[U-Boot] [PATCH PATCH v3 12/12] spl: fit: Allow the board to tell if more images must be loaded from FIT

[Jean-Jacques Hiblot]

spl_fit_get_image_name() is used to get the names of the images that the
SPL must load from the FIT. It relies on the content of a property present
in the FIT. The list of images is thus statically defined in the FIT.
With this scheme, it becomes quickly hard to manage combinations of more
than a hand few of images.
To address this problem, give the board-level code the opportunity to
add to the list of images. The images from the FIT property are loaded
first, and then the board_fit_get_additionnal_images() is called to
get more image names.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>

---

Changes in v3:
- removed the RFC prefix. This work will be needed soon by TI's AM65x
platform. and can probably benefit other modular platforms
- removed the last patch that provided an example of how to use this with
on a DRA76.
- removed the patch that made u-boot.img a symlink to u-boot.itb because
it breaks the build of many platforms (because files required to build the
ITB are missing)
- removed the patch to reduce the footprint of the am335x SPL. (already
merged)
- Made the boot flow more permissive (don't fail immediately if an overlay
is not present) and more verbose when an error occures
- handle the dependencies of the FIT generation in a more generic way
- use a dedicated kconfig option to enable the application of the overlays
by the SPL.

Changes in v2:
- reworked board_fit_get_additionnal_images() and how it used in spl_fit.c
- removed dtbo generation from dtso files and use .dts extension for the
  overlays
- add dynamic allocation usage in a separate patch
- defconfig change for the am335x_evm

 common/spl/spl_fit.c | 28 +++++++++++++++++++++++++---
 include/spl.h        | 16 ++++++++++++++++
 2 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/common/spl/spl_fit.c b/common/spl/spl_fit.c
index 8c5d15c3c8..f1e0ad8d73 100644
--- a/common/spl/spl_fit.c
+++ b/common/spl/spl_fit.c
@@ -25,6 +25,12 @@ __weak ulong board_spl_fit_size_align(ulong size)
 	return size;
 }
 
+__weak const char *board_fit_get_additionnal_images(int index,
+						    const char *type)
+{
+	return NULL;
+}
+
 /**
  * spl_fit_get_image_name(): By using the matching configuration subnode,
  * retrieve the name of an image, specified by a property name and an index
@@ -45,6 +51,7 @@ static int spl_fit_get_image_name(const void *fit, int images,
 	__maybe_unused int node;
 	int conf_node;
 	int len, i;
+	bool found = true;
 
 	conf_node = fit_find_config_node(fit);
 	if (conf_node < 0) {
@@ -70,12 +77,27 @@ static int spl_fit_get_image_name(const void *fit, int images,
 	for (i = 0; i < index; i++) {
 		str = strchr(str, '\0') + 1;
 		if (!str || (str - name >= len)) {
-			debug("no string for index %d\n", index);
-			return -E2BIG;
+			found = false;
+			break;
 		}
 	}
 
-	*outname = (char *)str;
+	if (!found) {
+		/*
+		 * no string in the property for this index. Check if the board
+		 * level code can supply one.
+		 */
+		str = board_fit_get_additionnal_images(index - i - 1, type);
+		if (str)
+			found = true;
+	}
+
+	if (!found) {
+		debug("no string for index %d\n", index);
+		return -E2BIG;
+	}
+
+	*outname = str;
 	return 0;
 }
 
diff --git a/include/spl.h b/include/spl.h
index a9aaef345f..b7a5d6a995 100644
--- a/include/spl.h
+++ b/include/spl.h
@@ -370,6 +370,22 @@ void board_spl_fit_post_load(ulong load_addr, size_t length);
  */
 ulong board_spl_fit_size_align(ulong size);
 
+/**
+ * board_fit_get_additionnal_images - Get additional image names from board-
+ *				      level code.
+ * This function can be used to provide the image names based on runtime
+ * detection. A classic use-case would when DTBOs are used to describe
+ * additionnal daughter cards.
+ *
+ * @param index	Index of the image. Starts at 0 and gets incremented after each
+ *		call to this function.
+ * @param type	The type of image. For example, "fdt" for DTBs
+ *
+ * @return	The name of the node describing the image. NULL indicates that
+ *		there no more images to get from this function.
+ */
+const char *board_fit_get_additionnal_images(int index, const char *type);
+
 /**
  * spl_perform_fixups() - arch/board-specific callback before processing
  *                        the boot-payload
-- 
2.17.1