[PATCH v2] board_f: Add support for CONFIG_OF_BOARD_FIXUP for XIP images

["Marek Behún" <kabel@kernel.org>]

From: Pali Rohár <pali@kernel.org>

When U-Boot is running from flash memory (execute in place) then
gd->fdt_blob before relocation points to read-only flash memory.

So U-Boot calls board_fix_fdt() with read-only gd->fdt_blob pointer which
cause immediate CPU crash when callback is trying to modify gd->fdt_blob.

Fix this issue by introducing a new config option
OF_DTB_READONLY_BEFORE_RELOC which moves fix_fdt callback after the
reloc_fdt callback. This makes CONFIG_OF_BOARD_FIXUP working also if
U-Boot before relocation is not running from read/write (S)RAM memory.

This is required for mpc85xx boards when booting from flash NOR.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
---
Changes since v1:
- just changed the new Kconfig option name and associated help string
---
 common/board_f.c | 8 +++++++-
 dts/Kconfig      | 6 ++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/common/board_f.c b/common/board_f.c
index 18e2246733..35fb4a0753 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -911,7 +911,7 @@ static const init_fnc_t init_sequence_f[] = {
 	 *  - board info struct
 	 */
 	setup_dest_addr,
-#ifdef CONFIG_OF_BOARD_FIXUP
+#if defined(CONFIG_OF_BOARD_FIXUP) && !defined(CONFIG_OF_DTB_READONLY_BEFORE_RELOC)
 	fix_fdt,
 #endif
 #ifdef CONFIG_PRAM
@@ -926,6 +926,10 @@ static const init_fnc_t init_sequence_f[] = {
 	reserve_board,
 	reserve_global_data,
 	reserve_fdt,
+#if defined(CONFIG_OF_BOARD_FIXUP) && defined(CONFIG_OF_DTB_READONLY_BEFORE_RELOC)
+	reloc_fdt,
+	fix_fdt,
+#endif
 	reserve_bootstage,
 	reserve_bloblist,
 	reserve_arch,
@@ -936,7 +940,9 @@ static const init_fnc_t init_sequence_f[] = {
 	setup_bdinfo,
 	display_new_sp,
 	INIT_FUNC_WATCHDOG_RESET
+#if !defined(CONFIG_OF_BOARD_FIXUP) || !defined(CONFIG_OF_DTB_READONLY_BEFORE_RELOC)
 	reloc_fdt,
+#endif
 	reloc_bootstage,
 	reloc_bloblist,
 	setup_reloc,
diff --git a/dts/Kconfig b/dts/Kconfig
index bc5f22029f..29e5248b15 100644
--- a/dts/Kconfig
+++ b/dts/Kconfig
@@ -105,6 +105,12 @@ config OF_EMBED
 
 endchoice
 
+config OF_DTB_READONLY_BEFORE_RELOC
+	bool "Initial DTB (before relocation) for DT control is read-only"
+	help
+	  If initial (before relocation) DTB for DT control is read-only,
+	  (e.g. points to memory-mapped flash memory), set this option.
+
 config OF_BOARD
 	bool "Provided by the board (e.g a previous loader) at runtime"
 	default y if SANDBOX || OF_HAS_PRIOR_STAGE
-- 
2.35.1