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libfdt: Add fdt_node_offset_by_prop_value()

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This patch adds a function to libfdt to locate nodes containing a
property with a specific value.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
David Gibson 2007-09-17 14:28:34 +10:00 • committed by Jon Loeliger
parent 592ea5888c
commit ae1454b311
5 changed files with 167 additions and 0 deletions
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51
libfdt/fdt_ro.c
View file

@ -407,3 +407,54 @@ int fdt_parent_offset(const void *fdt, int nodeoffset)
return fdt_supernode_atdepth_offset(fdt, nodeoffset,
nodedepth - 1, NULL);
}
int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
const char *propname,
const void *propval, int proplen)
{
uint32_t tag;
int offset, nextoffset;
const void *val;
int len;
CHECK_HEADER(fdt);
if (startoffset >= 0) {
tag = _fdt_next_tag(fdt, startoffset, &nextoffset);
if (tag != FDT_BEGIN_NODE)
return -FDT_ERR_BADOFFSET;
} else {
nextoffset = 0;
}
/* FIXME: The algorithm here is pretty horrible: we scan each
* property of a node in fdt_getprop(), then if that didn't
* find what we want, we scan over them again making our way
* to the next node. Still it's the easiest to implement
* approach; performance can come later. */
do {
offset = nextoffset;
tag = _fdt_next_tag(fdt, offset, &nextoffset);
switch (tag) {
case FDT_BEGIN_NODE:
val = fdt_getprop(fdt, offset, propname, &len);
if (val
&& (len == proplen)
&& (memcmp(val, propval, len) == 0))
return offset;
break;
case FDT_PROP:
case FDT_END:
case FDT_END_NODE:
case FDT_NOP:
break;
default:
return -FDT_ERR_BADSTRUCTURE;
}
} while (tag != FDT_END);
return -FDT_ERR_NOTFOUND;
}

4
libfdt/libfdt.h
View file

@ -146,6 +146,10 @@ int fdt_supernode_atdepth_offset(const void *fdt, int nodeoffset,
int fdt_node_depth(const void *fdt, int nodeoffset);
int fdt_parent_offset(const void *fdt, int nodeoffset);
int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
const char *propname,
const void *propval, int proplen);
/* Write-in-place functions */
int fdt_setprop_inplace(void *fdt, int nodeoffset, const char *name,
const void *val, int len);