Index: linux-2.6/drivers/acpi/processor_idle.c
===================================================================
--- linux-2.6.orig/drivers/acpi/processor_idle.c
+++ linux-2.6/drivers/acpi/processor_idle.c
@@ -397,8 +397,8 @@ static void acpi_processor_idle(void)
 	struct acpi_processor_cx *cx = NULL;
 	struct acpi_processor_cx *next_state = NULL;
 	int sleep_ticks = 0;
-	u32 t1, t2 = 0;
-
+	ktime_t kt1, kt2;
+	u64 sleep_interval;
 	/*
 	 * Interrupts must be disabled during bus mastering calculations and
 	 * for C2/C3 transitions.
@@ -543,23 +543,26 @@ static void acpi_processor_idle(void)
 		break;
 
 	case ACPI_STATE_C2:
-		/* Get start time (ticks) */
-		t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+		kt1 = ktime_get();
 		/* Tell the scheduler that we are going deep-idle: */
 		sched_clock_idle_sleep_event();
 		/* Invoke C2 */
 		acpi_state_timer_broadcast(pr, cx, 1);
 		acpi_cstate_enter(cx);
 		/* Get end time (ticks) */
-		t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-
+		kt2 = ktime_get();
 #if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
 		/* TSC halts in C2, so notify users */
 		if (tsc_halts_in_c(ACPI_STATE_C2))
 			mark_tsc_unstable("possible TSC halt in C2");
 #endif
+		/*
+		 * Use the function of ktime_sub to get the time interval and
+		 * then convert it to microsecond
+		 */
+		sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
 		/* Compute time (ticks) that we were actually asleep */
-		sleep_ticks = ticks_elapsed(t1, t2);
+		sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
 
 		/* Tell the scheduler how much we idled: */
 		sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -605,13 +608,13 @@ static void acpi_processor_idle(void)
 		}
 
 		/* Get start time (ticks) */
-		t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+		kt1 = ktime_get();
 		/* Invoke C3 */
 		/* Tell the scheduler that we are going deep-idle: */
 		sched_clock_idle_sleep_event();
 		acpi_cstate_enter(cx);
 		/* Get end time (ticks) */
-		t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+		kt2 = ktime_get();
 		if (pr->flags.bm_check && pr->flags.bm_control) {
 			/* Enable bus master arbitration */
 			atomic_dec(&c3_cpu_count);
@@ -623,8 +626,13 @@ static void acpi_processor_idle(void)
 		if (tsc_halts_in_c(ACPI_STATE_C3))
 			mark_tsc_unstable("TSC halts in C3");
 #endif
+		/*
+		 * Use the function of ktime_sub to get the time interval
+		 * and convert it to microsecond.
+		 */
+		sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
 		/* Compute time (ticks) that we were actually asleep */
-		sleep_ticks = ticks_elapsed(t1, t2);
+		sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
 		/* Tell the scheduler how much we idled: */
 		sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
 
@@ -1455,7 +1463,8 @@ static inline void acpi_idle_do_entry(st
 static int acpi_idle_enter_c1(struct cpuidle_device *dev,
 			      struct cpuidle_state *state)
 {
-	u32 t1, t2;
+	ktime_t kt1, kt2;
+	u64 sleep_interval;
 	struct acpi_processor *pr;
 	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
 
@@ -1476,14 +1485,18 @@ static int acpi_idle_enter_c1(struct cpu
 	if (pr->flags.bm_check)
 		acpi_idle_update_bm_rld(pr, cx);
 
-	t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+	kt1 = ktime_get();
 	acpi_idle_do_entry(cx);
-	t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+	kt2 = ktime_get();
 
 	local_irq_enable();
 	cx->usage++;
-
-	return ticks_elapsed_in_us(t1, t2);
+	/*
+	 * Use the ktime_sub to get the time interval and then convert
+	 * it to microseconds
+	 */
+	sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
+	return sleep_interval;
 }
 
 /**
@@ -1496,7 +1509,8 @@ static int acpi_idle_enter_simple(struct
 {
 	struct acpi_processor *pr;
 	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
-	u32 t1, t2;
+	ktime_t kt1, kt2;
+	u64 sleep_interval;
 	int sleep_ticks = 0;
 
 	pr = __get_cpu_var(processors);
@@ -1533,18 +1547,19 @@ static int acpi_idle_enter_simple(struct
 	if (cx->type == ACPI_STATE_C3)
 		ACPI_FLUSH_CPU_CACHE();
 
-	t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+	kt1 = ktime_get();
 	/* Tell the scheduler that we are going deep-idle: */
 	sched_clock_idle_sleep_event();
 	acpi_idle_do_entry(cx);
-	t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+	kt2 = ktime_get();
 
 #if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
 	/* TSC could halt in idle, so notify users */
 	if (tsc_halts_in_c(cx->type))
 		mark_tsc_unstable("TSC halts in idle");;
 #endif
-	sleep_ticks = ticks_elapsed(t1, t2);
+	sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
+	sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
 
 	/* Tell the scheduler how much we idled: */
 	sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -1556,7 +1571,7 @@ static int acpi_idle_enter_simple(struct
 
 	acpi_state_timer_broadcast(pr, cx, 0);
 	cx->time += sleep_ticks;
-	return ticks_elapsed_in_us(t1, t2);
+	return sleep_interval;
 }
 
 static int c3_cpu_count;
@@ -1574,7 +1589,8 @@ static int acpi_idle_enter_bm(struct cpu
 {
 	struct acpi_processor *pr;
 	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
-	u32 t1, t2;
+	ktime_t  kt1, kt2;
+	u64 sleep_interval;
 	int sleep_ticks = 0;
 
 	pr = __get_cpu_var(processors);
@@ -1643,10 +1659,9 @@ static int acpi_idle_enter_bm(struct cpu
 	} else if (!pr->flags.bm_check) {
 		ACPI_FLUSH_CPU_CACHE();
 	}
-
-	t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+	kt1 = ktime_get();
 	acpi_idle_do_entry(cx);
-	t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+	kt2 = ktime_get();
 
 	/* Re-enable bus master arbitration */
 	if (pr->flags.bm_check && pr->flags.bm_control) {
@@ -1661,7 +1676,8 @@ static int acpi_idle_enter_bm(struct cpu
 	if (tsc_halts_in_c(ACPI_STATE_C3))
 		mark_tsc_unstable("TSC halts in idle");
 #endif
-	sleep_ticks = ticks_elapsed(t1, t2);
+	sleep_interval = ktime_to_us(ktime_sub(kt2, kt1));
+	sleep_ticks = US_TO_PM_TIMER_TICKS(sleep_interval);
 	/* Tell the scheduler how much we idled: */
 	sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
 
@@ -1672,7 +1688,7 @@ static int acpi_idle_enter_bm(struct cpu
 
 	acpi_state_timer_broadcast(pr, cx, 0);
 	cx->time += sleep_ticks;
-	return ticks_elapsed_in_us(t1, t2);
+	return sleep_interval;
 }
 
 struct cpuidle_driver acpi_idle_driver = {
