arm64: Simplify checking for populated DT

Use of the of_scan_flat_dt() function predates libfdt and is discouraged as libfdt provides a nicer set of APIs. Rework dt_scan_depth1_nodes to use libfdt calls directly, and rename it to dt_is_stub() to reflect exactly what it checking.

Cc Catalin Marinas <[email protected]>

Cc Will Deacon <[email protected]>

Signed-off-by Rob Herring <[email protected]>

---
v2:
- Keep checking for only stub nodes

 arch/arm64/kernel/acpi.c | 35 ++++++++++++++---------------------
 1 file changed, 14 insertions(+), 21 deletions(-)

arch/arm64/kernel/acpi.c +14 -21

index 1c9c2f7a1c04..7df733427e04 100644
@@ -22,6 +22,7 @@
 #include <linux/irq_work.h>
 #include <linux/memblock.h>
 #include <linux/of_fdt.h>
+#include <linux/libfdt.h>
 #include <linux/smp.h>
 #include <linux/serial_core.h>
 #include <linux/pgtable.h>

@@ -62,29 +63,22 @@ static int __init parse_acpi(char *arg)
 }
 early_param("acpi", parse_acpi);
 
-static int __init dt_scan_depth1_nodes(unsigned long node,
-				       const char *uname, int depth,
-				       void *data)
+static bool __init dt_is_stub(void)
 {
-	/*
-	 * Ignore anything not directly under the root node; we'll
-	 * catch its parent instead.
-	 */
-	if (depth != 1)
-		return 0;
+	int node;
 
-	if (strcmp(uname, "chosen") == 0)
-		return 0;
+	fdt_for_each_subnode(node, initial_boot_params, 0) {
+		const char *name = fdt_get_name(initial_boot_params, node, NULL);
+		if (strcmp(name, "chosen") == 0)
+			continue;
+		if (strcmp(name, "hypervisor") == 0 &&
+		    of_flat_dt_is_compatible(node, "xen,xen"))
+			continue;
 
-	if (strcmp(uname, "hypervisor") == 0 &&
-	    of_flat_dt_is_compatible(node, "xen,xen"))
-		return 0;
+		return false;
+	}
 
-	/*
-	 * This node at depth 1 is neither a chosen node nor a xen node,
-	 * which we do not expect.
-	 */
-	return 1;
+	return true;
 }
 
 /*

@@ -205,8 +199,7 @@ void __init acpi_boot_table_init(void)
 	 *   and ACPI has not been [force] enabled (acpi=on|force)
 	 */
 	if (param_acpi_off ||
-	    (!param_acpi_on && !param_acpi_force &&
-	     of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
+	    (!param_acpi_on && !param_acpi_force && !dt_is_stub()))
 		goto done;
 
 	/*

Signature · 1 line

2.32.0

Use of the of_scan_flat_dt() function predates libfdt and is discouraged as libfdt provides a nicer set of APIs. Rework dt_scan_depth1_nodes to use libfdt calls directly, and rename it to dt_is_stub() to reflect exactly what it checking.