f39224a8c1
We weren't using the recommended sequence for putting the CPU into nap mode. When I changed the idle loop, for some reason 7447A cpus started hanging when we put them into nap mode. Changing to the recommended sequence fixes that. The complexity here is that the recommended sequence is a loop that keeps putting the cpu back into nap mode. Clearly we need some way to break out of the loop when an interrupt (external interrupt, decrementer, performance monitor) occurs. Here we use a bit in the thread_info struct to indicate that we need this, and the exception entry code notices this and arranges for the exception to return to the value in the link register, thus breaking out of the loop. We use a new `local_flags' field in the thread_info which we can alter without needing to use an atomic update sequence. The PPC970 has the same recommended sequence, so we do the same thing there too. This also fixes a bug in the kernel stack overflow handling code on 32-bit, since it was causing a value that we needed in a register to get trashed. Signed-off-by: Paul Mackerras <paulus@samba.org>
198 lines
5 KiB
ArmAsm
198 lines
5 KiB
ArmAsm
/*
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* This file contains the power_save function for 6xx & 7xxx CPUs
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* rewritten in assembler
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*
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* Warning ! This code assumes that if your machine has a 750fx
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* it will have PLL 1 set to low speed mode (used during NAP/DOZE).
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* if this is not the case some additional changes will have to
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* be done to check a runtime var (a bit like powersave-nap)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.h>
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#include <linux/threads.h>
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#include <asm/reg.h>
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#include <asm/page.h>
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#include <asm/cputable.h>
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#include <asm/thread_info.h>
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#include <asm/ppc_asm.h>
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#include <asm/asm-offsets.h>
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.text
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/*
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* Init idle, called at early CPU setup time from head.S for each CPU
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* Make sure no rest of NAP mode remains in HID0, save default
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* values for some CPU specific registers. Called with r24
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* containing CPU number and r3 reloc offset
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*/
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_GLOBAL(init_idle_6xx)
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BEGIN_FTR_SECTION
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mfspr r4,SPRN_HID0
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rlwinm r4,r4,0,10,8 /* Clear NAP */
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mtspr SPRN_HID0, r4
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b 1f
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END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP)
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blr
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1:
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slwi r5,r24,2
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add r5,r5,r3
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BEGIN_FTR_SECTION
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mfspr r4,SPRN_MSSCR0
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addis r6,r5, nap_save_msscr0@ha
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stw r4,nap_save_msscr0@l(r6)
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END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR)
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BEGIN_FTR_SECTION
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mfspr r4,SPRN_HID1
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addis r6,r5,nap_save_hid1@ha
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stw r4,nap_save_hid1@l(r6)
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END_FTR_SECTION_IFSET(CPU_FTR_DUAL_PLL_750FX)
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blr
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/*
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* Here is the power_save_6xx function. This could eventually be
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* split into several functions & changing the function pointer
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* depending on the various features.
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*/
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_GLOBAL(ppc6xx_idle)
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/* Check if we can nap or doze, put HID0 mask in r3
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*/
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lis r3, 0
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BEGIN_FTR_SECTION
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lis r3,HID0_DOZE@h
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END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
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BEGIN_FTR_SECTION
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/* We must dynamically check for the NAP feature as it
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* can be cleared by CPU init after the fixups are done
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*/
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lis r4,cur_cpu_spec@ha
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lwz r4,cur_cpu_spec@l(r4)
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lwz r4,CPU_SPEC_FEATURES(r4)
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andi. r0,r4,CPU_FTR_CAN_NAP
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beq 1f
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/* Now check if user or arch enabled NAP mode */
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lis r4,powersave_nap@ha
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lwz r4,powersave_nap@l(r4)
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cmpwi 0,r4,0
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beq 1f
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lis r3,HID0_NAP@h
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1:
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END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP)
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cmpwi 0,r3,0
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beqlr
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/* Some pre-nap cleanups needed on some CPUs */
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andis. r0,r3,HID0_NAP@h
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beq 2f
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BEGIN_FTR_SECTION
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/* Disable L2 prefetch on some 745x and try to ensure
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* L2 prefetch engines are idle. As explained by errata
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* text, we can't be sure they are, we just hope very hard
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* that well be enough (sic !). At least I noticed Apple
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* doesn't even bother doing the dcbf's here...
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*/
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mfspr r4,SPRN_MSSCR0
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rlwinm r4,r4,0,0,29
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sync
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mtspr SPRN_MSSCR0,r4
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sync
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isync
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lis r4,KERNELBASE@h
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dcbf 0,r4
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dcbf 0,r4
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dcbf 0,r4
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dcbf 0,r4
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END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR)
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2:
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BEGIN_FTR_SECTION
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/* Go to low speed mode on some 750FX */
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lis r4,powersave_lowspeed@ha
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lwz r4,powersave_lowspeed@l(r4)
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cmpwi 0,r4,0
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beq 1f
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mfspr r4,SPRN_HID1
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oris r4,r4,0x0001
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mtspr SPRN_HID1,r4
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1:
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END_FTR_SECTION_IFSET(CPU_FTR_DUAL_PLL_750FX)
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/* Go to NAP or DOZE now */
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mfspr r4,SPRN_HID0
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lis r5,(HID0_NAP|HID0_SLEEP)@h
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BEGIN_FTR_SECTION
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oris r5,r5,HID0_DOZE@h
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END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
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andc r4,r4,r5
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or r4,r4,r3
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BEGIN_FTR_SECTION
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oris r4,r4,HID0_DPM@h /* that should be done once for all */
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END_FTR_SECTION_IFCLR(CPU_FTR_NO_DPM)
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mtspr SPRN_HID0,r4
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BEGIN_FTR_SECTION
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DSSALL
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sync
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END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
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rlwinm r9,r1,0,0,31-THREAD_SHIFT /* current thread_info */
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lwz r8,TI_LOCAL_FLAGS(r9) /* set napping bit */
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ori r8,r8,_TLF_NAPPING /* so when we take an exception */
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stw r8,TI_LOCAL_FLAGS(r9) /* it will return to our caller */
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mfmsr r7
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ori r7,r7,MSR_EE
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oris r7,r7,MSR_POW@h
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1: sync
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mtmsr r7
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isync
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b 1b
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/*
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* Return from NAP/DOZE mode, restore some CPU specific registers,
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* we are called with DR/IR still off and r2 containing physical
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* address of current. R11 points to the exception frame (physical
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* address). We have to preserve r10.
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*/
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_GLOBAL(power_save_6xx_restore)
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lwz r9,_LINK(r11) /* interrupted in ppc6xx_idle: */
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stw r9,_NIP(r11) /* make it do a blr */
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#ifdef CONFIG_SMP
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mfspr r12,SPRN_SPRG3
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lwz r11,TI_CPU(r12) /* get cpu number * 4 */
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slwi r11,r11,2
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#else
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li r11,0
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#endif
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/* Todo make sure all these are in the same page
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* and load r11 (@ha part + CPU offset) only once
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*/
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BEGIN_FTR_SECTION
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mfspr r9,SPRN_HID0
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andis. r9,r9,HID0_NAP@h
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beq 1f
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addis r9,r11,(nap_save_msscr0-KERNELBASE)@ha
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lwz r9,nap_save_msscr0@l(r9)
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mtspr SPRN_MSSCR0, r9
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sync
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isync
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1:
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END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR)
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BEGIN_FTR_SECTION
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addis r9,r11,(nap_save_hid1-KERNELBASE)@ha
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lwz r9,nap_save_hid1@l(r9)
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mtspr SPRN_HID1, r9
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END_FTR_SECTION_IFSET(CPU_FTR_DUAL_PLL_750FX)
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b transfer_to_handler_cont
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.data
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_GLOBAL(nap_save_msscr0)
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.space 4*NR_CPUS
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_GLOBAL(nap_save_hid1)
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.space 4*NR_CPUS
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_GLOBAL(powersave_lowspeed)
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.long 0
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