dt: add helper for empty dt creation

We want to get rid of the concept of loading an external device tree and instead generate our own. However, to do this we need to also create a device tree template programatically. This patch adds a helper to create an empty device tree in memory. Signed-off-by: Alexander Graf <[email protected]> Reviewed-by: Peter Crosthwaite <[email protected]>
zhugh2333 · Jun 23, 2012 · ce36252 · ce36252
1 parent 7d5fd10
commit ce36252
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diff --git a/device_tree.c b/device_tree.c
@@ -25,6 +25,43 @@
 
 #include <libfdt.h>
 
+#define FDT_MAX_SIZE  0x10000
+
+void *create_device_tree(int *sizep)
+{
+    void *fdt;
+    int ret;
+
+    *sizep = FDT_MAX_SIZE;
+    fdt = g_malloc0(FDT_MAX_SIZE);
+    ret = fdt_create(fdt, FDT_MAX_SIZE);
+    if (ret < 0) {
+        goto fail;
+    }
+    ret = fdt_begin_node(fdt, "");
+    if (ret < 0) {
+        goto fail;
+    }
+    ret = fdt_end_node(fdt);
+    if (ret < 0) {
+        goto fail;
+    }
+    ret = fdt_finish(fdt);
+    if (ret < 0) {
+        goto fail;
+    }
+    ret = fdt_open_into(fdt, fdt, *sizep);
+    if (ret) {
+        fprintf(stderr, "Unable to copy device tree in memory\n");
+        exit(1);
+    }
+
+    return fdt;
+fail:
+    fprintf(stderr, "%s Couldn't create dt: %s\n", __func__, fdt_strerror(ret));
+    exit(1);
+}
+
 void *load_device_tree(const char *filename_path, int *sizep)
 {
     int dt_size;

diff --git a/device_tree.h b/device_tree.h
@@ -14,6 +14,7 @@
 #ifndef __DEVICE_TREE_H__
 #define __DEVICE_TREE_H__
 
+void *create_device_tree(int *sizep);
 void *load_device_tree(const char *filename_path, int *sizep);
 
 int qemu_devtree_setprop(void *fdt, const char *node_path,