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: Will Deacon <will@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20211029144055.2365814-1-robh@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index f3851724fe35611eb9d113e9e4aec6ee395b456f..e4dea8db6924cc60906b434dbf521c21071c583c 100644 (file)
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -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;
 
        /*