mirror of
https://source.denx.de/u-boot/u-boot.git
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83d290c56f
When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com>
168 lines
4.9 KiB
ArmAsm
168 lines
4.9 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* crt0 - C-runtime startup Code for ARM U-Boot
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*
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* Copyright (c) 2012 Albert ARIBAUD <albert.u.boot@aribaud.net>
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*/
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#include <config.h>
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#include <asm-offsets.h>
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#include <linux/linkage.h>
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#ifdef CONFIG_CPU_V7M
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#include <asm/armv7m.h>
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#endif
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/*
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* This file handles the target-independent stages of the U-Boot
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* start-up where a C runtime environment is needed. Its entry point
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* is _main and is branched into from the target's start.S file.
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*
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* _main execution sequence is:
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*
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* 1. Set up initial environment for calling board_init_f().
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* This environment only provides a stack and a place to store
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* the GD ('global data') structure, both located in some readily
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* available RAM (SRAM, locked cache...). In this context, VARIABLE
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* global data, initialized or not (BSS), are UNAVAILABLE; only
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* CONSTANT initialized data are available. GD should be zeroed
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* before board_init_f() is called.
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*
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* 2. Call board_init_f(). This function prepares the hardware for
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* execution from system RAM (DRAM, DDR...) As system RAM may not
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* be available yet, , board_init_f() must use the current GD to
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* store any data which must be passed on to later stages. These
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* data include the relocation destination, the future stack, and
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* the future GD location.
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*
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* 3. Set up intermediate environment where the stack and GD are the
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* ones allocated by board_init_f() in system RAM, but BSS and
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* initialized non-const data are still not available.
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*
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* 4a.For U-Boot proper (not SPL), call relocate_code(). This function
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* relocates U-Boot from its current location into the relocation
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* destination computed by board_init_f().
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*
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* 4b.For SPL, board_init_f() just returns (to crt0). There is no
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* code relocation in SPL.
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*
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* 5. Set up final environment for calling board_init_r(). This
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* environment has BSS (initialized to 0), initialized non-const
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* data (initialized to their intended value), and stack in system
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* RAM (for SPL moving the stack and GD into RAM is optional - see
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* CONFIG_SPL_STACK_R). GD has retained values set by board_init_f().
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*
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* 6. For U-Boot proper (not SPL), some CPUs have some work left to do
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* at this point regarding memory, so call c_runtime_cpu_setup.
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*
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* 7. Branch to board_init_r().
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*
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* For more information see 'Board Initialisation Flow in README.
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*/
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/*
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* entry point of crt0 sequence
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*/
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ENTRY(_main)
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/*
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* Set up initial C runtime environment and call board_init_f(0).
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*/
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#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
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ldr r0, =(CONFIG_SPL_STACK)
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#else
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ldr r0, =(CONFIG_SYS_INIT_SP_ADDR)
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#endif
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bic r0, r0, #7 /* 8-byte alignment for ABI compliance */
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mov sp, r0
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bl board_init_f_alloc_reserve
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mov sp, r0
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/* set up gd here, outside any C code */
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mov r9, r0
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bl board_init_f_init_reserve
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mov r0, #0
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bl board_init_f
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#if ! defined(CONFIG_SPL_BUILD)
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/*
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* Set up intermediate environment (new sp and gd) and call
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* relocate_code(addr_moni). Trick here is that we'll return
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* 'here' but relocated.
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*/
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ldr r0, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */
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bic r0, r0, #7 /* 8-byte alignment for ABI compliance */
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mov sp, r0
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ldr r9, [r9, #GD_BD] /* r9 = gd->bd */
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sub r9, r9, #GD_SIZE /* new GD is below bd */
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adr lr, here
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ldr r0, [r9, #GD_RELOC_OFF] /* r0 = gd->reloc_off */
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add lr, lr, r0
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#if defined(CONFIG_CPU_V7M)
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orr lr, #1 /* As required by Thumb-only */
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#endif
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ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
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b relocate_code
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here:
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/*
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* now relocate vectors
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*/
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bl relocate_vectors
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/* Set up final (full) environment */
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bl c_runtime_cpu_setup /* we still call old routine here */
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#endif
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#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_FRAMEWORK)
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# ifdef CONFIG_SPL_BUILD
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/* Use a DRAM stack for the rest of SPL, if requested */
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bl spl_relocate_stack_gd
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cmp r0, #0
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movne sp, r0
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movne r9, r0
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# endif
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ldr r0, =__bss_start /* this is auto-relocated! */
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#ifdef CONFIG_USE_ARCH_MEMSET
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ldr r3, =__bss_end /* this is auto-relocated! */
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mov r1, #0x00000000 /* prepare zero to clear BSS */
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subs r2, r3, r0 /* r2 = memset len */
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bl memset
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#else
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ldr r1, =__bss_end /* this is auto-relocated! */
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mov r2, #0x00000000 /* prepare zero to clear BSS */
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clbss_l:cmp r0, r1 /* while not at end of BSS */
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#if defined(CONFIG_CPU_V7M)
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itt lo
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#endif
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strlo r2, [r0] /* clear 32-bit BSS word */
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addlo r0, r0, #4 /* move to next */
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blo clbss_l
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#endif
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#if ! defined(CONFIG_SPL_BUILD)
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bl coloured_LED_init
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bl red_led_on
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#endif
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/* call board_init_r(gd_t *id, ulong dest_addr) */
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mov r0, r9 /* gd_t */
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ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */
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/* call board_init_r */
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#if CONFIG_IS_ENABLED(SYS_THUMB_BUILD)
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ldr lr, =board_init_r /* this is auto-relocated! */
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bx lr
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#else
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ldr pc, =board_init_r /* this is auto-relocated! */
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#endif
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/* we should not return here. */
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#endif
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ENDPROC(_main)
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