[PATCH v5 05/15] board: ns3: add api to save boot parameters passed from BL31

[Rayagonda Kokatanur]

From: Abhishek Shah <abhishek.shah at broadcom.com>

Add API to save boot parameters passed from BL31

Use assembly implementation of save_boot_params instead of c function.
Because generally ATF does not set up SP_EL2 on exiting.
Thus, usage of a C function immediately after exiting with no stack
setup done by ATF explicitly, may cause SP_EL2 to be not sane,
which in turn causes a crash if this boot was not lucky to get
an SP_EL2 in valid range. Replace C implementation with assembly one
which does not use stack this early, and let u-boot to set up its stack
later.

Signed-off-by: Abhishek Shah <abhishek.shah at broadcom.com>
Signed-off-by: Rajesh Ravi <rajesh.ravi at broadcom.com>
Signed-off-by: Vladimir Olovyannikov <vladimir.olovyannikov at broadcom.com>
Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur at broadcom.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
---
Changes from v4:                                                                
 -Address self review comments,                                                 
  Correction- u-boot to U-Boot.

 arch/arm/cpu/armv8/bcmns3/lowlevel.S         |  9 +++++++
 arch/arm/include/asm/arch-bcmns3/bl33_info.h | 26 ++++++++++++++++++++
 board/broadcom/bcmns3/ns3.c                  | 10 ++++++++
 3 files changed, 45 insertions(+)
 create mode 100644 arch/arm/include/asm/arch-bcmns3/bl33_info.h

diff --git a/arch/arm/cpu/armv8/bcmns3/lowlevel.S b/arch/arm/cpu/armv8/bcmns3/lowlevel.S
index 6709c9a188..bf1a17ab03 100644
--- a/arch/arm/cpu/armv8/bcmns3/lowlevel.S
+++ b/arch/arm/cpu/armv8/bcmns3/lowlevel.S
@@ -87,3 +87,12 @@ ENTRY(__asm_flush_l3_dcache)
 	mov	lr, x29
 	ret
 ENDPROC(__asm_flush_l3_dcache)
+
+ENTRY(save_boot_params)
+/*
+ * void set_boot_params(uint64_t x0, uint64_t x1, uint64_t x2, uint64_t x3)
+ */
+	adr	x4, bl33_info
+	str	x0, [x4]
+	b	save_boot_params_ret
+ENDPROC(save_boot_params)
diff --git a/arch/arm/include/asm/arch-bcmns3/bl33_info.h b/arch/arm/include/asm/arch-bcmns3/bl33_info.h
new file mode 100644
index 0000000000..bbc95b0186
--- /dev/null
+++ b/arch/arm/include/asm/arch-bcmns3/bl33_info.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2020 Broadcom.
+ *
+ */
+
+#ifndef BL33_INFO_H
+#define BL33_INFO_H
+#include <asm/io.h>
+
+/* Increase version number each time this file is modified */
+#define BL33_INFO_VERSION	1
+
+struct chip_info {
+	unsigned int chip_id;
+	unsigned int rev_id;
+};
+
+struct bl33_info {
+	unsigned int version;
+	struct chip_info chip;
+};
+
+extern struct bl33_info *bl33_info;
+
+#endif
diff --git a/board/broadcom/bcmns3/ns3.c b/board/broadcom/bcmns3/ns3.c
index e38156723c..e51263f85e 100644
--- a/board/broadcom/bcmns3/ns3.c
+++ b/board/broadcom/bcmns3/ns3.c
@@ -8,6 +8,7 @@
 #include <asm/io.h>
 #include <asm/system.h>
 #include <asm/armv8/mmu.h>
+#include <asm/arch-bcmns3/bl33_info.h>
 
 static struct mm_region ns3_mem_map[] = {
 	{
@@ -33,8 +34,17 @@ struct mm_region *mem_map = ns3_mem_map;
 
 DECLARE_GLOBAL_DATA_PTR;
 
+/*
+ * Force the bl33_info to the data-section, as .bss will not be valid
+ * when save_boot_params is invoked.
+ */
+struct bl33_info *bl33_info __section(".data");
+
 int board_init(void)
 {
+	if (bl33_info->version != BL33_INFO_VERSION)
+		printf("*** warning: ATF BL31 and U-Boot not in sync! ***\n");
+
 	return 0;
 }
 
-- 
2.17.1