[Qemu-devel] [PATCH 06/31] dt: add helper for empty dt creation

[Alexander Graf <agraf@suse.de>]

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 <agraf@suse.de>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@petalogix.com>
---
 device_tree.c |   37 +++++++++++++++++++++++++++++++++++++
 device_tree.h |    1 +
 2 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/device_tree.c b/device_tree.c
index 2f127b7..d037896 100644
--- 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
index 36fc9db..5f76f40 100644
--- 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,
-- 
1.6.0.2