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idle_6xx.S
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idle_6xx.S
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/*
* This file contains the power_save function for 6xx & 7xxx CPUs
* rewritten in assembler
*
* Warning ! This code assumes that if your machine has a 750fx
* it will have PLL 1 set to low speed mode (used during NAP/DOZE).
* if this is not the case some additional changes will have to
* be done to check a runtime var (a bit like powersave-nap)
*
* 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/reg.h>
#include <asm/page.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
.text
/*
* Init idle, called at early CPU setup time from head.S for each CPU
* Make sure no rest of NAP mode remains in HID0, save default
* values for some CPU specific registers. Called with r24
* containing CPU number and r3 reloc offset
*/
_GLOBAL(init_idle_6xx)
BEGIN_FTR_SECTION
mfspr r4,SPRN_HID0
rlwinm r4,r4,0,10,8 /* Clear NAP */
mtspr SPRN_HID0, r4
b 1f
END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP)
blr
1:
slwi r5,r24,2
add r5,r5,r3
BEGIN_FTR_SECTION
mfspr r4,SPRN_MSSCR0
addis r6,r5, nap_save_msscr0@ha
stw r4,nap_save_msscr0@l(r6)
END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR)
BEGIN_FTR_SECTION
mfspr r4,SPRN_HID1
addis r6,r5,nap_save_hid1@ha
stw r4,nap_save_hid1@l(r6)
END_FTR_SECTION_IFSET(CPU_FTR_DUAL_PLL_750FX)
blr
/*
* Here is the power_save_6xx function. This could eventually be
* split into several functions & changing the function pointer
* depending on the various features.
*/
_GLOBAL(ppc6xx_idle)
/* Check if we can nap or doze, put HID0 mask in r3
*/
lis r3, 0
BEGIN_FTR_SECTION
lis r3,HID0_DOZE@h
END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
BEGIN_FTR_SECTION
/* We must dynamically check for the NAP feature as it
* can be cleared by CPU init after the fixups are done
*/
lis r4,cur_cpu_spec@ha
lwz r4,cur_cpu_spec@l(r4)
lwz r4,CPU_SPEC_FEATURES(r4)
andi. r0,r4,CPU_FTR_CAN_NAP
beq 1f
/* Now check if user or arch enabled NAP mode */
lis r4,powersave_nap@ha
lwz r4,powersave_nap@l(r4)
cmpwi 0,r4,0
beq 1f
lis r3,HID0_NAP@h
1:
END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP)
cmpwi 0,r3,0
beqlr
/* Some pre-nap cleanups needed on some CPUs */
andis. r0,r3,HID0_NAP@h
beq 2f
BEGIN_FTR_SECTION
/* Disable L2 prefetch on some 745x and try to ensure
* L2 prefetch engines are idle. As explained by errata
* text, we can't be sure they are, we just hope very hard
* that well be enough (sic !). At least I noticed Apple
* doesn't even bother doing the dcbf's here...
*/
mfspr r4,SPRN_MSSCR0
rlwinm r4,r4,0,0,29
sync
mtspr SPRN_MSSCR0,r4
sync
isync
lis r4,KERNELBASE@h
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR)
2:
BEGIN_FTR_SECTION
/* Go to low speed mode on some 750FX */
lis r4,powersave_lowspeed@ha
lwz r4,powersave_lowspeed@l(r4)
cmpwi 0,r4,0
beq 1f
mfspr r4,SPRN_HID1
oris r4,r4,0x0001
mtspr SPRN_HID1,r4
1:
END_FTR_SECTION_IFSET(CPU_FTR_DUAL_PLL_750FX)
/* Go to NAP or DOZE now */
mfspr r4,SPRN_HID0
lis r5,(HID0_NAP|HID0_SLEEP)@h
BEGIN_FTR_SECTION
oris r5,r5,HID0_DOZE@h
END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
andc r4,r4,r5
or r4,r4,r3
BEGIN_FTR_SECTION
oris r4,r4,HID0_DPM@h /* that should be done once for all */
END_FTR_SECTION_IFCLR(CPU_FTR_NO_DPM)
mtspr SPRN_HID0,r4
BEGIN_FTR_SECTION
DSSALL
sync
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
rlwinm r9,r1,0,0,31-THREAD_SHIFT /* current thread_info */
lwz r8,TI_LOCAL_FLAGS(r9) /* set napping bit */
ori r8,r8,_TLF_NAPPING /* so when we take an exception */
stw r8,TI_LOCAL_FLAGS(r9) /* it will return to our caller */
mfmsr r7
ori r7,r7,MSR_EE
oris r7,r7,MSR_POW@h
1: sync
mtmsr r7
isync
b 1b
/*
* Return from NAP/DOZE mode, restore some CPU specific registers,
* we are called with DR/IR still off and r2 containing physical
* address of current. R11 points to the exception frame (physical
* address). We have to preserve r10.
*/
_GLOBAL(power_save_ppc32_restore)
lwz r9,_LINK(r11) /* interrupted in ppc6xx_idle: */
stw r9,_NIP(r11) /* make it do a blr */
#ifdef CONFIG_SMP
rlwinm r12,r11,0,0,31-THREAD_SHIFT
lwz r11,TI_CPU(r12) /* get cpu number * 4 */
slwi r11,r11,2
#else
li r11,0
#endif
/* Todo make sure all these are in the same page
* and load r11 (@ha part + CPU offset) only once
*/
BEGIN_FTR_SECTION
mfspr r9,SPRN_HID0
andis. r9,r9,HID0_NAP@h
beq 1f
addis r9,r11,(nap_save_msscr0-KERNELBASE)@ha
lwz r9,nap_save_msscr0@l(r9)
mtspr SPRN_MSSCR0, r9
sync
isync
1:
END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR)
BEGIN_FTR_SECTION
addis r9,r11,(nap_save_hid1-KERNELBASE)@ha
lwz r9,nap_save_hid1@l(r9)
mtspr SPRN_HID1, r9
END_FTR_SECTION_IFSET(CPU_FTR_DUAL_PLL_750FX)
b transfer_to_handler_cont
.data
_GLOBAL(nap_save_msscr0)
.space 4*NR_CPUS
_GLOBAL(nap_save_hid1)
.space 4*NR_CPUS
_GLOBAL(powersave_lowspeed)
.long 0