Commit e92716f2 authored by Jerone Young's avatar Jerone Young Committed by Josh Boyer
Browse files

[POWERPC] 4xx: Add idle wait support for 44x platforms 



This changes the cpu_idle loop for 44x platforms to utilize the Wait Enable
feature of the CPU.  This helps virtulization solutions know when the guest
Linux kernel is in an idle state.

A command line option called "idle" is also added to allow people to change
the idle loop back to the original variation.  This is done by setting
"idle=spin" on the kernel command line.

Signed-off-by: default avatarJerone Young <jyoung5@us.ibm.com>
Signed-off-by: default avatarJosh Boyer <jwboyer@linux.vnet.ibm.com>
parent 478d5dcb

arch/powerpc/platforms/44x/Makefile

+1 −1
Original line number Diff line number Diff line 
obj-$(CONFIG_44x)	:= misc_44x.o

obj-$(CONFIG_44x)	:= misc_44x.o idle.o

obj-$(CONFIG_EBONY)	+= ebony.o

obj-$(CONFIG_TAISHAN)	+= taishan.o

obj-$(CONFIG_BAMBOO)	+= bamboo.o

arch/powerpc/platforms/44x/idle.c

0 → 100644
+67 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2008 IBM Corp. 

 *

 * Based on arch/powerpc/platforms/pasemi/idle.c: 

 * Copyright (C) 2006-2007 PA Semi, Inc

 *

 * Added by: Jerone Young <jyoung5@us.ibm.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA

 *

 */



#include <linux/of.h>

#include <linux/kernel.h>

#include <asm/machdep.h>



static int mode_spin;



static void ppc44x_idle(void)

{

	unsigned long msr_save;



	msr_save = mfmsr();

	/* set wait state MSR */

	mtmsr(msr_save|MSR_WE|MSR_EE|MSR_CE|MSR_DE);

	isync();

	/* return to initial state */

	mtmsr(msr_save);

	isync();

}



int __init ppc44x_idle_init(void)

{

	if (!mode_spin) {

		/* If we are not setting spin mode 

                   then we set to wait mode */

		ppc_md.power_save = &ppc44x_idle;

	}



	return 0;

}



arch_initcall(ppc44x_idle_init);



static int __init idle_param(char *p)

{ 



	if (!strcmp("spin", p)) {

		mode_spin = 1;

		ppc_md.power_save = NULL;

	}



	return 0;

}



early_param("idle", idle_param);