIC to %016lx (%016lx)\n",
                                        __fix_to_virt(idx), ioapic_phys);
                        idx++;
                }
        }
}

/*
 * 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;
        int cpu = smp_processor_id();

        ver = GET_APIC_VERSION(apic_read(APIC_LVR));
        lvtt_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;

        if (cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask))
                lvtt_value |= APIC_LVT_MASKED;

        apic_write(APIC_LVTT, lvtt_value);

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

        apic_write(APIC_TMICT, clocks/APIC_DIVISOR);
}

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

        local_irq_save(flags);

        /* wait for irq slice */
        if (vxtime.hpet_address && hpet_use_timer) {
                int trigger = hpet_readl(HPET_T0_CMP);
                while (hpet_readl(HPET_COUNTER) >= trigger)
                        /* do nothing */ ;
                while (hpet_readl(HPET_COUNTER) <  trigger)
                        /* do nothing */ ;
        } else {
                int c1, c2;
                outb_p(0x00, 0x43);
                c2 = inb_p(0x40);
                c2 |= inb_p(0x40) << 8;
                do {
                        c1 = c2;
                        outb_p(0x00, 0x43);
                        c2 = inb_p(0x40);
                        c2 |= inb_p(0x40) << 8;
                } while (c2 - c1 < 300);
        }
        __setup_APIC_LVTT(clocks);
        /* Turn off PIT interrupt if we use APIC timer as main timer.
           Only works with the PM timer right now
           TBD fix it for HPET too. */
        if (vxtime.mode == VXTIME_PMTMR &&
                smp_processor_id() == boot_cpu_id &&
                apic_runs_main_timer == 1 &&
                !cpu_isset(boot_cpu_id, timer_interrupt_broadcast_ipi_mask)) {
                stop_timer_interrupt();
                apic_runs_main_timer++;
        }
        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.
 */

#define TICK_COUNT 100000000

static int __init calibrate_APIC_clock(void)
{
        int apic, apic_start, tsc, tsc_start;
        int result;
        /*
         * 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);

        apic_start = apic_read(APIC_TMCCT);
#ifdef CONFIG_X86_PM_TIMER
        if (apic_calibrate_pmtmr && pmtmr_ioport) {
                pmtimer_wait(5000);  /* 5ms wait */
                apic = apic_read(APIC_TMCCT);
                result = (apic_start - apic) * 1000L / 5;
        } else
#endif
        {
                rdtscl(tsc_start);

                do {
                        apic = apic_read(APIC_TMCCT);
                        rdtscl(tsc);
                } while ((tsc - tsc_start) < TICK_COUNT &&
                                (apic - apic_start) < TICK_COUNT);

                result = (apic_start - apic) * 1000L * cpu_khz /
                                        (tsc - tsc_start);
        }
        printk("result %d\n", result);


        printk(KERN_INFO "Detected %d.%03d MHz APIC timer.\n",
                result / 1000 / 1000, result / 1000 % 1000);

        return result * APIC_DIVISOR / HZ;
}

static unsigned int calibration_result;

void __init setup_boot_APIC_clock (void)
{
        if (disable_apic_timer) { 
                printk(KERN_INFO "Disabling APIC timer\n"); 
                return; 
        } 

        printk(KERN_INFO "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 __cpuinit setup_secondary_APIC_clock(void)
{
        local_irq_disable(); /* FIXME: Do we need this? --RR */
        setup_APIC_timer(calibration_result);
        local_irq_enable();
}

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

                v = apic_read(APIC_LVTT);
                /*
                 * When an illegal vector value (0-15) is written to an LVT
                 * entry and delivery mode is Fixed, the APIC may signal an
                 * illegal vector error, with out regard to whether the mask
                 * bit is set or whether an interrupt is actually seen on input.
                 *
                 * Boot sequence might call this function when the LVTT has
                 * '0' vector value. So make sure vector field is set to
                 * valid value.
                 */
                v |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
                apic_write(APIC_LVTT, v);
        }
}

void enable_APIC_timer(void)
{
        int cpu = smp_processor_id();

        if (using_apic_timer &&
            !cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask)) {
                unsigned long v;

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

void switch_APIC_timer_to_ipi(void *cpumask)
{
        cpumask_t mask = *(cpumask_t *)cpumask;
        int cpu = smp_processor_id();

        if (cpu_isset(cpu, mask) &&
            !cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask)) {
                disable_APIC_timer();
                cpu_set(cpu, timer_interrupt_broadcast_ipi_mask);
        }
}
EXPORT_SYMBOL(switch_APIC_timer_to_ipi);

void smp_send_timer_broadcast_ipi(void)
{
        cpumask_t mask;

        cpus_and(mask, cpu_online_map, timer_interrupt_broadcast_ipi_mask);
        if (!cpus_empty(mask)) {
                send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
        }
}

void switch_ipi_to_APIC_timer(void *cpumask)
{
        cpumask_t mask = *(cpumask_t *)cpumask;
        int cpu = smp_processor_id();

        if (cpu_isset(cpu, mask) &&
            cpu_isset(cpu, timer_interrupt_broadcast_ipi_mask)) {
                cpu_clear(cpu, timer_interrupt_broadcast_ipi_mask);
                enable_APIC_timer();
        }
}
EXPORT_SYMBOL(switch_ipi_to_APIC_timer);

int setup_profiling_timer(unsigned int multiplier)
{
        return -EINVAL;
}

void setup_APIC_extened_lvt(unsigned char lvt_off, unsigned char vector,
                            unsigned char msg_type, unsigned char mask)
{
        unsigned long reg = (lvt_off << 4) + K8_APIC_EXT_LVT_BASE;
        unsigned int  v   = (mask << 16) | (msg_type << 8) | vector;
        apic_write(reg, v);
}

#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.
 */

void smp_local_timer_interrupt(struct pt_regs *regs)
{
        profile_tick(CPU_PROFILING, regs);
#ifdef CONFIG_SMP
        update_process_times(user_mode(regs));
#endif
        if (apic_runs_main_timer > 1 && smp_processor_id() == boot_cpu_id)
                main_timer_handler(regs);
        /*
         * We take the 'long' return path, and there every subsystem
         * grabs the appropriate 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 ... ]
 */
void smp_apic_timer_interrupt(struct pt_regs *regs)
{
        /*
         * the NMI deadlock-detector uses this.
         */
        add_pda(apic_timer_irqs, 1);

        /*
         * 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.
         */
        exit_idle();
        irq_enter();
        smp_local_timer_interrupt(regs);
        irq_exit();
}

/*
 * apic_is_clustered_box() -- Check if we can expect good TSC
 *
 * Thus far, the major user of this is IBM's Summit2 series:
 *
 * Clustered boxes may have unsynced TSC problems if they are
 * multi-chassis. Use available data to take a good guess.
 * If in doubt, go HPET.
 */
__cpuinit int apic_is_clustered_box(void)
{
        int i, clusters, zeros;
        unsigned id;
        DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);

        bitmap_zero(clustermap, NUM_APIC_CLUSTERS);

        for (i = 0; i < NR_CPUS; i++) {
                id = bios_cpu_apicid[i];
                if (id != BAD_APICID)
                        __set_bit(APIC_CLUSTERID(id), clustermap);
        }

        /* Problem:  Partially populated chassis may not have CPUs in some of
         * the APIC clusters they have been allocated.  Only present CPUs have
         * bios_cpu_apicid entries, thus causing zeroes in the bitmap.  Since
         * clusters are allocated sequentially, count zeros only if they are
         * bounded by ones.
         */
        clusters = 0;
        zeros = 0;
        for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
                if (test_bit(i, clustermap)) {
                        clusters += 1 + zeros;
                        zeros = 0;
                } else
                        ++zeros;
        }

        /*
         * If clusters > 2, then should be multi-chassis.
         * May have to revisit this when multi-core + hyperthreaded CPUs come
         * out, but AFAIK this will work even for them.
         */
        return (clusters > 2);
}

/*
 * This interrupt should _never_ happen with our APIC/SMP architecture
 */
asmlinkage void smp_spurious_interrupt(void)
{
        unsigned int v;
        exit_idle();
        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();

#if 0
        static unsigned long last_warning; 
        static unsigned long skipped; 

        /* see sw-dev-man vol 3, chapter 7.4.13.5 */
        if (time_before(last_warning+30*HZ,jiffies)) { 
                printk(KERN_INFO "spurious APIC interrupt on CPU#%d, %ld skipped.\n",
                       smp_processor_id(), skipped);
                last_warning = jiffies; 
                skipped = 0;
        } else { 
                skipped++; 
        } 
#endif 
        irq_exit();
}

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

asmlinkage void smp_error_interrupt(void)
{
        unsigned int v, v1;

        exit_idle();
        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: %02x(%02x)\n",
                smp_processor_id(), v , v1);
        irq_exit();
}

int disable_apic; 

/*
 * This initializes the IO-APIC and APIC hardware if this is
 * a UP kernel.
 */
int __init APIC_init_uniprocessor (void)
{
        if (disable_apic) { 
                printk(KERN_INFO "Apic disabled\n");
                return -1; 
        }
        if (!cpu_has_apic) { 
                disable_apic = 1;
                printk(KERN_INFO "Apic disabled by BIOS\n");
                return -1;
        }

        verify_local_APIC();

        connect_bsp_APIC();

        phys_cpu_present_map = physid_mask_of_physid(boot_cpu_id);
        apic_write(APIC_ID, SET_APIC_ID(boot_cpu_id));

        setup_local_APIC();

        if (smp_found_config && !skip_ioapic_setup && nr_ioapics)
                setup_IO_APIC();
        else
                nr_ioapics = 0;
        setup_boot_APIC_clock();
        check_nmi_watchdog();
        return 0;
}

static __init int setup_disableapic(char *str) 
{ 
        disable_apic = 1;
        return 1;
} 

static __init int setup_nolapic(char *str) 
{ 
        disable_apic = 1;
        return 1;
} 

static __init int setup_noapictimer(char *str) 
{ 
        if (str[0] != ' ' && str[0] != 0)
                return 0;
        disable_apic_timer = 1;
        return 1;
} 

static __init int setup_apicmaintimer(char *str)
{
        apic_runs_main_timer = 1;
        nohpet = 1;
        return 1;
}
__setup("apicmaintimer", setup_apicmaintimer);

static __init int setup_noapicmaintimer(char *str)
{
        apic_runs_main_timer = -1;
        return 1;
}
__setup("noapicmaintimer", setup_noapicmaintimer);

static __init int setup_apicpmtimer(char *s)
{
        apic_calibrate_pmtmr = 1;
        notsc_setup(NULL);
        return setup_apicmaintimer(NULL);
}
__setup("apicpmtimer", setup_apicpmtimer);

/* dummy parsing: see setup.c */

__setup("disableapic", setup_disableapic); 
__setup("nolapic", setup_nolapic);  /* same as disableapic, for compatibility */

__setup("noapictimer", setup_noapictimer); 

/* no "lapic" flag - we only use the lapic when the BIOS tells us so. */