[PATCH v6 07/13] 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>
Reviewed-by: Patrick Delaunay <patrick.delaunay at foss.st.com>
---
Changes since V5:
* Shuffled the location of the TAMP_FWU_* macros as suggested by
  Patrick

 arch/arm/mach-stm32mp/include/mach/stm32.h | 5 +++++
 board/st/stm32mp1/stm32mp1.c               | 8 ++++++++
 include/fwu.h                              | 1 +
 3 files changed, 14 insertions(+)

diff --git a/arch/arm/mach-stm32mp/include/mach/stm32.h b/arch/arm/mach-stm32mp/include/mach/stm32.h
index 47e88fc3dc..0344de796e 100644
--- a/arch/arm/mach-stm32mp/include/mach/stm32.h
+++ b/arch/arm/mach-stm32mp/include/mach/stm32.h
@@ -100,11 +100,16 @@ 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_INFO_REG		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)
 #define TAMP_BOOTCOUNT			TAMP_BACKUP_REGISTER(21)
 
+#define TAMP_FWU_BOOT_IDX_MASK		GENMASK(3, 0)
+
+#define TAMP_FWU_BOOT_IDX_OFFSET	0
+
 #define TAMP_COPRO_STATE_OFF		0
 #define TAMP_COPRO_STATE_INIT		1
 #define TAMP_COPRO_STATE_CRUN		2
diff --git a/board/st/stm32mp1/stm32mp1.c b/board/st/stm32mp1/stm32mp1.c
index 3aa223d795..6b249fafbb 100644
--- a/board/st/stm32mp1/stm32mp1.c
+++ b/board/st/stm32mp1/stm32mp1.c
@@ -1006,4 +1006,12 @@ int fwu_plat_get_update_index(u32 *update_idx)
 
 	return ret;
 }
+
+void fwu_plat_get_bootidx(void *boot_idx)
+{
+	u32 *bootidx = boot_idx;
+
+	*bootidx = (readl(TAMP_FWU_BOOT_INFO_REG) >>
+		    TAMP_FWU_BOOT_IDX_OFFSET) & TAMP_FWU_BOOT_IDX_MASK;
+}
 #endif /* CONFIG_FWU_MULTI_BANK_UPDATE */
diff --git a/include/fwu.h b/include/fwu.h
index 38dceca9c5..edb28c9659 100644
--- a/include/fwu.h
+++ b/include/fwu.h
@@ -49,6 +49,7 @@ int fwu_revert_boot_index(void);
 int fwu_accept_image(efi_guid_t *img_type_id, u32 bank);
 int fwu_clear_accept_image(efi_guid_t *img_type_id, u32 bank);
 
+void fwu_plat_get_bootidx(void *boot_idx);
 int fwu_plat_get_alt_num(struct udevice *dev, efi_guid_t *image_guid,
 			 int *alt_num);
 int fwu_gpt_get_alt_num(struct blk_desc *desc, efi_guid_t *image_guid,
-- 
2.25.1