[PATCH v3 4/4] efi: payload: make CONFIG_STATE_OVERLAY (and BareboxState export) work on x86

[chalianis1@gmail.com]

From: Chali Anis <chalianis1@gmail.com>

barebox_register_of() - the only thing that ever registers a live
devicetree root pre-boot on x86 EFI - lived in boarddata.c, which was
compiled solely for CONFIG_EFI_STUB (the chain-loaded/ARM handoff-data
entry point). x86 uses CONFIG_EFI_PAYLOAD (entry-single.c's standalone
efi_main()), so no code ever called it there: of_get_root_node() stayed
NULL for the entire pre-boot sequence. That's what state_overlay_apply()
(CONFIG_STATE_OVERLAY's postcore_initcall) and state_to_efivars_export()
(the BareboxState UEFI variable export) both rely on, so neither ever
had anything to work with on x86. Compile boarddata.o for
CONFIG_EFI_PAYLOAD too - efi_register_of() only needs BS, which
entry-single.c's efi_main() already sets before any initcall runs, and
handle_efi_boarddata() already no-ops cleanly when there is no PBL
handoff data, the normal case for this entry point.

On x86, actually binding a struct state to the node CONFIG_STATE_OVERLAY
adds still needs a fresh of_probe() pass: barebox_register_of() already
ran one, before the overlay added anything, and the next one needs to
happen later still than state_overlay_apply()'s own postcore_initcall,
too - PCI/SATA enumeration (and thus the disk cdevs a partuuid-based
state backend resolves against) only completes well after that point.
Add efi_devices_probe() at device_efi_initcall to cover it.

Finally, now that a state node reachable via CONFIG_STATE_OVERLAY is
something x86 can actually end up with pre-boot, add efi_late_init()'s
"skip loading the standalone state.dtb whenever a 'state' alias is
already present" check - it's only meaningful once that can happen.

Tested on QEMU as the EFI payload with a partuuid-referenced backend.

Assisted-by: Claude Sonnet 5
Signed-off-by: Chali Anis <chalianis1@gmail.com>
---
 efi/payload/Makefile |  1 +
 efi/payload/init.c   | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/efi/payload/Makefile b/efi/payload/Makefile
index 6306540ab595..f8b19428a99c 100644
--- a/efi/payload/Makefile
+++ b/efi/payload/Makefile
@@ -11,3 +11,4 @@ obj-pbl-$(CONFIG_EFI_PAYLOAD) += early-mem.o
 obj-$(CONFIG_EFI_PAYLOAD) += entry-single.o
 pbl-$(CONFIG_EFI_STUB) += entry-multi.o
 obj-$(CONFIG_EFI_STUB) += boarddata.o
+obj-$(CONFIG_EFI_PAYLOAD) += boarddata.o
diff --git a/efi/payload/init.c b/efi/payload/init.c
index cdb73afffa2c..e644ec60bb87 100644
--- a/efi/payload/init.c
+++ b/efi/payload/init.c
@@ -355,7 +355,7 @@ static int efi_late_init(void)
 	void *fdt;
 	int ret;
 
-	if (!IS_ENABLED(CONFIG_STATE))
+	if (!IS_ENABLED(CONFIG_STATE) || of_find_node_by_alias(NULL, "state"))
 		return 0;
 
 	if (!get_mounted_path("/boot")) {
@@ -453,6 +453,22 @@ static int state_to_efivars_export(void)
 	return ret;
 }
 late_efi_initcall(state_to_efivars_export);
+
+/*
+ * On x86, PCI/SATA enumeration (and thus the disk cdevs a partuuid-based
+ * state backend resolves against) only completes well after the one
+ * of_probe() pass barebox_register_of() already did, before the state
+ * overlay even added its node. Re-probe once devices have actually shown
+ * up, so such a backend can still bind.
+ */
+static int __maybe_unused efi_devices_probe(void)
+{
+	return of_probe();
+}
+#if IS_ENABLED(CONFIG_X86)
+device_efi_initcall(efi_devices_probe);
+#endif
+
 static int do_efiexit(int argc, char *argv[])
 {
 	if (!BS)