| Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame^] | 1 | /* |
| 2 | * Startup code for use with the u-boot bootloader. |
| 3 | * |
| 4 | * Copyright (C) 2004-2006 Atmel Corporation |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | */ |
| 10 | #include <asm/setup.h> |
| 11 | #include <asm/thread_info.h> |
| 12 | #include <asm/sysreg.h> |
| 13 | |
| 14 | /* |
| 15 | * The kernel is loaded where we want it to be and all caches |
| 16 | * have just been flushed. We get two parameters from u-boot: |
| 17 | * |
| 18 | * r12 contains a magic number (ATAG_MAGIC) |
| 19 | * r11 points to a tag table providing information about |
| 20 | * the system. |
| 21 | */ |
| 22 | .section .init.text,"ax" |
| 23 | .global _start |
| 24 | _start: |
| 25 | /* Initialize .bss */ |
| 26 | lddpc r2, bss_start_addr |
| 27 | lddpc r3, end_addr |
| 28 | mov r0, 0 |
| 29 | mov r1, 0 |
| 30 | 1: st.d r2++, r0 |
| 31 | cp r2, r3 |
| 32 | brlo 1b |
| 33 | |
| 34 | /* Initialize status register */ |
| 35 | lddpc r0, init_sr |
| 36 | mtsr SYSREG_SR, r0 |
| 37 | |
| 38 | /* Set initial stack pointer */ |
| 39 | lddpc sp, stack_addr |
| 40 | sub sp, -THREAD_SIZE |
| 41 | |
| 42 | #ifdef CONFIG_FRAME_POINTER |
| 43 | /* Mark last stack frame */ |
| 44 | mov lr, 0 |
| 45 | mov r7, 0 |
| 46 | #endif |
| 47 | |
| 48 | /* Check if the boot loader actually provided a tag table */ |
| 49 | lddpc r0, magic_number |
| 50 | cp.w r12, r0 |
| 51 | brne no_tag_table |
| 52 | |
| 53 | /* |
| 54 | * Save the tag table address for later use. This must be done |
| 55 | * _after_ .bss has been initialized... |
| 56 | */ |
| 57 | lddpc r0, tag_table_addr |
| 58 | st.w r0[0], r11 |
| 59 | |
| 60 | /* Jump to loader-independent setup code */ |
| 61 | rjmp kernel_entry |
| 62 | |
| 63 | .align 2 |
| 64 | magic_number: |
| 65 | .long ATAG_MAGIC |
| 66 | tag_table_addr: |
| 67 | .long bootloader_tags |
| 68 | bss_start_addr: |
| 69 | .long __bss_start |
| 70 | end_addr: |
| 71 | .long _end |
| 72 | init_sr: |
| 73 | .long 0x007f0000 /* Supervisor mode, everything masked */ |
| 74 | stack_addr: |
| 75 | .long init_thread_union |
| 76 | panic_addr: |
| 77 | .long panic |
| 78 | |
| 79 | no_tag_table: |
| 80 | sub r12, pc, (. - 2f) |
| 81 | /* branch to panic() which can be far away with that construct */ |
| 82 | lddpc pc, panic_addr |
| 83 | 2: .asciz "Boot loader didn't provide correct magic number\n" |