[Xen-devel] [PATCH v7 1/4] dtb: correct handling of #address-cells and #size-cells.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

If a node does not have #*-cells then the parent's value should be
used. Currently we were asssuming zero which is useless.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v7: assert we don't skip any levels in the tree
---
 xen/arch/arm/domain_build.c   |    9 +++++++--
 xen/common/device_tree.c      |   12 ++++++++----
 xen/include/xen/device_tree.h |    3 ++-
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 7403f1a..9ce661b 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -195,11 +195,16 @@ static int write_nodes(struct domain *d, struct 
kernel_info *kinfo,
             continue;
         }
 
+        /* We cannot handle descending more than one level at a time */
+        ASSERT( depth <= last_depth + 1 );
+
         while ( last_depth-- >= depth )
             fdt_end_node(kinfo->fdt);
 
-        address_cells[depth] = device_tree_get_u32(fdt, node, 
"#address-cells");
-        size_cells[depth] = device_tree_get_u32(fdt, node, "#size-cells");
+        address_cells[depth] = device_tree_get_u32(fdt, node, "#address-cells",
+                                    depth > 0 ? address_cells[depth-1] : 0);
+        size_cells[depth] = device_tree_get_u32(fdt, node, "#size-cells",
+                                    depth > 0 ? size_cells[depth-1] : 0);
 
         fdt_begin_node(kinfo->fdt, name);
 
diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 5301d63..f3d3aa1 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -120,13 +120,14 @@ void device_tree_set_reg(u32 **cell, u32 address_cells, 
u32 size_cells,
     set_val(cell, size_cells, size);
 }
 
-u32 device_tree_get_u32(const void *fdt, int node, const char *prop_name)
+u32 device_tree_get_u32(const void *fdt, int node, const char *prop_name,
+                        u32 dflt)
 {
     const struct fdt_property *prop;
 
     prop = fdt_get_property(fdt, node, prop_name, NULL);
     if ( !prop || prop->len < sizeof(u32) )
-        return 0; /* default to 0 */
+        return dflt;
 
     return fdt32_to_cpu(*(uint32_t*)prop->data);
 }
@@ -164,8 +165,11 @@ int device_tree_for_each_node(const void *fdt,
             continue;
         }
 
-        address_cells[depth] = device_tree_get_u32(fdt, node, 
"#address-cells");
-        size_cells[depth] = device_tree_get_u32(fdt, node, "#size-cells");
+        address_cells[depth] = device_tree_get_u32(fdt, node, "#address-cells",
+                                depth > 0 ? address_cells[depth-1] : 0);
+        size_cells[depth] = device_tree_get_u32(fdt, node, "#size-cells",
+                                depth > 0 ? size_cells[depth-1] : 0);
+
 
         ret = func(fdt, node, name, depth,
                    address_cells[depth-1], size_cells[depth-1], data);
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index 1d04e4f..19bda98 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -66,7 +66,8 @@ void device_tree_get_reg(const u32 **cell, u32 address_cells, 
u32 size_cells,
                          u64 *start, u64 *size);
 void device_tree_set_reg(u32 **cell, u32 address_cells, u32 size_cells,
                          u64 start, u64 size);
-u32 device_tree_get_u32(const void *fdt, int node, const char *prop_name);
+u32 device_tree_get_u32(const void *fdt, int node, const char *prop_name,
+                       u32 dflt);
 bool_t device_tree_node_matches(const void *fdt, int node, const char *match);
 bool_t device_tree_node_compatible(const void *fdt, int node, const char 
*match);
 int find_compatible_node(const char *compatible, int *node, int *depth,
-- 
1.7.9.1


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