[PATCH 1/5] arm: Add new config option ARCH_VERY_EARLY_INIT

["Pali Rohár" <pali@kernel.org>]

When this option is set then ARM _main() function would call
arch_very_early_init() function at the beginning. It would be before
calling any other functions like debug_uart_init() and also before
initializing C runtime environment.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 arch/arm/Kconfig    | 6 ++++++
 arch/arm/lib/crt0.S | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0afec5155b1b..9898c7d68e1b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -401,6 +401,12 @@ config SYS_ARM_CACHE_WRITEALLOC
 	  write is performed.
 endchoice
 
+config ARCH_VERY_EARLY_INIT
+	bool
+
+config SPL_ARCH_VERY_EARLY_INIT
+	bool
+
 config ARCH_CPU_INIT
 	bool "Enable ARCH_CPU_INIT"
 	help
diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
index ba312901f331..612a2d5b698e 100644
--- a/arch/arm/lib/crt0.S
+++ b/arch/arm/lib/crt0.S
@@ -90,6 +90,11 @@ clbss_l:cmp	r0, r1			/* while not at end of BSS */
 
 ENTRY(_main)
 
+/* Call arch_very_early_init before initializing C runtime environment. */
+#if CONFIG_IS_ENABLED(ARCH_VERY_EARLY_INIT)
+	bl	arch_very_early_init
+#endif
+
 /*
  * Set up initial C runtime environment and call board_init_f(0).
  */
-- 
2.20.1