The libfdt read/write functions are now usable enough that it's become a
moderately common pattern to use them to build and manipulate a device
tree from scratch. For example, we do so ourself in our rw_tree1 testcase,
and qemu is starting to use this model when building device trees for some
targets such as e500.
However, the read/write functions require some sort of valid tree to begin
with, so this necessitates either having a trivial canned dtb to begin with
or, more commonly, creating an empty tree using the serial-write functions
first.
This patch adds a helper function which uses the serial-write functions to
create a trivial, empty but complete and valid tree in a supplied buffer,
ready for manipulation with the read/write functions.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
libfdt is supposed to easy to embed in projects all and sundry.
Often, it won't be practical to separate the embedded libfdt's
namespace from that of the surrounding project. Which means there can
be namespace conflicts between even libfdt's internal/static functions
and functions or macros coming from the surrounding project's headers
via libfdt_env.h.
This patch, therefore, renames a bunch of libfdt internal functions
and macros and makes a few other chances to reduce the chances of
namespace collisions with embedding projects. Specifically:
- Internal functions (even static ones) are now named _fdt_*()
- The type and (static) global for the error table in
fdt_strerror() gain an fdt_ prefix
- The unused macro PALIGN is removed
- The memeq and streq macros are removed and open-coded in the
users (they were only used once each)
- Other macros gain an FDT_ prefix
- To save some of the bulk from the previous change, an
FDT_TAGALIGN() macro is introduced, where FDT_TAGALIGN(x) ==
FDT_ALIGN(x, FDT_TAGSIZE)
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This fixes several small bugs related to fdt_strerror().
- an entry is added to the error table for FDT_ERR_BADLAYOUT.
- Incorrect usage of fdt_strerror() in check_property() and
check_getprop() is corrected (they were passing a positive error code,
when fdt_strerror() expects a negative code).
- Add code to properly retreive an error code from
fdt_get_property() in check_property(). With that a check that the
length returned by fdt_get_property() matches that stored in the
retreived property.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This function moves the fdt_strerror() function, currently found in
the test code into the fdt library proper. This makes life easier for
any library users who want to provide meaningful error messages. The
function goes into a module of its own, so that users who don't need
the function won't get a copy of it linked in.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
At present, the blob containing a device tree is passed to the various
fdt_*() functions as a (struct fdt_header *) i.e. a pointer to the
header structure at the beginning of the blob.
This patch changes all the functions so that they instead take a (void
*) pointing to the blob. Under some circumstances can avoid the need
for the caller to cast a blob pointer into a (struct fdt_header *)
before passing it to the fdt_*() functions.
Using a (void *) also reduce the temptation for users of the library
to directly dereference toe (struct fdt_header *) to access header
fields. Instead they must use the fdt_get_header() or
fdt_set_header() macros, or the fdt_magic(), fdt_totalsize()
etc. wrappers around them which are safer, since they will always
handle endian conversion.
With this change, the whole-tree moving, or manipulating functions:
fdt_move(), fdt_open_into() and fdt_pack() no longer need to return a
pointer to the "new" tree. The given (void *) buffer pointer they
take can instead be used directly by the caller as the new tree.
Those functions are thus changed to instead return an error code
(which in turn reduces the number of functions using the ugly encoding
of error values into pointers).
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This patch fixes a number of embarrasing oversights which meant libfdt
did not work correctly on little endian machines. With this patch the
testsuite now passes on x86. Device trees are always created
big-endian.
David Gibson