lowlevel_init.S
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/*
* (C) Copyright 2011-2012
* Pali Rohár <pali.rohar@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <config.h>
relocaddr: /* address of this relocaddr section after coping */
.word . /* address of section (calculated at compile time) */
startaddr: /* address of u-boot after copying */
.word CONFIG_SYS_TEXT_BASE
kernaddr: /* address of kernel after copying */
.word KERNEL_ADDRESS
kernsize: /* maximal size of kernel image */
.word KERNEL_MAXSIZE
kernoffs: /* offset of kernel image in loaded u-boot */
.word KERNEL_OFFSET
imagesize: /* maximal size of image */
.word IMAGE_MAXSIZE
ih_magic: /* IH_MAGIC in big endian from include/image.h */
.word 0x56190527
/*
* Routine: save_boot_params (called after reset from start.S)
* Description: Copy attached kernel to address KERNEL_ADDRESS
* Copy u-boot to address CONFIG_SYS_TEXT_BASE
* Return to copied u-boot address
*/
.global save_boot_params
save_boot_params:
/* Get return address */
ldr lr, =save_boot_params_ret
/* Copy valid attached kernel to address KERNEL_ADDRESS */
copy_kernel_start:
adr r0, relocaddr /* r0 - address of section relocaddr */
ldr r1, relocaddr /* r1 - address of relocaddr after relocation */
cmp r0, r1
/* r4 - calculated offset */
subhi r4, r0, r1
sublo r4, r1, r0
/* r0 - start of kernel before */
ldr r0, startaddr
addhi r0, r0, r4
sublo r0, r0, r4
ldr r1, kernoffs
add r0, r0, r1
/* r3 - start of kernel after */
ldr r3, kernaddr
/* r2 - end of kernel after */
ldr r1, kernsize
add r2, r3, r1
/* r1 - end of kernel before */
add r1, r0, r1
/* remove header in target kernel */
mov r5, #0
str r5, [r3]
/* check for valid kernel uImage */
ldr r4, [r0] /* r4 - 4 bytes header of kernel */
ldr r5, ih_magic /* r5 - IH_MAGIC */
cmp r4, r5
bne copy_kernel_end /* skip if invalid image */
copy_kernel_loop:
ldmdb r1!, {r3 - r10}
stmdb r2!, {r3 - r10}
cmp r1, r0
bhi copy_kernel_loop
copy_kernel_end:
mov r5, #0
str r5, [r0] /* remove 4 bytes header of kernel */
/* Fix u-boot code */
fix_start:
adr r0, relocaddr /* r0 - address of section relocaddr */
ldr r1, relocaddr /* r1 - address of relocaddr after relocation */
cmp r0, r1
beq copy_uboot_end /* skip if u-boot is on correct address */
/* r5 - calculated offset */
subhi r5, r0, r1
sublo r5, r1, r0
/* r6 - maximal u-boot size */
ldr r6, imagesize
/* fix return address */
subhi lr, lr, r5
addlo lr, lr, r5
/* r1 - start of u-boot after */
ldr r1, startaddr
/* r0 - start of u-boot before */
addhi r0, r1, r5
sublo r0, r1, r5
/* check if we need to move uboot copy code before calling it */
cmp r5, r6
bhi copy_uboot_start /* now coping u-boot code directly is safe */
copy_code_start:
/* r0 - start of u-boot before */
/* r1 - start of u-boot after */
/* r6 - maximal u-boot size */
/* r7 - maximal kernel size */
ldr r7, kernsize
/* r4 - end of kernel before */
add r4, r0, r6
add r4, r4, r7
/* r5 - end of u-boot after */
ldr r5, startaddr
add r5, r5, r6
/* r2 - start of loop code after */
cmp r4, r5 /* higher address (r4 or r5) */
movhs r2, r4
movlo r2, r5
/* r3 - end of loop code before */
adr r3, end
/* r4 - end of loop code after */
adr r4, copy_uboot_start
sub r4, r3, r4
add r4, r2, r4
copy_code_loop:
ldmdb r3!, {r7 - r10}
stmdb r4!, {r7 - r10}
cmp r4, r2
bhi copy_code_loop
copy_code_end:
mov pc, r2
/* Copy u-boot to address CONFIG_SYS_TEXT_BASE */
copy_uboot_start:
/* r0 - start of u-boot before */
/* r1 - start of u-boot after */
/* r6 - maximal u-boot size */
/* r2 - end of u-boot after */
add r2, r1, r6
/* condition for copying from left to right */
cmp r0, r1
addlo r1, r0, r6 /* r1 - end of u-boot before */
blo copy_uboot_loop_right
copy_uboot_loop_left:
ldmia r0!, {r3 - r10}
stmia r1!, {r3 - r10}
cmp r1, r2
blo copy_uboot_loop_left
b copy_uboot_end
copy_uboot_loop_right:
ldmdb r1!, {r3 - r10}
stmdb r2!, {r3 - r10}
cmp r1, r0
bhi copy_uboot_loop_right
copy_uboot_end:
bx lr
end: