scripts/dtc/libfdt/fdt_overlay.c

Source file repositories/reference/linux-study-clean/scripts/dtc/libfdt/fdt_overlay.c

File Facts

System
Linux kernel
Corpus path
scripts/dtc/libfdt/fdt_overlay.c
Extension
.c
Size
27480 bytes
Lines
1102
Domain
Support Tooling And Documentation
Bucket
scripts
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

if (!tree_val) {
			if (tree_len == -FDT_ERR_NOTFOUND)
				return -FDT_ERR_BADOVERLAY;

			return tree_len;
		}

		for (i = 0; i < fixup_len; i++) {
			fdt32_t *refp;

			refp = (fdt32_t *)(tree_val + fdt32_ld_(fixup_val + i));

			/*
			 * phandles to fixup can be unaligned, so use
			 * fdt32_{ld,st}() to read/write them.
			 */
			fdt32_st(refp, fdt32_ld(refp) + delta);
		}
	}

	fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
		const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
							    NULL);
		int tree_child;

		tree_child = fdt_subnode_offset(fdto, tree_node,
						fixup_child_name);
		if (tree_child == -FDT_ERR_NOTFOUND)
			return -FDT_ERR_BADOVERLAY;
		if (tree_child < 0)
			return tree_child;

		ret = overlay_update_local_node_references(fdto,
							   tree_child,
							   fixup_child,
							   delta);
		if (ret)
			return ret;
	}

	return 0;
}

/**
 * overlay_update_local_references - Adjust the overlay references
 * @fdto: Device tree overlay blob
 * @delta: Offset to shift the phandles of
 *
 * overlay_update_local_references() update all the phandles pointing
 * to a node within the device tree overlay by adding a constant
 * delta to not conflict with the base overlay.
 *
 * This is mainly used as part of a device tree application process,
 * where you want the device tree overlays phandles to not conflict
 * with the ones from the base device tree before merging them.
 *
 * returns:
 *      0 on success
 *      Negative error code on failure
 */
static int overlay_update_local_references(void *fdto, uint32_t delta)
{
	int fixups;

	fixups = fdt_path_offset(fdto, "/__local_fixups__");
	if (fixups < 0) {
		/* There's no local phandles to adjust, bail out */
		if (fixups == -FDT_ERR_NOTFOUND)
			return 0;

		return fixups;
	}

	/*
	 * Update our local references from the root of the tree
	 */
	return overlay_update_local_node_references(fdto, 0, fixups,
						    delta);
}

/**
 * overlay_fixup_one_phandle - Set an overlay phandle to the base one
 * @fdto: Device tree overlay blob
 * @symbols_off: Node offset of the symbols node in the base device tree
 * @path: Path to a node holding a phandle in the overlay
 * @path_len: number of path characters to consider
 * @name: Name of the property holding the phandle reference in the overlay
 * @name_len: number of name characters to consider
 * @poffset: Offset within the overlay property where the phandle is stored
 * @phandle: Phandle referencing the node

Annotation

Implementation Notes