Commit 269f1a67 authored by Frank Rowand's avatar Frank Rowand Committed by Rob Herring
Browse files

of: Update comments to reflect changes and increase clarity 



Update comments to better explain what functions are doing.

Signed-off-by: default avatarFrank Rowand <frank.rowand@am.sony.com>
Signed-off-by: default avatarRob Herring <robh@kernel.org>
parent ea8229b7

drivers/of/resolver.c

+47 −19
Original line number Diff line number Diff line
@@ -50,9 +50,6 @@ static struct device_node *find_node_by_full_name(struct device_node *node, 
	return NULL;

}



/*

 * Find live tree's maximum phandle value.

 */

static phandle live_tree_max_phandle(void)

{

	struct device_node *node;
@@ -71,9 +68,6 @@ static phandle live_tree_max_phandle(void) 
	return phandle;

}



/*

 * Adjust a subtree's phandle values by a given delta.

 */

static void adjust_overlay_phandles(struct device_node *overlay,

		int phandle_delta)

{
@@ -81,9 +75,11 @@ static void adjust_overlay_phandles(struct device_node *overlay, 
	struct property *prop;

	phandle phandle;



	/* adjust node's phandle in node */

	if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)

		overlay->phandle += phandle_delta;



	/* copy adjusted phandle into *phandle properties */

	for_each_property_of_node(overlay, prop) {



		if (of_prop_cmp(prop->name, "phandle") &&
@@ -118,6 +114,7 @@ static int update_usages_of_a_phandle_reference(struct device_node *overlay, 
		return -ENOMEM;

	memcpy(value, prop_fixup->value, prop_fixup->length);



	/* prop_fixup contains a list of tuples of path:property_name:offset */

	end = value + prop_fixup->length;

	for (cur = value; cur < end; cur += len + 1) {

		len = strlen(cur);
@@ -177,10 +174,14 @@ static int node_name_cmp(const struct device_node *dn1, 


/*

 * Adjust the local phandle references by the given phandle delta.

 * Assumes the existances of a __local_fixups__ node at the root.

 * Assumes that __of_verify_tree_phandle_references has been called.

 * Does not take any devtree locks so make sure you call this on a tree

 * which is at the detached state.

 *

 * Subtree @local_fixups, which is overlay node __local_fixups__,

 * mirrors the fragment node structure at the root of the overlay.

 *

 * For each property in the fragments that contains a phandle reference,

 * @local_fixups has a property of the same name that contains a list

 * of offsets of the phandle reference(s) within the respective property

 * value(s).  The values at these offsets will be fixed up.

 */

static int adjust_local_phandle_references(struct device_node *local_fixups,

		struct device_node *overlay, int phandle_delta)
@@ -225,6 +226,13 @@ static int adjust_local_phandle_references(struct device_node *local_fixups, 
		}

	}



	/*

	 * These nested loops recurse down two subtrees in parallel, where the

	 * node names in the two subtrees match.

	 *

	 * The roots of the subtrees are the overlay's __local_fixups__ node

	 * and the overlay's root node.

	 */

	for_each_child_of_node(local_fixups, child) {



		for_each_child_of_node(overlay, overlay_child)
@@ -244,17 +252,37 @@ static int adjust_local_phandle_references(struct device_node *local_fixups, 
}



/**

 * of_resolve	- Resolve the given node against the live tree.

 * of_resolve_phandles - Relocate and resolve overlay against live tree

 *

 * @overlay:	Pointer to devicetree overlay to relocate and resolve

 *

 * Modify (relocate) values of local phandles in @overlay to a range that

 * does not conflict with the live expanded devicetree.  Update references

 * to the local phandles in @overlay.  Update (resolve) phandle references

 * in @overlay that refer to the live expanded devicetree.

 *

 * Phandle values in the live tree are in the range of

 * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay

 * also begin with at 1.  Adjust the phandle values in the overlay to begin

 * at live_tree_max_phandle() + 1.  Update references to the phandles to

 * the adjusted phandle values.

 *

 * The name of each property in the "__fixups__" node in the overlay matches

 * the name of a symbol (a label) in the live tree.  The values of each

 * property in the "__fixups__" node is a list of the property values in the

 * overlay that need to be updated to contain the phandle reference

 * corresponding to that symbol in the live tree.  Update the references in

 * the overlay with the phandle values in the live tree.

 *

 * @overlay must be detached.

 *

 * @resolve:	Node to resolve

 * Resolving and applying @overlay to the live expanded devicetree must be

 * protected by a mechanism to ensure that multiple overlays are processed

 * in a single threaded manner so that multiple overlays will not relocate

 * phandles to overlapping ranges.  The mechanism to enforce this is not

 * yet implemented.

 *

 * Perform dynamic Device Tree resolution against the live tree

 * to the given node to resolve. This depends on the live tree

 * having a __symbols__ node, and the resolve node the __fixups__ &

 * __local_fixups__ nodes (if needed).

 * The result of the operation is a resolve node that it's contents

 * are fit to be inserted or operate upon the live tree.

 * Returns 0 on success or a negative error value on error.

 * Return: %0 on success or a negative error value on error.

 */

int of_resolve_phandles(struct device_node *overlay)

{