Merge commit 'v2.6.34-rc1' into perf/urgent

Conflicts:
	tools/perf/util/probe-event.c

Merge reason: Pick up -rc1 and resolve the conflict as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 784 insertions, 0 deletions

diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c
new file mode 100644
index 000000000000..4b7099526d2c
--- /dev/null
+++ b/arch/x86/kernel/apb_timer.c
@@ -0,0 +1,784 @@
+/*
+ * apb_timer.c: Driver for Langwell APB timers
+ *
+ * (C) Copyright 2009 Intel Corporation
+ * Author: Jacob Pan (jacob.jun.pan@intel.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ *
+ * Note:
+ * Langwell is the south complex of Intel Moorestown MID platform. There are
+ * eight external timers in total that can be used by the operating system.
+ * The timer information, such as frequency and addresses, is provided to the
+ * OS via SFI tables.
+ * Timer interrupts are routed via FW/HW emulated IOAPIC independently via
+ * individual redirection table entries (RTE).
+ * Unlike HPET, there is no master counter, therefore one of the timers are
+ * used as clocksource. The overall allocation looks like:
+ *  - timer 0 - NR_CPUs for per cpu timer
+ *  - one timer for clocksource
+ *  - one timer for watchdog driver.
+ * It is also worth notice that APB timer does not support true one-shot mode,
+ * free-running mode will be used here to emulate one-shot mode.
+ * APB timer can also be used as broadcast timer along with per cpu local APIC
+ * timer, but by default APB timer has higher rating than local APIC timers.
+ */
+
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/sysdev.h>
+#include <linux/pm.h>
+#include <linux/pci.h>
+#include <linux/sfi.h>
+#include <linux/interrupt.h>
+#include <linux/cpu.h>
+#include <linux/irq.h>
+
+#include <asm/fixmap.h>
+#include <asm/apb_timer.h>
+
+#define APBT_MASK			CLOCKSOURCE_MASK(32)
+#define APBT_SHIFT			22
+#define APBT_CLOCKEVENT_RATING		150
+#define APBT_CLOCKSOURCE_RATING		250
+#define APBT_MIN_DELTA_USEC		200
+
+#define EVT_TO_APBT_DEV(evt) container_of(evt, struct apbt_dev, evt)
+#define APBT_CLOCKEVENT0_NUM   (0)
+#define APBT_CLOCKEVENT1_NUM   (1)
+#define APBT_CLOCKSOURCE_NUM   (2)
+
+static unsigned long apbt_address;
+static int apb_timer_block_enabled;
+static void __iomem *apbt_virt_address;
+static int phy_cs_timer_id;
+
+/*
+ * Common DW APB timer info
+ */
+static uint64_t apbt_freq;
+
+static void apbt_set_mode(enum clock_event_mode mode,
+			  struct clock_event_device *evt);
+static int apbt_next_event(unsigned long delta,
+			   struct clock_event_device *evt);
+static cycle_t apbt_read_clocksource(struct clocksource *cs);
+static void apbt_restart_clocksource(struct clocksource *cs);
+
+struct apbt_dev {
+	struct clock_event_device evt;
+	unsigned int num;
+	int cpu;
+	unsigned int irq;
+	unsigned int tick;
+	unsigned int count;
+	unsigned int flags;
+	char name[10];
+};
+
+int disable_apbt_percpu __cpuinitdata;
+
+static DEFINE_PER_CPU(struct apbt_dev, cpu_apbt_dev);
+
+#ifdef CONFIG_SMP
+static unsigned int apbt_num_timers_used;
+static struct apbt_dev *apbt_devs;
+#endif
+
+static	inline unsigned long apbt_readl_reg(unsigned long a)
+{
+	return readl(apbt_virt_address + a);
+}
+
+static inline void apbt_writel_reg(unsigned long d, unsigned long a)
+{
+	writel(d, apbt_virt_address + a);
+}
+
+static inline unsigned long apbt_readl(int n, unsigned long a)
+{
+	return readl(apbt_virt_address + a + n * APBTMRS_REG_SIZE);
+}
+
+static inline void apbt_writel(int n, unsigned long d, unsigned long a)
+{
+	writel(d, apbt_virt_address + a + n * APBTMRS_REG_SIZE);
+}
+
+static inline void apbt_set_mapping(void)
+{
+	struct sfi_timer_table_entry *mtmr;
+
+	if (apbt_virt_address) {
+		pr_debug("APBT base already mapped\n");
+		return;
+	}
+	mtmr = sfi_get_mtmr(APBT_CLOCKEVENT0_NUM);
+	if (mtmr == NULL) {
+		printk(KERN_ERR "Failed to get MTMR %d from SFI\n",
+		       APBT_CLOCKEVENT0_NUM);
+		return;
+	}
+	apbt_address = (unsigned long)mtmr->phys_addr;
+	if (!apbt_address) {
+		printk(KERN_WARNING "No timer base from SFI, use default\n");
+		apbt_address = APBT_DEFAULT_BASE;
+	}
+	apbt_virt_address = ioremap_nocache(apbt_address, APBT_MMAP_SIZE);
+	if (apbt_virt_address) {
+		pr_debug("Mapped APBT physical addr %p at virtual addr %p\n",\
+			 (void *)apbt_address, (void *)apbt_virt_address);
+	} else {
+		pr_debug("Failed mapping APBT phy address at %p\n",\
+			 (void *)apbt_address);
+		goto panic_noapbt;
+	}
+	apbt_freq = mtmr->freq_hz / USEC_PER_SEC;
+	sfi_free_mtmr(mtmr);
+
+	/* Now figure out the physical timer id for clocksource device */
+	mtmr = sfi_get_mtmr(APBT_CLOCKSOURCE_NUM);
+	if (mtmr == NULL)
+		goto panic_noapbt;
+
+	/* Now figure out the physical timer id */
+	phy_cs_timer_id = (unsigned int)(mtmr->phys_addr & 0xff)
+		/ APBTMRS_REG_SIZE;
+	pr_debug("Use timer %d for clocksource\n", phy_cs_timer_id);
+	return;
+
+panic_noapbt:
+	panic("Failed to setup APB system timer\n");
+
+}
+
+static inline void apbt_clear_mapping(void)
+{
+	iounmap(apbt_virt_address);
+	apbt_virt_address = NULL;
+}
+
+/*
+ * APBT timer interrupt enable / disable
+ */
+static inline int is_apbt_capable(void)
+{
+	return apbt_virt_address ? 1 : 0;
+}
+
+static struct clocksource clocksource_apbt = {
+	.name		= "apbt",
+	.rating		= APBT_CLOCKSOURCE_RATING,
+	.read		= apbt_read_clocksource,
+	.mask		= APBT_MASK,
+	.shift		= APBT_SHIFT,
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+	.resume		= apbt_restart_clocksource,
+};
+
+/* boot APB clock event device */
+static struct clock_event_device apbt_clockevent = {
+	.name		= "apbt0",
+	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.set_mode	= apbt_set_mode,
+	.set_next_event = apbt_next_event,
+	.shift		= APBT_SHIFT,
+	.irq		= 0,
+	.rating		= APBT_CLOCKEVENT_RATING,
+};
+
+/*
+ * if user does not want to use per CPU apb timer, just give it a lower rating
+ * than local apic timer and skip the late per cpu timer init.
+ */
+static inline int __init setup_x86_mrst_timer(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	if (strcmp("apbt_only", arg) == 0)
+		disable_apbt_percpu = 0;
+	else if (strcmp("lapic_and_apbt", arg) == 0)
+		disable_apbt_percpu = 1;
+	else {
+		pr_warning("X86 MRST timer option %s not recognised"
+			   " use x86_mrst_timer=apbt_only or lapic_and_apbt\n",
+			   arg);
+		return -EINVAL;
+	}
+	return 0;
+}
+__setup("x86_mrst_timer=", setup_x86_mrst_timer);
+
+/*
+ * start count down from 0xffff_ffff. this is done by toggling the enable bit
+ * then load initial load count to ~0.
+ */
+static void apbt_start_counter(int n)
+{
+	unsigned long ctrl = apbt_readl(n, APBTMR_N_CONTROL);
+
+	ctrl &= ~APBTMR_CONTROL_ENABLE;
+	apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+	apbt_writel(n, ~0, APBTMR_N_LOAD_COUNT);
+	/* enable, mask interrupt */
+	ctrl &= ~APBTMR_CONTROL_MODE_PERIODIC;
+	ctrl |= (APBTMR_CONTROL_ENABLE | APBTMR_CONTROL_INT);
+	apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+	/* read it once to get cached counter value initialized */
+	apbt_read_clocksource(&clocksource_apbt);
+}
+
+static irqreturn_t apbt_interrupt_handler(int irq, void *data)
+{
+	struct apbt_dev *dev = (struct apbt_dev *)data;
+	struct clock_event_device *aevt = &dev->evt;
+
+	if (!aevt->event_handler) {
+		printk(KERN_INFO "Spurious APBT timer interrupt on %d\n",
+		       dev->num);
+		return IRQ_NONE;
+	}
+	aevt->event_handler(aevt);
+	return IRQ_HANDLED;
+}
+
+static void apbt_restart_clocksource(struct clocksource *cs)
+{
+	apbt_start_counter(phy_cs_timer_id);
+}
+
+/* Setup IRQ routing via IOAPIC */
+#ifdef CONFIG_SMP
+static void apbt_setup_irq(struct apbt_dev *adev)
+{
+	struct irq_chip *chip;
+	struct irq_desc *desc;
+
+	/* timer0 irq has been setup early */
+	if (adev->irq == 0)
+		return;
+	desc = irq_to_desc(adev->irq);
+	chip = get_irq_chip(adev->irq);
+	disable_irq(adev->irq);
+	desc->status |= IRQ_MOVE_PCNTXT;
+	irq_set_affinity(adev->irq, cpumask_of(adev->cpu));
+	/* APB timer irqs are set up as mp_irqs, timer is edge triggerred */
+	set_irq_chip_and_handler_name(adev->irq, chip, handle_edge_irq, "edge");
+	enable_irq(adev->irq);
+	if (system_state == SYSTEM_BOOTING)
+		if (request_irq(adev->irq, apbt_interrupt_handler,
+				IRQF_TIMER | IRQF_DISABLED | IRQF_NOBALANCING,
+				adev->name, adev)) {
+			printk(KERN_ERR "Failed request IRQ for APBT%d\n",
+			       adev->num);
+		}
+}
+#endif
+
+static void apbt_enable_int(int n)
+{
+	unsigned long ctrl = apbt_readl(n, APBTMR_N_CONTROL);
+	/* clear pending intr */
+	apbt_readl(n, APBTMR_N_EOI);
+	ctrl &= ~APBTMR_CONTROL_INT;
+	apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+}
+
+static void apbt_disable_int(int n)
+{
+	unsigned long ctrl = apbt_readl(n, APBTMR_N_CONTROL);
+
+	ctrl |= APBTMR_CONTROL_INT;
+	apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+}
+
+
+static int __init apbt_clockevent_register(void)
+{
+	struct sfi_timer_table_entry *mtmr;
+	struct apbt_dev *adev = &__get_cpu_var(cpu_apbt_dev);
+
+	mtmr = sfi_get_mtmr(APBT_CLOCKEVENT0_NUM);
+	if (mtmr == NULL) {
+		printk(KERN_ERR "Failed to get MTMR %d from SFI\n",
+		       APBT_CLOCKEVENT0_NUM);
+		return -ENODEV;
+	}
+
+	/*
+	 * We need to calculate the scaled math multiplication factor for
+	 * nanosecond to apbt tick conversion.
+	 * mult = (nsec/cycle)*2^APBT_SHIFT
+	 */
+	apbt_clockevent.mult = div_sc((unsigned long) mtmr->freq_hz
+				      , NSEC_PER_SEC, APBT_SHIFT);
+
+	/* Calculate the min / max delta */
+	apbt_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
+							   &apbt_clockevent);
+	apbt_clockevent.min_delta_ns = clockevent_delta2ns(
+		APBT_MIN_DELTA_USEC*apbt_freq,
+		&apbt_clockevent);
+	/*
+	 * Start apbt with the boot cpu mask and make it
+	 * global if not used for per cpu timer.
+	 */
+	apbt_clockevent.cpumask = cpumask_of(smp_processor_id());
+	adev->num = smp_processor_id();
+	memcpy(&adev->evt, &apbt_clockevent, sizeof(struct clock_event_device));
+
+	if (disable_apbt_percpu) {
+		apbt_clockevent.rating = APBT_CLOCKEVENT_RATING - 100;
+		global_clock_event = &adev->evt;
+		printk(KERN_DEBUG "%s clockevent registered as global\n",
+		       global_clock_event->name);
+	}
+
+	if (request_irq(apbt_clockevent.irq, apbt_interrupt_handler,
+			IRQF_TIMER | IRQF_DISABLED | IRQF_NOBALANCING,
+			apbt_clockevent.name, adev)) {
+		printk(KERN_ERR "Failed request IRQ for APBT%d\n",
+		       apbt_clockevent.irq);
+	}
+
+	clockevents_register_device(&adev->evt);
+	/* Start APBT 0 interrupts */
+	apbt_enable_int(APBT_CLOCKEVENT0_NUM);
+
+	sfi_free_mtmr(mtmr);
+	return 0;
+}
+
+#ifdef CONFIG_SMP
+/* Should be called with per cpu */
+void apbt_setup_secondary_clock(void)
+{
+	struct apbt_dev *adev;
+	struct clock_event_device *aevt;
+	int cpu;
+
+	/* Don't register boot CPU clockevent */
+	cpu = smp_processor_id();
+	if (cpu == boot_cpu_id)
+		return;
+	/*
+	 * We need to calculate the scaled math multiplication factor for
+	 * nanosecond to apbt tick conversion.
+	 * mult = (nsec/cycle)*2^APBT_SHIFT
+	 */
+	printk(KERN_INFO "Init per CPU clockevent %d\n", cpu);
+	adev = &per_cpu(cpu_apbt_dev, cpu);
+	aevt = &adev->evt;
+
+	memcpy(aevt, &apbt_clockevent, sizeof(*aevt));
+	aevt->cpumask = cpumask_of(cpu);
+	aevt->name = adev->name;
+	aevt->mode = CLOCK_EVT_MODE_UNUSED;
+
+	printk(KERN_INFO "Registering CPU %d clockevent device %s, mask %08x\n",
+	       cpu, aevt->name, *(u32 *)aevt->cpumask);
+
+	apbt_setup_irq(adev);
+
+	clockevents_register_device(aevt);
+
+	apbt_enable_int(cpu);
+
+	return;
+}
+
+/*
+ * this notify handler process CPU hotplug events. in case of S0i3, nonboot
+ * cpus are disabled/enabled frequently, for performance reasons, we keep the
+ * per cpu timer irq registered so that we do need to do free_irq/request_irq.
+ *
+ * TODO: it might be more reliable to directly disable percpu clockevent device
+ * without the notifier chain. currently, cpu 0 may get interrupts from other
+ * cpu timers during the offline process due to the ordering of notification.
+ * the extra interrupt is harmless.
+ */
+static int apbt_cpuhp_notify(struct notifier_block *n,
+			     unsigned long action, void *hcpu)
+{
+	unsigned long cpu = (unsigned long)hcpu;
+	struct apbt_dev *adev = &per_cpu(cpu_apbt_dev, cpu);
+
+	switch (action & 0xf) {
+	case CPU_DEAD:
+		apbt_disable_int(cpu);
+		if (system_state == SYSTEM_RUNNING)
+			pr_debug("skipping APBT CPU %lu offline\n", cpu);
+		else if (adev) {
+			pr_debug("APBT clockevent for cpu %lu offline\n", cpu);
+			free_irq(adev->irq, adev);
+		}
+		break;
+	default:
+		pr_debug(KERN_INFO "APBT notified %lu, no action\n", action);
+	}
+	return NOTIFY_OK;
+}
+
+static __init int apbt_late_init(void)
+{
+	if (disable_apbt_percpu)
+		return 0;
+	/* This notifier should be called after workqueue is ready */
+	hotcpu_notifier(apbt_cpuhp_notify, -20);
+	return 0;
+}
+fs_initcall(apbt_late_init);
+#else
+
+void apbt_setup_secondary_clock(void) {}
+
+#endif /* CONFIG_SMP */
+
+static void apbt_set_mode(enum clock_event_mode mode,
+			  struct clock_event_device *evt)
+{
+	unsigned long ctrl;
+	uint64_t delta;
+	int timer_num;
+	struct apbt_dev *adev = EVT_TO_APBT_DEV(evt);
+
+	timer_num = adev->num;
+	pr_debug("%s CPU %d timer %d mode=%d\n",
+		 __func__, first_cpu(*evt->cpumask), timer_num, mode);
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * apbt_clockevent.mult;
+		delta >>= apbt_clockevent.shift;
+		ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+		ctrl |= APBTMR_CONTROL_MODE_PERIODIC;
+		apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+		/*
+		 * DW APB p. 46, have to disable timer before load counter,
+		 * may cause sync problem.
+		 */
+		ctrl &= ~APBTMR_CONTROL_ENABLE;
+		apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+		udelay(1);
+		pr_debug("Setting clock period %d for HZ %d\n", (int)delta, HZ);
+		apbt_writel(timer_num, delta, APBTMR_N_LOAD_COUNT);
+		ctrl |= APBTMR_CONTROL_ENABLE;
+		apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+		break;
+		/* APB timer does not have one-shot mode, use free running mode */
+	case CLOCK_EVT_MODE_ONESHOT:
+		ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+		/*
+		 * set free running mode, this mode will let timer reload max
+		 * timeout which will give time (3min on 25MHz clock) to rearm
+		 * the next event, therefore emulate the one-shot mode.
+		 */
+		ctrl &= ~APBTMR_CONTROL_ENABLE;
+		ctrl &= ~APBTMR_CONTROL_MODE_PERIODIC;
+
+		apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+		/* write again to set free running mode */
+		apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+
+		/*
+		 * DW APB p. 46, load counter with all 1s before starting free
+		 * running mode.
+		 */
+		apbt_writel(timer_num, ~0, APBTMR_N_LOAD_COUNT);
+		ctrl &= ~APBTMR_CONTROL_INT;
+		ctrl |= APBTMR_CONTROL_ENABLE;
+		apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+		break;
+
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		apbt_disable_int(timer_num);
+		ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+		ctrl &= ~APBTMR_CONTROL_ENABLE;
+		apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+		break;
+
+	case CLOCK_EVT_MODE_RESUME:
+		apbt_enable_int(timer_num);
+		break;
+	}
+}
+
+static int apbt_next_event(unsigned long delta,
+			   struct clock_event_device *evt)
+{
+	unsigned long ctrl;
+	int timer_num;
+
+	struct apbt_dev *adev = EVT_TO_APBT_DEV(evt);
+
+	timer_num = adev->num;
+	/* Disable timer */
+	ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+	ctrl &= ~APBTMR_CONTROL_ENABLE;
+	apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+	/* write new count */
+	apbt_writel(timer_num, delta, APBTMR_N_LOAD_COUNT);
+	ctrl |= APBTMR_CONTROL_ENABLE;
+	apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+	return 0;
+}
+
+/*
+ * APB timer clock is not in sync with pclk on Langwell, which translates to
+ * unreliable read value caused by sampling error. the error does not add up
+ * overtime and only happens when sampling a 0 as a 1 by mistake. so the time
+ * would go backwards. the following code is trying to prevent time traveling
+ * backwards. little bit paranoid.
+ */
+static cycle_t apbt_read_clocksource(struct clocksource *cs)
+{
+	unsigned long t0, t1, t2;
+	static unsigned long last_read;
+
+bad_count:
+	t1 = apbt_readl(phy_cs_timer_id,
+			APBTMR_N_CURRENT_VALUE);
+	t2 = apbt_readl(phy_cs_timer_id,
+			APBTMR_N_CURRENT_VALUE);
+	if (unlikely(t1 < t2)) {
+		pr_debug("APBT: read current count error %lx:%lx:%lx\n",
+			 t1, t2, t2 - t1);
+		goto bad_count;
+	}
+	/*
+	 * check against cached last read, makes sure time does not go back.
+	 * it could be a normal rollover but we will do tripple check anyway
+	 */
+	if (unlikely(t2 > last_read)) {
+		/* check if we have a normal rollover */
+		unsigned long raw_intr_status =
+			apbt_readl_reg(APBTMRS_RAW_INT_STATUS);
+		/*
+		 * cs timer interrupt is masked but raw intr bit is set if
+		 * rollover occurs. then we read EOI reg to clear it.
+		 */
+		if (raw_intr_status & (1 << phy_cs_timer_id)) {
+			apbt_readl(phy_cs_timer_id, APBTMR_N_EOI);
+			goto out;
+		}
+		pr_debug("APB CS going back %lx:%lx:%lx ",
+			 t2, last_read, t2 - last_read);
+bad_count_x3:
+		pr_debug(KERN_INFO "tripple check enforced\n");
+		t0 = apbt_readl(phy_cs_timer_id,
+				APBTMR_N_CURRENT_VALUE);
+		udelay(1);
+		t1 = apbt_readl(phy_cs_timer_id,
+				APBTMR_N_CURRENT_VALUE);
+		udelay(1);
+		t2 = apbt_readl(phy_cs_timer_id,
+				APBTMR_N_CURRENT_VALUE);
+		if ((t2 > t1) || (t1 > t0)) {
+			printk(KERN_ERR "Error: APB CS tripple check failed\n");
+			goto bad_count_x3;
+		}
+	}
+out:
+	last_read = t2;
+	return (cycle_t)~t2;
+}
+
+static int apbt_clocksource_register(void)
+{
+	u64 start, now;
+	cycle_t t1;
+
+	/* Start the counter, use timer 2 as source, timer 0/1 for event */
+	apbt_start_counter(phy_cs_timer_id);
+
+	/* Verify whether apbt counter works */
+	t1 = apbt_read_clocksource(&clocksource_apbt);
+	rdtscll(start);
+
+	/*
+	 * We don't know the TSC frequency yet, but waiting for
+	 * 200000 TSC cycles is safe:
+	 * 4 GHz == 50us
+	 * 1 GHz == 200us
+	 */
+	do {
+		rep_nop();
+		rdtscll(now);
+	} while ((now - start) < 200000UL);
+
+	/* APBT is the only always on clocksource, it has to work! */
+	if (t1 == apbt_read_clocksource(&clocksource_apbt))
+		panic("APBT counter not counting. APBT disabled\n");
+
+	/*
+	 * initialize and register APBT clocksource
+	 * convert that to ns/clock cycle
+	 * mult = (ns/c) * 2^APBT_SHIFT
+	 */
+	clocksource_apbt.mult = div_sc(MSEC_PER_SEC,
+				       (unsigned long) apbt_freq, APBT_SHIFT);
+	clocksource_register(&clocksource_apbt);
+
+	return 0;
+}
+
+/*
+ * Early setup the APBT timer, only use timer 0 for booting then switch to
+ * per CPU timer if possible.
+ * returns 1 if per cpu apbt is setup
+ * returns 0 if no per cpu apbt is chosen
+ * panic if set up failed, this is the only platform timer on Moorestown.
+ */
+void __init apbt_time_init(void)
+{
+#ifdef CONFIG_SMP
+	int i;
+	struct sfi_timer_table_entry *p_mtmr;
+	unsigned int percpu_timer;
+	struct apbt_dev *adev;
+#endif
+
+	if (apb_timer_block_enabled)
+		return;
+	apbt_set_mapping();
+	if (apbt_virt_address) {
+		pr_debug("Found APBT version 0x%lx\n",\
+			 apbt_readl_reg(APBTMRS_COMP_VERSION));
+	} else
+		goto out_noapbt;
+	/*
+	 * Read the frequency and check for a sane value, for ESL model
+	 * we extend the possible clock range to allow time scaling.
+	 */
+
+	if (apbt_freq < APBT_MIN_FREQ || apbt_freq > APBT_MAX_FREQ) {
+		pr_debug("APBT has invalid freq 0x%llx\n", apbt_freq);
+		goto out_noapbt;
+	}
+	if (apbt_clocksource_register()) {
+		pr_debug("APBT has failed to register clocksource\n");
+		goto out_noapbt;
+	}
+	if (!apbt_clockevent_register())
+		apb_timer_block_enabled = 1;
+	else {
+		pr_debug("APBT has failed to register clockevent\n");
+		goto out_noapbt;
+	}
+#ifdef CONFIG_SMP
+	/* kernel cmdline disable apb timer, so we will use lapic timers */
+	if (disable_apbt_percpu) {
+		printk(KERN_INFO "apbt: disabled per cpu timer\n");
+		return;
+	}
+	pr_debug("%s: %d CPUs online\n", __func__, num_online_cpus());
+	if (num_possible_cpus() <= sfi_mtimer_num) {
+		percpu_timer = 1;
+		apbt_num_timers_used = num_possible_cpus();
+	} else {
+		percpu_timer = 0;
+		apbt_num_timers_used = 1;
+		adev = &per_cpu(cpu_apbt_dev, 0);
+		adev->flags &= ~APBT_DEV_USED;
+	}
+	pr_debug("%s: %d APB timers used\n", __func__, apbt_num_timers_used);
+
+	/* here we set up per CPU timer data structure */
+	apbt_devs = kzalloc(sizeof(struct apbt_dev) * apbt_num_timers_used,
+			    GFP_KERNEL);
+	if (!apbt_devs) {
+		printk(KERN_ERR "Failed to allocate APB timer devices\n");
+		return;
+	}
+	for (i = 0; i < apbt_num_timers_used; i++) {
+		adev = &per_cpu(cpu_apbt_dev, i);
+		adev->num = i;
+		adev->cpu = i;
+		p_mtmr = sfi_get_mtmr(i);
+		if (p_mtmr) {
+			adev->tick = p_mtmr->freq_hz;
+			adev->irq = p_mtmr->irq;
+		} else
+			printk(KERN_ERR "Failed to get timer for cpu %d\n", i);
+		adev->count = 0;
+		sprintf(adev->name, "apbt%d", i);
+	}
+#endif
+
+	return;
+
+out_noapbt:
+	apbt_clear_mapping();
+	apb_timer_block_enabled = 0;
+	panic("failed to enable APB timer\n");
+}
+
+static inline void apbt_disable(int n)
+{
+	if (is_apbt_capable()) {
+		unsigned long ctrl =  apbt_readl(n, APBTMR_N_CONTROL);
+		ctrl &= ~APBTMR_CONTROL_ENABLE;
+		apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+	}
+}
+
+/* called before apb_timer_enable, use early map */
+unsigned long apbt_quick_calibrate()
+{
+	int i, scale;
+	u64 old, new;
+	cycle_t t1, t2;
+	unsigned long khz = 0;
+	u32 loop, shift;
+
+	apbt_set_mapping();
+	apbt_start_counter(phy_cs_timer_id);
+
+	/* check if the timer can count down, otherwise return */
+	old = apbt_read_clocksource(&clocksource_apbt);
+	i = 10000;
+	while (--i) {
+		if (old != apbt_read_clocksource(&clocksource_apbt))
+			break;
+	}
+	if (!i)
+		goto failed;
+
+	/* count 16 ms */
+	loop = (apbt_freq * 1000) << 4;
+
+	/* restart the timer to ensure it won't get to 0 in the calibration */
+	apbt_start_counter(phy_cs_timer_id);
+
+	old = apbt_read_clocksource(&clocksource_apbt);
+	old += loop;
+
+	t1 = __native_read_tsc();
+
+	do {
+		new = apbt_read_clocksource(&clocksource_apbt);
+	} while (new < old);
+
+	t2 = __native_read_tsc();
+
+	shift = 5;
+	if (unlikely(loop >> shift == 0)) {
+		printk(KERN_INFO
+		       "APBT TSC calibration failed, not enough resolution\n");
+		return 0;
+	}
+	scale = (int)div_u64((t2 - t1), loop >> shift);
+	khz = (scale * apbt_freq * 1000) >> shift;
+	printk(KERN_INFO "TSC freq calculated by APB timer is %lu khz\n", khz);
+	return khz;
+failed:
+	return 0;
+}