arch/cris/arch-v10/boot/compressed/head.S

   1 /*
   2  *  arch/cris/boot/compressed/head.S
   3  *
   4  *  Copyright (C) 1999, 2001 Axis Communications AB
   5  *
   6  *  Code that sets up the DRAM registers, calls the
   7  *  decompressor to unpack the piggybacked kernel, and jumps.
   8  *
   9  */
  10
  11 #include <linux/config.h>
  12 #define ASSEMBLER_MACROS_ONLY
  13 #include <asm/arch/sv_addr_ag.h>
  14
  15 #define RAM_INIT_MAGIC 0x56902387
  16
  17         ;; Exported symbols
  18
  19         .globl  _input_data
  20
  21
  22         .text
  23
  24         nop
  25         di
  26
  27 ;; We need to initialze DRAM registers before we start using the DRAM
  28
  29         cmp.d   RAM_INIT_MAGIC, r8      ; Already initialized?
  30         beq     dram_init_finished
  31         nop
  32
  33 #include "../../lib/dram_init.S"
  34
  35 dram_init_finished:
  36
  37         ;; Initiate the PA and PB ports
  38
  39         move.b   CONFIG_ETRAX_DEF_R_PORT_PA_DATA, r0
  40         move.b   r0, [R_PORT_PA_DATA]
  41
  42         move.b   CONFIG_ETRAX_DEF_R_PORT_PA_DIR, r0
  43         move.b   r0, [R_PORT_PA_DIR]
  44
  45         move.b   CONFIG_ETRAX_DEF_R_PORT_PB_DATA, r0
  46         move.b   r0, [R_PORT_PB_DATA]
  47
  48         move.b   CONFIG_ETRAX_DEF_R_PORT_PB_DIR, r0
  49         move.b   r0, [R_PORT_PB_DIR]
  50
  51         ;; Setup the stack to a suitably high address.
  52         ;; We assume 8 MB is the minimum DRAM in an eLinux
  53         ;; product and put the sp at the top for now.
  54
  55         move.d  0x40800000, sp
  56
  57         ;; Figure out where the compressed piggyback image is
  58         ;; in the flash (since we wont try to copy it to DRAM
  59         ;; before unpacking). It is at _edata, but in flash.
  60         ;; Use (_edata - basse) as offset to the current PC.
  61
  62 basse:  move.d  pc, r5
  63         and.d   0x7fffffff, r5  ; strip any non-cache bit
  64         subq    2, r5           ; compensate for the move.d pc instr
  65         move.d  r5, r0          ; save for later - flash address of 'basse'
  66         add.d   _edata, r5
  67         sub.d   basse, r5       ; r5 = flash address of '_edata'
  68
  69         ;; Copy text+data to DRAM
  70
  71         move.d  basse, r1       ; destination
  72         move.d  _edata, r2      ; end destination
  73 1:      move.w  [r0+], r3
  74         move.w  r3, [r1+]
  75         cmp.d   r2, r1
  76         bcs     1b
  77         nop
  78
  79         move.d  r5, [_input_data] ; for the decompressor
  80
  81
  82         ;; Clear the decompressors BSS (between _edata and _end)
  83
  84         moveq   0, r0
  85         move.d  _edata, r1
  86         move.d  _end, r2
  87 1:      move.w  r0, [r1+]
  88         cmp.d   r2, r1
  89         bcs     1b
  90         nop
  91
  92         ;; Do the decompression and save compressed size in _inptr
  93
  94         jsr     _decompress_kernel
  95
  96         ;; Put start address of root partition in r9 so the kernel can use it
  97         ;; when mounting from flash
  98
  99         move.d  [_input_data], r9       ; flash address of compressed kernel
 100         add.d   [_inptr], r9            ; size of compressed kernel
 101
 102         ;; Enter the decompressed kernel
 103         move.d  RAM_INIT_MAGIC, r8      ; Tell kernel that DRAM is initialized
 104         jump    0x40004000      ; kernel is linked to this address
 105
 106         .data
 107
 108 _input_data:
 109         .dword  0               ; used by the decompressor
 110
 111 #include "../../lib/hw_settings.S"