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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
/*
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* Copyright 2008 IBM Corp.
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*
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* Based on arch/powerpc/platforms/pasemi/idle.c:
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* Copyright (C) 2006-2007 PA Semi, Inc
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*
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* Added by: Jerone Young <jyoung5@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/of.h>
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#include <linux/kernel.h>
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#include <asm/machdep.h>
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static int mode_spin;
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static void ppc44x_idle(void)
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{
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unsigned long msr_save;
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msr_save = mfmsr();
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/* set wait state MSR */
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mtmsr(msr_save|MSR_WE|MSR_EE|MSR_CE|MSR_DE);
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isync();
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/* return to initial state */
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mtmsr(msr_save);
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isync();
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}
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int __init ppc44x_idle_init(void)
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{
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if (!mode_spin) {
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/* If we are not setting spin mode
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then we set to wait mode */
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ppc_md.power_save = &ppc44x_idle;
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}
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return 0;
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}
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arch_initcall(ppc44x_idle_init);
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static int __init idle_param(char *p)
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{
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if (!strcmp("spin", p)) {
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mode_spin = 1;
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ppc_md.power_save = NULL;
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}
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return 0;
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}
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early_param("idle", idle_param);
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