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authorAngelos Mouzakitis <a.mouzakitis@virtualopensystems.com>2023-10-10 14:33:42 +0000
committerAngelos Mouzakitis <a.mouzakitis@virtualopensystems.com>2023-10-10 14:33:42 +0000
commitaf1a266670d040d2f4083ff309d732d648afba2a (patch)
tree2fc46203448ddcc6f81546d379abfaeb323575e9 /roms/u-boot/arch/arm/lib/crt0.S
parente02cda008591317b1625707ff8e115a4841aa889 (diff)
Add submodule dependency filesHEADmaster
Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec
Diffstat (limited to 'roms/u-boot/arch/arm/lib/crt0.S')
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diff --git a/roms/u-boot/arch/arm/lib/crt0.S b/roms/u-boot/arch/arm/lib/crt0.S
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+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * crt0 - C-runtime startup Code for ARM U-Boot
+ *
+ * Copyright (c) 2012 Albert ARIBAUD <albert.u.boot@aribaud.net>
+ */
+
+#include <config.h>
+#include <asm-offsets.h>
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * This file handles the target-independent stages of the U-Boot
+ * start-up where a C runtime environment is needed. Its entry point
+ * is _main and is branched into from the target's start.S file.
+ *
+ * _main execution sequence is:
+ *
+ * 1. Set up initial environment for calling board_init_f().
+ * This environment only provides a stack and a place to store
+ * the GD ('global data') structure, both located in some readily
+ * available RAM (SRAM, locked cache...). In this context, VARIABLE
+ * global data, initialized or not (BSS), are UNAVAILABLE; only
+ * CONSTANT initialized data are available. GD should be zeroed
+ * before board_init_f() is called.
+ *
+ * 2. Call board_init_f(). This function prepares the hardware for
+ * execution from system RAM (DRAM, DDR...) As system RAM may not
+ * be available yet, , board_init_f() must use the current GD to
+ * store any data which must be passed on to later stages. These
+ * data include the relocation destination, the future stack, and
+ * the future GD location.
+ *
+ * 3. Set up intermediate environment where the stack and GD are the
+ * ones allocated by board_init_f() in system RAM, but BSS and
+ * initialized non-const data are still not available.
+ *
+ * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
+ * relocates U-Boot from its current location into the relocation
+ * destination computed by board_init_f().
+ *
+ * 4b.For SPL, board_init_f() just returns (to crt0). There is no
+ * code relocation in SPL.
+ *
+ * 5. Set up final environment for calling board_init_r(). This
+ * environment has BSS (initialized to 0), initialized non-const
+ * data (initialized to their intended value), and stack in system
+ * RAM (for SPL moving the stack and GD into RAM is optional - see
+ * CONFIG_SPL_STACK_R). GD has retained values set by board_init_f().
+ *
+ * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
+ * at this point regarding memory, so call c_runtime_cpu_setup.
+ *
+ * 7. Branch to board_init_r().
+ *
+ * For more information see 'Board Initialisation Flow in README.
+ */
+
+/*
+ * Macro for clearing BSS during SPL execution. Usually called during the
+ * relocation process for most boards before entering board_init_r(), but
+ * can also be done early before entering board_init_f() on plaforms that
+ * can afford it due to sufficient memory being available early.
+ */
+
+.macro CLEAR_BSS
+ ldr r0, =__bss_start /* this is auto-relocated! */
+
+#ifdef CONFIG_USE_ARCH_MEMSET
+ ldr r3, =__bss_end /* this is auto-relocated! */
+ mov r1, #0x00000000 /* prepare zero to clear BSS */
+
+ subs r2, r3, r0 /* r2 = memset len */
+ bl memset
+#else
+ ldr r1, =__bss_end /* this is auto-relocated! */
+ mov r2, #0x00000000 /* prepare zero to clear BSS */
+
+clbss_l:cmp r0, r1 /* while not at end of BSS */
+ strlo r2, [r0] /* clear 32-bit BSS word */
+ addlo r0, r0, #4 /* move to next */
+ blo clbss_l
+#endif
+.endm
+
+/*
+ * entry point of crt0 sequence
+ */
+
+ENTRY(_main)
+
+/*
+ * Set up initial C runtime environment and call board_init_f(0).
+ */
+
+#if defined(CONFIG_TPL_BUILD) && defined(CONFIG_TPL_NEEDS_SEPARATE_STACK)
+ ldr r0, =(CONFIG_TPL_STACK)
+#elif defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
+ ldr r0, =(CONFIG_SPL_STACK)
+#else
+ ldr r0, =(CONFIG_SYS_INIT_SP_ADDR)
+#endif
+ bic r0, r0, #7 /* 8-byte alignment for ABI compliance */
+ mov sp, r0
+ bl board_init_f_alloc_reserve
+ mov sp, r0
+ /* set up gd here, outside any C code */
+ mov r9, r0
+ bl board_init_f_init_reserve
+
+#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_EARLY_BSS)
+ CLEAR_BSS
+#endif
+
+ mov r0, #0
+ bl board_init_f
+
+#if ! defined(CONFIG_SPL_BUILD)
+
+/*
+ * Set up intermediate environment (new sp and gd) and call
+ * relocate_code(addr_moni). Trick here is that we'll return
+ * 'here' but relocated.
+ */
+
+ ldr r0, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */
+ bic r0, r0, #7 /* 8-byte alignment for ABI compliance */
+ mov sp, r0
+ ldr r9, [r9, #GD_NEW_GD] /* r9 <- gd->new_gd */
+
+ adr lr, here
+ ldr r0, [r9, #GD_RELOC_OFF] /* r0 = gd->reloc_off */
+ add lr, lr, r0
+#if defined(CONFIG_CPU_V7M)
+ orr lr, #1 /* As required by Thumb-only */
+#endif
+ ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
+ b relocate_code
+here:
+/*
+ * now relocate vectors
+ */
+
+ bl relocate_vectors
+
+/* Set up final (full) environment */
+
+ bl c_runtime_cpu_setup /* we still call old routine here */
+#endif
+#if !defined(CONFIG_SPL_BUILD) || CONFIG_IS_ENABLED(FRAMEWORK)
+
+#if !defined(CONFIG_SPL_BUILD) || !defined(CONFIG_SPL_EARLY_BSS)
+ CLEAR_BSS
+#endif
+
+# ifdef CONFIG_SPL_BUILD
+ /* Use a DRAM stack for the rest of SPL, if requested */
+ bl spl_relocate_stack_gd
+ cmp r0, #0
+ movne sp, r0
+ movne r9, r0
+# endif
+
+#if ! defined(CONFIG_SPL_BUILD)
+ bl coloured_LED_init
+ bl red_led_on
+#endif
+ /* call board_init_r(gd_t *id, ulong dest_addr) */
+ mov r0, r9 /* gd_t */
+ ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */
+ /* call board_init_r */
+#if CONFIG_IS_ENABLED(SYS_THUMB_BUILD)
+ ldr lr, =board_init_r /* this is auto-relocated! */
+ bx lr
+#else
+ ldr pc, =board_init_r /* this is auto-relocated! */
+#endif
+ /* we should not return here. */
+#endif
+
+ENDPROC(_main)