mach-snapdragon: track boot source

Keep track of whether we were loaded via ABL or if U-Boot is running as
a first-stage bootloader.

For now we set this based on if we have a valid external FDT or not,
since it isn't possible to chainload U-Boot from ABL without there being
an external FDT.

This will be used to inform the capsule update logic which partition
U-Boot is flashed to.

Signed-off-by: Caleb Connolly <[email protected]>
Link: https://lore.kernel.org/r/20250411-b4-qcom-capsule-update-improvements-v2-1-27f6b2fcc4a9@linaro.org
Signed-off-by: Casey Connolly <[email protected]>

2 files changed, 40 insertions, 0 deletions

diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c
index fe29f2ea6e9..8f7fc19cadc 100644
--- a/arch/arm/mach-snapdragon/board.c
+++ b/arch/arm/mach-snapdragon/board.c
@@ -37,6 +37,8 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+enum qcom_boot_source qcom_boot_source __section(".data") = 0;
+
 static struct mm_region rbx_mem_map[CONFIG_NR_DRAM_BANKS + 2] = { { 0 } };
 
 struct mm_region *mem_map = rbx_mem_map;
@@ -238,6 +240,12 @@ int board_fdt_blob_setup(void **fdtp)
 	if (ret < 0)
 		panic("No valid memory ranges found!\n");
 
+	/* If we have an external FDT, it can only have come from the Android bootloader. */
+	if (external_valid)
+		qcom_boot_source = QCOM_BOOT_SOURCE_ANDROID;
+	else
+		qcom_boot_source = QCOM_BOOT_SOURCE_XBL;
+
 	debug("ram_base = %#011lx, ram_size = %#011llx\n",
 	      gd->ram_base, gd->ram_size);
 
@@ -481,6 +489,23 @@ static void configure_env(void)
 	qcom_set_serialno();
 }
 
+void qcom_show_boot_source(void)
+{
+	const char *name = "UNKNOWN";
+
+	switch (qcom_boot_source) {
+	case QCOM_BOOT_SOURCE_ANDROID:
+		name = "ABL";
+		break;
+	case QCOM_BOOT_SOURCE_XBL:
+		name = "XBL";
+		break;
+	}
+
+	log_info("U-Boot loaded from %s\n", name);
+	env_set("boot_source", name);
+}
+
 void __weak qcom_late_init(void)
 {
 }
@@ -528,6 +553,7 @@ int board_late_init(void)
 	configure_env();
 	qcom_late_init();
 
+	qcom_show_boot_source();
 	/* Configure the dfu_string for capsule updates */
 	qcom_configure_capsule_updates();
 
diff --git a/arch/arm/mach-snapdragon/qcom-priv.h b/arch/arm/mach-snapdragon/qcom-priv.h
index 4f398e2ba37..b8bf574e8bb 100644
--- a/arch/arm/mach-snapdragon/qcom-priv.h
+++ b/arch/arm/mach-snapdragon/qcom-priv.h
@@ -3,6 +3,20 @@
 #ifndef __QCOM_PRIV_H__
 #define __QCOM_PRIV_H__
 
+/**
+ * enum qcom_boot_source - Track where we got loaded from.
+ * Used for capsule update logic.
+ *
+ * @QCOM_BOOT_SOURCE_ANDROID: chainloaded (typically from ABL)
+ * @QCOM_BOOT_SOURCE_XBL: flashed to the XBL or UEFI partition
+ */
+enum qcom_boot_source {
+	QCOM_BOOT_SOURCE_ANDROID = 1,
+	QCOM_BOOT_SOURCE_XBL,
+};
+
+extern enum qcom_boot_source qcom_boot_source;
+
 #if IS_ENABLED(CONFIG_EFI_HAVE_CAPSULE_SUPPORT)
 void qcom_configure_capsule_updates(void);
 #else