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author | Simon Glass <sjg@chromium.org> | 2015-06-23 15:38:26 -0600 |
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committer | Simon Glass <sjg@chromium.org> | 2015-07-21 17:39:20 -0600 |
commit | 8f6e2e1ee17bb1ecce03518b8eceda6965617477 (patch) | |
tree | 0c227e0e9daf32f4879f8a331e0a1062d80c0c2b | |
parent | 5b9d44df2307fc882b2ae666fd28fb2c7c2d5b11 (diff) | |
download | u-boot-8f6e2e1ee17bb1ecce03518b8eceda6965617477.zip u-boot-8f6e2e1ee17bb1ecce03518b8eceda6965617477.tar.gz u-boot-8f6e2e1ee17bb1ecce03518b8eceda6965617477.tar.bz2 |
fdt: Add a function to remove unused strings from a device tree
Property names are stored in a string table. When a node property is
removed, the string table is not updated since other nodes may have a
property with the same name.
Thus it is possible for the string table to build up a number of unused
strings. Add a function to remove these. This works by building a new device
tree from the old one, adding strings one by one as needed.
Signed-off-by: Simon Glass <sjg@chromium.org>
-rw-r--r-- | include/libfdt.h | 17 | ||||
-rw-r--r-- | lib/libfdt/fdt_rw.c | 32 |
2 files changed, 49 insertions, 0 deletions
diff --git a/include/libfdt.h b/include/libfdt.h index 421d64f..d0017d8 100644 --- a/include/libfdt.h +++ b/include/libfdt.h @@ -1646,6 +1646,23 @@ int fdt_del_node(void *fdt, int nodeoffset); const char *fdt_strerror(int errval); +/** + * fdt_remove_unused_strings() - Remove any unused strings from an FDT + * + * This creates a new device tree in @new with unused strings removed. The + * called can then use fdt_pack() to minimise the space consumed. + * + * @old: Old device tree blog + * @new: Place to put new device tree blob, which must be as large as + * @old + * @return + * 0, on success + * -FDT_ERR_BADOFFSET, corrupt device tree + * -FDT_ERR_NOSPACE, out of space, which should not happen unless there + * is something very wrong with the device tree input + */ +int fdt_remove_unused_strings(const void *old, void *new); + struct fdt_region { int offset; int size; diff --git a/lib/libfdt/fdt_rw.c b/lib/libfdt/fdt_rw.c index bec8b8a..1a358a8 100644 --- a/lib/libfdt/fdt_rw.c +++ b/lib/libfdt/fdt_rw.c @@ -449,3 +449,35 @@ int fdt_pack(void *fdt) return 0; } + +int fdt_remove_unused_strings(const void *old, void *new) +{ + const struct fdt_property *old_prop; + struct fdt_property *new_prop; + int size = fdt_totalsize(old); + int next_offset, offset; + const char *str; + int ret; + int tag = FDT_PROP; + + /* Make a copy and remove the strings */ + memcpy(new, old, size); + fdt_set_size_dt_strings(new, 0); + + /* Add every property name back into the new string table */ + for (offset = 0; tag != FDT_END; offset = next_offset) { + tag = fdt_next_tag(old, offset, &next_offset); + if (tag != FDT_PROP) + continue; + old_prop = fdt_get_property_by_offset(old, offset, NULL); + new_prop = (struct fdt_property *)(unsigned long) + fdt_get_property_by_offset(new, offset, NULL); + str = fdt_string(old, fdt32_to_cpu(old_prop->nameoff)); + ret = _fdt_find_add_string(new, str); + if (ret < 0) + return ret; + new_prop->nameoff = cpu_to_fdt32(ret); + } + + return 0; +} |