[PATCH v3 01/10] arm: arm926ej-s: start.S: port save_boot_params support from armv7 code

Jesse Taube
2022-01-29T15:23:35Z

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>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Jesse Taube <Mr.Bossman075@gmail.com>
---
V1->V2:
* Nothing done
V2->V3:
* 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