arm: Allow lr to be saved by board code
The link register value can be required on some boards (e.g. FEL mode on
sunxi) so use a branch instruction to jump to save_boot_params() instead
of a branch link.
This requires a branch back to save_boot_params_ret so adjust the users
to deal with this. For exynos just drop the function since it doesn't
do anything.
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/arch/arm/cpu/armv7/exynos/spl_boot.c b/arch/arm/cpu/armv7/exynos/spl_boot.c
index bc237c9..c7f943e 100644
--- a/arch/arm/cpu/armv7/exynos/spl_boot.c
+++ b/arch/arm/cpu/armv7/exynos/spl_boot.c
@@ -309,4 +309,3 @@
while (1)
;
}
-void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3) {}
diff --git a/arch/arm/cpu/armv7/omap-common/lowlevel_init.S b/arch/arm/cpu/armv7/omap-common/lowlevel_init.S
index 86c0e42..e19c7ae 100644
--- a/arch/arm/cpu/armv7/omap-common/lowlevel_init.S
+++ b/arch/arm/cpu/armv7/omap-common/lowlevel_init.S
@@ -19,7 +19,7 @@
ENTRY(save_boot_params)
ldr r1, =OMAP_SRAM_SCRATCH_BOOT_PARAMS
str r0, [r1]
- bx lr
+ b save_boot_params_ret
ENDPROC(save_boot_params)
ENTRY(set_pl310_ctrl_reg)
diff --git a/arch/arm/cpu/armv7/omap3/lowlevel_init.S b/arch/arm/cpu/armv7/omap3/lowlevel_init.S
index 78577b1..80cb263 100644
--- a/arch/arm/cpu/armv7/omap3/lowlevel_init.S
+++ b/arch/arm/cpu/armv7/omap3/lowlevel_init.S
@@ -23,7 +23,7 @@
ldr r5, [r0, #0x4]
and r5, r5, #0xff
str r5, [r4]
- bx lr
+ b save_boot_params_ret
ENDPROC(save_boot_params)
#endif
diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 70048c1..9b49ece 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -31,9 +31,12 @@
*************************************************************************/
.globl reset
+ .globl save_boot_params_ret
reset:
- bl save_boot_params
+ /* Allow the board to save important registers */
+ b save_boot_params
+save_boot_params_ret:
/*
* disable interrupts (FIQ and IRQ), also set the cpu to SVC32 mode,
* except if in HYP mode already
@@ -96,7 +99,7 @@
*
*************************************************************************/
ENTRY(save_boot_params)
- bx lr @ back to my caller
+ b save_boot_params_ret @ back to my caller
ENDPROC(save_boot_params)
.weak save_boot_params
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index 89f2294..7820486 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -142,6 +142,21 @@
#ifndef __ASSEMBLY__
+/**
+ * save_boot_params() - Save boot parameters before starting reset sequence
+ *
+ * If you provide this function it will be called immediately U-Boot starts,
+ * both for SPL and U-Boot proper.
+ *
+ * All registers are unchanged from U-Boot entry. No registers need be
+ * preserved.
+ *
+ * This is not a normal C function. There is no stack. Return by branching to
+ * save_boot_params_ret.
+ *
+ * void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3);
+ */
+
#define isb() __asm__ __volatile__ ("" : : : "memory")
#define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");