[U-Boot] [PATCH v4 1/3] arm: spl: Fix SPL booting for OMAP3

[Stefan Roese <sr@denx.de>]

Fix a problem with a re-assignment of r8 in the SPL version.

This patch now moves the call to s_init() to a later stage, right before
calling board_init_f(). And makes sure that r8 is correctly initialized
before s_init() is called. r8 now is only written in crt0.S.

This error was detected on the SPL port for the Compulab CM-T35 board
(OMAP3530).

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Tom Rini <trini@ti.com>
Acked-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
---
v4:
- Corrected commit text to reflect changed patch

v3:
- Some code shuffling in crt0.S as requested by Albert

v2:
- Change handling/initializing of r8 as suggested by Albert.
  It should only be written in crt0.S.
  
Tom, while working on this version one question came up:
Is lowlevel_init() (file arch/arm/cpu/armv7/omap3/lowlevel_init.S)
needed any more? It calls cpy_clk_code() to copy some clk init
code into SRAM. But I fail to see if and where this code is really
executed from SRAM. Maybe I missed something. Perhaps you could
shed some light into this.

Thanks, Stefan

 arch/arm/cpu/armv7/omap3/board.c         | 2 --
 arch/arm/cpu/armv7/omap3/lowlevel_init.S | 3 +--
 arch/arm/lib/crt0.S                      | 5 +++++
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm/cpu/armv7/omap3/board.c b/arch/arm/cpu/armv7/omap3/board.c
index b72fadc..8f41dcd 100644
--- a/arch/arm/cpu/armv7/omap3/board.c
+++ b/arch/arm/cpu/armv7/omap3/board.c
@@ -256,8 +256,6 @@ void s_init(void)
 #endif
 
 #ifdef CONFIG_SPL_BUILD
-	gd = &gdata;
-
 	preloader_console_init();
 
 	timer_init();
diff --git a/arch/arm/cpu/armv7/omap3/lowlevel_init.S b/arch/arm/cpu/armv7/omap3/lowlevel_init.S
index eacfef8..8539093 100644
--- a/arch/arm/cpu/armv7/omap3/lowlevel_init.S
+++ b/arch/arm/cpu/armv7/omap3/lowlevel_init.S
@@ -226,8 +226,7 @@ ENTRY(lowlevel_init)
 #endif /* NAND Boot */
 	mov	lr, ip		/* restore link reg */
 	ldr	ip, [sp]	/* restore save ip */
-	/* tail-call s_init to setup pll, mux, memory */
-	b	s_init
+	mov	pc, lr
 
 ENDPROC(lowlevel_init)
 
diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
index a5bffb8..9bd7c24 100644
--- a/arch/arm/lib/crt0.S
+++ b/arch/arm/lib/crt0.S
@@ -83,9 +83,14 @@ ENTRY(_main)
 	ldr	sp, =(CONFIG_SYS_INIT_SP_ADDR)
 #endif
 	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
+#if defined(CONFIG_SPL_BUILD)
+	ldr	r8, =gdata	/* SPL assigns r8 directly to &gdata */
+	bl	s_init		/* s_init() needs GD to be setup */
+#else
 	sub	sp, #GD_SIZE	/* allocate one GD above SP */
 	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
 	mov	r8, sp		/* GD is above SP */
+#endif
 	mov	r0, #0
 	bl	board_init_f
 
-- 
1.8.2.3