[RFC PATCH 06/10] FWU: STM32MP1: Add support to read boot index from backup register

[Sughosh Ganu]

The FWU Multi Bank Update feature allows the platform to boot the
firmware images from one of the partitions(banks). The first stage
bootloader(fsbl) passes the value of the boot index, i.e. the bank
from which the firmware images were booted from to U-Boot. On the
STM32MP157C-DK2 board, this value is passed through one of the SoC's
backup register. Add a function to read the boot index value from the
backup register.

Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
---
 arch/arm/mach-stm32mp/include/mach/stm32.h | 1 +
 board/st/stm32mp1/stm32mp1.c               | 7 +++++++
 include/fwu_metadata.h                     | 1 +
 3 files changed, 9 insertions(+)

diff --git a/arch/arm/mach-stm32mp/include/mach/stm32.h b/arch/arm/mach-stm32mp/include/mach/stm32.h
index c11a9903f2..21ed9f12e4 100644
--- a/arch/arm/mach-stm32mp/include/mach/stm32.h
+++ b/arch/arm/mach-stm32mp/include/mach/stm32.h
@@ -97,6 +97,7 @@ enum boot_device {
 #define TAMP_BACKUP_REGISTER(x)		(STM32_TAMP_BASE + 0x100 + 4 * x)
 #define TAMP_BACKUP_MAGIC_NUMBER	TAMP_BACKUP_REGISTER(4)
 #define TAMP_BACKUP_BRANCH_ADDRESS	TAMP_BACKUP_REGISTER(5)
+#define TAMP_FWU_BOOT_IDX		TAMP_BACKUP_REGISTER(10)
 #define TAMP_COPRO_RSC_TBL_ADDRESS	TAMP_BACKUP_REGISTER(17)
 #define TAMP_COPRO_STATE		TAMP_BACKUP_REGISTER(18)
 #define TAMP_BOOT_CONTEXT		TAMP_BACKUP_REGISTER(20)
diff --git a/board/st/stm32mp1/stm32mp1.c b/board/st/stm32mp1/stm32mp1.c
index a6884d2772..32bba71289 100644
--- a/board/st/stm32mp1/stm32mp1.c
+++ b/board/st/stm32mp1/stm32mp1.c
@@ -990,6 +990,13 @@ int fwu_plat_get_blk_desc(struct blk_desc **desc)
 	return 0;
 }
 
+void fwu_plat_get_bootidx(void *boot_idx)
+{
+	u32 *bootidx = boot_idx;
+
+	*bootidx = readl(TAMP_FWU_BOOT_IDX);
+}
+
 struct fwu_metadata_ops *get_plat_fwu_metadata_ops(void)
 {
 	if (CONFIG_IS_ENABLED(TARGET_ST_STM32MP15x) &&
diff --git a/include/fwu_metadata.h b/include/fwu_metadata.h
index 6a5e814ab6..44f06f4c6a 100644
--- a/include/fwu_metadata.h
+++ b/include/fwu_metadata.h
@@ -124,5 +124,6 @@ int fwu_get_metadata(struct fwu_metadata **metadata);
 
 int fwu_plat_get_update_index(u32 *update_idx);
 int fwu_plat_get_blk_desc(struct blk_desc **desc);
+void fwu_plat_get_bootidx(void *boot_idx);
 
 #endif /* _FWU_METADATA_H_ */
-- 
2.17.1