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author | Angelos Mouzakitis <a.mouzakitis@virtualopensystems.com> | 2023-10-10 14:33:42 +0000 |
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committer | Angelos Mouzakitis <a.mouzakitis@virtualopensystems.com> | 2023-10-10 14:33:42 +0000 |
commit | af1a266670d040d2f4083ff309d732d648afba2a (patch) | |
tree | 2fc46203448ddcc6f81546d379abfaeb323575e9 /roms/u-boot/arch/arm/lib/crt0.S | |
parent | e02cda008591317b1625707ff8e115a4841aa889 (diff) |
Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec
Diffstat (limited to 'roms/u-boot/arch/arm/lib/crt0.S')
-rw-r--r-- | roms/u-boot/arch/arm/lib/crt0.S | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/roms/u-boot/arch/arm/lib/crt0.S b/roms/u-boot/arch/arm/lib/crt0.S new file mode 100644 index 000000000..46b6be21a --- /dev/null +++ b/roms/u-boot/arch/arm/lib/crt0.S @@ -0,0 +1,182 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * crt0 - C-runtime startup Code for ARM U-Boot + * + * Copyright (c) 2012 Albert ARIBAUD <albert.u.boot@aribaud.net> + */ + +#include <config.h> +#include <asm-offsets.h> +#include <linux/linkage.h> +#include <asm/assembler.h> + +/* + * This file handles the target-independent stages of the U-Boot + * start-up where a C runtime environment is needed. Its entry point + * is _main and is branched into from the target's start.S file. + * + * _main execution sequence is: + * + * 1. Set up initial environment for calling board_init_f(). + * This environment only provides a stack and a place to store + * the GD ('global data') structure, both located in some readily + * available RAM (SRAM, locked cache...). In this context, VARIABLE + * global data, initialized or not (BSS), are UNAVAILABLE; only + * CONSTANT initialized data are available. GD should be zeroed + * before board_init_f() is called. + * + * 2. Call board_init_f(). This function prepares the hardware for + * execution from system RAM (DRAM, DDR...) As system RAM may not + * be available yet, , board_init_f() must use the current GD to + * store any data which must be passed on to later stages. These + * data include the relocation destination, the future stack, and + * the future GD location. + * + * 3. Set up intermediate environment where the stack and GD are the + * ones allocated by board_init_f() in system RAM, but BSS and + * initialized non-const data are still not available. + * + * 4a.For U-Boot proper (not SPL), call relocate_code(). This function + * relocates U-Boot from its current location into the relocation + * destination computed by board_init_f(). + * + * 4b.For SPL, board_init_f() just returns (to crt0). There is no + * code relocation in SPL. + * + * 5. Set up final environment for calling board_init_r(). This + * environment has BSS (initialized to 0), initialized non-const + * data (initialized to their intended value), and stack in system + * RAM (for SPL moving the stack and GD into RAM is optional - see + * CONFIG_SPL_STACK_R). GD has retained values set by board_init_f(). + * + * 6. For U-Boot proper (not SPL), some CPUs have some work left to do + * at this point regarding memory, so call c_runtime_cpu_setup. + * + * 7. Branch to board_init_r(). + * + * For more information see 'Board Initialisation Flow in README. + */ + +/* + * Macro for clearing BSS during SPL execution. Usually called during the + * relocation process for most boards before entering board_init_r(), but + * can also be done early before entering board_init_f() on plaforms that + * can afford it due to sufficient memory being available early. + */ + +.macro CLEAR_BSS + ldr r0, =__bss_start /* this is auto-relocated! */ + +#ifdef CONFIG_USE_ARCH_MEMSET + ldr r3, =__bss_end /* this is auto-relocated! */ + mov r1, #0x00000000 /* prepare zero to clear BSS */ + + subs r2, r3, r0 /* r2 = memset len */ + bl memset +#else + ldr r1, =__bss_end /* this is auto-relocated! */ + mov r2, #0x00000000 /* prepare zero to clear BSS */ + +clbss_l:cmp r0, r1 /* while not at end of BSS */ + strlo r2, [r0] /* clear 32-bit BSS word */ + addlo r0, r0, #4 /* move to next */ + blo clbss_l +#endif +.endm + +/* + * entry point of crt0 sequence + */ + +ENTRY(_main) + +/* + * Set up initial C runtime environment and call board_init_f(0). + */ + +#if defined(CONFIG_TPL_BUILD) && defined(CONFIG_TPL_NEEDS_SEPARATE_STACK) + ldr r0, =(CONFIG_TPL_STACK) +#elif defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK) + ldr r0, =(CONFIG_SPL_STACK) +#else + ldr r0, =(CONFIG_SYS_INIT_SP_ADDR) +#endif + bic r0, r0, #7 /* 8-byte alignment for ABI compliance */ + mov sp, r0 + bl board_init_f_alloc_reserve + mov sp, r0 + /* set up gd here, outside any C code */ + mov r9, r0 + bl board_init_f_init_reserve + +#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_EARLY_BSS) + CLEAR_BSS +#endif + + mov r0, #0 + bl board_init_f + +#if ! defined(CONFIG_SPL_BUILD) + +/* + * Set up intermediate environment (new sp and gd) and call + * relocate_code(addr_moni). Trick here is that we'll return + * 'here' but relocated. + */ + + ldr r0, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */ + bic r0, r0, #7 /* 8-byte alignment for ABI compliance */ + mov sp, r0 + ldr r9, [r9, #GD_NEW_GD] /* r9 <- gd->new_gd */ + + adr lr, here + ldr r0, [r9, #GD_RELOC_OFF] /* r0 = gd->reloc_off */ + add lr, lr, r0 +#if defined(CONFIG_CPU_V7M) + orr lr, #1 /* As required by Thumb-only */ +#endif + ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */ + b relocate_code +here: +/* + * now relocate vectors + */ + + bl relocate_vectors + +/* Set up final (full) environment */ + + bl c_runtime_cpu_setup /* we still call old routine here */ +#endif +#if !defined(CONFIG_SPL_BUILD) || CONFIG_IS_ENABLED(FRAMEWORK) + +#if !defined(CONFIG_SPL_BUILD) || !defined(CONFIG_SPL_EARLY_BSS) + CLEAR_BSS +#endif + +# ifdef CONFIG_SPL_BUILD + /* Use a DRAM stack for the rest of SPL, if requested */ + bl spl_relocate_stack_gd + cmp r0, #0 + movne sp, r0 + movne r9, r0 +# endif + +#if ! defined(CONFIG_SPL_BUILD) + bl coloured_LED_init + bl red_led_on +#endif + /* call board_init_r(gd_t *id, ulong dest_addr) */ + mov r0, r9 /* gd_t */ + ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */ + /* call board_init_r */ +#if CONFIG_IS_ENABLED(SYS_THUMB_BUILD) + ldr lr, =board_init_r /* this is auto-relocated! */ + bx lr +#else + ldr pc, =board_init_r /* this is auto-relocated! */ +#endif + /* we should not return here. */ +#endif + +ENDPROC(_main) |