[IA64] Convert to generic timekeeping/clocksource

This is a merge of Peter Keilty's initial patch (which was
revived by Bob Picco) for this with Hidetoshi Seto's fixes
and scaling improvements.
Acked-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

Documentation/kernel-parameters.txt

@@ -1154,6 +1154,8 @@ and is between 256 and 4096 characters. It is defined in the file
 
 	nointroute	[IA-64]
 
+	nojitter	[IA64] Disables jitter checking for ITC timers.
+
 	nolapic		[IA-32,APIC] Do not enable or use the local APIC.
 
 	nolapic_timer	[IA-32,APIC] Do not use the local APIC timer.

arch/ia64/Kconfig

@@ -62,7 +62,11 @@ config GENERIC_CALIBRATE_DELAY
 	bool
 	default y
 
-config TIME_INTERPOLATION
+config GENERIC_TIME
+	bool
+	default y
+
+config GENERIC_TIME_VSYSCALL
 	bool
 	default y
 

arch/ia64/configs/bigsur_defconfig

@@ -85,7 +85,7 @@ CONFIG_MMU=y
 CONFIG_SWIOTLB=y
 CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
-CONFIG_TIME_INTERPOLATION=y
+CONFIG_GENERIC_TIME=y
 CONFIG_EFI=y
 CONFIG_GENERIC_IOMAP=y
 CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER=y

arch/ia64/configs/gensparse_defconfig

@@ -86,7 +86,7 @@ CONFIG_MMU=y
 CONFIG_SWIOTLB=y
 CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
-CONFIG_TIME_INTERPOLATION=y
+CONFIG_GENERIC_TIME=y
 CONFIG_EFI=y
 CONFIG_GENERIC_IOMAP=y
 CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER=y

arch/ia64/configs/sim_defconfig

@@ -86,7 +86,7 @@ CONFIG_MMU=y
 CONFIG_SWIOTLB=y
 CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
-CONFIG_TIME_INTERPOLATION=y
+CONFIG_GENERIC_TIME=y
 CONFIG_EFI=y
 CONFIG_GENERIC_IOMAP=y
 CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER=y

arch/ia64/configs/sn2_defconfig

@@ -93,7 +93,7 @@ CONFIG_SWIOTLB=y
 CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 CONFIG_GENERIC_FIND_NEXT_BIT=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
-CONFIG_TIME_INTERPOLATION=y
+CONFIG_GENERIC_TIME=y
 CONFIG_DMI=y
 CONFIG_EFI=y
 CONFIG_GENERIC_IOMAP=y

arch/ia64/configs/tiger_defconfig

@@ -98,7 +98,7 @@ CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 # CONFIG_ARCH_HAS_ILOG2_U64 is not set
 CONFIG_GENERIC_FIND_NEXT_BIT=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
-CONFIG_TIME_INTERPOLATION=y
+CONFIG_GENERIC_TIME=y
 CONFIG_DMI=y
 CONFIG_EFI=y
 CONFIG_GENERIC_IOMAP=y

arch/ia64/configs/zx1_defconfig

@@ -96,7 +96,7 @@ CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 # CONFIG_ARCH_HAS_ILOG2_U64 is not set
 CONFIG_GENERIC_FIND_NEXT_BIT=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
-CONFIG_TIME_INTERPOLATION=y
+CONFIG_GENERIC_TIME=y
 CONFIG_DMI=y
 CONFIG_EFI=y
 CONFIG_GENERIC_IOMAP=y

arch/ia64/defconfig

@@ -98,7 +98,7 @@ CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 # CONFIG_ARCH_HAS_ILOG2_U64 is not set
 CONFIG_GENERIC_FIND_NEXT_BIT=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
-CONFIG_TIME_INTERPOLATION=y
+CONFIG_GENERIC_TIME=y
 CONFIG_DMI=y
 CONFIG_EFI=y
 CONFIG_GENERIC_IOMAP=y

arch/ia64/kernel/asm-offsets.c

@@ -7,6 +7,7 @@
 #define ASM_OFFSETS_C 1
 
 #include <linux/sched.h>
+#include <linux/clocksource.h>
 
 #include <asm-ia64/processor.h>
 #include <asm-ia64/ptrace.h>
@@ -15,6 +16,7 @@
 #include <asm-ia64/mca.h>
 
 #include "../kernel/sigframe.h"
+#include "../kernel/fsyscall_gtod_data.h"
 
 #define DEFINE(sym, val) \
         asm volatile("\n->" #sym " %0 " #val : : "i" (val))
@@ -256,17 +258,24 @@ void foo(void)
 	BLANK();
 
 	/* used by fsys_gettimeofday in arch/ia64/kernel/fsys.S */
-	DEFINE(IA64_TIME_INTERPOLATOR_ADDRESS_OFFSET, offsetof (struct time_interpolator, addr));
-	DEFINE(IA64_TIME_INTERPOLATOR_SOURCE_OFFSET, offsetof (struct time_interpolator, source));
-	DEFINE(IA64_TIME_INTERPOLATOR_SHIFT_OFFSET, offsetof (struct time_interpolator, shift));
-	DEFINE(IA64_TIME_INTERPOLATOR_NSEC_OFFSET, offsetof (struct time_interpolator, nsec_per_cyc));
-	DEFINE(IA64_TIME_INTERPOLATOR_OFFSET_OFFSET, offsetof (struct time_interpolator, offset));
-	DEFINE(IA64_TIME_INTERPOLATOR_LAST_CYCLE_OFFSET, offsetof (struct time_interpolator, last_cycle));
-	DEFINE(IA64_TIME_INTERPOLATOR_LAST_COUNTER_OFFSET, offsetof (struct time_interpolator, last_counter));
-	DEFINE(IA64_TIME_INTERPOLATOR_JITTER_OFFSET, offsetof (struct time_interpolator, jitter));
-	DEFINE(IA64_TIME_INTERPOLATOR_MASK_OFFSET, offsetof (struct time_interpolator, mask));
-	DEFINE(IA64_TIME_SOURCE_CPU, TIME_SOURCE_CPU);
-	DEFINE(IA64_TIME_SOURCE_MMIO64, TIME_SOURCE_MMIO64);
-	DEFINE(IA64_TIME_SOURCE_MMIO32, TIME_SOURCE_MMIO32);
-	DEFINE(IA64_TIMESPEC_TV_NSEC_OFFSET, offsetof (struct timespec, tv_nsec));
+	DEFINE(IA64_GTOD_LOCK_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, lock));
+	DEFINE(IA64_GTOD_WALL_TIME_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, wall_time));
+	DEFINE(IA64_GTOD_MONO_TIME_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, monotonic_time));
+	DEFINE(IA64_CLKSRC_MASK_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, clk_mask));
+	DEFINE(IA64_CLKSRC_MULT_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, clk_mult));
+	DEFINE(IA64_CLKSRC_SHIFT_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, clk_shift));
+	DEFINE(IA64_CLKSRC_MMIO_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, clk_fsys_mmio));
+	DEFINE(IA64_CLKSRC_CYCLE_LAST_OFFSET,
+		offsetof (struct fsyscall_gtod_data_t, clk_cycle_last));
+	DEFINE(IA64_ITC_JITTER_OFFSET,
+		offsetof (struct itc_jitter_data_t, itc_jitter));
+	DEFINE(IA64_ITC_LASTCYCLE_OFFSET,
+		offsetof (struct itc_jitter_data_t, itc_lastcycle));
 }

arch/ia64/kernel/cyclone.c

@@ -3,6 +3,7 @@
 #include <linux/time.h>
 #include <linux/errno.h>
 #include <linux/timex.h>
+#include <linux/clocksource.h>
 #include <asm/io.h>
 
 /* IBM Summit (EXA) Cyclone counter code*/
@@ -18,13 +19,21 @@ void __init cyclone_setup(void)
 	use_cyclone = 1;
 }
 
+static void __iomem *cyclone_mc;
 
-struct time_interpolator cyclone_interpolator = {
-	.source =	TIME_SOURCE_MMIO64,
-	.shift =	16,
-	.frequency =	CYCLONE_TIMER_FREQ,
-	.drift =	-100,
-	.mask =		(1LL << 40) - 1
+static cycle_t read_cyclone(void)
+{
+	return (cycle_t)readq((void __iomem *)cyclone_mc);
+}
+
+static struct clocksource clocksource_cyclone = {
+        .name           = "cyclone",
+        .rating         = 300,
+        .read           = read_cyclone,
+        .mask           = (1LL << 40) - 1,
+        .mult           = 0, /*to be caluclated*/
+        .shift          = 16,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
 int __init init_cyclone_clock(void)
@@ -44,13 +53,15 @@ int __init init_cyclone_clock(void)
 	offset = (CYCLONE_CBAR_ADDR);
 	reg = (u64*)ioremap_nocache(offset, sizeof(u64));
 	if(!reg){
-		printk(KERN_ERR "Summit chipset: Could not find valid CBAR register.\n");
+		printk(KERN_ERR "Summit chipset: Could not find valid CBAR"
+				" register.\n");
 		use_cyclone = 0;
 		return -ENODEV;
 	}
 	base = readq(reg);
 	if(!base){
-		printk(KERN_ERR "Summit chipset: Could not find valid CBAR value.\n");
+		printk(KERN_ERR "Summit chipset: Could not find valid CBAR"
+				" value.\n");
 		use_cyclone = 0;
 		return -ENODEV;
 	}
@@ -60,7 +71,8 @@ int __init init_cyclone_clock(void)
 	offset = (base + CYCLONE_PMCC_OFFSET);
 	reg = (u64*)ioremap_nocache(offset, sizeof(u64));
 	if(!reg){
-		printk(KERN_ERR "Summit chipset: Could not find valid PMCC register.\n");
+		printk(KERN_ERR "Summit chipset: Could not find valid PMCC"
+				" register.\n");
 		use_cyclone = 0;
 		return -ENODEV;
 	}
@@ -71,7 +83,8 @@ int __init init_cyclone_clock(void)
 	offset = (base + CYCLONE_MPCS_OFFSET);
 	reg = (u64*)ioremap_nocache(offset, sizeof(u64));
 	if(!reg){
-		printk(KERN_ERR "Summit chipset: Could not find valid MPCS register.\n");
+		printk(KERN_ERR "Summit chipset: Could not find valid MPCS"
+				" register.\n");
 		use_cyclone = 0;
 		return -ENODEV;
 	}
@@ -82,7 +95,8 @@ int __init init_cyclone_clock(void)
 	offset = (base + CYCLONE_MPMC_OFFSET);
 	cyclone_timer = (u32*)ioremap_nocache(offset, sizeof(u32));
 	if(!cyclone_timer){
-		printk(KERN_ERR "Summit chipset: Could not find valid MPMC register.\n");
+		printk(KERN_ERR "Summit chipset: Could not find valid MPMC"
+				" register.\n");
 		use_cyclone = 0;
 		return -ENODEV;
 	}
@@ -93,7 +107,8 @@ int __init init_cyclone_clock(void)
 		int stall = 100;
 		while(stall--) barrier();
 		if(readl(cyclone_timer) == old){
-			printk(KERN_ERR "Summit chipset: Counter not counting! DISABLED\n");
+			printk(KERN_ERR "Summit chipset: Counter not counting!"
+					" DISABLED\n");
 			iounmap(cyclone_timer);
 			cyclone_timer = 0;
 			use_cyclone = 0;
@@ -101,8 +116,11 @@ int __init init_cyclone_clock(void)
 		}
 	}
 	/* initialize last tick */
-	cyclone_interpolator.addr = cyclone_timer;
-	register_time_interpolator(&cyclone_interpolator);
+	cyclone_mc = cyclone_timer;
+	clocksource_cyclone.fsys_mmio = cyclone_timer;
+	clocksource_cyclone.mult = clocksource_hz2mult(CYCLONE_TIMER_FREQ,
+						clocksource_cyclone.shift);
+	clocksource_register(&clocksource_cyclone);
 
 	return 0;
 }

arch/ia64/kernel/fsyscall_gtod_data.h

+/*
+ * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
+ *        Contributed by Peter Keilty <peter.keilty@hp.com>
+ *
+ * fsyscall gettimeofday data
+ */
+
+struct fsyscall_gtod_data_t {
+	seqlock_t	lock;
+	struct timespec	wall_time;
+	struct timespec monotonic_time;
+	cycle_t		clk_mask;
+	u32		clk_mult;
+	u32		clk_shift;
+	void		*clk_fsys_mmio;
+	cycle_t		clk_cycle_last;
+} __attribute__ ((aligned (L1_CACHE_BYTES)));
+
+struct itc_jitter_data_t {
+	int		itc_jitter;
+	cycle_t		itc_lastcycle;
+} __attribute__ ((aligned (L1_CACHE_BYTES)));
+

arch/ia64/kernel/time.c

@@ -19,6 +19,7 @@
 #include <linux/interrupt.h>
 #include <linux/efi.h>
 #include <linux/timex.h>
+#include <linux/clocksource.h>
 
 #include <asm/machvec.h>
 #include <asm/delay.h>
@@ -28,6 +29,16 @@
 #include <asm/sections.h>
 #include <asm/system.h>
 
+#include "fsyscall_gtod_data.h"
+
+static cycle_t itc_get_cycles(void);
+
+struct fsyscall_gtod_data_t fsyscall_gtod_data = {
+	.lock = SEQLOCK_UNLOCKED,
+};
+
+struct itc_jitter_data_t itc_jitter_data;
+
 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
 
 #ifdef CONFIG_IA64_DEBUG_IRQ
@@ -37,11 +48,16 @@ EXPORT_SYMBOL(last_cli_ip);
 
 #endif
 
-static struct time_interpolator itc_interpolator = {
-	.shift = 16,
-	.mask = 0xffffffffffffffffLL,
-	.source = TIME_SOURCE_CPU
+static struct clocksource clocksource_itc = {
+        .name           = "itc",
+        .rating         = 350,
+        .read           = itc_get_cycles,
+        .mask           = 0xffffffffffffffff,
+        .mult           = 0, /*to be caluclated*/
+        .shift          = 16,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
+static struct clocksource *itc_clocksource;
 
 static irqreturn_t
 timer_interrupt (int irq, void *dev_id)
@@ -210,8 +226,6 @@ ia64_init_itm (void)
 					+ itc_freq/2)/itc_freq;
 
 	if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
-		itc_interpolator.frequency = local_cpu_data->itc_freq;
-		itc_interpolator.drift = itc_drift;
 #ifdef CONFIG_SMP
 		/* On IA64 in an SMP configuration ITCs are never accurately synchronized.
 		 * Jitter compensation requires a cmpxchg which may limit
@@ -223,15 +237,50 @@ ia64_init_itm (void)
 		 * even going backward) if the ITC offsets between the individual CPUs
 		 * are too large.
 		 */
-		if (!nojitter) itc_interpolator.jitter = 1;
+		if (!nojitter)
+			itc_jitter_data.itc_jitter = 1;
 #endif
-		register_time_interpolator(&itc_interpolator);
 	}
 
 	/* Setup the CPU local timer tick */
 	ia64_cpu_local_tick();
+
+	if (!itc_clocksource) {
+		/* Sort out mult/shift values: */
+		clocksource_itc.mult =
+			clocksource_hz2mult(local_cpu_data->itc_freq,
+						clocksource_itc.shift);
+		clocksource_register(&clocksource_itc);
+		itc_clocksource = &clocksource_itc;
+	}
 }
 
+static cycle_t itc_get_cycles()
+{
+	u64 lcycle, now, ret;
+
+	if (!itc_jitter_data.itc_jitter)
+		return get_cycles();
+
+	lcycle = itc_jitter_data.itc_lastcycle;
+	now = get_cycles();
+	if (lcycle && time_after(lcycle, now))
+		return lcycle;
+
+	/*
+	 * Keep track of the last timer value returned.
+	 * In an SMP environment, you could lose out in contention of
+	 * cmpxchg. If so, your cmpxchg returns new value which the
+	 * winner of contention updated to. Use the new value instead.
+	 */
+	ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
+	if (unlikely(ret != lcycle))
+		return ret;
+
+	return now;
+}
+
+
 static struct irqaction timer_irqaction = {
 	.handler =	timer_interrupt,
 	.flags =	IRQF_DISABLED | IRQF_IRQPOLL,
@@ -307,3 +356,34 @@ ia64_setup_printk_clock(void)
 	if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT))
 		ia64_printk_clock = ia64_itc_printk_clock;
 }
+
+void update_vsyscall(struct timespec *wall, struct clocksource *c)
+{
+        unsigned long flags;
+
+        write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags);
+
+        /* copy fsyscall clock data */
+        fsyscall_gtod_data.clk_mask = c->mask;
+        fsyscall_gtod_data.clk_mult = c->mult;
+        fsyscall_gtod_data.clk_shift = c->shift;
+        fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio;
+        fsyscall_gtod_data.clk_cycle_last = c->cycle_last;
+
+	/* copy kernel time structures */
+        fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
+        fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
+        fsyscall_gtod_data.monotonic_time.tv_sec = wall_to_monotonic.tv_sec
+							+ wall->tv_sec;
+        fsyscall_gtod_data.monotonic_time.tv_nsec = wall_to_monotonic.tv_nsec
+							+ wall->tv_nsec;
+
+	/* normalize */
+	while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
+		fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
+		fsyscall_gtod_data.monotonic_time.tv_sec++;
+	}
+
+        write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags);
+}
+

arch/ia64/sn/kernel/sn2/timer.c

@@ -11,6 +11,7 @@
 #include <linux/sched.h>
 #include <linux/time.h>
 #include <linux/interrupt.h>
+#include <linux/clocksource.h>
 
 #include <asm/hw_irq.h>
 #include <asm/system.h>
@@ -22,11 +23,21 @@
 
 extern unsigned long sn_rtc_cycles_per_second;
 
-static struct time_interpolator sn2_interpolator = {
-	.drift = -1,
-	.shift = 10,
-	.mask = (1LL << 55) - 1,
-	.source = TIME_SOURCE_MMIO64
+static void __iomem *sn2_mc;
+
+static cycle_t read_sn2(void)
+{
+	return (cycle_t)readq(sn2_mc);
+}
+
+static struct clocksource clocksource_sn2 = {
+        .name           = "sn2_rtc",
+        .rating         = 300,
+        .read           = read_sn2,
+        .mask           = (1LL << 55) - 1,
+        .mult           = 0,
+        .shift          = 10,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
 /*
@@ -47,9 +58,11 @@ ia64_sn_udelay (unsigned long usecs)
 
 void __init sn_timer_init(void)
 {
-	sn2_interpolator.frequency = sn_rtc_cycles_per_second;
-	sn2_interpolator.addr = RTC_COUNTER_ADDR;
-	register_time_interpolator(&sn2_interpolator);
+	sn2_mc = RTC_COUNTER_ADDR;
+	clocksource_sn2.fsys_mmio = RTC_COUNTER_ADDR;
+	clocksource_sn2.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
+							clocksource_sn2.shift);
+	clocksource_register(&clocksource_sn2);
 
 	ia64_udelay = &ia64_sn_udelay;
 }

drivers/acpi/processor_idle.c

@@ -475,7 +475,7 @@ static void acpi_processor_idle(void)
 		/* Get end time (ticks) */
 		t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
 
-#ifdef CONFIG_GENERIC_TIME
+#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86_TSC)
 		/* TSC halts in C2, so notify users */
 		mark_tsc_unstable("possible TSC halt in C2");
 #endif
@@ -517,7 +517,7 @@ static void acpi_processor_idle(void)
 			acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
 		}
 
-#ifdef CONFIG_GENERIC_TIME
+#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86_TSC)
 		/* TSC halts in C3, so notify users */
 		mark_tsc_unstable("TSC halts in C3");
 #endif

drivers/char/hpet.c

@@ -29,6 +29,7 @@
 #include <linux/bcd.h>
 #include <linux/seq_file.h>
 #include <linux/bitops.h>
+#include <linux/clocksource.h>
 
 #include <asm/current.h>
 #include <asm/uaccess.h>
@@ -51,8 +52,34 @@
 
 #define HPET_RANGE_SIZE		1024	/* from HPET spec */
 
+#if BITS_PER_LONG == 64
+#define	write_counter(V, MC)	writeq(V, MC)
+#define	read_counter(MC)	readq(MC)
+#else
+#define	write_counter(V, MC)	writel(V, MC)
+#define	read_counter(MC)	readl(MC)
+#endif
+
 static u32 hpet_nhpet, hpet_max_freq = HPET_USER_FREQ;
 
+static void __iomem *hpet_mctr;
+
+static cycle_t read_hpet(void)
+{
+	return (cycle_t)read_counter((void __iomem *)hpet_mctr);
+}
+
+static struct clocksource clocksource_hpet = {
+        .name           = "hpet",
+        .rating         = 250,
+        .read           = read_hpet,
+        .mask           = 0xffffffffffffffff,
+        .mult           = 0, /*to be caluclated*/
+        .shift          = 10,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+static struct clocksource *hpet_clocksource;
+
 /* A lock for concurrent access by app and isr hpet activity. */
 static DEFINE_SPINLOCK(hpet_lock);
 /* A lock for concurrent intermodule access to hpet and isr hpet activity. */
@@ -79,7 +106,7 @@ struct hpets {
 	struct hpets *hp_next;
 	struct hpet __iomem *hp_hpet;
 	unsigned long hp_hpet_phys;
-	struct time_interpolator *hp_interpolator;
+	struct clocksource *hp_clocksource;
 	unsigned long long hp_tick_freq;
 	unsigned long hp_delta;
 	unsigned int hp_ntimer;
@@ -94,13 +121,6 @@ static struct hpets *hpets;
 #define	HPET_PERIODIC		0x0004
 #define	HPET_SHARED_IRQ		0x0008
 
-#if BITS_PER_LONG == 64
-#define	write_counter(V, MC)	writeq(V, MC)
-#define	read_counter(MC)	readq(MC)
-#else
-#define	write_counter(V, MC) 	writel(V, MC)
-#define	read_counter(MC)	readl(MC)
-#endif
 
 #ifndef readq
 static inline unsigned long long readq(void __iomem *addr)
@@ -737,27 +757,6 @@ static ctl_table dev_root[] = {
 
 static struct ctl_table_header *sysctl_header;
 
-static void hpet_register_interpolator(struct hpets *hpetp)
-{
-#ifdef	CONFIG_TIME_INTERPOLATION
-	struct time_interpolator *ti;
-
-	ti = kzalloc(sizeof(*ti), GFP_KERNEL);
-	if (!ti)
-		return;
-
-	ti->source = TIME_SOURCE_MMIO64;
-	ti->shift = 10;
-	ti->addr = &hpetp->hp_hpet->hpet_mc;
-	ti->frequency = hpetp->hp_tick_freq;
-	ti->drift = HPET_DRIFT;
-	ti->mask = -1;
-
-	hpetp->hp_interpolator = ti;
-	register_time_interpolator(ti);
-#endif
-}
-
 /*
  * Adjustment for when arming the timer with
  * initial conditions.  That is, main counter
@@ -909,7 +908,16 @@ int hpet_alloc(struct hpet_data *hdp)
 	}
 
 	hpetp->hp_delta = hpet_calibrate(hpetp);
-	hpet_register_interpolator(hpetp);
+
+	if (!hpet_clocksource) {
+		hpet_mctr = (void __iomem *)&hpetp->hp_hpet->hpet_mc;
+		CLKSRC_FSYS_MMIO_SET(clocksource_hpet.fsys_mmio, hpet_mctr);
+		clocksource_hpet.mult = clocksource_hz2mult(hpetp->hp_tick_freq,
+						clocksource_hpet.shift);
+		clocksource_register(&clocksource_hpet);
+		hpetp->hp_clocksource = &clocksource_hpet;
+		hpet_clocksource = &clocksource_hpet;
+	}
 
 	return 0;
 }
@@ -995,7 +1003,7 @@ static int hpet_acpi_add(struct acpi_device *device)
 
 static int hpet_acpi_remove(struct acpi_device *device, int type)
 {
-	/* XXX need to unregister interpolator, dealloc mem, etc */
+	/* XXX need to unregister clocksource, dealloc mem, etc */
 	return -EINVAL;
 }
 

include/linux/clocksource.h

@@ -67,6 +67,12 @@ struct clocksource {
 	unsigned long flags;
 	cycle_t (*vread)(void);
 	void (*resume)(void);
+#ifdef CONFIG_IA64
+	void *fsys_mmio;        /* used by fsyscall asm code */
+#define CLKSRC_FSYS_MMIO_SET(mmio, addr)      ((mmio) = (addr))
+#else
+#define CLKSRC_FSYS_MMIO_SET(mmio, addr)      do { } while (0)
+#endif
 
 	/* timekeeping specific data, ignore */
 	cycle_t cycle_interval;