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authorGraeme Russ <graeme.russ@gmail.com>2012-01-01 15:06:39 +1100
committerGraeme Russ <graeme.russ@gmail.com>2012-01-04 22:17:20 +1100
commitf48dd6fc6cc9fdf15408e98132dc5575a31026cf (patch)
tree2fe660cd6af72843d0798497a5f1bbb8c813b9ff /arch/x86
parent74bfbe1ba5ba99adccdc26dc4adbfb9221849310 (diff)
downloadu-boot-linaro-stable-f48dd6fc6cc9fdf15408e98132dc5575a31026cf.tar.gz
x86: Simplify Flash-to-RAM code execution transition
Move the relocation offset calculation out of assembler and into C. This also paves the way for the upcoming init sequence simplification by adding the board_init_f_r flash to RAM transitional function -- Changes for v2: - Added commit message - Minor adjustment to new stack address comment
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/cpu/start.S22
-rw-r--r--arch/x86/include/asm/u-boot-x86.h2
-rw-r--r--arch/x86/lib/board.c25
3 files changed, 30 insertions, 19 deletions
diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S
index 6027f5418..69a9b2cdd 100644
--- a/arch/x86/cpu/start.S
+++ b/arch/x86/cpu/start.S
@@ -96,32 +96,22 @@ car_init_ret:
movw $0x85, %ax
jmp die
-.globl relocate_code
-.type relocate_code, @function
-relocate_code:
+.globl board_init_f_r_trampoline
+.type board_init_f_r_trampoline, @function
+board_init_f_r_trampoline:
/*
* SDRAM has been initialised, U-Boot code has been copied into
* RAM, BSS has been cleared and relocation adjustments have been
* made. It is now time to jump into the in-RAM copy of U-Boot
*
- * %eax = Address of top of stack
- * %edx = Address of Global Data
- * %ecx = Base address of in-RAM copy of U-Boot
+ * %eax = Address of top of new stack
*/
/* Setup stack in RAM */
movl %eax, %esp
- /* Setup call address of in-RAM copy of board_init_r() */
- movl $board_init_r, %ebp
- addl (GENERATED_GD_RELOC_OFF)(%edx), %ebp
-
- /* Setup parameters to board_init_r() */
- movl %edx, %eax
- movl %ecx, %edx
-
- /* Jump to in-RAM copy of board_init_r() */
- call *%ebp
+ /* Re-enter U-Boot by calling board_init_f_r */
+ call board_init_f_r
die:
hlt
diff --git a/arch/x86/include/asm/u-boot-x86.h b/arch/x86/include/asm/u-boot-x86.h
index 755f88af0..c3d227783 100644
--- a/arch/x86/include/asm/u-boot-x86.h
+++ b/arch/x86/include/asm/u-boot-x86.h
@@ -61,5 +61,7 @@ u32 isa_map_rom(u32 bus_addr, int size);
int video_bios_init(void);
int video_init(void);
+void board_init_f_r_trampoline(ulong) __attribute__ ((noreturn));
+void board_init_f_r(void) __attribute__ ((noreturn));
#endif /* _U_BOOT_I386_H_ */
diff --git a/arch/x86/lib/board.c b/arch/x86/lib/board.c
index f9eb15bed..382ada784 100644
--- a/arch/x86/lib/board.c
+++ b/arch/x86/lib/board.c
@@ -253,10 +253,29 @@ void board_init_f(ulong boot_flags)
gd->flags |= GD_FLG_RELOC;
- /* Enter the relocated U-Boot! */
- relocate_code(gd->start_addr_sp, gd, gd->relocaddr);
+ /*
+ * SDRAM is now initialised, U-Boot has been copied into SDRAM,
+ * the BSS has been cleared etc. The final stack can now be setup
+ * in SDRAM. Code execution will continue (momentarily) in Flash,
+ * but with the stack in SDRAM and Global Data in temporary memory
+ * (CPU cache)
+ */
+ board_init_f_r_trampoline(gd->start_addr_sp);
+
+ /* NOTREACHED - board_init_f_r_trampoline() does not return */
+ while (1)
+ ;
+}
+
+void board_init_f_r(void)
+{
+ /*
+ * Transfer execution from Flash to RAM by calculating the address
+ * of the in-RAM copy of board_init_r() and calling it
+ */
+ (board_init_r + gd->reloc_off)(gd, gd->relocaddr);
- /* NOTREACHED - relocate_code() does not return */
+ /* NOTREACHED - board_init_r() does not return */
while (1)
;
}