linux/arch/powerpc/kernel/cpu_setup_ppc970.S
Olof Johansson 5b43d20a4d [POWERPC] powerpc: Enable DEEPNAP power savings mode on 970MP
Without this patch, on an idle system I get:

cpu-power-0:21.638
cpu-power-1:27.102
cpu-power-2:29.343
cpu-power-3:25.784
Total: 103.8W

With this patch:

cpu-power-0:11.730
cpu-power-1:17.185
cpu-power-2:18.547
cpu-power-3:17.528
Total: 65.0W

If I lower HZ to 100, I can get it as low as:

cpu-power-0:10.938
cpu-power-1:16.021
cpu-power-2:17.245
cpu-power-3:16.145
Total: 60.2W

Another (older) Quad G5 went from 54W to 39W at HZ=250.

Coming back out of Deep Nap takes 40-70 cycles longer than coming back
from just Nap (which already takes quite a while). I don't think it'll
be a performance issue (interrupt latency on an idle system), but in
case someone does measurements feel free to report them.

Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-10-16 16:32:25 +10:00

192 lines
3.6 KiB
ArmAsm

/*
* This file contains low level CPU setup functions.
* Copyright (C) 2003 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 <asm/processor.h>
#include <asm/page.h>
#include <asm/cputable.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/cache.h>
_GLOBAL(__cpu_preinit_ppc970)
/* Do nothing if not running in HV mode */
mfmsr r0
rldicl. r0,r0,4,63
beqlr
/* Make sure HID4:rm_ci is off before MMU is turned off, that large
* pages are enabled with HID4:61 and clear HID5:DCBZ_size and
* HID5:DCBZ32_ill
*/
li r0,0
mfspr r3,SPRN_HID4
rldimi r3,r0,40,23 /* clear bit 23 (rm_ci) */
rldimi r3,r0,2,61 /* clear bit 61 (lg_pg_en) */
sync
mtspr SPRN_HID4,r3
isync
sync
mfspr r3,SPRN_HID5
rldimi r3,r0,6,56 /* clear bits 56 & 57 (DCBZ*) */
sync
mtspr SPRN_HID5,r3
isync
sync
/* Setup some basic HID1 features */
mfspr r0,SPRN_HID1
li r3,0x1200 /* enable i-fetch cacheability */
sldi r3,r3,44 /* and prefetch */
or r0,r0,r3
mtspr SPRN_HID1,r0
mtspr SPRN_HID1,r0
isync
/* Clear HIOR */
li r0,0
sync
mtspr SPRN_HIOR,0 /* Clear interrupt prefix */
isync
blr
/* Definitions for the table use to save CPU states */
#define CS_HID0 0
#define CS_HID1 8
#define CS_HID4 16
#define CS_HID5 24
#define CS_SIZE 32
.data
.balign L1_CACHE_BYTES,0
cpu_state_storage:
.space CS_SIZE
.balign L1_CACHE_BYTES,0
.text
_GLOBAL(__setup_cpu_ppc970)
/* Do nothing if not running in HV mode */
mfmsr r0
rldicl. r0,r0,4,63
beqlr
mfspr r0,SPRN_HID0
li r11,5 /* clear DOZE and SLEEP */
rldimi r0,r11,52,8 /* set NAP and DPM */
li r11,0
rldimi r0,r11,32,31 /* clear EN_ATTN */
b load_hids /* Jump to shared code */
_GLOBAL(__setup_cpu_ppc970MP)
/* Do nothing if not running in HV mode */
mfmsr r0
rldicl. r0,r0,4,63
beqlr
mfspr r0,SPRN_HID0
li r11,0x15 /* clear DOZE and SLEEP */
rldimi r0,r11,52,6 /* set DEEPNAP, NAP and DPM */
li r11,0
rldimi r0,r11,32,31 /* clear EN_ATTN */
load_hids:
mtspr SPRN_HID0,r0
mfspr r0,SPRN_HID0
mfspr r0,SPRN_HID0
mfspr r0,SPRN_HID0
mfspr r0,SPRN_HID0
mfspr r0,SPRN_HID0
mfspr r0,SPRN_HID0
sync
isync
/* Save away cpu state */
LOAD_REG_IMMEDIATE(r5,cpu_state_storage)
/* Save HID0,1,4 and 5 */
mfspr r3,SPRN_HID0
std r3,CS_HID0(r5)
mfspr r3,SPRN_HID1
std r3,CS_HID1(r5)
mfspr r3,SPRN_HID4
std r3,CS_HID4(r5)
mfspr r3,SPRN_HID5
std r3,CS_HID5(r5)
blr
/* Called with no MMU context (typically MSR:IR/DR off) to
* restore CPU state as backed up by the previous
* function. This does not include cache setting
*/
_GLOBAL(__restore_cpu_ppc970)
/* Do nothing if not running in HV mode */
mfmsr r0
rldicl. r0,r0,4,63
beqlr
LOAD_REG_IMMEDIATE(r5,cpu_state_storage)
/* Before accessing memory, we make sure rm_ci is clear */
li r0,0
mfspr r3,SPRN_HID4
rldimi r3,r0,40,23 /* clear bit 23 (rm_ci) */
sync
mtspr SPRN_HID4,r3
isync
sync
/* Clear interrupt prefix */
li r0,0
sync
mtspr SPRN_HIOR,0
isync
/* Restore HID0 */
ld r3,CS_HID0(r5)
sync
isync
mtspr SPRN_HID0,r3
mfspr r3,SPRN_HID0
mfspr r3,SPRN_HID0
mfspr r3,SPRN_HID0
mfspr r3,SPRN_HID0
mfspr r3,SPRN_HID0
mfspr r3,SPRN_HID0
sync
isync
/* Restore HID1 */
ld r3,CS_HID1(r5)
sync
isync
mtspr SPRN_HID1,r3
mtspr SPRN_HID1,r3
sync
isync
/* Restore HID4 */
ld r3,CS_HID4(r5)
sync
isync
mtspr SPRN_HID4,r3
sync
isync
/* Restore HID5 */
ld r3,CS_HID5(r5)
sync
isync
mtspr SPRN_HID5,r3
sync
isync
blr