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