ppc64: rework idle loop, separate iSeries and pSeries

arch/ppc64/kernel/idle.c

 /*
- * Idle daemon for PowerPC.  Idle daemon will handle any action
- * that needs to be taken when the system becomes idle.
- *
- * Written by Cort Dougan (cort@cs.nmt.edu)
+ * idle.c
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */
+
 #include <linux/config.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
@@ -28,8 +26,10 @@
 #include <asm/processor.h>
 #include <asm/mmu.h>
 #include <asm/cache.h>
-
 #include <asm/time.h>
+
+#ifdef CONFIG_PPC_ISERIES
+
 #include <asm/iSeries/LparData.h>
 #include <asm/iSeries/HvCall.h>
 #include <asm/iSeries/ItLpQueue.h>
@@ -37,99 +37,109 @@
 unsigned long maxYieldTime = 0;
 unsigned long minYieldTime = 0xffffffffffffffffUL;
 
-#ifdef CONFIG_PPC_ISERIES
 static void yield_shared_processor(void)
 {
-	struct Paca *paca;
 	unsigned long tb;
 	unsigned long yieldTime;
 
-	paca = (struct Paca *)mfspr(SPRG3);
-	HvCall_setEnabledInterrupts( HvCall_MaskIPI |
+	HvCall_setEnabledInterrupts(HvCall_MaskIPI |
 				    HvCall_MaskLpEvent |
 				    HvCall_MaskLpProd |
-				     HvCall_MaskTimeout );
+				    HvCall_MaskTimeout);
 
 	tb = get_tb();
 	/* Compute future tb value when yield should expire */
-	HvCall_yieldProcessor( HvCall_YieldTimed, tb+tb_ticks_per_jiffy );
+	HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy);
 
 	yieldTime = get_tb() - tb;
-	if ( yieldTime > maxYieldTime )
+	if (yieldTime > maxYieldTime)
 		maxYieldTime = yieldTime;
 
-	if ( yieldTime < minYieldTime )
+	if (yieldTime < minYieldTime)
 		minYieldTime = yieldTime;
 	
-	/* The decrementer stops during the yield.  Force a fake decrementer
+	/*
+	 * The decrementer stops during the yield.  Force a fake decrementer
 	 * here and let the timer_interrupt code sort out the actual time.
 	 */
-	paca->xLpPaca.xIntDword.xFields.xDecrInt = 1;
+	get_paca()->xLpPaca.xIntDword.xFields.xDecrInt = 1;
 	process_iSeries_events();
 }
-#endif /* CONFIG_PPC_ISERIES */
 
-int idled(void)
+int cpu_idle(void)
 {
 	struct Paca *paca;
 	long oldval;
-#ifdef CONFIG_PPC_ISERIES
 	unsigned long CTRL;
-#endif
 
-	/* endless loop with no priority at all */
-#ifdef CONFIG_PPC_ISERIES
 	/* ensure iSeries run light will be out when idle */
 	current->thread.flags &= ~PPC_FLAG_RUN_LIGHT;
 	CTRL = mfspr(CTRLF);
 	CTRL &= ~RUNLATCH;
 	mtspr(CTRLT, CTRL);
-#endif
 
-	paca = (struct Paca *)mfspr(SPRG3);
+	paca = get_paca();
 
-	while(1) {
-		if (need_resched())
-			schedule();
-	}
-
-	for (;;) {
-#ifdef CONFIG_PPC_ISERIES
-		if ( paca->xLpPaca.xSharedProc ) {
-			if ( ItLpQueue_isLpIntPending( paca->lpQueuePtr ) )
+	while (1) {
+		if (paca->xLpPaca.xSharedProc) {
+			if (ItLpQueue_isLpIntPending(paca->lpQueuePtr))
 				process_iSeries_events();
 			if (!need_resched())
 				yield_shared_processor();
-		}
-		else 
-#endif
-		{
-			if (!need_resched()) {
+		} else {
+			oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+
+			if (!oldval) {
 				set_thread_flag(TIF_POLLING_NRFLAG);
-				while (!test_thread_flag(TIF_NEED_RESCHED)) {
-#ifdef CONFIG_PPC_ISERIES
+
+				while (!need_resched()) {
 					HMT_medium();
 					if (ItLpQueue_isLpIntPending(paca->lpQueuePtr))
 						process_iSeries_events();
-#endif
 					HMT_low();
 				}
+
+				HMT_medium();
 				clear_thread_flag(TIF_POLLING_NRFLAG);
+			} else {
+				set_need_resched();
 			}
 		}
-		HMT_medium();
+
 		if (need_resched())
 			schedule();
 	}
+
 	return 0;
 }
 
-/*
- * SMP entry into the idle task - calls the same thing as the
- * non-smp versions. -- Cort
- */
+#else /* CONFIG_PPC_ISERIES */
+
 int cpu_idle(void)
 {
-	idled();
+	long oldval;
+
+	while (1) {
+		oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
+
+		if (!oldval) {
+			set_thread_flag(TIF_POLLING_NRFLAG);
+
+			while (!need_resched()) {
+				barrier();
+				HMT_low();
+			}
+
+			HMT_medium();
+			clear_thread_flag(TIF_POLLING_NRFLAG);
+		} else {
+			set_need_resched();
+		}
+
+		schedule();
+	}
+
 	return 0;
 }
+
+#endif /* CONFIG_PPC_ISERIES */