[PATCH v1 1/3] efi_loader: Add platform hook for FDT loading

[Aswin Murugan]

Introduce a weak function efi_load_platform_fdt() to allow platforms
to provide custom device tree selection logic. This enables platforms
with special requirements (such as multi-DTB selection based on
hardware detection) to load fdt.

The default weak implementation does nothing, Platforms can provide
a strong implementation to load platform-specific device trees.

Signed-off-by: Aswin Murugan <aswin.murugan at oss.qualcomm.com>
---
 include/efi_loader.h         |  2 ++
 lib/efi_loader/efi_bootmgr.c |  4 ++++
 lib/efi_loader/efi_fdt.c     | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 3e70ac07055..62c3df48f71 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -1303,4 +1303,6 @@ int efi_get_distro_fdt_name(char *fname, int size, int seq);
 
 void efi_load_distro_fdt(efi_handle_t handle, void **fdt, efi_uintn_t *fdt_size);
 
+void efi_load_platform_fdt(efi_handle_t handle, void **fdt, efi_uintn_t *fdt_size);
+
 #endif /* _EFI_LOADER_H */
diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
index a687f4d8e85..ed06a65feb7 100644
--- a/lib/efi_loader/efi_bootmgr.c
+++ b/lib/efi_loader/efi_bootmgr.c
@@ -1332,6 +1332,10 @@ efi_status_t efi_bootmgr_run(void *fdt)
 			efi_load_distro_fdt(handle, &fdt_distro, &fdt_size);
 			fdt = fdt_distro;
 		}
+		if (!fdt) {
+			efi_load_platform_fdt(handle, &fdt_distro, &fdt_size);
+			fdt = fdt_distro;
+		}
 	}
 
 	/*
diff --git a/lib/efi_loader/efi_fdt.c b/lib/efi_loader/efi_fdt.c
index bfaa9cfc207..bfcfd933adf 100644
--- a/lib/efi_loader/efi_fdt.c
+++ b/lib/efi_loader/efi_fdt.c
@@ -78,6 +78,29 @@ int efi_get_distro_fdt_name(char *fname, int size, int seq)
 	return 0;
 }
 
+/**
+ * efi_load_platform_fdt() - Platform-specific FDT loading hook (weak)
+ *
+ * @handle:	handle of loaded image
+ * @fdt:	on return device-tree, must be freed via efi_free_pages()
+ * @fdt_size:	buffer size
+ *
+ * This weak function allows platforms to provide custom DTB selection logic.
+ * The default implementation does nothing, allowing the standard distro boot
+ * path to handle FDT loading. Platforms can override this function to
+ * implement custom multi-DTB selection or other platform-specific logic.
+ *
+ * If this function successfully loads a DTB, it should set *fdt to point to
+ * the loaded DTB and return. If it cannot load a DTB, it should set *fdt to
+ * NULL, and the standard distro boot logic will be used as fallback.
+ */
+__weak void efi_load_platform_fdt(efi_handle_t handle, void **fdt,
+				  efi_uintn_t *fdt_size)
+{
+	/* Default: do nothing, let standard distro boot handle it */
+	*fdt = NULL;
+}
+
 /**
  * efi_load_distro_fdt() - load distro device-tree
  *
-- 
2.34.1