| /* SPDX-License-Identifier: GPL-2.0+ */ |
| /* |
| * crt0 - C-runtime startup Code for AArch64 U-Boot |
| * |
| * (C) Copyright 2013 |
| * David Feng <fenghua@phytium.com.cn> |
| * |
| * (C) Copyright 2012 |
| * Albert ARIBAUD <albert.u.boot@aribaud.net> |
| */ |
| |
| #include <config.h> |
| #include <asm-offsets.h> |
| #include <asm/macro.h> |
| #include <linux/linkage.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(). |
| * |
| * TODO: For SPL, implement stack relocation on AArch64. |
| * |
| * 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. |
| */ |
| |
| 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 x0, =(CONFIG_TPL_STACK) |
| #elif defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK) |
| ldr x0, =(CONFIG_SPL_STACK) |
| #elif defined(CONFIG_INIT_SP_RELATIVE) |
| #if CONFIG_POSITION_INDEPENDENT |
| adrp x0, __bss_start /* x0 <- Runtime &__bss_start */ |
| add x0, x0, #:lo12:__bss_start |
| #else |
| adr x0, __bss_start |
| #endif |
| add x0, x0, #CONFIG_SYS_INIT_SP_BSS_OFFSET |
| #else |
| ldr x0, =(CONFIG_SYS_INIT_SP_ADDR) |
| #endif |
| bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */ |
| mov x0, sp |
| bl board_init_f_alloc_reserve |
| mov sp, x0 |
| /* set up gd here, outside any C code */ |
| mov x18, x0 |
| bl board_init_f_init_reserve |
| |
| mov x0, #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 x0, [x18, #GD_START_ADDR_SP] /* x0 <- gd->start_addr_sp */ |
| bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */ |
| ldr x18, [x18, #GD_NEW_GD] /* x18 <- gd->new_gd */ |
| |
| /* Skip relocation in case gd->gd_flags & GD_FLG_SKIP_RELOC */ |
| ldr x0, [x18, #GD_FLAGS] /* x0 <- gd->flags */ |
| tbnz x0, 11, relocation_return /* GD_FLG_SKIP_RELOC is bit 11 */ |
| |
| adr lr, relocation_return |
| #if CONFIG_POSITION_INDEPENDENT |
| /* Add in link-vs-runtime offset */ |
| adrp x0, _start /* x0 <- Runtime value of _start */ |
| add x0, x0, #:lo12:_start |
| ldr x9, _TEXT_BASE /* x9 <- Linked value of _start */ |
| sub x9, x9, x0 /* x9 <- Run-vs-link offset */ |
| add lr, lr, x9 |
| #if defined(CONFIG_SYS_RELOC_GD_ENV_ADDR) |
| ldr x0, [x18, #GD_ENV_ADDR] /* x0 <- gd->env_addr */ |
| add x0, x0, x9 |
| str x0, [x18, #GD_ENV_ADDR] |
| #endif |
| #endif |
| /* Add in link-vs-relocation offset */ |
| ldr x9, [x18, #GD_RELOC_OFF] /* x9 <- gd->reloc_off */ |
| add lr, lr, x9 /* new return address after relocation */ |
| ldr x0, [x18, #GD_RELOCADDR] /* x0 <- gd->relocaddr */ |
| b relocate_code |
| |
| relocation_return: |
| |
| /* |
| * Set up final (full) environment |
| */ |
| bl c_runtime_cpu_setup /* still call old routine */ |
| #endif /* !CONFIG_SPL_BUILD */ |
| #if !defined(CONFIG_SPL_BUILD) || CONFIG_IS_ENABLED(FRAMEWORK) |
| #if defined(CONFIG_SPL_BUILD) |
| bl spl_relocate_stack_gd /* may return NULL */ |
| /* set up gd here, outside any C code, if new stack is returned */ |
| cmp x0, #0 |
| csel x18, x0, x18, ne |
| /* |
| * Perform 'sp = (x0 != NULL) ? x0 : sp' while working |
| * around the constraint that conditional moves can not |
| * have 'sp' as an operand |
| */ |
| mov x1, sp |
| cmp x0, #0 |
| csel x0, x0, x1, ne |
| mov sp, x0 |
| #endif |
| |
| /* |
| * Clear BSS section |
| */ |
| ldr x0, =__bss_start /* this is auto-relocated! */ |
| ldr x1, =__bss_end /* this is auto-relocated! */ |
| clear_loop: |
| str xzr, [x0], #8 |
| cmp x0, x1 |
| b.lo clear_loop |
| |
| /* call board_init_r(gd_t *id, ulong dest_addr) */ |
| mov x0, x18 /* gd_t */ |
| ldr x1, [x18, #GD_RELOCADDR] /* dest_addr */ |
| b board_init_r /* PC relative jump */ |
| |
| /* NOTREACHED - board_init_r() does not return */ |
| #endif |
| |
| ENDPROC(_main) |