[PATCH v2 01/12] arm: arm926ej-s: start.S: port save_boot_params support from armv7 code

[Jesse Taube <mr.bossman075@gmail.com>]

From: Icenowy Zheng <icenowy@aosc.io>

The ARMv7 start code has support for saving some boot params at the
entry point, which is used by some SoCs to return to BROM.

Port this to ARM926EJ-S start code.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Jesse Taube <Mr.Bossman075@gmail.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
---
V1->V2:
* Nothing done
---
 arch/arm/cpu/arm926ejs/start.S | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/arm/cpu/arm926ejs/start.S b/arch/arm/cpu/arm926ejs/start.S
index 0afcc47aad..aca7793c57 100644
--- a/arch/arm/cpu/arm926ejs/start.S
+++ b/arch/arm/cpu/arm926ejs/start.S
@@ -17,6 +17,7 @@
 #include <asm-offsets.h>
 #include <config.h>
 #include <common.h>
+#include <linux/linkage.h>
 
 /*
  *************************************************************************
@@ -32,8 +33,13 @@
  */
 
 	.globl	reset
+	.globl	save_boot_params_ret
+	.type   save_boot_params_ret,%function
 
 reset:
+	/* Allow the board to save important registers */
+	b	save_boot_params
+save_boot_params_ret:
 	/*
 	 * set the cpu to SVC32 mode
 	 */
@@ -110,3 +116,16 @@ flush_dcache:
 #endif
 	mov	pc, lr		/* back to my caller */
 #endif /* CONFIG_IS_ENABLED(SKIP_LOWLEVEL_INIT) */
+
+/*************************************************************************
+ *
+ * void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
+ *	__attribute__((weak));
+ *
+ * Stack pointer is not yet initialized at this moment
+ * Don't save anything to stack even if compiled with -O0
+ *
+ *************************************************************************/
+WEAK(save_boot_params)
+	b	save_boot_params_ret	/* back to my caller */
+ENDPROC(save_boot_params)
-- 
2.34.1