arm: init: export prev_bl_fdt_addr

When booting U-Boot on board with a locked down first-stage bootloader,
we emulate the Linux boot header. By passing the U-Boot FDT through this
first-stage bootloader and retrieving it afterwards we can pre-populate
the memory nodes and other info like the KASLR address.

Add a function to export the FDT addr so that boards can use it over the
built-in FDT.

Don't check is_addr_accessible() here because we might not yet have a
valid mem_map if it's going to be populated from the FDT, let the board
do their own validation instead.

Reviewed-by: Tom Rini <[email protected]>
Reviewed-by: Sumit Garg <[email protected]>
Tested-by: Sumit Garg <[email protected]> #qcs404
Signed-off-by: Caleb Connolly <[email protected]>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/init.h b/include/init.h
index 9a1951d10a0..630d86729c4 100644
--- a/include/init.h
+++ b/include/init.h
@@ -168,6 +168,17 @@ defined(CONFIG_SAVE_PREV_BL_FDT_ADDR)
  * Return: 0 if ok; -ENODATA on error
  */
 int save_prev_bl_data(void);
+
+/**
+ * get_prev_bl_fdt_addr - When u-boot is chainloaded, get the address
+ * of the FDT passed by the previous bootloader.
+ *
+ * Return: the address of the FDT passed by the previous bootloader
+ * or 0 if not found.
+ */
+phys_addr_t get_prev_bl_fdt_addr(void);
+#else
+#define get_prev_bl_fdt_addr() 0LLU
 #endif
 
 /**