[U-Boot] [PATCH v5 3/8] ARMv7: PSCI: update the place of saving target PC

[macro.wave.z at gmail.com]

From: Hongbo Zhang <hongbo.zhang at nxp.com>

The legacy code saves target PC at stack top, this patch changes it to stack
bottom, because we will save more contents for PSCI v1.0, by this way we don't
need to adjust the stack pointer when more contents are saved.

Signed-off-by: Hongbo Zhang <hongbo.zhang at nxp.com>
Signed-off-by: Wang Dongsheng <dongsheng.wang at nxp.com>
---
 arch/arm/cpu/armv7/psci.S   | 9 +++++----
 arch/arm/include/asm/psci.h | 4 ++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/arm/cpu/armv7/psci.S b/arch/arm/cpu/armv7/psci.S
index 3b92f1d..5b235df 100644
--- a/arch/arm/cpu/armv7/psci.S
+++ b/arch/arm/cpu/armv7/psci.S
@@ -259,7 +259,8 @@ ENTRY(psci_cpu_on_common)
 
 	mov	r0, r1
 	bl	psci_get_cpu_stack_top		@ get stack top of target CPU
-	str	r2, [r0]			@ store target PC at stack top
+	sub	r5, r0, #PSCI_TARGET_PC_OFFSET
+	str	r2, [r5]			@ store target PC
 	dsb
 
 	pop	{pc}
@@ -286,14 +287,13 @@ ENDPROC(psci_cpu_off_common)
 
 @ expects CPU ID in r0 and returns stack top in r0
 ENTRY(psci_get_cpu_stack_top)
-	mov	r5, #0x400			@ 1kB of stack per CPU
+	mov	r5, #PSCI_PERCPU_STACK_SIZE	@ 1kB of stack per CPU
 	mul	r0, r0, r5
 
 	ldr	r5, =psci_text_end		@ end of monitor text
 	add	r5, r5, #0x2000			@ Skip two pages
 	lsr	r5, r5, #12			@ Align to start of page
 	lsl	r5, r5, #12
-	sub	r5, r5, #4			@ reserve 1 word for target PC
 	sub	r0, r5, r0			@ here's our stack!
 
 	bx	lr
@@ -306,7 +306,8 @@ ENTRY(psci_cpu_entry)
 
 	bl	psci_get_cpu_id			@ CPU ID => r0
 	bl	psci_get_cpu_stack_top		@ stack top => r0
-	ldr	r0, [r0]			@ target PC at stack top
+	sub	r0, r0, #PSCI_TARGET_PC_OFFSET
+	ldr	r0, [r0]			@ get target PC
 	b	_do_nonsec_entry
 ENDPROC(psci_cpu_entry)
 
diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
index 2367ec0..cb08544 100644
--- a/arch/arm/include/asm/psci.h
+++ b/arch/arm/include/asm/psci.h
@@ -63,6 +63,10 @@
 #define ARM_PSCI_1_0_FN_STAT_RESIDENCY		ARM_PSCI_0_2_FN(16)
 #define ARM_PSCI_1_0_FN_STAT_COUNT		ARM_PSCI_0_2_FN(17)
 
+/* size of percpu stack, 1kB */
+#define PSCI_PERCPU_STACK_SIZE		0x400
+#define PSCI_TARGET_PC_OFFSET		(PSCI_PERCPU_STACK_SIZE - 4)
+
 #ifndef __ASSEMBLY__
 int psci_update_dt(void *fdt);
 void psci_board_init(void);
-- 
2.1.4