diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 1b6e96b07..51e94be61 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -805,6 +805,11 @@ int mmc_part_switch_user(void)
 	return ret;
 }
 
+size_t mmc_boot_part_size(void)
+{
+	return mmc_ext_csd[CMD_EXTCSD_BOOT_SIZE_MULT] * SZ_128K;
+}
+
 size_t mmc_boot_part_read_blocks(int lba, uintptr_t buf, size_t size)
 {
 	size_t size_read;
diff --git a/include/drivers/mmc.h b/include/drivers/mmc.h
index e973248f7..e94693dd7 100644
--- a/include/drivers/mmc.h
+++ b/include/drivers/mmc.h
@@ -62,6 +62,7 @@
 #define CMD_EXTCSD_HS_TIMING		185
 #define CMD_EXTCSD_PART_SWITCH_TIME	199
 #define CMD_EXTCSD_SEC_CNT		212
+#define CMD_EXTCSD_BOOT_SIZE_MULT	226
 
 #define EXT_CSD_PART_CONFIG_ACC_MASK	GENMASK(2, 0)
 #define PART_CFG_BOOT_PARTITION1_ENABLE	(U(1) << 3)
@@ -262,6 +263,7 @@ size_t mmc_write_blocks(int lba, const uintptr_t buf, size_t size);
 size_t mmc_erase_blocks(int lba, size_t size);
 int mmc_part_switch_current_boot(void);
 int mmc_part_switch_user(void);
+size_t mmc_boot_part_size(void);
 size_t mmc_boot_part_read_blocks(int lba, uintptr_t buf, size_t size);
 int mmc_init(const struct mmc_ops *ops_ptr, unsigned int clk,
 	     unsigned int width, unsigned int flags,