arch/arm26/kernel/head.S

   1 /*
   2  *  linux/arch/arm26/kernel/head.S
   3  *
   4  *  Copyright (C) 1994-2000 Russell King
   5  *  Copyright (C) 2003 Ian Molton
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  *  26-bit kernel startup code
  12  */
  13 #include <linux/linkage.h>
  14 #include <asm/mach-types.h>
  15
  16                 .globl  swapper_pg_dir
  17                 .equ    swapper_pg_dir, 0x0207d000
  18
  19 /*
  20  * Entry point.
  21  */
  22                 .section ".init.text",#alloc,#execinstr
  23 ENTRY(stext)
  24
  25 __entry:
  26                 cmp     pc, #0x02000000
  27                 ldrlt   pc, LC0                 @ if 0x01800000, call at 0x02080000
  28                 teq     r0, #0                  @ Check for old calling method
  29                 blne    oldparams               @ Move page if old
  30
  31                 adr     r0, LC0
  32                 ldmib   r0, {r2-r5, sp}         @ Setup stack (and fetch other values)
  33
  34                 mov     r0, #0                  @ Clear BSS
  35 1:              cmp     r2, r3
  36                 strcc   r0, [r2], #4
  37                 bcc     1b
  38
  39                 bl      detect_proc_type
  40                 str     r0, [r4]
  41                 bl      detect_arch_type
  42                 str     r0, [r5]
  43
  44 #ifdef CONFIG_XIP_KERNEL
  45                ldr     r3, ETEXT                       @ data section copy
  46                ldr     r4, SDATA
  47                ldr     r5, EDATA
  48 1:
  49                ldr     r6, [r3], #4
  50                str     r6, [r4], #4
  51                cmp     r4, r5
  52                blt     1b
  53 #endif
  54                 mov     fp, #0
  55                 b       start_kernel
  56
  57 LC0:            .word   _stext
  58                 .word   __bss_start             @ r2
  59                 .word   _end                    @ r3
  60                 .word   processor_id            @ r4
  61                 .word   __machine_arch_type     @ r5
  62                 .word   init_thread_union+8192  @ sp
  63 #ifdef CONFIG_XIP_KERNEL
  64 ETEXT:          .word   _endtext
  65 SDATA:          .word   _sdata
  66 EDATA:          .word   __bss_start
  67 #endif
  68
  69 arm2_id:        .long   0x41560200  @ ARM2 and 250 dont have a CPUID
  70 arm250_id:      .long   0x41560250  @ So we create some after probing for them
  71                 .align
  72
  73 oldparams:      mov     r4, #0x02000000
  74                 add     r3, r4, #0x00080000
  75                 add     r4, r4, #0x0007c000
  76 1:              ldmia   r0!, {r5 - r12}
  77                 stmia   r4!, {r5 - r12}
  78                 cmp     r4, r3
  79                 blt     1b
  80                 mov     pc, lr
  81
  82 /*
  83  * We need some way to automatically detect the difference between
  84  * these two machines.  Unfortunately, it is not possible to detect
  85  * the presence of the SuperIO chip, because that will hang the old
  86  * Archimedes machines solid.
  87  */
  88 /* DAG: Outdated, these have been combined !!!!!!! */
  89 detect_arch_type:
  90 #if defined(CONFIG_ARCH_ARC)
  91                 mov     r0, #MACH_TYPE_ARCHIMEDES
  92 #elif defined(CONFIG_ARCH_A5K)
  93                 mov     r0, #MACH_TYPE_A5K
  94 #endif
  95                 mov     pc, lr
  96
  97 detect_proc_type:
  98                 mov     ip, lr
  99                 mov     r2, #0xea000000         @ Point undef instr to continuation
 100                 adr     r0, continue - 12
 101                 orr     r0, r2, r0, lsr #2
 102                 mov     r1, #0
 103                 str     r0, [r1, #4]
 104                 ldr     r0, arm2_id
 105                 swp     r2, r2, [r1]            @ check for swp (ARM2 cant)
 106                 ldr     r0, arm250_id
 107                 mrc     15, 0, r3, c0, c0       @ check for CP#15 (ARM250 cant)
 108                 mov     r0, r3
 109 continue:       mov     r2, #0xeb000000         @ Make undef vector loop
 110                 sub     r2, r2, #2
 111                 str     r2, [r1, #4]
 112                 mov     pc, ip