arch/ppc/kernel/idle_power4.S

   1 /*
   2  *  This file contains the power_save function for 6xx & 7xxx CPUs
   3  *  rewritten in assembler
   4  *
   5  *  Warning ! This code assumes that if your machine has a 750fx
   6  *  it will have PLL 1 set to low speed mode (used during NAP/DOZE).
   7  *  if this is not the case some additional changes will have to
   8  *  be done to check a runtime var (a bit like powersave-nap)
   9  *
  10  *  This program is free software; you can redistribute it and/or
  11  *  modify it under the terms of the GNU General Public License
  12  *  as published by the Free Software Foundation; either version
  13  *  2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <linux/config.h>
  17 #include <linux/threads.h>
  18 #include <asm/processor.h>
  19 #include <asm/page.h>
  20 #include <asm/cputable.h>
  21 #include <asm/thread_info.h>
  22 #include <asm/ppc_asm.h>
  23 #include <asm/offsets.h>
  24
  25 #undef DEBUG
  26
  27         .text
  28
  29 /*
  30  * Init idle, called at early CPU setup time from head.S for each CPU
  31  * So nothing for now. Called with r24 containing CPU number and r3
  32  * reloc offset
  33  */
  34         .globl  init_idle_power4
  35 init_idle_power4:
  36         blr
  37
  38 /*
  39  * Here is the power_save_6xx function. This could eventually be
  40  * split into several functions & changing the function pointer
  41  * depending on the various features.
  42  */
  43         .globl  power4_idle
  44 power4_idle:
  45 BEGIN_FTR_SECTION
  46         blr
  47 END_FTR_SECTION_IFCLR(CPU_FTR_CAN_NAP)
  48         /* We must dynamically check for the NAP feature as it
  49          * can be cleared by CPU init after the fixups are done
  50          */
  51         lis     r4,cur_cpu_spec@ha
  52         lwz     r4,cur_cpu_spec@l(r4)
  53         lwz     r4,CPU_SPEC_FEATURES(r4)
  54         andi.   r0,r4,CPU_FTR_CAN_NAP
  55         beqlr
  56         /* Now check if user or arch enabled NAP mode */
  57         lis     r4,powersave_nap@ha
  58         lwz     r4,powersave_nap@l(r4)
  59         cmpwi   0,r4,0
  60         beqlr
  61
  62         /* Clear MSR:EE */
  63         mfmsr   r7
  64         rlwinm  r0,r7,0,17,15
  65         mtmsr   r0
  66
  67         /* Check current_thread_info()->flags */
  68         rlwinm  r4,r1,0,0,18
  69         lwz     r4,TI_FLAGS(r4)
  70         andi.   r0,r4,_TIF_NEED_RESCHED
  71         beq     1f
  72         mtmsr   r7      /* out of line this ? */
  73         blr
  74 1:
  75         /* Go to NAP now */
  76 BEGIN_FTR_SECTION
  77         DSSALL
  78         sync
  79 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
  80         ori     r7,r7,MSR_EE /* Could be ommited (already set) */
  81         oris    r7,r7,MSR_POW@h
  82         sync
  83         isync
  84         mtmsr   r7
  85         isync
  86         sync
  87         blr
  88
  89         .globl powersave_nap
  90 powersave_nap:
  91         .long   0