[PATCH v8 1/1] of/lib: Allow scripts/dtc/libfdt to be used from kernel code

[David Daney <ddaney.cavm@gmail.com>]

From: David Daney <david.daney@cavium.com>

libfdt is part of the device tree support in scripts/dtc/libfdt.  For
some platforms that use the Device Tree, we want to be able to edit
the flattened device tree form.

We don't want to burden kernel builds that do not require it, so we
gate compilation of libfdt files with CONFIG_LIBFDT.  So if it is
needed, you need to do this in your Kconfig:

	select LIBFDT

And in the Makefile of the code using libfdt something like:

ccflags-y := -I$(src)/../../../scripts/dtc/libfdt

Signed-off-by: David Daney <david.daney@cavium.com>
---
This patch has been seen several times before as part of a larger
patch set for my OCTEON Device Tree work.  After further refinement to
my patches that depend on core Device Tree functionality, this is the
only remaining patch to the common 'core' code.

Here is the history:

v8: Rebased lib/Makefile to avoid merge conflict.

v7: No changes other that to split from other, now unneeded, patches.

v6: No changes other than to split these out of the MIPS/OCTEON patch
    set to allow them to be merged separately if desired.

v5: Build libfdt in the lib directory instead of devices/of, and
    include all libfdt files.

    Changes to of_find_node_by_path() requested by Grant Likely.

v4: No changes to these two patches.

v3: libfdt building moved to devices/of/libfdt.  Cleanup and style
    improvements as suggested by Grant Likely.

v2: No changes to these two patches.

There are a couple of possibility for merging this.

1) Via the Device Tree maintainers, thus blocking the follow-ons until
   it is merged.

2) Via Ralf's Linux/MIPS tree with the rest of the patches after
   Device Tree maintainer sign-off.

 include/linux/libfdt.h     |    8 ++++++++
 include/linux/libfdt_env.h |   13 +++++++++++++
 lib/Kconfig                |    6 ++++++
 lib/Makefile               |    5 +++++
 lib/fdt.c                  |    2 ++
 lib/fdt_ro.c               |    2 ++
 lib/fdt_rw.c               |    2 ++
 lib/fdt_strerror.c         |    2 ++
 lib/fdt_sw.c               |    2 ++
 lib/fdt_wip.c              |    2 ++
 10 files changed, 44 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/libfdt.h
 create mode 100644 include/linux/libfdt_env.h
 create mode 100644 lib/fdt.c
 create mode 100644 lib/fdt_ro.c
 create mode 100644 lib/fdt_rw.c
 create mode 100644 lib/fdt_strerror.c
 create mode 100644 lib/fdt_sw.c
 create mode 100644 lib/fdt_wip.c

diff --git a/include/linux/libfdt.h b/include/linux/libfdt.h
new file mode 100644
index 0000000..4c0306c
--- /dev/null
+++ b/include/linux/libfdt.h
@@ -0,0 +1,8 @@
+#ifndef _INCLUDE_LIBFDT_H_
+#define _INCLUDE_LIBFDT_H_
+
+#include <linux/libfdt_env.h>
+#include "../../scripts/dtc/libfdt/fdt.h"
+#include "../../scripts/dtc/libfdt/libfdt.h"
+
+#endif /* _INCLUDE_LIBFDT_H_ */
diff --git a/include/linux/libfdt_env.h b/include/linux/libfdt_env.h
new file mode 100644
index 0000000..01508c7
--- /dev/null
+++ b/include/linux/libfdt_env.h
@@ -0,0 +1,13 @@
+#ifndef _LIBFDT_ENV_H
+#define _LIBFDT_ENV_H
+
+#include <linux/string.h>
+
+#include <asm/byteorder.h>
+
+#define fdt32_to_cpu(x) be32_to_cpu(x)
+#define cpu_to_fdt32(x) cpu_to_be32(x)
+#define fdt64_to_cpu(x) be64_to_cpu(x)
+#define cpu_to_fdt64(x) cpu_to_be64(x)
+
+#endif /* _LIBFDT_ENV_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index a9e1540..e091300 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -395,4 +395,10 @@ config SIGNATURE
 	  Digital signature verification. Currently only RSA is supported.
 	  Implementation is done using GnuPG MPI library
 
+#
+# libfdt files, only selected if needed.
+#
+config LIBFDT
+	bool
+
 endmenu
diff --git a/lib/Makefile b/lib/Makefile
index 8c31a0c..2f2be5a 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -130,6 +130,11 @@ obj-$(CONFIG_GENERIC_STRNLEN_USER) += strnlen_user.o
 
 obj-$(CONFIG_STMP_DEVICE) += stmp_device.o
 
+libfdt_files = fdt.o fdt_ro.o fdt_wip.o fdt_rw.o fdt_sw.o fdt_strerror.o
+$(foreach file, $(libfdt_files), \
+	$(eval CFLAGS_$(file) = -I$(src)/../scripts/dtc/libfdt))
+lib-$(CONFIG_LIBFDT) += $(libfdt_files)
+
 hostprogs-y	:= gen_crc32table
 clean-files	:= crc32table.h
 
diff --git a/lib/fdt.c b/lib/fdt.c
new file mode 100644
index 0000000..97f2006
--- /dev/null
+++ b/lib/fdt.c
@@ -0,0 +1,2 @@
+#include <linux/libfdt_env.h>
+#include "../scripts/dtc/libfdt/fdt.c"
diff --git a/lib/fdt_ro.c b/lib/fdt_ro.c
new file mode 100644
index 0000000..f73c04e
--- /dev/null
+++ b/lib/fdt_ro.c
@@ -0,0 +1,2 @@
+#include <linux/libfdt_env.h>
+#include "../scripts/dtc/libfdt/fdt_ro.c"
diff --git a/lib/fdt_rw.c b/lib/fdt_rw.c
new file mode 100644
index 0000000..0c1f0f4
--- /dev/null
+++ b/lib/fdt_rw.c
@@ -0,0 +1,2 @@
+#include <linux/libfdt_env.h>
+#include "../scripts/dtc/libfdt/fdt_rw.c"
diff --git a/lib/fdt_strerror.c b/lib/fdt_strerror.c
new file mode 100644
index 0000000..8713e3f
--- /dev/null
+++ b/lib/fdt_strerror.c
@@ -0,0 +1,2 @@
+#include <linux/libfdt_env.h>
+#include "../scripts/dtc/libfdt/fdt_strerror.c"
diff --git a/lib/fdt_sw.c b/lib/fdt_sw.c
new file mode 100644
index 0000000..9ac7e50
--- /dev/null
+++ b/lib/fdt_sw.c
@@ -0,0 +1,2 @@
+#include <linux/libfdt_env.h>
+#include "../scripts/dtc/libfdt/fdt_sw.c"
diff --git a/lib/fdt_wip.c b/lib/fdt_wip.c
new file mode 100644
index 0000000..45b3fc3
--- /dev/null
+++ b/lib/fdt_wip.c
@@ -0,0 +1,2 @@
+#include <linux/libfdt_env.h>
+#include "../scripts/dtc/libfdt/fdt_wip.c"
-- 
1.7.2.3