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Tom Rini83d290c2018-05-06 17:58:06 -04001/* SPDX-License-Identifier: GPL-2.0+ */
David Feng0ae76532013-12-14 11:47:35 +08002/*
3 * crt0 - C-runtime startup Code for AArch64 U-Boot
4 *
5 * (C) Copyright 2013
6 * David Feng <fenghua@phytium.com.cn>
7 *
8 * (C) Copyright 2012
9 * Albert ARIBAUD <albert.u.boot@aribaud.net>
David Feng0ae76532013-12-14 11:47:35 +080010 */
11
12#include <config.h>
13#include <asm-offsets.h>
14#include <asm/macro.h>
15#include <linux/linkage.h>
16
17/*
18 * This file handles the target-independent stages of the U-Boot
19 * start-up where a C runtime environment is needed. Its entry point
20 * is _main and is branched into from the target's start.S file.
21 *
22 * _main execution sequence is:
23 *
24 * 1. Set up initial environment for calling board_init_f().
25 * This environment only provides a stack and a place to store
26 * the GD ('global data') structure, both located in some readily
27 * available RAM (SRAM, locked cache...). In this context, VARIABLE
28 * global data, initialized or not (BSS), are UNAVAILABLE; only
Simon Glassed641902015-08-01 08:55:46 -060029 * CONSTANT initialized data are available. GD should be zeroed
30 * before board_init_f() is called.
David Feng0ae76532013-12-14 11:47:35 +080031 *
32 * 2. Call board_init_f(). This function prepares the hardware for
33 * execution from system RAM (DRAM, DDR...) As system RAM may not
34 * be available yet, , board_init_f() must use the current GD to
35 * store any data which must be passed on to later stages. These
36 * data include the relocation destination, the future stack, and
37 * the future GD location.
38 *
David Feng0ae76532013-12-14 11:47:35 +080039 * 3. Set up intermediate environment where the stack and GD are the
40 * ones allocated by board_init_f() in system RAM, but BSS and
41 * initialized non-const data are still not available.
42 *
Simon Glassed641902015-08-01 08:55:46 -060043 * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
44 * relocates U-Boot from its current location into the relocation
45 * destination computed by board_init_f().
46 *
47 * 4b.For SPL, board_init_f() just returns (to crt0). There is no
48 * code relocation in SPL.
David Feng0ae76532013-12-14 11:47:35 +080049 *
50 * 5. Set up final environment for calling board_init_r(). This
51 * environment has BSS (initialized to 0), initialized non-const
52 * data (initialized to their intended value), and stack in system
Simon Glassed641902015-08-01 08:55:46 -060053 * RAM (for SPL moving the stack and GD into RAM is optional - see
54 * CONFIG_SPL_STACK_R). GD has retained values set by board_init_f().
David Feng0ae76532013-12-14 11:47:35 +080055 *
Simon Glassed641902015-08-01 08:55:46 -060056 * TODO: For SPL, implement stack relocation on AArch64.
57 *
58 * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
59 * at this point regarding memory, so call c_runtime_cpu_setup.
60 *
61 * 7. Branch to board_init_r().
62 *
63 * For more information see 'Board Initialisation Flow in README.
David Feng0ae76532013-12-14 11:47:35 +080064 */
65
66ENTRY(_main)
67
68/*
69 * Set up initial C runtime environment and call board_init_f(0).
70 */
Philipp Tomsichfaa18db2017-07-28 20:04:09 +020071#if defined(CONFIG_TPL_BUILD) && defined(CONFIG_TPL_NEEDS_SEPARATE_STACK)
Philipp Tomsichc3be6192017-07-04 11:02:14 +020072 ldr x0, =(CONFIG_TPL_STACK)
73#elif defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
Scott Woodb2d5ac52015-03-24 13:25:02 -070074 ldr x0, =(CONFIG_SPL_STACK)
Stephen Warrene6c90442017-12-19 18:30:36 -070075#elif defined(CONFIG_SYS_INIT_SP_BSS_OFFSET)
76 adr x0, __bss_start
77 add x0, x0, #CONFIG_SYS_INIT_SP_BSS_OFFSET
Scott Woodb2d5ac52015-03-24 13:25:02 -070078#else
David Feng0ae76532013-12-14 11:47:35 +080079 ldr x0, =(CONFIG_SYS_INIT_SP_ADDR)
Scott Woodb2d5ac52015-03-24 13:25:02 -070080#endif
David Feng0ae76532013-12-14 11:47:35 +080081 bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */
Albert ARIBAUDecc30662015-11-25 17:56:32 +010082 mov x0, sp
83 bl board_init_f_alloc_reserve
Simon Glass931bec32015-10-19 06:49:59 -060084 mov sp, x0
Stephen Warrena7370282016-01-14 14:03:11 -070085 /* set up gd here, outside any C code */
86 mov x18, x0
Albert ARIBAUDecc30662015-11-25 17:56:32 +010087 bl board_init_f_init_reserve
Simon Glass931bec32015-10-19 06:49:59 -060088
David Feng0ae76532013-12-14 11:47:35 +080089 mov x0, #0
90 bl board_init_f
91
Scott Woodb2d5ac52015-03-24 13:25:02 -070092#if !defined(CONFIG_SPL_BUILD)
David Feng0ae76532013-12-14 11:47:35 +080093/*
94 * Set up intermediate environment (new sp and gd) and call
95 * relocate_code(addr_moni). Trick here is that we'll return
96 * 'here' but relocated.
97 */
98 ldr x0, [x18, #GD_START_ADDR_SP] /* x0 <- gd->start_addr_sp */
99 bic sp, x0, #0xf /* 16-byte alignment for ABI compliance */
zijun_hu01a83592017-09-22 14:39:13 +0800100 ldr x18, [x18, #GD_NEW_GD] /* x18 <- gd->new_gd */
David Feng0ae76532013-12-14 11:47:35 +0800101
102 adr lr, relocation_return
Stephen Warren49e93872017-11-02 18:11:27 -0600103#if CONFIG_POSITION_INDEPENDENT
104 /* Add in link-vs-runtime offset */
105 adr x0, _start /* x0 <- Runtime value of _start */
106 ldr x9, _TEXT_BASE /* x9 <- Linked value of _start */
107 sub x9, x9, x0 /* x9 <- Run-vs-link offset */
108 add lr, lr, x9
109#endif
110 /* Add in link-vs-relocation offset */
David Feng0ae76532013-12-14 11:47:35 +0800111 ldr x9, [x18, #GD_RELOC_OFF] /* x9 <- gd->reloc_off */
112 add lr, lr, x9 /* new return address after relocation */
113 ldr x0, [x18, #GD_RELOCADDR] /* x0 <- gd->relocaddr */
114 b relocate_code
115
116relocation_return:
117
118/*
119 * Set up final (full) environment
120 */
121 bl c_runtime_cpu_setup /* still call old routine */
Jeremy Huntb8cb51d2016-07-18 12:01:02 -0400122#endif /* !CONFIG_SPL_BUILD */
Philipp Tomsich7a70c992017-03-01 21:04:15 +0100123#if defined(CONFIG_SPL_BUILD)
124 bl spl_relocate_stack_gd /* may return NULL */
York Sune421b642017-12-07 13:16:07 -0800125 /* set up gd here, outside any C code, if new stack is returned */
126 cmp x0, #0
127 csel x18, x0, x18, ne
Philipp Tomsich7a70c992017-03-01 21:04:15 +0100128 /*
129 * Perform 'sp = (x0 != NULL) ? x0 : sp' while working
130 * around the constraint that conditional moves can not
131 * have 'sp' as an operand
132 */
133 mov x1, sp
134 cmp x0, #0
135 csel x0, x0, x1, ne
136 mov sp, x0
137#endif
Simon Glassed641902015-08-01 08:55:46 -0600138
David Feng0ae76532013-12-14 11:47:35 +0800139/*
140 * Clear BSS section
141 */
142 ldr x0, =__bss_start /* this is auto-relocated! */
143 ldr x1, =__bss_end /* this is auto-relocated! */
David Feng0ae76532013-12-14 11:47:35 +0800144clear_loop:
Masahiro Yamada07a63c72017-01-27 16:15:30 +0900145 str xzr, [x0], #8
David Feng0ae76532013-12-14 11:47:35 +0800146 cmp x0, x1
147 b.lo clear_loop
148
149 /* call board_init_r(gd_t *id, ulong dest_addr) */
150 mov x0, x18 /* gd_t */
151 ldr x1, [x18, #GD_RELOCADDR] /* dest_addr */
152 b board_init_r /* PC relative jump */
153
154 /* NOTREACHED - board_init_r() does not return */
155
David Feng0ae76532013-12-14 11:47:35 +0800156ENDPROC(_main)