[Xen-devel] [PATCH v5 1/7] xen/arm: pass node to device_tree_for_each_node

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Add a new parameter to device_tree_for_each_node: node, the node to
start the search from. Passing 0 triggers the old behavior.

Set min_depth to depth of the current node + 1 and replace the for
loop with a do/while loop to avoid scanning siblings of the initial node
passed as an argument.

We need this change because in follow-up patches we want to be able to
use reuse device_tree_for_each_node to call a function for each children
nodes of a provided node and the node itself.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
---
Changes in v5:
- go back to v3
- code style improvement in acpi/boot.c
- improve comments and commit message
- increase min_depth to avoid parsing siblings
- replace for with do/while loop and increase min_depth to avoid
  scanning siblings of the initial node
- pass only node, calculate depth

Changes in v3:
- improve commit message
- improve in-code comments
- improve code style

Changes in v2:
- new
---
 xen/arch/arm/acpi/boot.c      |  8 +++++---
 xen/arch/arm/bootfdt.c        | 19 ++++++++++---------
 xen/include/xen/device_tree.h |  6 +++---
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/xen/arch/arm/acpi/boot.c b/xen/arch/arm/acpi/boot.c
index 9b29769a10..d4957cca06 100644
--- a/xen/arch/arm/acpi/boot.c
+++ b/xen/arch/arm/acpi/boot.c
@@ -246,9 +246,11 @@ int __init acpi_boot_table_init(void)
      * - the device tree is not empty (it has more than just a /chosen node)
      *   and ACPI has not been force enabled (acpi=force)
      */
-    if ( param_acpi_off || ( !param_acpi_force
-                             && 
device_tree_for_each_node(device_tree_flattened,
-                                                   dt_scan_depth1_nodes, 
NULL)))
+    if ( param_acpi_off)
+        goto disable;
+       if ( !param_acpi_force &&
+                device_tree_for_each_node(device_tree_flattened, 0,
+                                              dt_scan_depth1_nodes, NULL) )
         goto disable;
 
     /*
diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
index 891b4b66ff..a872ea57d6 100644
--- a/xen/arch/arm/bootfdt.c
+++ b/xen/arch/arm/bootfdt.c
@@ -77,6 +77,7 @@ static u32 __init device_tree_get_u32(const void *fdt, int 
node,
 /**
  * device_tree_for_each_node - iterate over all device tree nodes
  * @fdt: flat device tree.
+ * @node: node to start the search from
  * @func: function to call for each node.
  * @data: data to pass to @func.
  *
@@ -85,20 +86,17 @@ static u32 __init device_tree_get_u32(const void *fdt, int 
node,
  * Returns 0 if all nodes were iterated over successfully.  If @func
  * returns a value different from 0, that value is returned immediately.
  */
-int __init device_tree_for_each_node(const void *fdt,
+int __init device_tree_for_each_node(const void *fdt, int node,
                                      device_tree_node_func func,
                                      void *data)
 {
-    int node;
-    int depth;
+    int depth = fdt_node_depth(fdt, node);
+    int min_depth = depth + 1;
     u32 address_cells[DEVICE_TREE_MAX_DEPTH];
     u32 size_cells[DEVICE_TREE_MAX_DEPTH];
     int ret;
 
-    for ( node = 0, depth = 0;
-          node >=0 && depth >= 0;
-          node = fdt_next_node(fdt, node, &depth) )
-    {
+    do {
         const char *name = fdt_get_name(fdt, node, NULL);
         u32 as, ss;
 
@@ -120,7 +118,10 @@ int __init device_tree_for_each_node(const void *fdt,
         ret = func(fdt, node, name, depth, as, ss, data);
         if ( ret != 0 )
             return ret;
-    }
+
+        node = fdt_next_node(fdt, node, &depth);
+    } while ( node >= 0 && depth >= min_depth );
+
     return 0;
 }
 
@@ -357,7 +358,7 @@ size_t __init boot_fdt_info(const void *fdt, paddr_t paddr)
 
     add_boot_module(BOOTMOD_FDT, paddr, fdt_totalsize(fdt), false);
 
-    device_tree_for_each_node((void *)fdt, early_scan_node, NULL);
+    device_tree_for_each_node((void *)fdt, 0, early_scan_node, NULL);
     early_print_info();
 
     return fdt_totalsize(fdt);
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index 83156297e2..9a7a8f2dab 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -158,9 +158,9 @@ typedef int (*device_tree_node_func)(const void *fdt,
 
 extern const void *device_tree_flattened;
 
-int device_tree_for_each_node(const void *fdt,
-                                     device_tree_node_func func,
-                                     void *data);
+int device_tree_for_each_node(const void *fdt, int node,
+                              device_tree_node_func func,
+                              void *data);
 
 /**
  * dt_unflatten_host_device_tree - Unflatten the host device tree
-- 
2.17.1


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