From a0652fc9a28c3ef8cd59264bfcb089c44d1b0e06 Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@samba.org>
Date: Mon, 27 Mar 2006 15:03:03 +1100
Subject: powerpc: Unify the 32 and 64 bit idle loops

This unifies the 32-bit (ARCH=ppc and ARCH=powerpc) and 64-bit idle
loops.  It brings over the concept of having a ppc_md.power_save
function from 32-bit to ARCH=powerpc, which lets us get rid of
native_idle().  With this we will also be able to simplify the idle
handling for pSeries and cell.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kernel/idle.c | 122 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 arch/powerpc/kernel/idle.c

(limited to 'arch/powerpc/kernel/idle.c')

diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
new file mode 100644
index 000000000000..e9f321d74d85
--- /dev/null
+++ b/arch/powerpc/kernel/idle.c
@@ -0,0 +1,122 @@
+/*
+ * Idle daemon for PowerPC.  Idle daemon will handle any action
+ * that needs to be taken when the system becomes idle.
+ *
+ * Originally written by Cort Dougan (cort@cs.nmt.edu).
+ * Subsequent 32-bit hacking by Tom Rini, Armin Kuster,
+ * Paul Mackerras and others.
+ *
+ * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
+ *
+ * Additional shared processor, SMT, and firmware support
+ *    Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
+ *
+ * 32-bit and 64-bit versions merged by Paul Mackerras <paulus@samba.org>
+ *
+ * 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/sched.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/cpu.h>
+#include <linux/sysctl.h>
+
+#include <asm/system.h>
+#include <asm/processor.h>
+#include <asm/cputable.h>
+#include <asm/time.h>
+#include <asm/machdep.h>
+#include <asm/smp.h>
+
+#ifdef CONFIG_HOTPLUG_CPU
+#define cpu_should_die()	(cpu_is_offline(smp_processor_id()) && \
+				 system_state == SYSTEM_RUNNING)
+#else
+#define cpu_should_die()	0
+#endif
+
+/*
+ * The body of the idle task.
+ */
+void cpu_idle(void)
+{
+	if (ppc_md.idle_loop)
+		ppc_md.idle_loop();	/* doesn't return */
+
+	set_thread_flag(TIF_POLLING_NRFLAG);
+	while (1) {
+		ppc64_runlatch_off();
+
+		while (!need_resched() && !cpu_should_die()) {
+			if (ppc_md.power_save) {
+				clear_thread_flag(TIF_POLLING_NRFLAG);
+				/*
+				 * smp_mb is so clearing of TIF_POLLING_NRFLAG
+				 * is ordered w.r.t. need_resched() test.
+				 */
+				smp_mb();
+				local_irq_disable();
+
+				/* check again after disabling irqs */
+				if (!need_resched() && !cpu_should_die())
+					ppc_md.power_save();
+
+				local_irq_enable();
+				set_thread_flag(TIF_POLLING_NRFLAG);
+
+			} else {
+				/*
+				 * Go into low thread priority and possibly
+				 * low power mode.
+				 */
+				HMT_low();
+				HMT_very_low();
+			}
+		}
+
+		HMT_medium();
+		ppc64_runlatch_on();
+		if (cpu_should_die())
+			cpu_die();
+		preempt_enable_no_resched();
+		schedule();
+		preempt_disable();
+	}
+}
+
+int powersave_nap;
+
+#ifdef CONFIG_SYSCTL
+/*
+ * Register the sysctl to set/clear powersave_nap.
+ */
+static ctl_table powersave_nap_ctl_table[]={
+	{
+		.ctl_name	= KERN_PPC_POWERSAVE_NAP,
+		.procname	= "powersave-nap",
+		.data		= &powersave_nap,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
+	{ 0, },
+};
+static ctl_table powersave_nap_sysctl_root[] = {
+	{ 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
+ 	{ 0,},
+};
+
+static int __init
+register_powersave_nap_sysctl(void)
+{
+	register_sysctl_table(powersave_nap_sysctl_root, 0);
+
+	return 0;
+}
+__initcall(register_powersave_nap_sysctl);
+#endif
-- 
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