arm/lib/crt0.S

1 /* SPDX-License-Identifier: GPL-2.0+ */
3  *  crt0 - C-runtime startup Code for ARM U-Boot
9 #include <asm-offsets.h>
14  * This file handles the target-independent stages of the U-Boot
15  * start-up where a C runtime environment is needed. Its entry point
23  *    available RAM (SRAM, locked cache...). In this context, VARIABLE
29  *    execution from system RAM (DRAM, DDR...) As system RAM may not
36  *    ones allocated by board_init_f() in system RAM, but BSS and
37  *    initialized non-const data are still not available.
39  * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
40  *    relocates U-Boot from its current location into the relocation
44  *    code relocation in SPL.
47  *    environment has BSS (initialized to 0), initialized non-const
49  *    RAM (for SPL moving the stack and GD into RAM is optional - see
52  * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
75 	bic	r0, r0, #7	/* 8-byte alignment for ABI compliance */
79 	/* set up gd here, outside any C code */
94 	ldr	r0, [r9, #GD_START_ADDR_SP]	/* sp = gd->start_addr_sp */
95 	bic	r0, r0, #7	/* 8-byte alignment for ABI compliance */
99 	ldr	r9, [r9, #GD_BD]		/* r9 = gd->bd */
116 	ldr	r0, [r9, #GD_ENV_ADDR]		/* r0 = gd->env_addr */
120 	ldr	r0, [r9, #GD_RELOC_OFF]		/* r0 = gd->reloc_off */
123 	orr	lr, #1				/* As required by Thumb-only */
125 	ldr	r0, [r9, #GD_RELOCADDR]		/* r0 = gd->relocaddr */
146 	ldr	r0, =__bss_start	/* this is auto-relocated! */
149 	ldr	r3, =__bss_end		/* this is auto-relocated! */
155 	ldr	r1, =__bss_end		/* this is auto-relocated! */
159 	strlo	r2, [r0]		/* clear 32-bit BSS word */
173 	ldr	lr, =board_init_r	/* this is auto-relocated! */
176 	ldr	pc, =board_init_r	/* this is auto-relocated! */
184 	.word _start - _main