clocksource: apb: Share APB timer code with other platforms

The APB timers are an IP block from Synopsys (DesignWare APB timers)
and are also found in other systems including ARM SoC's.  This patch
adds functions for creating clock_event_devices and clocksources from
APB timers but does not do the resource allocation.  This is handled
in a higher layer to allow the timers to be created from multiple
methods such as platform_devices.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

7 files changed, 533 insertions, 360 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index da34972..10ce62f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -617,6 +617,7 @@ config HPET_EMULATE_RTC
 config APB_TIMER
        def_bool y if MRST
        prompt "Langwell APB Timer Support" if X86_MRST
+       select DW_APB_TIMER
        help
          APB timer is the replacement for 8254, HPET on X86 MID platforms.
          The APBT provides a stable time base on SMP
diff --git a/arch/x86/include/asm/apb_timer.h b/arch/x86/include/asm/apb_timer.h
index 2fefa50..230000f 100644
--- a/arch/x86/include/asm/apb_timer.h
+++ b/arch/x86/include/asm/apb_timer.h
@@ -18,24 +18,6 @@
 
 #ifdef CONFIG_APB_TIMER
 
-/* Langwell DW APB timer registers */
-#define APBTMR_N_LOAD_COUNT    0x00
-#define APBTMR_N_CURRENT_VALUE 0x04
-#define APBTMR_N_CONTROL       0x08
-#define APBTMR_N_EOI           0x0c
-#define APBTMR_N_INT_STATUS    0x10
-
-#define APBTMRS_INT_STATUS     0xa0
-#define APBTMRS_EOI            0xa4
-#define APBTMRS_RAW_INT_STATUS 0xa8
-#define APBTMRS_COMP_VERSION   0xac
-#define APBTMRS_REG_SIZE       0x14
-
-/* register bits */
-#define APBTMR_CONTROL_ENABLE  (1<<0)
-#define APBTMR_CONTROL_MODE_PERIODIC   (1<<1) /*1: periodic 0:free running */
-#define APBTMR_CONTROL_INT     (1<<2)
-
 /* default memory mapped register base */
 #define LNW_SCU_ADDR           0xFF100000
 #define LNW_EXT_TIMER_OFFSET   0x1B800
@@ -43,8 +25,8 @@
 #define LNW_EXT_TIMER_PGOFFSET         0x800
 
 /* APBT clock speed range from PCLK to fabric base, 25-100MHz */
-#define APBT_MAX_FREQ          50
-#define APBT_MIN_FREQ          1
+#define APBT_MAX_FREQ          50000000
+#define APBT_MIN_FREQ          1000000
 #define APBT_MMAP_SIZE         1024
 
 #define APBT_DEV_USED  1
diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c
index 289e928..033d3ec 100644
--- a/arch/x86/kernel/apb_timer.c
+++ b/arch/x86/kernel/apb_timer.c
@@ -27,15 +27,12 @@
  * 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/dw_apb_timer.h>
 #include <linux/errno.h>
 #include <linux/init.h>
-#include <linux/sysdev.h>
 #include <linux/slab.h>
 #include <linux/pm.h>
-#include <linux/pci.h>
 #include <linux/sfi.h>
 #include <linux/interrupt.h>
 #include <linux/cpu.h>
@@ -45,75 +42,46 @@
 #include <asm/apb_timer.h>
 #include <asm/mrst.h>
 
-#define APBT_MASK			CLOCKSOURCE_MASK(32)
-#define APBT_SHIFT			22
 #define APBT_CLOCKEVENT_RATING		110
 #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 phys_addr_t 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);
+static unsigned long apbt_freq;
 
 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];
+	struct dw_apb_clock_event_device	*timer;
+	unsigned int				num;
+	int					cpu;
+	unsigned int				irq;
+	char					name[10];
 };
 
-static DEFINE_PER_CPU(struct apbt_dev, cpu_apbt_dev);
+static struct dw_apb_clocksource *clocksource_apbt;
 
-#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)
+static inline void __iomem *adev_virt_addr(struct apbt_dev *adev)
 {
-	return readl(apbt_virt_address + a);
+	return apbt_virt_address + adev->num * APBTMRS_REG_SIZE;
 }
 
-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 DEFINE_PER_CPU(struct apbt_dev, cpu_apbt_dev);
 
-static inline void apbt_writel(int n, unsigned long d, unsigned long a)
-{
-	writel(d, apbt_virt_address + a + n * APBTMRS_REG_SIZE);
-}
+#ifdef CONFIG_SMP
+static unsigned int apbt_num_timers_used;
+#endif
 
 static inline void apbt_set_mapping(void)
 {
 	struct sfi_timer_table_entry *mtmr;
+	int phy_cs_timer_id = 0;
 
 	if (apbt_virt_address) {
 		pr_debug("APBT base already mapped\n");
@@ -125,21 +93,18 @@ static inline void apbt_set_mapping(void)
 		       APBT_CLOCKEVENT0_NUM);
 		return;
 	}
-	apbt_address = (unsigned long)mtmr->phys_addr;
+	apbt_address = (phys_addr_t)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);
+	if (!apbt_virt_address) {
+		pr_debug("Failed mapping APBT phy address at %lu\n",\
+			 (unsigned long)apbt_address);
 		goto panic_noapbt;
 	}
-	apbt_freq = mtmr->freq_hz / USEC_PER_SEC;
+	apbt_freq = mtmr->freq_hz;
 	sfi_free_mtmr(mtmr);
 
 	/* Now figure out the physical timer id for clocksource device */
@@ -148,9 +113,14 @@ static inline void apbt_set_mapping(void)
 		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);
+	pr_debug("Use timer %d for clocksource\n",
+		 (int)(mtmr->phys_addr & 0xff) / APBTMRS_REG_SIZE);
+	phy_cs_timer_id = (unsigned int)(mtmr->phys_addr & 0xff) /
+		APBTMRS_REG_SIZE;
+
+	clocksource_apbt = dw_apb_clocksource_init(APBT_CLOCKSOURCE_RATING,
+		"apbt0", apbt_virt_address + phy_cs_timer_id *
+		APBTMRS_REG_SIZE, apbt_freq);
 	return;
 
 panic_noapbt:
@@ -172,82 +142,6 @@ 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,
-	.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,
-};
-
-/*
- * 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);
-}
-
-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;
@@ -260,45 +154,21 @@ static int __init apbt_clockevent_register(void)
 		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));
+	adev->timer = dw_apb_clockevent_init(smp_processor_id(), "apbt0",
+		mrst_timer_options == MRST_TIMER_LAPIC_APBT ?
+		APBT_CLOCKEVENT_RATING - 100 : APBT_CLOCKEVENT_RATING,
+		adev_virt_addr(adev), 0, apbt_freq);
+	/* Firmware does EOI handling for us. */
+	adev->timer->eoi = NULL;
 
 	if (mrst_timer_options == MRST_TIMER_LAPIC_APBT) {
-		adev->evt.rating = APBT_CLOCKEVENT_RATING - 100;
-		global_clock_event = &adev->evt;
+		global_clock_event = &adev->timer->ced;
 		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);
+	dw_apb_clockevent_register(adev->timer);
 
 	sfi_free_mtmr(mtmr);
 	return 0;
@@ -316,52 +186,34 @@ static void apbt_setup_irq(struct apbt_dev *adev)
 	irq_set_affinity(adev->irq, cpumask_of(adev->cpu));
 	/* APB timer irqs are set up as mp_irqs, timer is edge type */
 	__irq_set_handler(adev->irq, handle_edge_irq, 0, "edge");
-
-	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);
-		}
-	} else
-		enable_irq(adev->irq);
 }
 
 /* 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)
 		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;
+	adev = &__get_cpu_var(cpu_apbt_dev);
+	if (!adev->timer) {
+		adev->timer = dw_apb_clockevent_init(cpu, adev->name,
+			APBT_CLOCKEVENT_RATING, adev_virt_addr(adev),
+			adev->irq, apbt_freq);
+		adev->timer->eoi = NULL;
+	} else {
+		dw_apb_clockevent_resume(adev->timer);
+	}
 
-	printk(KERN_INFO "Registering CPU %d clockevent device %s, mask %08x\n",
-	       cpu, aevt->name, *(u32 *)aevt->cpumask);
+	printk(KERN_INFO "Registering CPU %d clockevent device %s, cpu %08x\n",
+	       cpu, adev->name, adev->cpu);
 
 	apbt_setup_irq(adev);
-
-	clockevents_register_device(aevt);
-
-	apbt_enable_int(cpu);
+	dw_apb_clockevent_register(adev->timer);
 
 	return;
 }
@@ -384,13 +236,12 @@ static int apbt_cpuhp_notify(struct notifier_block *n,
 
 	switch (action & 0xf) {
 	case CPU_DEAD:
-		disable_irq(adev->irq);
-		apbt_disable_int(cpu);
+		dw_apb_clockevent_pause(adev->timer);
 		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);
+			dw_apb_clockevent_stop(adev->timer);
 		}
 		break;
 	default:
@@ -415,116 +266,16 @@ 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);
-
-	BUG_ON(!apbt_virt_address);
-
-	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;
-}
-
-static cycle_t apbt_read_clocksource(struct clocksource *cs)
-{
-	unsigned long current_count;
-
-	current_count = apbt_readl(phy_cs_timer_id, APBTMR_N_CURRENT_VALUE);
-	return (cycle_t)~current_count;
-}
-
 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);
+	dw_apb_clocksource_start(clocksource_apbt);
 
 	/* Verify whether apbt counter works */
-	t1 = apbt_read_clocksource(&clocksource_apbt);
+	t1 = dw_apb_clocksource_read(clocksource_apbt);
 	rdtscll(start);
 
 	/*
@@ -539,10 +290,10 @@ static int apbt_clocksource_register(void)
 	} while ((now - start) < 200000UL);
 
 	/* APBT is the only always on clocksource, it has to work! */
-	if (t1 == apbt_read_clocksource(&clocksource_apbt))
+	if (t1 == dw_apb_clocksource_read(clocksource_apbt))
 		panic("APBT counter not counting. APBT disabled\n");
 
-	clocksource_register_khz(&clocksource_apbt, (u32)apbt_freq*1000);
+	dw_apb_clocksource_register(clocksource_apbt);
 
 	return 0;
 }
@@ -566,10 +317,7 @@ void __init apbt_time_init(void)
 	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
+	if (!apbt_virt_address)
 		goto out_noapbt;
 	/*
 	 * Read the frequency and check for a sane value, for ESL model
@@ -577,7 +325,7 @@ void __init apbt_time_init(void)
 	 */
 
 	if (apbt_freq < APBT_MIN_FREQ || apbt_freq > APBT_MAX_FREQ) {
-		pr_debug("APBT has invalid freq 0x%llx\n", apbt_freq);
+		pr_debug("APBT has invalid freq 0x%lx\n", apbt_freq);
 		goto out_noapbt;
 	}
 	if (apbt_clocksource_register()) {
@@ -603,30 +351,20 @@ void __init apbt_time_init(void)
 	} 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;
+		if (p_mtmr)
 			adev->irq = p_mtmr->irq;
-		} else
+		else
 			printk(KERN_ERR "Failed to get timer for cpu %d\n", i);
-		adev->count = 0;
-		sprintf(adev->name, "apbt%d", i);
+		snprintf(adev->name, sizeof(adev->name) - 1, "apbt%d", i);
 	}
 #endif
 
@@ -638,17 +376,8 @@ out_noapbt:
 	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()
+unsigned long apbt_quick_calibrate(void)
 {
 	int i, scale;
 	u64 old, new;
@@ -657,31 +386,31 @@ unsigned long apbt_quick_calibrate()
 	u32 loop, shift;
 
 	apbt_set_mapping();
-	apbt_start_counter(phy_cs_timer_id);
+	dw_apb_clocksource_start(clocksource_apbt);
 
 	/* check if the timer can count down, otherwise return */
-	old = apbt_read_clocksource(&clocksource_apbt);
+	old = dw_apb_clocksource_read(clocksource_apbt);
 	i = 10000;
 	while (--i) {
-		if (old != apbt_read_clocksource(&clocksource_apbt))
+		if (old != dw_apb_clocksource_read(clocksource_apbt))
 			break;
 	}
 	if (!i)
 		goto failed;
 
 	/* count 16 ms */
-	loop = (apbt_freq * 1000) << 4;
+	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);
+	dw_apb_clocksource_start(clocksource_apbt);
 
-	old = apbt_read_clocksource(&clocksource_apbt);
+	old = dw_apb_clocksource_read(clocksource_apbt);
 	old += loop;
 
 	t1 = __native_read_tsc();
 
 	do {
-		new = apbt_read_clocksource(&clocksource_apbt);
+		new = dw_apb_clocksource_read(clocksource_apbt);
 	} while (new < old);
 
 	t2 = __native_read_tsc();
@@ -693,7 +422,7 @@ unsigned long apbt_quick_calibrate()
 		return 0;
 	}
 	scale = (int)div_u64((t2 - t1), loop >> shift);
-	khz = (scale * apbt_freq * 1000) >> shift;
+	khz = (scale * (apbt_freq / 1000)) >> shift;
 	printk(KERN_INFO "TSC freq calculated by APB timer is %lu khz\n", khz);
 	return khz;
 failed:
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 96c92191..141417f 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -3,3 +3,6 @@ config CLKSRC_I8253
 
 config CLKSRC_MMIO
 	bool
+
+config DW_APB_TIMER
+	bool
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index b995942..4c3d8fd 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_SH_TIMER_MTU2)	+= sh_mtu2.o
 obj-$(CONFIG_SH_TIMER_TMU)	+= sh_tmu.o
 obj-$(CONFIG_CLKSRC_I8253)	+= i8253.o
 obj-$(CONFIG_CLKSRC_MMIO)	+= mmio.o
+obj-$(CONFIG_DW_APB_TIMER)	+= dw_apb_timer.o
diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c
new file mode 100644
index 0000000..580f870
--- /dev/null
+++ b/drivers/clocksource/dw_apb_timer.c
@@ -0,0 +1,401 @@
+/*
+ * (C) Copyright 2009 Intel Corporation
+ * Author: Jacob Pan (jacob.jun.pan@intel.com)
+ *
+ * Shared with ARM platforms, Jamie Iles, Picochip 2011
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Support for the Synopsys DesignWare APB Timers.
+ */
+#include <linux/dw_apb_timer.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+
+#define APBT_MIN_PERIOD			4
+#define APBT_MIN_DELTA_USEC		200
+
+#define APBTMR_N_LOAD_COUNT		0x00
+#define APBTMR_N_CURRENT_VALUE		0x04
+#define APBTMR_N_CONTROL		0x08
+#define APBTMR_N_EOI			0x0c
+#define APBTMR_N_INT_STATUS		0x10
+
+#define APBTMRS_INT_STATUS		0xa0
+#define APBTMRS_EOI			0xa4
+#define APBTMRS_RAW_INT_STATUS		0xa8
+#define APBTMRS_COMP_VERSION		0xac
+
+#define APBTMR_CONTROL_ENABLE		(1 << 0)
+/* 1: periodic, 0:free running. */
+#define APBTMR_CONTROL_MODE_PERIODIC	(1 << 1)
+#define APBTMR_CONTROL_INT		(1 << 2)
+
+static inline struct dw_apb_clock_event_device *
+ced_to_dw_apb_ced(struct clock_event_device *evt)
+{
+	return container_of(evt, struct dw_apb_clock_event_device, ced);
+}
+
+static inline struct dw_apb_clocksource *
+clocksource_to_dw_apb_clocksource(struct clocksource *cs)
+{
+	return container_of(cs, struct dw_apb_clocksource, cs);
+}
+
+static unsigned long apbt_readl(struct dw_apb_timer *timer, unsigned long offs)
+{
+	return readl(timer->base + offs);
+}
+
+static void apbt_writel(struct dw_apb_timer *timer, unsigned long val,
+		 unsigned long offs)
+{
+	writel(val, timer->base + offs);
+}
+
+static void apbt_disable_int(struct dw_apb_timer *timer)
+{
+	unsigned long ctrl = apbt_readl(timer, APBTMR_N_CONTROL);
+
+	ctrl |= APBTMR_CONTROL_INT;
+	apbt_writel(timer, ctrl, APBTMR_N_CONTROL);
+}
+
+/**
+ * dw_apb_clockevent_pause() - stop the clock_event_device from running
+ *
+ * @dw_ced:	The APB clock to stop generating events.
+ */
+void dw_apb_clockevent_pause(struct dw_apb_clock_event_device *dw_ced)
+{
+	disable_irq(dw_ced->timer.irq);
+	apbt_disable_int(&dw_ced->timer);
+}
+
+static void apbt_eoi(struct dw_apb_timer *timer)
+{
+	apbt_readl(timer, APBTMR_N_EOI);
+}
+
+static irqreturn_t dw_apb_clockevent_irq(int irq, void *data)
+{
+	struct clock_event_device *evt = data;
+	struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt);
+
+	if (!evt->event_handler) {
+		pr_info("Spurious APBT timer interrupt %d", irq);
+		return IRQ_NONE;
+	}
+
+	if (dw_ced->eoi)
+		dw_ced->eoi(&dw_ced->timer);
+
+	evt->event_handler(evt);
+	return IRQ_HANDLED;
+}
+
+static void apbt_enable_int(struct dw_apb_timer *timer)
+{
+	unsigned long ctrl = apbt_readl(timer, APBTMR_N_CONTROL);
+	/* clear pending intr */
+	apbt_readl(timer, APBTMR_N_EOI);
+	ctrl &= ~APBTMR_CONTROL_INT;
+	apbt_writel(timer, ctrl, APBTMR_N_CONTROL);
+}
+
+static void apbt_set_mode(enum clock_event_mode mode,
+			  struct clock_event_device *evt)
+{
+	unsigned long ctrl;
+	unsigned long period;
+	struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt);
+
+	pr_debug("%s CPU %d mode=%d\n", __func__, first_cpu(*evt->cpumask),
+		 mode);
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		period = DIV_ROUND_UP(dw_ced->timer.freq, HZ);
+		ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL);
+		ctrl |= APBTMR_CONTROL_MODE_PERIODIC;
+		apbt_writel(&dw_ced->timer, 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(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+		udelay(1);
+		pr_debug("Setting clock period %lu for HZ %d\n", period, HZ);
+		apbt_writel(&dw_ced->timer, period, APBTMR_N_LOAD_COUNT);
+		ctrl |= APBTMR_CONTROL_ENABLE;
+		apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+		break;
+
+	case CLOCK_EVT_MODE_ONESHOT:
+		ctrl = apbt_readl(&dw_ced->timer, 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(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+		/* write again to set free running mode */
+		apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+
+		/*
+		 * DW APB p. 46, load counter with all 1s before starting free
+		 * running mode.
+		 */
+		apbt_writel(&dw_ced->timer, ~0, APBTMR_N_LOAD_COUNT);
+		ctrl &= ~APBTMR_CONTROL_INT;
+		ctrl |= APBTMR_CONTROL_ENABLE;
+		apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+		break;
+
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL);
+		ctrl &= ~APBTMR_CONTROL_ENABLE;
+		apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+		break;
+
+	case CLOCK_EVT_MODE_RESUME:
+		apbt_enable_int(&dw_ced->timer);
+		break;
+	}
+}
+
+static int apbt_next_event(unsigned long delta,
+			   struct clock_event_device *evt)
+{
+	unsigned long ctrl;
+	struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt);
+
+	/* Disable timer */
+	ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL);
+	ctrl &= ~APBTMR_CONTROL_ENABLE;
+	apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+	/* write new count */
+	apbt_writel(&dw_ced->timer, delta, APBTMR_N_LOAD_COUNT);
+	ctrl |= APBTMR_CONTROL_ENABLE;
+	apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+
+	return 0;
+}
+
+/**
+ * dw_apb_clockevent_init() - use an APB timer as a clock_event_device
+ *
+ * @cpu:	The CPU the events will be targeted at.
+ * @name:	The name used for the timer and the IRQ for it.
+ * @rating:	The rating to give the timer.
+ * @base:	I/O base for the timer registers.
+ * @irq:	The interrupt number to use for the timer.
+ * @freq:	The frequency that the timer counts at.
+ *
+ * This creates a clock_event_device for using with the generic clock layer
+ * but does not start and register it.  This should be done with
+ * dw_apb_clockevent_register() as the next step.  If this is the first time
+ * it has been called for a timer then the IRQ will be requested, if not it
+ * just be enabled to allow CPU hotplug to avoid repeatedly requesting and
+ * releasing the IRQ.
+ */
+struct dw_apb_clock_event_device *
+dw_apb_clockevent_init(int cpu, const char *name, unsigned rating,
+		       void __iomem *base, int irq, unsigned long freq)
+{
+	struct dw_apb_clock_event_device *dw_ced =
+		kzalloc(sizeof(*dw_ced), GFP_KERNEL);
+	int err;
+
+	if (!dw_ced)
+		return NULL;
+
+	dw_ced->timer.base = base;
+	dw_ced->timer.irq = irq;
+	dw_ced->timer.freq = freq;
+
+	clockevents_calc_mult_shift(&dw_ced->ced, freq, APBT_MIN_PERIOD);
+	dw_ced->ced.max_delta_ns = clockevent_delta2ns(0x7fffffff,
+						       &dw_ced->ced);
+	dw_ced->ced.min_delta_ns = clockevent_delta2ns(5000, &dw_ced->ced);
+	dw_ced->ced.cpumask = cpumask_of(cpu);
+	dw_ced->ced.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+	dw_ced->ced.set_mode = apbt_set_mode;
+	dw_ced->ced.set_next_event = apbt_next_event;
+	dw_ced->ced.irq = dw_ced->timer.irq;
+	dw_ced->ced.rating = rating;
+	dw_ced->ced.name = name;
+
+	dw_ced->irqaction.name		= dw_ced->ced.name;
+	dw_ced->irqaction.handler	= dw_apb_clockevent_irq;
+	dw_ced->irqaction.dev_id	= &dw_ced->ced;
+	dw_ced->irqaction.irq		= irq;
+	dw_ced->irqaction.flags		= IRQF_TIMER | IRQF_IRQPOLL |
+					  IRQF_NOBALANCING |
+					  IRQF_DISABLED;
+
+	dw_ced->eoi = apbt_eoi;
+	err = setup_irq(irq, &dw_ced->irqaction);
+	if (err) {
+		pr_err("failed to request timer irq\n");
+		kfree(dw_ced);
+		dw_ced = NULL;
+	}
+
+	return dw_ced;
+}
+
+/**
+ * dw_apb_clockevent_resume() - resume a clock that has been paused.
+ *
+ * @dw_ced:	The APB clock to resume.
+ */
+void dw_apb_clockevent_resume(struct dw_apb_clock_event_device *dw_ced)
+{
+	enable_irq(dw_ced->timer.irq);
+}
+
+/**
+ * dw_apb_clockevent_stop() - stop the clock_event_device and release the IRQ.
+ *
+ * @dw_ced:	The APB clock to stop generating the events.
+ */
+void dw_apb_clockevent_stop(struct dw_apb_clock_event_device *dw_ced)
+{
+	free_irq(dw_ced->timer.irq, &dw_ced->ced);
+}
+
+/**
+ * dw_apb_clockevent_register() - register the clock with the generic layer
+ *
+ * @dw_ced:	The APB clock to register as a clock_event_device.
+ */
+void dw_apb_clockevent_register(struct dw_apb_clock_event_device *dw_ced)
+{
+	apbt_writel(&dw_ced->timer, 0, APBTMR_N_CONTROL);
+	clockevents_register_device(&dw_ced->ced);
+	apbt_enable_int(&dw_ced->timer);
+}
+
+/**
+ * dw_apb_clocksource_start() - start the clocksource counting.
+ *
+ * @dw_cs:	The clocksource to start.
+ *
+ * This is used to start the clocksource before registration and can be used
+ * to enable calibration of timers.
+ */
+void dw_apb_clocksource_start(struct dw_apb_clocksource *dw_cs)
+{
+	/*
+	 * start count down from 0xffff_ffff. this is done by toggling the
+	 * enable bit then load initial load count to ~0.
+	 */
+	unsigned long ctrl = apbt_readl(&dw_cs->timer, APBTMR_N_CONTROL);
+
+	ctrl &= ~APBTMR_CONTROL_ENABLE;
+	apbt_writel(&dw_cs->timer, ctrl, APBTMR_N_CONTROL);
+	apbt_writel(&dw_cs->timer, ~0, APBTMR_N_LOAD_COUNT);
+	/* enable, mask interrupt */
+	ctrl &= ~APBTMR_CONTROL_MODE_PERIODIC;
+	ctrl |= (APBTMR_CONTROL_ENABLE | APBTMR_CONTROL_INT);
+	apbt_writel(&dw_cs->timer, ctrl, APBTMR_N_CONTROL);
+	/* read it once to get cached counter value initialized */
+	dw_apb_clocksource_read(dw_cs);
+}
+
+static cycle_t __apbt_read_clocksource(struct clocksource *cs)
+{
+	unsigned long current_count;
+	struct dw_apb_clocksource *dw_cs =
+		clocksource_to_dw_apb_clocksource(cs);
+
+	current_count = apbt_readl(&dw_cs->timer, APBTMR_N_CURRENT_VALUE);
+
+	return (cycle_t)~current_count;
+}
+
+static void apbt_restart_clocksource(struct clocksource *cs)
+{
+	struct dw_apb_clocksource *dw_cs =
+		clocksource_to_dw_apb_clocksource(cs);
+
+	dw_apb_clocksource_start(dw_cs);
+}
+
+/**
+ * dw_apb_clocksource_init() - use an APB timer as a clocksource.
+ *
+ * @rating:	The rating to give the clocksource.
+ * @name:	The name for the clocksource.
+ * @base:	The I/O base for the timer registers.
+ * @freq:	The frequency that the timer counts at.
+ *
+ * This creates a clocksource using an APB timer but does not yet register it
+ * with the clocksource system.  This should be done with
+ * dw_apb_clocksource_register() as the next step.
+ */
+struct dw_apb_clocksource *
+dw_apb_clocksource_init(unsigned rating, char *name, void __iomem *base,
+			unsigned long freq)
+{
+	struct dw_apb_clocksource *dw_cs = kzalloc(sizeof(*dw_cs), GFP_KERNEL);
+
+	if (!dw_cs)
+		return NULL;
+
+	dw_cs->timer.base = base;
+	dw_cs->timer.freq = freq;
+	dw_cs->cs.name = name;
+	dw_cs->cs.rating = rating;
+	dw_cs->cs.read = __apbt_read_clocksource;
+	dw_cs->cs.mask = CLOCKSOURCE_MASK(32);
+	dw_cs->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+	dw_cs->cs.resume = apbt_restart_clocksource;
+
+	return dw_cs;
+}
+
+/**
+ * dw_apb_clocksource_register() - register the APB clocksource.
+ *
+ * @dw_cs:	The clocksource to register.
+ */
+void dw_apb_clocksource_register(struct dw_apb_clocksource *dw_cs)
+{
+	clocksource_register_hz(&dw_cs->cs, dw_cs->timer.freq);
+}
+
+/**
+ * dw_apb_clocksource_read() - read the current value of a clocksource.
+ *
+ * @dw_cs:	The clocksource to read.
+ */
+cycle_t dw_apb_clocksource_read(struct dw_apb_clocksource *dw_cs)
+{
+	return (cycle_t)~apbt_readl(&dw_cs->timer, APBTMR_N_CURRENT_VALUE);
+}
+
+/**
+ * dw_apb_clocksource_unregister() - unregister and free a clocksource.
+ *
+ * @dw_cs:	The clocksource to unregister/free.
+ */
+void dw_apb_clocksource_unregister(struct dw_apb_clocksource *dw_cs)
+{
+	clocksource_unregister(&dw_cs->cs);
+
+	kfree(dw_cs);
+}
diff --git a/include/linux/dw_apb_timer.h b/include/linux/dw_apb_timer.h
new file mode 100644
index 0000000..49638ea
--- /dev/null
+++ b/include/linux/dw_apb_timer.h
@@ -0,0 +1,56 @@
+/*
+ * (C) Copyright 2009 Intel Corporation
+ * Author: Jacob Pan (jacob.jun.pan@intel.com)
+ *
+ * Shared with ARM platforms, Jamie Iles, Picochip 2011
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Support for the Synopsys DesignWare APB Timers.
+ */
+#ifndef __DW_APB_TIMER_H__
+#define __DW_APB_TIMER_H__
+
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+
+#define APBTMRS_REG_SIZE       0x14
+
+struct dw_apb_timer {
+	void __iomem				*base;
+	unsigned long				freq;
+	int					irq;
+};
+
+struct dw_apb_clock_event_device {
+	struct clock_event_device		ced;
+	struct dw_apb_timer			timer;
+	struct irqaction			irqaction;
+	void					(*eoi)(struct dw_apb_timer *);
+};
+
+struct dw_apb_clocksource {
+	struct dw_apb_timer			timer;
+	struct clocksource			cs;
+};
+
+void dw_apb_clockevent_register(struct dw_apb_clock_event_device *dw_ced);
+void dw_apb_clockevent_pause(struct dw_apb_clock_event_device *dw_ced);
+void dw_apb_clockevent_resume(struct dw_apb_clock_event_device *dw_ced);
+void dw_apb_clockevent_stop(struct dw_apb_clock_event_device *dw_ced);
+
+struct dw_apb_clock_event_device *
+dw_apb_clockevent_init(int cpu, const char *name, unsigned rating,
+		       void __iomem *base, int irq, unsigned long freq);
+struct dw_apb_clocksource *
+dw_apb_clocksource_init(unsigned rating, char *name, void __iomem *base,
+			unsigned long freq);
+void dw_apb_clocksource_register(struct dw_apb_clocksource *dw_cs);
+void dw_apb_clocksource_start(struct dw_apb_clocksource *dw_cs);
+cycle_t dw_apb_clocksource_read(struct dw_apb_clocksource *dw_cs);
+void dw_apb_clocksource_unregister(struct dw_apb_clocksource *dw_cs);
+
+#endif /* __DW_APB_TIMER_H__ */