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