mirror of
https://github.com/torvalds/linux.git
synced 2024-12-21 18:42:44 +00:00
e92716f2aa
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: Jerone Young <jyoung5@us.ibm.com> Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
/*
|
|
* 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);
|