On 11/29/21 5:59 PM, Rob Herring wrote:

On Fri, Nov 19, 2021 at 02:24:07PM -0800, Lizhi Hou wrote:

quoted

When OF_FLATTREE is selected and there is not a device tree, create an
empty device tree root node. of/unittest.c code is referenced.

What does the last sentence mean? You copied the code? If so, that's a
sign you should refactor the unittest code to use this.

I looked into unittest.c for how the of_root is created.  And you are 
right, this could should be unified with unittest.c. I will change it 
with next patch set.

Thanks,

Lizhi

quoted

Signed-off-by: Sonal Santan <redacted>
Signed-off-by: Max Zhen <redacted>
Signed-off-by: Lizhi Hou <redacted>
---
  drivers/of/Makefile        |  2 +-
  drivers/of/fdt.c           | 20 ++++++++++++++++++++
  drivers/of/fdt_default.dts |  5 +++++
  drivers/of/of_private.h    |  5 +++++
  4 files changed, 31 insertions(+), 1 deletion(-)
  create mode 100644 drivers/of/fdt_default.dts

diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index c13b982084a3..815f5220465b 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile

@@ -2,7 +2,7 @@
  obj-y = base.o device.o platform.o property.o
  obj-$(CONFIG_OF_KOBJ) += kobj.o
  obj-$(CONFIG_OF_DYNAMIC) += dynamic.o
-obj-$(CONFIG_OF_FLATTREE) += fdt.o
+obj-$(CONFIG_OF_FLATTREE) += fdt.o fdt_default.dtb.o
  obj-$(CONFIG_OF_EARLY_FLATTREE) += fdt_address.o
  obj-$(CONFIG_OF_PROMTREE) += pdt.o
  obj-$(CONFIG_OF_ADDRESS)  += address.o

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index d64445e43ceb..3d6e4543419e 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c

@@ -481,6 +481,26 @@ void *of_fdt_unflatten_tree(const unsigned long *blob,
  }
  EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);

+static int __init of_fdt_root_init(void)
+{
+     struct device_node *np;
+
+     if (of_root)
+             return 0;
+
+     if (!of_fdt_unflatten_tree((const unsigned long *)__dtb_fdt_default_begin,
+                                NULL, &of_root)) {
+             pr_warn("%s: unflatten default tree failed\n", __func__);
+             return -ENODATA;
+     }
+
+     for_each_of_allnodes(np)
+             __of_attach_node_sysfs(np);
+
+     return 0;
+}
+late_initcall(of_fdt_root_init);
+
  /* Everything below here references initial_boot_params directly. */
  int __initdata dt_root_addr_cells;
  int __initdata dt_root_size_cells;

diff --git a/drivers/of/fdt_default.dts b/drivers/of/fdt_default.dts
new file mode 100644
index 000000000000..d1f12a76dfc6
--- /dev/null
+++ b/drivers/of/fdt_default.dts

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+
+/ {
+};

diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 631489f7f8c0..47c6bb47ef25 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h

@@ -41,6 +41,11 @@ extern struct mutex of_mutex;
  extern struct list_head aliases_lookup;
  extern struct kset *of_kset;

+#if defined(CONFIG_OF_FLATTREE)
+extern u8 __dtb_fdt_default_begin[];
+extern u8 __dtb_fdt_default_end[];
+#endif
+
  #if defined(CONFIG_OF_DYNAMIC)
  extern int of_property_notify(int action, struct device_node *np,
                             struct property *prop, struct property *old_prop);
--

2.27.0