[U-Boot] [PATCH v5 1/3] arm: spl: Fix SPL booting for OMAP3

[Stefan Roese]

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 at denx.de>
Cc: Tom Rini <trini at ti.com>
Cc: Albert ARIBAUD <albert.u.boot at aribaud.net>
---
Albert, I'm not really happy with this patch as it evolves now. As you
will see, I had to make some further additions to crt0.S to fix a
problem for non-SPL builds and to fix compilation errors for non-OMAP
platforms. This gets quite ugly now. Looking back at my patch v1, this
looks much less intrusive.

What do you think?

v5:
- Fix a problem with non-SPL build on OMAP3 where s_init() needs
  to get called (if CONFIG_SKIP_LOWLEVEL_INIT is not defined).
  With the "code shuffling" in v3, s_init() was only called in the
  SPL U-Boot version.
- Fix compilation problem for non-OMAP platforms with assigning
  gdata to r8 (e.g. tx25).
  
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.
  
 arch/arm/cpu/armv7/omap3/board.c         | 2 --
 arch/arm/cpu/armv7/omap3/lowlevel_init.S | 3 +--
 arch/arm/lib/crt0.S                      | 8 ++++++++
 3 files changed, 9 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..78eb951 100644
--- a/arch/arm/lib/crt0.S
+++ b/arch/arm/lib/crt0.S
@@ -83,9 +83,17 @@ ENTRY(_main)
 	ldr	sp, =(CONFIG_SYS_INIT_SP_ADDR)
 #endif
 	bic	sp, sp, #7	/* 8-byte alignment for ABI compliance */
+#if defined(CONFIG_OMAP34XX) && defined(CONFIG_SPL_BUILD)
+	ldr	r8, =gdata	/* SPL assigns r8 directly to &gdata */
+#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
+#if defined(CONFIG_OMAP34XX) && \
+	(defined(CONFIG_SPL_BUILD) || !defined(CONFIG_SKIP_LOWLEVEL_INIT))
+	bl	s_init		/* s_init() needs GD to be setup */
+#endif
 	mov	r0, #0
 	bl	board_init_f
 
-- 
1.8.3.1