[PATCH 1/2] ia64 clocksource

["Bob Picco" <bob.picco@hp.com>]

Andrew and Tony:

I'd like to get this into -mm with the intent of targeting for 2.6.24. There
is only documentation change since Pete's last posting on ia64 ml. I doubt
Pete's email address exists because of his early retirement the end of May.

bob

From: Peter Keilty <peter.keilty@hp.com>

Initial ia64 conversion to the generic timekeeping/clocksource code.
Performance measurements for single calls (ITC cycles):

A. 32 way Intel IA64 SMP system 8640 (montecito)
A.1. Current code itc cmpxchg
gettimeofday cycles: 39 37 37 37 37 37 37 37 37 37 
clock_gettime(REAL) cycles: 49 35 35 35 35 35 35 35 35 35
clock_gettime(MONO) cycles: 42 36 36 36 36 36 36 36 36 36

A.2 New code itc cmpxchg
gettimeofday cycles: 39 38 37 37 38 37 38 37 37 37
clock_gettime(REAL) cycles: 53 35 35 36 35 35 35 35 35 35
clock_gettime(MONO) cycles: 44 38 36 36 36 36 36 36 36 36

A.3 New code itc cmpxchg switched off (nojitter kernel option)
gettimeofday cycles: 35 35 36 35 36 35 36 35 35 35
clock_gettime(REAL) cycles: 49 33 33 34 33 33 33 33 33 33
clock_gettime(MONO) cycles: 38 33 33 33 33 33 33 33 33 33

A.4 New code with hpet as clocksource, mmio space read


Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Peter Keilty <peter.keilty@hp.com>

 Documentation/kernel-parameters.txt   |    2 
 arch/ia64/Kconfig                     |    6 +
 arch/ia64/configs/bigsur_defconfig    |    2 
 arch/ia64/configs/gensparse_defconfig |    2 
 arch/ia64/configs/sim_defconfig       |    2 
 arch/ia64/configs/sn2_defconfig       |    2 
 arch/ia64/configs/tiger_defconfig     |    2 
 arch/ia64/configs/zx1_defconfig       |    2 
 arch/ia64/defconfig                   |    2 
 arch/ia64/kernel/asm-offsets.c        |   23 ++----
 arch/ia64/kernel/cyclone.c            |   46 +++++++++----
 arch/ia64/kernel/fsys.S               |  119 +++++++++++++++-------------------
 arch/ia64/kernel/fsyscall_gtod_data.h |   18 +++++
 arch/ia64/kernel/time.c               |   85 ++++++++++++++++++++++--
 arch/ia64/sn/kernel/sn2/timer.c       |   29 ++++++--
 drivers/acpi/processor_idle.c         |    4 -
 drivers/char/hpet.c                   |   70 +++++++++++---------
 include/linux/clocksource.h           |    6 +
 18 files changed, 274 insertions(+), 148 deletions(-)

Index: linux-2.6.22/arch/ia64/Kconfig
=================================--- linux-2.6.22.orig/arch/ia64/Kconfig	2007-07-09 06:19:09.000000000 -0400
+++ linux-2.6.22/arch/ia64/Kconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
 
Index: linux-2.6.22/arch/ia64/configs/bigsur_defconfig
=================================--- linux-2.6.22.orig/arch/ia64/configs/bigsur_defconfig	2007-07-09 06:17:14.000000000 -0400
+++ linux-2.6.22/arch/ia64/configs/bigsur_defconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/arch/ia64/configs/gensparse_defconfig
=================================--- linux-2.6.22.orig/arch/ia64/configs/gensparse_defconfig	2007-07-09 06:17:26.000000000 -0400
+++ linux-2.6.22/arch/ia64/configs/gensparse_defconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/arch/ia64/configs/sim_defconfig
=================================--- linux-2.6.22.orig/arch/ia64/configs/sim_defconfig	2007-07-09 06:17:14.000000000 -0400
+++ linux-2.6.22/arch/ia64/configs/sim_defconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/arch/ia64/configs/sn2_defconfig
=================================--- linux-2.6.22.orig/arch/ia64/configs/sn2_defconfig	2007-07-09 06:18:01.000000000 -0400
+++ linux-2.6.22/arch/ia64/configs/sn2_defconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/arch/ia64/kernel/asm-offsets.c
=================================--- linux-2.6.22.orig/arch/ia64/kernel/asm-offsets.c	2007-07-09 06:18:41.000000000 -0400
+++ linux-2.6.22/arch/ia64/kernel/asm-offsets.c	2007-07-09 06:21:23.000000000 -0400
@@ -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 +258,12 @@ 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_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_LASTCYCLE_OFFSET, offsetof (struct fsyscall_gtod_data_t, itc_lastcycle));
+	DEFINE(IA64_ITC_JITTER_OFFSET, offsetof (struct fsyscall_gtod_data_t, itc_jitter));
 }
Index: linux-2.6.22/arch/ia64/kernel/cyclone.c
=================================--- linux-2.6.22.orig/arch/ia64/kernel/cyclone.c	2007-07-09 06:17:14.000000000 -0400
+++ linux-2.6.22/arch/ia64/kernel/cyclone.c	2007-07-09 06:21:23.000000000 -0400
@@ -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;
 }
Index: linux-2.6.22/arch/ia64/kernel/fsys.S
=================================--- linux-2.6.22.orig/arch/ia64/kernel/fsys.S	2007-07-09 06:18:41.000000000 -0400
+++ linux-2.6.22/arch/ia64/kernel/fsys.S	2007-07-09 06:21:23.000000000 -0400
@@ -147,12 +147,8 @@ ENTRY(fsys_set_tid_address)
 	FSYS_RETURN
 END(fsys_set_tid_address)
 
-/*
- * Ensure that the time interpolator structure is compatible with the asm code
- */
-#if IA64_TIME_INTERPOLATOR_SOURCE_OFFSET !=0 || IA64_TIME_INTERPOLATOR_SHIFT_OFFSET != 2 \
-	|| IA64_TIME_INTERPOLATOR_JITTER_OFFSET != 3 || IA64_TIME_INTERPOLATOR_NSEC_OFFSET != 4
-#error fsys_gettimeofday incompatible with changes to struct time_interpolator
+#if IA64_GTOD_LOCK_OFFSET !=0
+#error fsys_gettimeofday incompatible with changes to struct fsyscall_gtod_data_t
 #endif
 #define CLOCK_REALTIME 0
 #define CLOCK_MONOTONIC 1
@@ -179,19 +175,18 @@ ENTRY(fsys_gettimeofday)
 	// r11 = preserved: saved ar.pfs
 	// r12 = preserved: memory stack
 	// r13 = preserved: thread pointer
-	// r14 = address of mask / mask
+	// r14 = address of mask / mask value
 	// r15 = preserved: system call number
 	// r16 = preserved: current task pointer
 	// r17 = wall to monotonic use
-	// r18 = time_interpolator->offset
-	// r19 = address of wall_to_monotonic
-	// r20 = pointer to struct time_interpolator / pointer to time_interpolator->address
-	// r21 = shift factor
-	// r22 = address of time interpolator->last_counter
-	// r23 = address of time_interpolator->last_cycle
-	// r24 = adress of time_interpolator->offset
-	// r25 = last_cycle value
-	// r26 = last_counter value
+	// r19 = address of itc_lastcycle
+	// r20 = struct fsyscall_gtod_data  / address of first element
+	// r21 = address of mmio_ptr
+	// r22 = address of  wall_to_monotonic
+	// r23 = address of shift/ value
+	// r24 = address mult factor / cycle_last value
+	// r25 = itc_lastcycle value
+	// r26 = address clocksource cycle_last
 	// r27 = pointer to xtime
 	// r28 = sequence number at the beginning of critcal section
 	// r29 = address of seqlock
@@ -201,10 +196,10 @@ ENTRY(fsys_gettimeofday)
 	// p6,p7 short term use
 	// p8 = timesource ar.itc
 	// p9 = timesource mmio64
-	// p10 = timesource mmio32
+	// p10 = timesource mmio32 - not used
 	// p11 = timesource not to be handled by asm code
-	// p12 = memory time source ( = p9 | p10)
-	// p13 = do cmpxchg with time_interpolator_last_cycle
+	// p12 = memory time source ( = p9 | p10) - not used
+	// p13 = do cmpxchg with itc_lastcycle
 	// p14 = Divide by 1000
 	// p15 = Add monotonic
 	//
@@ -214,61 +209,56 @@ ENTRY(fsys_gettimeofday)
 	tnat.nz p6,p0 = r31	// branch deferred since it does not fit into bundle structure
 	mov pr = r30,0xc000	// Set predicates according to function
 	add r2 = TI_FLAGS+IA64_TASK_SIZE,r16
-	movl r20 = time_interpolator
+	movl r20 = fsyscall_gtod_data // load fsyscall gettimeofday data address
 	;;
-	ld8 r20 = [r20]		// get pointer to time_interpolator structure
-	movl r29 = xtime_lock
-	ld4 r2 = [r2]		// process work pending flags
+	add r29 = IA64_ITC_JITTER_OFFSET,r20
 	movl r27 = xtime
-	;;	// only one bundle here
-	ld8 r21 = [r20]		// first quad with control information
+	ld4 r2 = [r2]		// process work pending flags
+(p15)	movl r22 = wall_to_monotonic
+	;;
+	add r21 = IA64_CLKSRC_MMIO_OFFSET,r20
+	add r19 = IA64_ITC_LASTCYCLE_OFFSET,r20
 	and r2 = TIF_ALLWORK_MASK,r2
 (p6)    br.cond.spnt.few .fail_einval	// deferred branch
 	;;
-	add r10 = IA64_TIME_INTERPOLATOR_ADDRESS_OFFSET,r20
-	extr r3 = r21,32,32	// time_interpolator->nsec_per_cyc
-	extr r8 = r21,0,16	// time_interpolator->source
+	add r26 = IA64_CLKSRC_CYCLE_LAST_OFFSET,r20 // clksrc_cycle_last
 	cmp.ne p6, p0 = 0, r2	// Fallback if work is scheduled
 (p6)    br.cond.spnt.many fsys_fallback_syscall
-	;;
-	cmp.eq p8,p12 = 0,r8	// Check for cpu timer
-	cmp.eq p9,p0 = 1,r8	// MMIO64 ?
-	extr r2 = r21,24,8	// time_interpolator->jitter
-	cmp.eq p10,p0 = 2,r8	// MMIO32 ?
-	cmp.ltu p11,p0 = 2,r8	// function or other clock
-(p11)	br.cond.spnt.many fsys_fallback_syscall
-	;;
-	setf.sig f7 = r3	// Setup for scaling of counter
-(p15)	movl r19 = wall_to_monotonic
-(p12)	ld8 r30 = [r10]
-	cmp.ne p13,p0 = r2,r0	// need jitter compensation?
-	extr r21 = r21,16,8	// shift factor
-	;;
+	;; // get lock.seq here new code, outer loop2!
 .time_redo:
-	.pred.rel.mutex p8,p9,p10
-	ld4.acq r28 = [r29]	// xtime_lock.sequence. Must come first for locking purposes
+	ld4.acq r28 = [r20]	// gtod_lock.sequence, Must be first in struct
+	ld8 r30 = [r21]		// clocksource->mmio_ptr
+	add r24 = IA64_CLKSRC_MULT_OFFSET,r20
+	ld4 r2 = [r29]		// itc_jitter value
+	add r23 = IA64_CLKSRC_SHIFT_OFFSET,r20
+	add r14 = IA64_CLKSRC_MASK_OFFSET,r20
+	;;
+	ld4 r3 = [r24]		// clocksource mult value
+	ld8 r14 = [r14]         // clocksource mask value
+	cmp.eq p8,p9 = 0,r30	// Check for cpu timer, no mmio_ptr, set p8, clear p9
+	;;
+	setf.sig f7 = r3	// Setup for mult scaling of counter
+(p8)	cmp.ne p13,p0 = r2,r0	// need itc_jitter compensation, set p13
+	ld4 r23 = [r23]		// clocksource shift value
+	ld8 r24 = [r26]		// get clksrc_cycle_last value
+(p9)	cmp.eq p13,p0 = 0,r30	// if mmio_ptr, clear p13 jitter control
+	;; // old position for lock seq, new inner loop1!
+.cmpxchg_redo:
+	.pred.rel.mutex p8,p9
 (p8)	mov r2 = ar.itc		// CPU_TIMER. 36 clocks latency!!!
-	add r22 = IA64_TIME_INTERPOLATOR_LAST_COUNTER_OFFSET,r20
 (p9)	ld8 r2 = [r30]		// readq(ti->address). Could also have latency issues..
-(p10)	ld4 r2 = [r30]		// readw(ti->address)
-(p13)	add r23 = IA64_TIME_INTERPOLATOR_LAST_CYCLE_OFFSET,r20
+(p13)	ld8 r25 = [r19]		// get itc_lastcycle value
 	;;			// could be removed by moving the last add upward
-	ld8 r26 = [r22]		// time_interpolator->last_counter
-(p13)	ld8 r25 = [r23]		// time interpolator->last_cycle
-	add r24 = IA64_TIME_INTERPOLATOR_OFFSET_OFFSET,r20
-(p15)	ld8 r17 = [r19],IA64_TIMESPEC_TV_NSEC_OFFSET
  	ld8 r9 = [r27],IA64_TIMESPEC_TV_NSEC_OFFSET
-	add r14 = IA64_TIME_INTERPOLATOR_MASK_OFFSET, r20
+(p15)	ld8 r17 = [r22],IA64_TIMESPEC_TV_NSEC_OFFSET
 	;;
-	ld8 r18 = [r24]		// time_interpolator->offset
 	ld8 r8 = [r27],-IA64_TIMESPEC_TV_NSEC_OFFSET	// xtime.tv_nsec
-(p13)	sub r3 = r25,r2	// Diff needed before comparison (thanks davidm)
+(p13)	sub r3 = r25,r2		// Diff needed before comparison (thanks davidm)
 	;;
-	ld8 r14 = [r14]		// time_interpolator->mask
-(p13)	cmp.gt.unc p6,p7 = r3,r0	// check if it is less than last. p6,p7 cleared
-	sub r10 = r2,r26	// current_counter - last_counter
+(p13)	cmp.gt.unc p6,p7 = r3,r0 // check if it is less than last. p6,p7 cleared
+	sub r10 = r2,r24	// current_counter - last_counter
 	;;
-(p6)	sub r10 = r25,r26	// time we got was less than last_cycle
+(p6)	sub r10 = r25,r24	// time we got was less than last_cycle
 (p7)	mov ar.ccv = r25	// more than last_cycle. Prep for cmpxchg
 	;;
 	and r10 = r10,r14	// Apply mask
@@ -276,27 +266,28 @@ ENTRY(fsys_gettimeofday)
 	setf.sig f8 = r10
 	nop.i 123
 	;;
-(p7)	cmpxchg8.rel r3 = [r23],r2,ar.ccv
+(p7)	cmpxchg8.rel r3 = [r19],r2,ar.ccv
 EX(.fail_efault, probe.w.fault r31, 3)	// This takes 5 cycles and we have spare time
 	xmpy.l f8 = f8,f7	// nsec_per_cyc*(counter-last_counter)
 (p15)	add r9 = r9,r17		// Add wall to monotonic.secs to result secs
 	;;
-(p15)	ld8 r17 = [r19],-IA64_TIMESPEC_TV_NSEC_OFFSET
+	// End cmpxchg critical section loop1
+(p15)	ld8 r17 = [r22],-IA64_TIMESPEC_TV_NSEC_OFFSET
 (p7)	cmp.ne p7,p0 = r25,r3	// if cmpxchg not successful redo
+(p7)	br.cond.dpnt.few .cmpxchg_redo	// inner loop1
 	// simulate tbit.nz.or p7,p0 = r28,0
 	and r28 = ~1,r28	// Make sequence even to force retry if odd
 	getf.sig r2 = f8
 	mf
-	add r8 = r8,r18		// Add time interpolator offset
 	;;
-	ld4 r10 = [r29]		// xtime_lock.sequence
+	ld4 r10 = [r20]		// gtod_lock.sequence, old xtime_lock.sequence
 (p15)	add r8 = r8, r17	// Add monotonic.nsecs to nsecs
-	shr.u r2 = r2,r21
+	shr.u r2 = r2,r23	// shift by factor
 	;;		// overloaded 3 bundles!
 	// End critical section.
 	add r8 = r8,r2		// Add xtime.nsecs
 	cmp4.ne.or p7,p0 = r28,r10
-(p7)	br.cond.dpnt.few .time_redo	// sequence number changed ?
+(p7)	br.cond.dpnt.few .time_redo	// sequence number changed, outer loop2
 	// Now r8=tv->tv_nsec and r9=tv->tv_sec
 	mov r10 = r0
 	movl r2 = 1000000000
Index: linux-2.6.22/arch/ia64/kernel/time.c
=================================--- linux-2.6.22.orig/arch/ia64/kernel/time.c	2007-07-09 06:19:09.000000000 -0400
+++ linux-2.6.22/arch/ia64/kernel/time.c	2007-07-09 06:21:23.000000000 -0400
@@ -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 +29,14 @@
 #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,
+};
+
 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
 
 #ifdef CONFIG_IA64_DEBUG_IRQ
@@ -37,11 +46,16 @@ 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 +224,6 @@ 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 +235,55 @@ 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)
+			fsyscall_gtod_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;
+	u64 now;
+
+	if (!fsyscall_gtod_data.itc_jitter)
+		return get_cycles();
+	do {
+		lcycle = fsyscall_gtod_data.itc_lastcycle;
+		now = get_cycles();
+		if (lcycle && time_after(lcycle, now))
+			return lcycle;
+
+		/* When holding the xtime write lock, there's no need
+		 * to add the overhead of the cmpxchg.  Readers are
+		 * force to retry until the write lock is released.
+		 */
+		if (spin_is_locked(&xtime_lock.lock)) {
+			fsyscall_gtod_data.itc_lastcycle = now;
+			return now;
+		}
+		/* Keep track of the last timer value returned.
+		 * The use of cmpxchg here will cause contention in
+		 * an SMP environment.
+		 */
+	} while (likely(cmpxchg(&fsyscall_gtod_data.itc_lastcycle,
+				lcycle, now) != lcycle));
+	return now;
+}
+
+
 static struct irqaction timer_irqaction = {
 	.handler =	timer_interrupt,
 	.flags =	IRQF_DISABLED | IRQF_IRQPOLL,
@@ -307,3 +359,20 @@ 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;
+
+        write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags);
+}
+
Index: linux-2.6.22/arch/ia64/sn/kernel/sn2/timer.c
=================================--- linux-2.6.22.orig/arch/ia64/sn/kernel/sn2/timer.c	2007-07-09 06:17:14.000000000 -0400
+++ linux-2.6.22/arch/ia64/sn/kernel/sn2/timer.c	2007-07-09 06:21:23.000000000 -0400
@@ -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;
 }
Index: linux-2.6.22/drivers/acpi/processor_idle.c
=================================--- linux-2.6.22.orig/drivers/acpi/processor_idle.c	2007-07-09 06:19:10.000000000 -0400
+++ linux-2.6.22/drivers/acpi/processor_idle.c	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/drivers/char/hpet.c
=================================--- linux-2.6.22.orig/drivers/char/hpet.c	2007-07-09 06:18:42.000000000 -0400
+++ linux-2.6.22/drivers/char/hpet.c	2007-07-09 06:21:23.000000000 -0400
@@ -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_dev
 
 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;
 }
 
Index: linux-2.6.22/include/linux/clocksource.h
=================================--- linux-2.6.22.orig/include/linux/clocksource.h	2007-07-09 06:19:12.000000000 -0400
+++ linux-2.6.22/include/linux/clocksource.h	2007-07-09 06:21:23.000000000 -0400
@@ -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)      (0)
+#endif
 
 	/* timekeeping specific data, ignore */
 	cycle_t cycle_interval;
Index: linux-2.6.22/arch/ia64/configs/tiger_defconfig
=================================--- linux-2.6.22.orig/arch/ia64/configs/tiger_defconfig	2007-07-09 06:18:41.000000000 -0400
+++ linux-2.6.22/arch/ia64/configs/tiger_defconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/arch/ia64/configs/zx1_defconfig
=================================--- linux-2.6.22.orig/arch/ia64/configs/zx1_defconfig	2007-07-09 06:18:41.000000000 -0400
+++ linux-2.6.22/arch/ia64/configs/zx1_defconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/arch/ia64/defconfig
=================================--- linux-2.6.22.orig/arch/ia64/defconfig	2007-07-09 06:19:09.000000000 -0400
+++ linux-2.6.22/arch/ia64/defconfig	2007-07-09 06:21:23.000000000 -0400
@@ -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
Index: linux-2.6.22/arch/ia64/kernel/fsyscall_gtod_data.h
=================================--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.22/arch/ia64/kernel/fsyscall_gtod_data.h	2007-07-09 06:21:23.000000000 -0400
@@ -0,0 +1,18 @@
+/*
+ * (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;
+	cycle_t		clk_mask;
+	u32		clk_mult;
+	u32		clk_shift;
+	void		*clk_fsys_mmio;
+	cycle_t		clk_cycle_last;
+	cycle_t		itc_lastcycle;
+	int		itc_jitter;
+} __attribute__ ((aligned (L1_CACHE_BYTES)));
+
Index: linux-2.6.22/Documentation/kernel-parameters.txt
=================================--- linux-2.6.22.orig/Documentation/kernel-parameters.txt	2007-07-09 06:19:09.000000000 -0400
+++ linux-2.6.22/Documentation/kernel-parameters.txt	2007-07-09 06:21:23.000000000 -0400
@@ -1193,6 +1193,8 @@ and is between 256 and 4096 characters. 
 
 	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.