[PATCH v2 1/4] efi: payload: ignore ESP state.dtb if device tree is populated

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

In preparation for allowing the state nodes to ship inside the barebox
binary (as we do for non-EFI-payload already), add provisions to skip
the external file if barebox already has a populated DT.

Do the check before looking at the ESP, so a system with a built-in
state doesn't log that it was unable to read state.dtb. We only warn
if the file exists and is ignored.

Also for the case that a state had already been set up, skip manual
creation of the state node.

Assisted-by: Claude:opus-5
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 efi/payload/init.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/efi/payload/init.c b/efi/payload/init.c
index 1e5f2eb8cf56..a79f51ea38fc 100644
--- a/efi/payload/init.c
+++ b/efi/payload/init.c
@@ -284,6 +284,7 @@ static int efi_late_init(void)
 {
 	const char *state_desc = "/boot/EFI/barebox/state.dtb";
 	struct device_node *state_root = NULL;
+	struct device_node *root;
 	size_t size;
 	void *fdt;
 	int ret;
@@ -291,6 +292,19 @@ static int efi_late_init(void)
 	if (!IS_ENABLED(CONFIG_STATE))
 		return 0;
 
+	/*
+	 * A device tree built into barebox takes precedence: any state it
+	 * describes has been instantiated by the state driver already.
+	 */
+	root = of_get_root_node();
+	if (root && !list_empty(&root->children)) {
+		struct stat s;
+
+		if (!stat(state_desc, &s))
+			pr_warn("device tree is populated, ignoring %s\n", state_desc);
+		return 0;
+	}
+
 	if (!get_mounted_path("/boot")) {
 		pr_warn("boot device couldn't be determined%s\n",
 			IS_ENABLED(CONFIG_FS_EFI) ? "" : " without CONFIG_FS_EFI");
@@ -320,6 +334,10 @@ static int efi_late_init(void)
 			return 0;
 		}
 
+		/* probing the registered tree may have instantiated it already */
+		if (state_by_node(np))
+			return 0;
+
 		state = state_new_from_node(np, false);
 		if (IS_ERR(state))
 			return PTR_ERR(state);
-- 
2.47.3