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[fdt] Provide ability to locate the parent device node

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Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-05-30 16:37:28 +01:00
parent d64250918c
commit 1762568ec5
3 changed files with 109 additions and 1 deletions
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96
src/core/fdt.c
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@@ -181,7 +181,7 @@ static int fdt_next ( struct fdt *fdt, struct fdt_descriptor *desc ) {
* @ret rc Return status code
*/
static int fdt_enter ( struct fdt *fdt, unsigned int offset,
struct fdt_descriptor *desc ) {
struct fdt_descriptor *desc ) {
int rc;
/* Find begin node token */
@@ -212,6 +212,100 @@ static int fdt_enter ( struct fdt *fdt, unsigned int offset,
}
}
/**
* Find node relative depth
*
* @v fdt Device tree
* @v offset Starting node offset
* @v target Target node offset
* @ret depth Depth, or negative error
*/
static int fdt_depth ( struct fdt *fdt, unsigned int offset,
unsigned int target ) {
struct fdt_descriptor desc;
int depth;
int rc;
/* Enter node */
if ( ( rc = fdt_enter ( fdt, offset, &desc ) ) != 0 )
return rc;
/* Find target node */
for ( depth = 0 ; depth >= 0 ; depth += desc.depth ) {
/* Describe token */
if ( ( rc = fdt_next ( fdt, &desc ) ) != 0 ) {
DBGC ( fdt, "FDT +%#04x has malformed node: %s\n",
offset, strerror ( rc ) );
return rc;
}
/* Check for target node */
if ( desc.offset == target ) {
DBGC2 ( fdt, "FDT +%#04x has descendant node +%#04x "
"at depth +%d\n", offset, target, depth );
return depth;
}
}
DBGC ( fdt, "FDT +#%04x has no descendant node +%#04x\n",
offset, target );
return -ENOENT;
}
/**
* Find parent node
*
* @v fdt Device tree
* @v offset Starting node offset
* @v parent Parent node offset to fill in
* @ret rc Return status code
*/
int fdt_parent ( struct fdt *fdt, unsigned int offset, unsigned int *parent ) {
struct fdt_descriptor desc;
int pdepth;
int depth;
int rc;
/* Find depth from root of tree */
depth = fdt_depth ( fdt, 0, offset );
if ( depth < 0 ) {
rc = depth;
return rc;
}
pdepth = ( depth - 1 );
/* Enter root node */
if ( ( rc = fdt_enter ( fdt, 0, &desc ) ) != 0 )
return rc;
*parent = desc.offset;
/* Find parent node */
for ( depth = 0 ; depth >= 0 ; depth += desc.depth ) {
/* Describe token */
if ( ( rc = fdt_next ( fdt, &desc ) ) != 0 ) {
DBGC ( fdt, "FDT +%#04x has malformed node: %s\n",
offset, strerror ( rc ) );
return rc;
}
/* Record possible parent node */
if ( ( depth == pdepth ) && desc.name && ( ! desc.data ) )
*parent = desc.offset;
/* Check for target node */
if ( desc.offset == offset ) {
DBGC2 ( fdt, "FDT +%#04x has parent node at +%#04x\n",
offset, *parent );
return 0;
}
}
DBGC ( fdt, "FDT +#%04x has no parent node\n", offset );
return -ENOENT;
}
/**
* Find child node
*