[PATCH 01/21] arm: init: export prev_bl_fdt_addr

[Caleb Connolly]

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.

Signed-off-by: Caleb Connolly <caleb.connolly at linaro.org>
---
This patch has no dependencies

Cc: Simon Glass <sjg at chromium.org>
---
 arch/arm/lib/save_prev_bl_data.c |  5 +++++
 include/init.h                   | 11 +++++++++++
 2 files changed, 16 insertions(+)

diff --git a/arch/arm/lib/save_prev_bl_data.c b/arch/arm/lib/save_prev_bl_data.c
index f7b23faf0d66..b286bac9bf00 100644
--- a/arch/arm/lib/save_prev_bl_data.c
+++ b/arch/arm/lib/save_prev_bl_data.c
@@ -45,6 +45,11 @@ bool is_addr_accessible(phys_addr_t addr)
 	return false;
 }
 
+phys_addr_t get_prev_bl_fdt_addr(void)
+{
+	return reg0;
+}
+
 int save_prev_bl_data(void)
 {
 	struct fdt_header *fdt_blob;
diff --git a/include/init.h b/include/init.h
index d57a24fd00dd..7a3ab152b65f 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
 
 /**

-- 
2.42.1