[U-Boot] [PATCH v3 08/12] armv7: start.S: fixes and enhancements for SPL

[Aneesh V]

- Allow SPL to have .bss disjoint from rest of the image
- Allow for .bss setup in CONFIG_SPL_BUILD case too.
- Take care of the special case where relocation offset = 0.
- Compile out exception handling code and install a simpler
  vector

Signed-off-by: Aneesh V <aneesh at ti.com>
---
V3:
* Taken care of the case where .bss is at a lower address
  comapred to  _start
---
 arch/arm/cpu/armv7/start.S    |   50 ++++++++++++++++++++++++++++++----------
 arch/arm/cpu/armv7/u-boot.lds |    2 +
 2 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index d2a6207..5be436f 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -42,7 +42,16 @@ _start: b	reset
 	ldr	pc, _not_used
 	ldr	pc, _irq
 	ldr	pc, _fiq
-
+#ifdef CONFIG_SPL_BUILD
+_undefined_instruction: .word _undefined_instruction
+_software_interrupt:	.word _software_interrupt
+_prefetch_abort:	.word _prefetch_abort
+_data_abort:		.word _data_abort
+_not_used:		.word _not_used
+_irq:			.word _irq
+_fiq:			.word _fiq
+_pad:			.word 0x12345678 /* now 16*4=64 */
+#else
 _undefined_instruction: .word undefined_instruction
 _software_interrupt:	.word software_interrupt
 _prefetch_abort:	.word prefetch_abort
@@ -51,6 +60,8 @@ _not_used:		.word not_used
 _irq:			.word irq
 _fiq:			.word fiq
 _pad:			.word 0x12345678 /* now 16*4=64 */
+#endif	/* CONFIG_SPL_BUILD */
+
 .global _end_vect
 _end_vect:
 
@@ -89,6 +100,10 @@ _armboot_start:
 _bss_start_ofs:
 	.word __bss_start - _start
 
+.global	_image_copy_end_ofs
+_image_copy_end_ofs:
+	.word 	__image_copy_end - _start
+
 .globl _bss_end_ofs
 _bss_end_ofs:
 	.word __bss_end__ - _start
@@ -182,12 +197,11 @@ stack_setup:
 	mov	sp, r4
 
 	adr	r0, _start
-#ifndef CONFIG_SPL_BUILD
 	cmp	r0, r6
+	moveq	r9, #0		/* no relocation. relocation offset(r9) = 0 */
 	beq	clear_bss		/* skip relocation */
-#endif
 	mov	r1, r6			/* r1 <- scratch for copy_loop */
-	ldr	r3, _bss_start_ofs
+	ldr	r3, _image_copy_end_ofs
 	add	r2, r0, r3		/* r2 <- source end address	    */
 
 copy_loop:
@@ -235,20 +249,34 @@ fixnext:
 	add	r2, r2, #8		/* each rel.dyn entry is 8 bytes */
 	cmp	r2, r3
 	blo	fixloop
+	b	clear_bss
+_rel_dyn_start_ofs:
+	.word __rel_dyn_start - _start
+_rel_dyn_end_ofs:
+	.word __rel_dyn_end - _start
+_dynsym_start_ofs:
+	.word __dynsym_start - _start
+
+#endif	/* #ifndef CONFIG_SPL_BUILD */
 
 clear_bss:
+#ifdef CONFIG_SPL_BUILD
+	/* No relocation for SPL */
+	ldr	r0, =__bss_start
+	ldr	r1, =__bss_end__
+#else
 	ldr	r0, _bss_start_ofs
 	ldr	r1, _bss_end_ofs
 	mov	r4, r6			/* reloc addr */
 	add	r0, r0, r4
 	add	r1, r1, r4
+#endif
 	mov	r2, #0x00000000		/* clear			    */
 
 clbss_l:str	r2, [r0]		/* clear loop...		    */
 	add	r0, r0, #4
 	cmp	r0, r1
 	bne	clbss_l
-#endif	/* #ifndef CONFIG_SPL_BUILD */
 
 /*
  * We are done. Do not return, instead branch to second part of board
@@ -276,13 +304,6 @@ jump_2_ram:
 _board_init_r_ofs:
 	.word board_init_r - _start
 
-_rel_dyn_start_ofs:
-	.word __rel_dyn_start - _start
-_rel_dyn_end_ofs:
-	.word __rel_dyn_end - _start
-_dynsym_start_ofs:
-	.word __dynsym_start - _start
-
 /*************************************************************************
  *
  * CPU_init_critical registers
@@ -327,6 +348,8 @@ cpu_init_crit:
 	bl	lowlevel_init		@ go setup pll,mux,memory
 	mov	lr, ip			@ restore link
 	mov	pc, lr			@ back to my caller
+
+#ifndef CONFIG_SPL_BUILD
 /*
  *************************************************************************
  *
@@ -514,4 +537,5 @@ fiq:
 	bad_save_user_regs
 	bl	do_fiq
 
-#endif
+#endif /* CONFIG_USE_IRQ */
+#endif /* CONFIG_SPL_BUILD */
diff --git a/arch/arm/cpu/armv7/u-boot.lds b/arch/arm/cpu/armv7/u-boot.lds
index dbae54d..40ecf78 100644
--- a/arch/arm/cpu/armv7/u-boot.lds
+++ b/arch/arm/cpu/armv7/u-boot.lds
@@ -55,6 +55,8 @@ SECTIONS
 
 	. = ALIGN(4);
 
+	__image_copy_end = .;
+
 	.rel.dyn : {
 		__rel_dyn_start = .;
 		*(.rel*)
-- 
1.7.0.4