[PATCH 0/2] of: Allow scripts/dtc/libfdt to be used from kernel code and more...

[PATCH 0/2] of: Allow scripts/dtc/libfdt to be used from kernel code and more...

[ddaney.cavm-Re5JQEeQqe8AvxtiuMwx3w]

From: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>

My next patch set for OCTEON device tree support relies on these two
patches.  I split these out as they are architecture independent.

I iterated on these several times under the guise of an RFC, this is
their first appearance as a request to be merged.

Thanks,

David Daney (2):
  of/lib: Allow scripts/dtc/libfdt to be used from kernel code
  of: Make of_find_node_by_path() traverse /aliases for relative paths.

 drivers/of/base.c          |   65 +++++++++++++++++++++++++++++++++++++++++--
 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 +
 11 files changed, 106 insertions(+), 3 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

-- 
1.7.2.3

[PATCH 1/2] of/lib: Allow scripts/dtc/libfdt to be used from kernel code

[ddaney.cavm]

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>
---
 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 32f3e5a..48d55b4 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -276,4 +276,10 @@ config CORDIC
 	  so its calculations are in fixed point. Modules can select this
 	  when they require this function. Module will be called cordic.
 
+#
+# libfdt files, only selected if needed.
+#
+config LIBFDT
+	bool
+
 endmenu
diff --git a/lib/Makefile b/lib/Makefile
index a4da283..f5254d2 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -115,6 +115,11 @@ obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o
 
 obj-$(CONFIG_CORDIC) += cordic.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

[PATCH 2/2] of: Make of_find_node_by_path() traverse /aliases for relative paths.

[ddaney.cavm-Re5JQEeQqe8AvxtiuMwx3w]

From: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>

Currently all paths passed to of_find_node_by_path() must begin with a
'/', indicating a full path to the desired node.

Augment the look-up code so that if a path does *not* begin with '/',
the path is used as the name of an /aliases property.  The value of
this alias is then used as the full node path to be found.

Signed-off-by: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org>
---
 drivers/of/base.c |   65 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 9b6588e..cf765c7 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -365,22 +365,81 @@ EXPORT_SYMBOL(of_get_next_child);
 
 /**
  *	of_find_node_by_path - Find a node matching a full OF path
- *	@path:	The full path to match
+ *	@path: Either the full path to match, or if the path does not
+ *	       start with '/', the name of a property of the /aliases
+ *	       node (an alias).  In the case of an alias, the node
+ *	       matching the alias' value will be returned.
  *
  *	Returns a node pointer with refcount incremented, use
  *	of_node_put() on it when done.
  */
 struct device_node *of_find_node_by_path(const char *path)
 {
-	struct device_node *np = allnodes;
+	struct device_node *np = NULL;
+	struct device_node *aliases = NULL;
+	char *alias = NULL;
+	char *new_path = NULL;
+	char *ps;
 
 	read_lock(&devtree_lock);
-	for (; np; np = np->allnext) {
+
+	/*
+	 * The following code has three possibilities:
+	 * 1) '/' at start of string; path == ps; (based at root)
+	 * 2) '/' at offset in string; path < ps; (relative to alias)
+	 * 3) '/' not found; ps == NULL; (alias only)
+	 *
+	 * If ps != path, then it is either a pure alias (ps == NULL),
+	 * or an alias with a relative path (path < ps).  Either way,
+	 * look up the path pointed to by the alias.
+	 */
+	ps = strchr(path, '/');
+	if (path != ps) {
+		aliases = of_find_node_by_path("/aliases");
+		if (!aliases)
+			goto out;
+
+		/*
+		 * Duplicate the alias part of the string so it can be
+		 * NULL terminated.
+		 */
+		alias = kstrndup(path,
+				 ps ? (ps - path) : strlen(path), GFP_KERNEL);
+		if (!alias)
+			goto out;
+		path = of_get_property(aliases, alias, NULL);
+		if (!path || path[0] != '/')
+			goto out;
+
+		/* If ps is not NULL, then there is a relative path to append */
+		if (ps) {
+			new_path = kzalloc(strlen(path) + strlen(ps) + 1,
+					   GFP_KERNEL);
+			if (!new_path)
+				goto out;
+
+			sprintf(new_path, "%s%s", path, ps);
+			path = new_path;
+		}
+	}
+
+	/*
+	 * At this point, path now points to the full unaliased path
+	 * to a node, regardless of whether or not it started with an
+	 * alias.
+	 */
+
+	for (np = allnodes; np; np = np->allnext) {
 		if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
 		    && of_node_get(np))
 			break;
 	}
+out:
+	if (aliases)
+		of_node_put(aliases);
 	read_unlock(&devtree_lock);
+	kfree(alias);
+	kfree(new_path);
 	return np;
 }
 EXPORT_SYMBOL(of_find_node_by_path);
-- 
1.7.2.3