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linux/arch/ppc/platforms/pmac_cache.S
Benjamin Herrenschmidt 15fd56867b [PATCH] ppc32: Workaround a cache flush issue on sleep 
We are experiencing a problem when flushing the CPU caches before sleep
on some laptop models using the 750FX CPU rev 1.X. While I haven't been
able to figure out a proper explanation for what's going on, I do have a
workaround that seem to work reliably and allows those machine to sleep
and wakeup properly again.

I'll re-update that code if/when I ever find exactly what is happening
with those CPU revisions.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-01 18:22:34 -07:00

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/*
* This file contains low-level cache management functions
* used for sleep and CPU speed changes on Apple machines.
* (In fact the only thing that is Apple-specific is that we assume
* that we can read from ROM at physical address 0xfff00000.)
*
* Copyright (C) 2004 Paul Mackerras (paulus@samba.org) and
* Benjamin Herrenschmidt (benh@kernel.crashing.org)
*
* 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/config.h>
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/cputable.h>
/*
* Flush and disable all data caches (dL1, L2, L3). This is used
* when going to sleep, when doing a PMU based cpufreq transition,
* or when "offlining" a CPU on SMP machines. This code is over
* paranoid, but I've had enough issues with various CPU revs and
* bugs that I decided it was worth beeing over cautious
*/
_GLOBAL(flush_disable_caches)
#ifndef CONFIG_6xx
blr
#else
BEGIN_FTR_SECTION
b flush_disable_745x
END_FTR_SECTION_IFSET(CPU_FTR_SPEC7450)
BEGIN_FTR_SECTION
b flush_disable_75x
END_FTR_SECTION_IFSET(CPU_FTR_L2CR)
b __flush_disable_L1
/* This is the code for G3 and 74[01]0 */
flush_disable_75x:
mflr r10
/* Turn off EE and DR in MSR */
mfmsr r11
rlwinm r0,r11,0,~MSR_EE
rlwinm r0,r0,0,~MSR_DR
sync
mtmsr r0
isync
/* Stop DST streams */
BEGIN_FTR_SECTION
DSSALL
sync
END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
/* Stop DPM */
mfspr r8,SPRN_HID0 /* Save SPRN_HID0 in r8 */
rlwinm r4,r8,0,12,10 /* Turn off HID0[DPM] */
sync
mtspr SPRN_HID0,r4 /* Disable DPM */
sync
/* Disp-flush L1. We have a weird problem here that I never
* totally figured out. On 750FX, using the ROM for the flush
* results in a non-working flush. We use that workaround for
* now until I finally understand what's going on. --BenH
*/
/* ROM base by default */
lis r4,0xfff0
mfpvr r3
srwi r3,r3,16
cmplwi cr0,r3,0x7000
bne+ 1f
/* RAM base on 750FX */
li r4,0
1: li r4,0x4000
mtctr r4
1: lwz r0,0(r4)
addi r4,r4,32
bdnz 1b
sync
isync
/* Disable / invalidate / enable L1 data */
mfspr r3,SPRN_HID0
rlwinm r3,r3,0,~(HID0_DCE | HID0_ICE)
mtspr SPRN_HID0,r3
sync
isync
ori r3,r3,(HID0_DCE|HID0_DCI|HID0_ICE|HID0_ICFI)
sync
isync
mtspr SPRN_HID0,r3
xori r3,r3,(HID0_DCI|HID0_ICFI)
mtspr SPRN_HID0,r3
sync
/* Get the current enable bit of the L2CR into r4 */
mfspr r5,SPRN_L2CR
/* Set to data-only (pre-745x bit) */
oris r3,r5,L2CR_L2DO@h
b 2f
/* When disabling L2, code must be in L1 */
.balign 32
1: mtspr SPRN_L2CR,r3
3: sync
isync
b 1f
2: b 3f
3: sync
isync
b 1b
1: /* disp-flush L2. The interesting thing here is that the L2 can be
* up to 2Mb ... so using the ROM, we'll end up wrapping back to memory
* but that is probbaly fine. We disp-flush over 4Mb to be safe
*/
lis r4,2
mtctr r4
lis r4,0xfff0
1: lwz r0,0(r4)
addi r4,r4,32
bdnz 1b
sync
isync
lis r4,2
mtctr r4
lis r4,0xfff0
1: dcbf 0,r4
addi r4,r4,32
bdnz 1b
sync
isync
/* now disable L2 */
rlwinm r5,r5,0,~L2CR_L2E
b 2f
/* When disabling L2, code must be in L1 */
.balign 32
1: mtspr SPRN_L2CR,r5
3: sync
isync
b 1f
2: b 3f
3: sync
isync
b 1b
1: sync
isync
/* Invalidate L2. This is pre-745x, we clear the L2I bit ourselves */
oris r4,r5,L2CR_L2I@h
mtspr SPRN_L2CR,r4
sync
isync
/* Wait for the invalidation to complete */
1: mfspr r3,SPRN_L2CR
rlwinm. r0,r3,0,31,31
bne 1b
/* Clear L2I */
xoris r4,r4,L2CR_L2I@h
sync
mtspr SPRN_L2CR,r4
sync
/* now disable the L1 data cache */
mfspr r0,SPRN_HID0
rlwinm r0,r0,0,~(HID0_DCE|HID0_ICE)
mtspr SPRN_HID0,r0
sync
isync
/* Restore HID0[DPM] to whatever it was before */
sync
mfspr r0,SPRN_HID0
rlwimi r0,r8,0,11,11 /* Turn back HID0[DPM] */
mtspr SPRN_HID0,r0
sync
/* restore DR and EE */
sync
mtmsr r11
isync
mtlr r10
blr
/* This code is for 745x processors */
flush_disable_745x:
/* Turn off EE and DR in MSR */
mfmsr r11
rlwinm r0,r11,0,~MSR_EE
rlwinm r0,r0,0,~MSR_DR
sync
mtmsr r0
isync
/* Stop prefetch streams */
DSSALL
sync
/* Disable L2 prefetching */
mfspr r0,SPRN_MSSCR0
rlwinm r0,r0,0,0,29
mtspr SPRN_MSSCR0,r0
sync
isync
lis r4,0
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
dcbf 0,r4
/* Due to a bug with the HW flush on some CPU revs, we occasionally
* experience data corruption. I'm adding a displacement flush along
* with a dcbf loop over a few Mb to "help". The problem isn't totally
* fixed by this in theory, but at least, in practice, I couldn't reproduce
* it even with a big hammer...
*/
lis r4,0x0002
mtctr r4
li r4,0
1:
lwz r0,0(r4)
addi r4,r4,32 /* Go to start of next cache line */
bdnz 1b
isync
/* Now, flush the first 4MB of memory */
lis r4,0x0002
mtctr r4
li r4,0
sync
1:
dcbf 0,r4
addi r4,r4,32 /* Go to start of next cache line */
bdnz 1b
/* Flush and disable the L1 data cache */
mfspr r6,SPRN_LDSTCR
lis r3,0xfff0 /* read from ROM for displacement flush */
li r4,0xfe /* start with only way 0 unlocked */
li r5,128 /* 128 lines in each way */
1: mtctr r5
rlwimi r6,r4,0,24,31
mtspr SPRN_LDSTCR,r6
sync
isync
2: lwz r0,0(r3) /* touch each cache line */
addi r3,r3,32
bdnz 2b
rlwinm r4,r4,1,24,30 /* move on to the next way */
ori r4,r4,1
cmpwi r4,0xff /* all done? */
bne 1b
/* now unlock the L1 data cache */
li r4,0
rlwimi r6,r4,0,24,31
sync
mtspr SPRN_LDSTCR,r6
sync
isync
/* Flush the L2 cache using the hardware assist */
mfspr r3,SPRN_L2CR
cmpwi r3,0 /* check if it is enabled first */
bge 4f
oris r0,r3,(L2CR_L2IO_745x|L2CR_L2DO_745x)@h
b 2f
/* When disabling/locking L2, code must be in L1 */
.balign 32
1: mtspr SPRN_L2CR,r0 /* lock the L2 cache */
3: sync
isync
b 1f
2: b 3f
3: sync
isync
b 1b
1: sync
isync
ori r0,r3,L2CR_L2HWF_745x
sync
mtspr SPRN_L2CR,r0 /* set the hardware flush bit */
3: mfspr r0,SPRN_L2CR /* wait for it to go to 0 */
andi. r0,r0,L2CR_L2HWF_745x
bne 3b
sync
rlwinm r3,r3,0,~L2CR_L2E
b 2f
/* When disabling L2, code must be in L1 */
.balign 32
1: mtspr SPRN_L2CR,r3 /* disable the L2 cache */
3: sync
isync
b 1f
2: b 3f
3: sync
isync
b 1b
1: sync
isync
oris r4,r3,L2CR_L2I@h
mtspr SPRN_L2CR,r4
sync
isync
1: mfspr r4,SPRN_L2CR
andis. r0,r4,L2CR_L2I@h
bne 1b
sync
BEGIN_FTR_SECTION
/* Flush the L3 cache using the hardware assist */
4: mfspr r3,SPRN_L3CR
cmpwi r3,0 /* check if it is enabled */
bge 6f
oris r0,r3,L3CR_L3IO@h
ori r0,r0,L3CR_L3DO
sync
mtspr SPRN_L3CR,r0 /* lock the L3 cache */
sync
isync
ori r0,r0,L3CR_L3HWF
sync
mtspr SPRN_L3CR,r0 /* set the hardware flush bit */
5: mfspr r0,SPRN_L3CR /* wait for it to go to zero */
andi. r0,r0,L3CR_L3HWF
bne 5b
rlwinm r3,r3,0,~L3CR_L3E
sync
mtspr SPRN_L3CR,r3 /* disable the L3 cache */
sync
ori r4,r3,L3CR_L3I
mtspr SPRN_L3CR,r4
1: mfspr r4,SPRN_L3CR
andi. r0,r4,L3CR_L3I
bne 1b
sync
END_FTR_SECTION_IFSET(CPU_FTR_L3CR)
6: mfspr r0,SPRN_HID0 /* now disable the L1 data cache */
rlwinm r0,r0,0,~HID0_DCE
mtspr SPRN_HID0,r0
sync
isync
mtmsr r11 /* restore DR and EE */
isync
blr
#endif /* CONFIG_6xx */
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