linux/arch/powerpc/kernel/idle_power4.S
Johannes Berg d9333afd6a [POWERPC] powermac: Support G5 CPU hotplug
This allows "hotplugging" of CPUs on G5 machines.  CPUs that are
disabled are put into an idle loop with the decrementer frequency set
to minimum.  To wake them up again we kick them just like when bringing
them up.  To stop those CPUs from messing with any global state we stop
them from entering the timer interrupt.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-05-07 20:31:13 +10:00

76 lines
1.7 KiB
ArmAsm

/*
* This file contains the power_save function for 970-family CPUs.
*
* 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/threads.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#undef DEBUG
.text
_GLOBAL(power4_idle)
BEGIN_FTR_SECTION
blr
END_FTR_SECTION_IFCLR(CPU_FTR_CAN_NAP)
/* Now check if user or arch enabled NAP mode */
LOAD_REG_ADDRBASE(r3,powersave_nap)
lwz r4,ADDROFF(powersave_nap)(r3)
cmpwi 0,r4,0
beqlr
/* Go to NAP now */
mfmsr r7
rldicl r0,r7,48,1
rotldi r0,r0,16
mtmsrd r0,1 /* hard-disable interrupts */
li r0,1
stb r0,PACASOFTIRQEN(r13) /* we'll hard-enable shortly */
stb r0,PACAHARDIRQEN(r13)
BEGIN_FTR_SECTION
DSSALL
sync
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
clrrdi r9,r1,THREAD_SHIFT /* current thread_info */
ld r8,TI_LOCAL_FLAGS(r9) /* set napping bit */
ori r8,r8,_TLF_NAPPING /* so when we take an exception */
std r8,TI_LOCAL_FLAGS(r9) /* it will return to our caller */
ori r7,r7,MSR_EE
oris r7,r7,MSR_POW@h
1: sync
isync
mtmsrd r7
isync
b 1b
_GLOBAL(power4_cpu_offline_powersave)
/* Go to NAP now */
mfmsr r7
rldicl r0,r7,48,1
rotldi r0,r0,16
mtmsrd r0,1 /* hard-disable interrupts */
li r0,1
li r6,0
stb r0,PACAHARDIRQEN(r13) /* we'll hard-enable shortly */
stb r6,PACASOFTIRQEN(r13) /* soft-disable irqs */
BEGIN_FTR_SECTION
DSSALL
sync
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
ori r7,r7,MSR_EE
oris r7,r7,MSR_POW@h
sync
isync
mtmsrd r7
isync
blr