10ae76531SDavid Feng/* 20ae76531SDavid Feng * crt0 - C-runtime startup Code for AArch64 U-Boot 30ae76531SDavid Feng * 40ae76531SDavid Feng * (C) Copyright 2013 50ae76531SDavid Feng * David Feng <fenghua@phytium.com.cn> 60ae76531SDavid Feng * 70ae76531SDavid Feng * (C) Copyright 2012 80ae76531SDavid Feng * Albert ARIBAUD <albert.u.boot@aribaud.net> 90ae76531SDavid Feng * 100ae76531SDavid Feng * SPDX-License-Identifier: GPL-2.0+ 110ae76531SDavid Feng */ 120ae76531SDavid Feng 130ae76531SDavid Feng#include <config.h> 140ae76531SDavid Feng#include <asm-offsets.h> 150ae76531SDavid Feng#include <asm/macro.h> 160ae76531SDavid Feng#include <linux/linkage.h> 170ae76531SDavid Feng 180ae76531SDavid Feng/* 190ae76531SDavid Feng * This file handles the target-independent stages of the U-Boot 200ae76531SDavid Feng * start-up where a C runtime environment is needed. Its entry point 210ae76531SDavid Feng * is _main and is branched into from the target's start.S file. 220ae76531SDavid Feng * 230ae76531SDavid Feng * _main execution sequence is: 240ae76531SDavid Feng * 250ae76531SDavid Feng * 1. Set up initial environment for calling board_init_f(). 260ae76531SDavid Feng * This environment only provides a stack and a place to store 270ae76531SDavid Feng * the GD ('global data') structure, both located in some readily 280ae76531SDavid Feng * available RAM (SRAM, locked cache...). In this context, VARIABLE 290ae76531SDavid Feng * global data, initialized or not (BSS), are UNAVAILABLE; only 30ed64190fSSimon Glass * CONSTANT initialized data are available. GD should be zeroed 31ed64190fSSimon Glass * before board_init_f() is called. 320ae76531SDavid Feng * 330ae76531SDavid Feng * 2. Call board_init_f(). This function prepares the hardware for 340ae76531SDavid Feng * execution from system RAM (DRAM, DDR...) As system RAM may not 350ae76531SDavid Feng * be available yet, , board_init_f() must use the current GD to 360ae76531SDavid Feng * store any data which must be passed on to later stages. These 370ae76531SDavid Feng * data include the relocation destination, the future stack, and 380ae76531SDavid Feng * the future GD location. 390ae76531SDavid Feng * 400ae76531SDavid Feng * 3. Set up intermediate environment where the stack and GD are the 410ae76531SDavid Feng * ones allocated by board_init_f() in system RAM, but BSS and 420ae76531SDavid Feng * initialized non-const data are still not available. 430ae76531SDavid Feng * 44ed64190fSSimon Glass * 4a.For U-Boot proper (not SPL), call relocate_code(). This function 45ed64190fSSimon Glass * relocates U-Boot from its current location into the relocation 46ed64190fSSimon Glass * destination computed by board_init_f(). 47ed64190fSSimon Glass * 48ed64190fSSimon Glass * 4b.For SPL, board_init_f() just returns (to crt0). There is no 49ed64190fSSimon Glass * code relocation in SPL. 500ae76531SDavid Feng * 510ae76531SDavid Feng * 5. Set up final environment for calling board_init_r(). This 520ae76531SDavid Feng * environment has BSS (initialized to 0), initialized non-const 530ae76531SDavid Feng * data (initialized to their intended value), and stack in system 54ed64190fSSimon Glass * RAM (for SPL moving the stack and GD into RAM is optional - see 55ed64190fSSimon Glass * CONFIG_SPL_STACK_R). GD has retained values set by board_init_f(). 560ae76531SDavid Feng * 57ed64190fSSimon Glass * TODO: For SPL, implement stack relocation on AArch64. 58ed64190fSSimon Glass * 59ed64190fSSimon Glass * 6. For U-Boot proper (not SPL), some CPUs have some work left to do 60ed64190fSSimon Glass * at this point regarding memory, so call c_runtime_cpu_setup. 61ed64190fSSimon Glass * 62ed64190fSSimon Glass * 7. Branch to board_init_r(). 63ed64190fSSimon Glass * 64ed64190fSSimon Glass * For more information see 'Board Initialisation Flow in README. 650ae76531SDavid Feng */ 660ae76531SDavid Feng 670ae76531SDavid FengENTRY(_main) 680ae76531SDavid Feng 690ae76531SDavid Feng/* 700ae76531SDavid Feng * Set up initial C runtime environment and call board_init_f(0). 710ae76531SDavid Feng */ 72b2d5ac59SScott Wood#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK) 73b2d5ac59SScott Wood ldr x0, =(CONFIG_SPL_STACK) 74b2d5ac59SScott Wood#else 750ae76531SDavid Feng ldr x0, =(CONFIG_SYS_INIT_SP_ADDR) 76b2d5ac59SScott Wood#endif 770ae76531SDavid Feng bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */ 78*931bec31SSimon Glass bl board_init_f_mem 79*931bec31SSimon Glass mov sp, x0 80*931bec31SSimon Glass 810ae76531SDavid Feng mov x0, #0 820ae76531SDavid Feng bl board_init_f 830ae76531SDavid Feng 84b2d5ac59SScott Wood#if !defined(CONFIG_SPL_BUILD) 850ae76531SDavid Feng/* 860ae76531SDavid Feng * Set up intermediate environment (new sp and gd) and call 870ae76531SDavid Feng * relocate_code(addr_moni). Trick here is that we'll return 880ae76531SDavid Feng * 'here' but relocated. 890ae76531SDavid Feng */ 900ae76531SDavid Feng ldr x0, [x18, #GD_START_ADDR_SP] /* x0 <- gd->start_addr_sp */ 910ae76531SDavid Feng bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */ 920ae76531SDavid Feng ldr x18, [x18, #GD_BD] /* x18 <- gd->bd */ 930ae76531SDavid Feng sub x18, x18, #GD_SIZE /* new GD is below bd */ 940ae76531SDavid Feng 950ae76531SDavid Feng adr lr, relocation_return 960ae76531SDavid Feng ldr x9, [x18, #GD_RELOC_OFF] /* x9 <- gd->reloc_off */ 970ae76531SDavid Feng add lr, lr, x9 /* new return address after relocation */ 980ae76531SDavid Feng ldr x0, [x18, #GD_RELOCADDR] /* x0 <- gd->relocaddr */ 990ae76531SDavid Feng b relocate_code 1000ae76531SDavid Feng 1010ae76531SDavid Fengrelocation_return: 1020ae76531SDavid Feng 1030ae76531SDavid Feng/* 1040ae76531SDavid Feng * Set up final (full) environment 1050ae76531SDavid Feng */ 1060ae76531SDavid Feng bl c_runtime_cpu_setup /* still call old routine */ 1070ae76531SDavid Feng 108ed64190fSSimon Glass/* TODO: For SPL, call spl_relocate_stack_gd() to alloc stack relocation */ 109ed64190fSSimon Glass 1100ae76531SDavid Feng/* 1110ae76531SDavid Feng * Clear BSS section 1120ae76531SDavid Feng */ 1130ae76531SDavid Feng ldr x0, =__bss_start /* this is auto-relocated! */ 1140ae76531SDavid Feng ldr x1, =__bss_end /* this is auto-relocated! */ 1150ae76531SDavid Feng mov x2, #0 1160ae76531SDavid Fengclear_loop: 1170ae76531SDavid Feng str x2, [x0] 1180ae76531SDavid Feng add x0, x0, #8 1190ae76531SDavid Feng cmp x0, x1 1200ae76531SDavid Feng b.lo clear_loop 1210ae76531SDavid Feng 1220ae76531SDavid Feng /* call board_init_r(gd_t *id, ulong dest_addr) */ 1230ae76531SDavid Feng mov x0, x18 /* gd_t */ 1240ae76531SDavid Feng ldr x1, [x18, #GD_RELOCADDR] /* dest_addr */ 1250ae76531SDavid Feng b board_init_r /* PC relative jump */ 1260ae76531SDavid Feng 1270ae76531SDavid Feng /* NOTREACHED - board_init_r() does not return */ 1280ae76531SDavid Feng 129b2d5ac59SScott Wood#endif /* !CONFIG_SPL_BUILD */ 130b2d5ac59SScott Wood 1310ae76531SDavid FengENDPROC(_main) 132