root/arch/nios2/boot/compressed/head.S

   1 /*
   2  * Copyright (C) 2009 Thomas Chou <thomas@wytron.com.tw>
   3  *
   4  * Based on arch/nios2/kernel/head.S
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License. See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  *
  10  */
  11 
  12 /*
  13  *  This code can be loaded anywhere, eg FLASH ROM as reset vector,
  14  *  as long as output does not overlap it.
  15  */
  16 
  17 #include <linux/linkage.h>
  18 #include <asm/cache.h>
  19 
  20         .text
  21         .set noat
  22 ENTRY(_start)
  23         wrctl   status, r0              /* disable interrupt */
  24         /* invalidate all instruction cache */
  25         movia   r1, NIOS2_ICACHE_SIZE
  26         movui   r2, NIOS2_ICACHE_LINE_SIZE
  27 1:      initi   r1
  28         sub     r1, r1, r2
  29         bgt     r1, r0, 1b
  30         /* invalidate all data cache */
  31         movia   r1, NIOS2_DCACHE_SIZE
  32         movui   r2, NIOS2_DCACHE_LINE_SIZE
  33 1:      initd   0(r1)
  34         sub     r1, r1, r2
  35         bgt     r1, r0, 1b
  36 
  37         nextpc  r1                      /* Find out where we are */
  38 chkadr:
  39         movia   r2, chkadr
  40         beq     r1, r2, finish_move     /* We are running in correct address,
  41                                            done */
  42         /* move code, r1: src, r2: dest, r3: last dest */
  43         addi    r1, r1, (_start - chkadr)       /* Source */
  44         movia   r2, _start              /* Destination */
  45         movia   r3, __bss_start         /* End of copy */
  46 1:      ldw     r8, 0(r1)               /* load a word from [r1] */
  47         stw     r8, 0(r2)               /* stort a word to dest [r2] */
  48         addi    r1, r1, 4               /* inc the src addr */
  49         addi    r2, r2, 4               /* inc the dest addr */
  50         blt     r2, r3, 1b
  51         /* flush the data cache after moving */
  52         movia   r1, NIOS2_DCACHE_SIZE
  53         movui   r2, NIOS2_DCACHE_LINE_SIZE
  54 1:      flushd  0(r1)
  55         sub     r1, r1, r2
  56         bgt     r1, r0, 1b
  57         movia   r1, finish_move
  58         jmp     r1                      /* jmp to linked address */
  59 
  60 finish_move:
  61         /* zero out the .bss segment (uninitialized common data) */
  62         movia   r2, __bss_start         /* presume nothing is between */
  63         movia   r1, _end                /* the .bss and _end. */
  64 1:      stb     r0, 0(r2)
  65         addi    r2, r2, 1
  66         bne     r1, r2, 1b
  67         /*
  68          * set up the stack pointer, some where higher than _end.
  69          * The stack space must be greater than 32K for decompress.
  70          */
  71         movia   sp, 0x10000
  72         add     sp, sp, r1
  73         /* save args passed from u-boot, maybe */
  74         addi    sp, sp, -16
  75         stw     r4, 0(sp)
  76         stw     r5, 4(sp)
  77         stw     r6, 8(sp)
  78         stw     r7, 12(sp)
  79         /* decompress the kernel */
  80         call    decompress_kernel
  81         /* pass saved args to kernel */
  82         ldw     r4, 0(sp)
  83         ldw     r5, 4(sp)
  84         ldw     r6, 8(sp)
  85         ldw     r7, 12(sp)
  86 
  87         /* flush all data cache after decompressing */
  88         movia   r1, NIOS2_DCACHE_SIZE
  89         movui   r2, NIOS2_DCACHE_LINE_SIZE
  90 1:      flushd  0(r1)
  91         sub     r1, r1, r2
  92         bgt     r1, r0, 1b
  93         /* flush all instruction cache */
  94         movia   r1, NIOS2_ICACHE_SIZE
  95         movui   r2, NIOS2_ICACHE_LINE_SIZE
  96 1:      flushi  r1
  97         sub     r1, r1, r2
  98         bgt     r1, r0, 1b
  99         flushp
 100         /* jump to start real kernel */
 101         movia   r1, (CONFIG_NIOS2_MEM_BASE | CONFIG_NIOS2_KERNEL_REGION_BASE)
 102         jmp     r1
 103 
 104         .balign 512
 105 fake_headers_as_bzImage:
 106         .short  0
 107         .ascii  "HdrS"
 108         .short  0x0202
 109         .short  0
 110         .short  0
 111         .byte   0x00, 0x10
 112         .short  0
 113         .byte   0
 114         .byte   1
 115         .byte   0x00, 0x80
 116         .long   0
 117         .long   0