1 files changed, 81 insertions, 0 deletions
diff --git a/arch/ppc64/kernel/iSeries_setup.c b/arch/ppc64/kernel/iSeries_setup.c
index b3f770f6d402..1139e27e1713 100644
--- a/arch/ppc64/kernel/iSeries_setup.c
+++ b/arch/ppc64/kernel/iSeries_setup.c
@@ -834,6 +834,87 @@ static int __init iSeries_src_init(void)
 
 late_initcall(iSeries_src_init);
 
+static unsigned long maxYieldTime = 0;
+static unsigned long minYieldTime = 0xffffffffffffffffUL;
+
+static inline void process_iSeries_events(void)
+{
+	asm volatile ("li 0,0x5555; sc" : : : "r0", "r3");
+}
+
+static void yield_shared_processor(void)
+{
+	unsigned long tb;
+	unsigned long yieldTime;
+
+	HvCall_setEnabledInterrupts(HvCall_MaskIPI |
+				    HvCall_MaskLpEvent |
+				    HvCall_MaskLpProd |
+				    HvCall_MaskTimeout);
+
+	tb = get_tb();
+	/* Compute future tb value when yield should expire */
+	HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy);
+
+	yieldTime = get_tb() - tb;
+	if (yieldTime > maxYieldTime)
+		maxYieldTime = yieldTime;
+
+	if (yieldTime < minYieldTime)
+		minYieldTime = yieldTime;
+
+	/*
+	 * The decrementer stops during the yield.  Force a fake decrementer
+	 * here and let the timer_interrupt code sort out the actual time.
+	 */
+	get_paca()->lppaca.int_dword.fields.decr_int = 1;
+	process_iSeries_events();
+}
+
+static int iSeries_idle(void)
+{
+	struct paca_struct *lpaca;
+	long oldval;
+
+	/* ensure iSeries run light will be out when idle */
+	ppc64_runlatch_off();
+
+	lpaca = get_paca();
+
+	while (1) {
+		if (lpaca->lppaca.shared_proc) {
+			if (hvlpevent_is_pending())
+				process_iSeries_events();
+			if (!need_resched())
+				yield_shared_processor();
+		} else {
+			oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+
+			if (!oldval) {
+				set_thread_flag(TIF_POLLING_NRFLAG);
+
+				while (!need_resched()) {
+					HMT_medium();
+					if (hvlpevent_is_pending())
+						process_iSeries_events();
+					HMT_low();
+				}
+
+				HMT_medium();
+				clear_thread_flag(TIF_POLLING_NRFLAG);
+			} else {
+				set_need_resched();
+			}
+		}
+
+		ppc64_runlatch_on();
+		schedule();
+		ppc64_runlatch_off();
+	}
+
+	return 0;
+}
+
 #ifndef CONFIG_PCI
 void __init iSeries_init_IRQ(void) { }
 #endif