arch/.unmaintained/ppc-native/exec/disable.s

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 /*****************************************************************************
   7
   8     NAME
   9
  10         AROS_LH0(void, Disable,
  11
  12     LOCATION
  13         struct ExecBase *, SysBase, 20, Exec)
  14
  15     FUNCTION
  16         This function disables the delivery of all interrupts until a matching
  17         call to Enable() is done. This implies a Forbid(). Since the system
  18         needs the regular delivery of all interrupts it is forbidden to disable
  19         them for longer than ~250 microseconds.
  20
  21         THIS CALL IS VERY DANGEROUS!!!
  22
  23         Do not use it without thinking very well about it or better do not use
  24         it at all. Most of the time you can live without it by using semaphores
  25         or similar.
  26
  27         Calls to Disable() nest, i.e. for each call to Disable() you need one
  28         call to Enable().
  29
  30     INPUTS
  31
  32     RESULT
  33
  34     NOTES
  35         This function preserves all registers.
  36
  37         This function may be used from interrupts to disable all higher
  38         priority interrupts. Lower priority interrupts are disabled anyway.
  39
  40         To prevent deadlocks calling Wait() in disabled state breaks the
  41         disable - thus interrupts and taskswitches may happen again.
  42
  43     EXAMPLE
  44
  45     BUGS
  46
  47     SEE ALSO
  48         Forbid(), Permit(), Enable(), Wait()
  49
  50     INTERNALS
  51         This is literal rewrite of MC68000 version plus code to clear
  52         EE bit in MSR
  53
  54     HISTORY
  55
  56 ******************************************************************************/
  57
  58         INTENA      =   0xdff09a
  59         INTEN       =   0x4000
  60         SET         =   0x8000
  61
  62         #include "machine.i"
  63
  64         .text
  65         .balign 4
  66         .globl  AROS_SLIB_ENTRY(Disable,Exec)
  67         .type   AROS_SLIB_ENTRY(Disable,Exec),@function
  68 AROS_SLIB_ENTRY(Disable,Exec):
  69         subr
  70         push    scr
  71
  72         /* disable amiga chipset interrupts */
  73         li      scr,INTEN
  74         stw     scr,INTENA
  75         /* disable external interrupts in PPC, must be executed in supervisor */
  76         lwz     arg0,_disab(0)
  77         jsrlvo  Supervisor,base
  78         /* we should come back here from _disab */
  79         /* increment nesting count and return */
  80         lbz     scr,IDNestCnt(base)
  81         addi    scr,scr,1
  82         stb     scr,IDNestCnt(base)
  83
  84         pop     scr
  85         rts
  86
  87 _disab:
  88         mfmsr   scr
  89         andi.   scr,scr,0xFFFF7FFF
  90         isync
  91         mtmsr   scr
  92         sync
  93         rfi