arch/powerpc/kernel/idle_e500.S

   1 /*
   2  * Copyright (C) 2008 Freescale Semiconductor, Inc. All rights reserved.
   3  * Dave Liu <daveliu@freescale.com>
   4  * copy from idle_6xx.S and modify for e500 based processor,
   5  * implement the power_save function in idle.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/threads.h>
  14 #include <asm/reg.h>
  15 #include <asm/page.h>
  16 #include <asm/cputable.h>
  17 #include <asm/thread_info.h>
  18 #include <asm/ppc_asm.h>
  19 #include <asm/asm-offsets.h>
  20
  21         .text
  22
  23 _GLOBAL(e500_idle)
  24         CURRENT_THREAD_INFO(r3, r1)
  25         lwz     r4,TI_LOCAL_FLAGS(r3)   /* set napping bit */
  26         ori     r4,r4,_TLF_NAPPING      /* so when we take an exception */
  27         stw     r4,TI_LOCAL_FLAGS(r3)   /* it will return to our caller */
  28
  29 #ifdef CONFIG_PPC_E500MC
  30         wrteei  1
  31 1:      wait
  32
  33         /*
  34          * Guard against spurious wakeups (e.g. from a hypervisor) --
  35          * any real interrupt will cause us to return to LR due to
  36          * _TLF_NAPPING.
  37          */
  38         b       1b
  39 #else
  40         /* Check if we can nap or doze, put HID0 mask in r3 */
  41         lis     r3,0
  42 BEGIN_FTR_SECTION
  43         lis     r3,HID0_DOZE@h
  44 END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
  45
  46 BEGIN_FTR_SECTION
  47         /* Now check if user enabled NAP mode */
  48         lis     r4,powersave_nap@ha
  49         lwz     r4,powersave_nap@l(r4)
  50         cmpwi   0,r4,0
  51         beq     1f
  52         stwu    r1,-16(r1)
  53         mflr    r0
  54         stw     r0,20(r1)
  55         bl      flush_dcache_L1
  56         lwz     r0,20(r1)
  57         addi    r1,r1,16
  58         mtlr    r0
  59         lis     r3,HID0_NAP@h
  60 END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP)
  61 1:
  62         /* Go to NAP or DOZE now */
  63         mfspr   r4,SPRN_HID0
  64         rlwinm  r4,r4,0,~(HID0_DOZE|HID0_NAP|HID0_SLEEP)
  65         or      r4,r4,r3
  66         isync
  67         mtspr   SPRN_HID0,r4
  68         isync
  69
  70         mfmsr   r7
  71         oris    r7,r7,MSR_WE@h
  72         ori     r7,r7,MSR_EE
  73         msync
  74         mtmsr   r7
  75         isync
  76 2:      b       2b
  77 #endif /* !E500MC */
  78
  79 /*
  80  * Return from NAP/DOZE mode, restore some CPU specific registers,
  81  * r2 containing physical address of current.
  82  * r11 points to the exception frame (physical address).
  83  * We have to preserve r10.
  84  */
  85 _GLOBAL(power_save_ppc32_restore)
  86         lwz     r9,_LINK(r11)           /* interrupted in e500_idle */
  87         stw     r9,_NIP(r11)            /* make it do a blr */
  88
  89 #ifdef CONFIG_SMP
  90         CURRENT_THREAD_INFO(r12, r1)
  91         lwz     r11,TI_CPU(r12)         /* get cpu number * 4 */
  92         slwi    r11,r11,2
  93 #else
  94         li      r11,0
  95 #endif
  96
  97         b       transfer_to_handler_cont