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David Feng0ae76532013-12-14 11:47:35 +08001/*
2 * crt0 - C-runtime startup Code for AArch64 U-Boot
3 *
4 * (C) Copyright 2013
5 * David Feng <fenghua@phytium.com.cn>
6 *
7 * (C) Copyright 2012
8 * Albert ARIBAUD <albert.u.boot@aribaud.net>
9 *
10 * SPDX-License-Identifier: GPL-2.0+
11 */
12
13#include <config.h>
14#include <asm-offsets.h>
15#include <asm/macro.h>
16#include <linux/linkage.h>
17
18/*
19 * This file handles the target-independent stages of the U-Boot
20 * start-up where a C runtime environment is needed. Its entry point
21 * is _main and is branched into from the target's start.S file.
22 *
23 * _main execution sequence is:
24 *
25 * 1. Set up initial environment for calling board_init_f().
26 * This environment only provides a stack and a place to store
27 * the GD ('global data') structure, both located in some readily
28 * available RAM (SRAM, locked cache...). In this context, VARIABLE
29 * global data, initialized or not (BSS), are UNAVAILABLE; only
Simon Glassed641902015-08-01 08:55:46 -060030 * CONSTANT initialized data are available. GD should be zeroed
31 * before board_init_f() is called.
David Feng0ae76532013-12-14 11:47:35 +080032 *
33 * 2. Call board_init_f(). This function prepares the hardware for
34 * execution from system RAM (DRAM, DDR...) As system RAM may not
35 * be available yet, , board_init_f() must use the current GD to
36 * store any data which must be passed on to later stages. These
37 * data include the relocation destination, the future stack, and
38 * the future GD location.
39 *
David Feng0ae76532013-12-14 11:47:35 +080040 * 3. Set up intermediate environment where the stack and GD are the
41 * ones allocated by board_init_f() in system RAM, but BSS and
42 * initialized non-const data are still not available.
43 *
Simon Glassed641902015-08-01 08:55:46 -060044 * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
45 * relocates U-Boot from its current location into the relocation
46 * destination computed by board_init_f().
47 *
48 * 4b.For SPL, board_init_f() just returns (to crt0). There is no
49 * code relocation in SPL.
David Feng0ae76532013-12-14 11:47:35 +080050 *
51 * 5. Set up final environment for calling board_init_r(). This
52 * environment has BSS (initialized to 0), initialized non-const
53 * data (initialized to their intended value), and stack in system
Simon Glassed641902015-08-01 08:55:46 -060054 * RAM (for SPL moving the stack and GD into RAM is optional - see
55 * CONFIG_SPL_STACK_R). GD has retained values set by board_init_f().
David Feng0ae76532013-12-14 11:47:35 +080056 *
Simon Glassed641902015-08-01 08:55:46 -060057 * TODO: For SPL, implement stack relocation on AArch64.
58 *
59 * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
60 * at this point regarding memory, so call c_runtime_cpu_setup.
61 *
62 * 7. Branch to board_init_r().
63 *
64 * For more information see 'Board Initialisation Flow in README.
David Feng0ae76532013-12-14 11:47:35 +080065 */
66
67ENTRY(_main)
68
69/*
70 * Set up initial C runtime environment and call board_init_f(0).
71 */
Scott Woodb2d5ac52015-03-24 13:25:02 -070072#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
73 ldr x0, =(CONFIG_SPL_STACK)
74#else
David Feng0ae76532013-12-14 11:47:35 +080075 ldr x0, =(CONFIG_SYS_INIT_SP_ADDR)
Scott Woodb2d5ac52015-03-24 13:25:02 -070076#endif
David Feng0ae76532013-12-14 11:47:35 +080077 bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */
Albert ARIBAUDecc30662015-11-25 17:56:32 +010078 mov x0, sp
79 bl board_init_f_alloc_reserve
Simon Glass931bec32015-10-19 06:49:59 -060080 mov sp, x0
Stephen Warrena7370282016-01-14 14:03:11 -070081 /* set up gd here, outside any C code */
82 mov x18, x0
Albert ARIBAUDecc30662015-11-25 17:56:32 +010083 bl board_init_f_init_reserve
Simon Glass931bec32015-10-19 06:49:59 -060084
David Feng0ae76532013-12-14 11:47:35 +080085 mov x0, #0
86 bl board_init_f
87
Scott Woodb2d5ac52015-03-24 13:25:02 -070088#if !defined(CONFIG_SPL_BUILD)
David Feng0ae76532013-12-14 11:47:35 +080089/*
90 * Set up intermediate environment (new sp and gd) and call
91 * relocate_code(addr_moni). Trick here is that we'll return
92 * 'here' but relocated.
93 */
94 ldr x0, [x18, #GD_START_ADDR_SP] /* x0 <- gd->start_addr_sp */
95 bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */
96 ldr x18, [x18, #GD_BD] /* x18 <- gd->bd */
97 sub x18, x18, #GD_SIZE /* new GD is below bd */
98
99 adr lr, relocation_return
100 ldr x9, [x18, #GD_RELOC_OFF] /* x9 <- gd->reloc_off */
101 add lr, lr, x9 /* new return address after relocation */
102 ldr x0, [x18, #GD_RELOCADDR] /* x0 <- gd->relocaddr */
103 b relocate_code
104
105relocation_return:
106
107/*
108 * Set up final (full) environment
109 */
110 bl c_runtime_cpu_setup /* still call old routine */
Jeremy Huntb8cb51d2016-07-18 12:01:02 -0400111#endif /* !CONFIG_SPL_BUILD */
Philipp Tomsich7a70c992017-03-01 21:04:15 +0100112#if defined(CONFIG_SPL_BUILD)
113 bl spl_relocate_stack_gd /* may return NULL */
114 /*
115 * Perform 'sp = (x0 != NULL) ? x0 : sp' while working
116 * around the constraint that conditional moves can not
117 * have 'sp' as an operand
118 */
119 mov x1, sp
120 cmp x0, #0
121 csel x0, x0, x1, ne
122 mov sp, x0
123#endif
Simon Glassed641902015-08-01 08:55:46 -0600124
David Feng0ae76532013-12-14 11:47:35 +0800125/*
126 * Clear BSS section
127 */
128 ldr x0, =__bss_start /* this is auto-relocated! */
129 ldr x1, =__bss_end /* this is auto-relocated! */
David Feng0ae76532013-12-14 11:47:35 +0800130clear_loop:
Masahiro Yamada07a63c72017-01-27 16:15:30 +0900131 str xzr, [x0], #8
David Feng0ae76532013-12-14 11:47:35 +0800132 cmp x0, x1
133 b.lo clear_loop
134
135 /* call board_init_r(gd_t *id, ulong dest_addr) */
136 mov x0, x18 /* gd_t */
137 ldr x1, [x18, #GD_RELOCADDR] /* dest_addr */
138 b board_init_r /* PC relative jump */
139
140 /* NOTREACHED - board_init_r() does not return */
141
David Feng0ae76532013-12-14 11:47:35 +0800142ENDPROC(_main)