From e92716f2aa68cdfbf6ec24d6f31f08b072e1a246 Mon Sep 17 00:00:00 2001 From: Jerone Young Date: Sat, 12 Apr 2008 05:03:33 +1000 Subject: [PATCH] [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: Jerone Young Signed-off-by: Josh Boyer --- arch/powerpc/platforms/44x/Makefile | 2 +- arch/powerpc/platforms/44x/idle.c | 67 +++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+), 1 deletion(-) create mode 100644 arch/powerpc/platforms/44x/idle.c diff --git a/arch/powerpc/platforms/44x/Makefile b/arch/powerpc/platforms/44x/Makefile index 2320ae5dc8a7..774165f9acdd 100644 --- a/arch/powerpc/platforms/44x/Makefile +++ b/arch/powerpc/platforms/44x/Makefile @@ -1,4 +1,4 @@ -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 diff --git a/arch/powerpc/platforms/44x/idle.c b/arch/powerpc/platforms/44x/idle.c new file mode 100644 index 000000000000..7a81f921fef9 --- /dev/null +++ b/arch/powerpc/platforms/44x/idle.c @@ -0,0 +1,67 @@ +/* + * Copyright 2008 IBM Corp. + * + * Based on arch/powerpc/platforms/pasemi/idle.c: + * Copyright (C) 2006-2007 PA Semi, Inc + * + * Added by: Jerone Young + * + * 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 +#include +#include + +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);