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// SPDX-License-Identifier: GPL-2.0
/*
* Functions for working with device tree overlays
*
* Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
* Copyright (C) 2012 Texas Instruments Inc.
* Copyright (C) 2019 Pengutronix, Michael Tretter <m.tretter@pengutronix.de>
*/
#define pr_fmt(fmt) "of_overlay: " fmt
#include <common.h>
#include <of.h>
#include <errno.h>
static struct device_node *find_target(struct device_node *root,
struct device_node *fragment)
{
struct device_node *node;
const char *path;
u32 phandle;
int ret;
ret = of_property_read_u32(fragment, "target", &phandle);
if (!ret) {
node = of_find_node_by_phandle_from(phandle, root);
if (!node)
pr_err("fragment %pOF: phandle 0x%x not found\n",
fragment, phandle);
return node;
}
ret = of_property_read_string(fragment, "target-path", &path);
if (!ret) {
node = of_find_node_by_path_from(root, path);
if (!node)
pr_err("fragment %pOF: path '%s' not found\n",
fragment, path);
return node;
}
pr_err("fragment %pOF: no target property\n", fragment);
return NULL;
}
static int of_overlay_apply(struct device_node *target,
const struct device_node *overlay)
{
struct device_node *child;
struct device_node *target_child;
struct property *prop;
int err;
if (target == NULL || overlay == NULL)
return -EINVAL;
list_for_each_entry(prop, &overlay->properties, list) {
if (of_prop_cmp(prop->name, "name") == 0)
continue;
err = of_set_property(target, prop->name, prop->value,
prop->length, true);
if (err)
return err;
}
for_each_child_of_node(overlay, child) {
target_child = of_get_child_by_name(target, child->name);
if (!target_child)
target_child = of_new_node(target, child->name);
if (!target_child)
return -ENOMEM;
err = of_overlay_apply(target_child, child);
if (err)
return err;
}
return 0;
}
static char *of_overlay_fix_path(struct device_node *root,
struct device_node *overlay, const char *path)
{
struct device_node *fragment;
struct device_node *target;
const char *path_tail;
const char *prefix;
fragment = of_find_node_by_path_from(overlay, path);
while ((fragment = of_get_parent(fragment)) != NULL) {
if (of_get_child_by_name(fragment, "__overlay__"))
break;
}
if (!fragment)
return NULL;
target = find_target(root, fragment);
if (!target)
return NULL;
prefix = of_get_child_by_name(fragment, "__overlay__")->full_name;
path_tail = path + strlen(prefix);
return basprintf("%s%s", target->full_name, path_tail);
}
static int of_overlay_apply_symbols(struct device_node *root,
struct device_node *overlay)
{
const char *old_path;
char *new_path;
struct property *prop;
struct device_node *root_symbols;
struct device_node *overlay_symbols;
root_symbols = of_get_child_by_name(root, "__symbols__");
if (!root_symbols)
return -EINVAL;
overlay_symbols = of_get_child_by_name(overlay, "__symbols__");
if (!overlay_symbols)
return -EINVAL;
list_for_each_entry(prop, &overlay_symbols->properties, list) {
if (of_prop_cmp(prop->name, "name") == 0)
continue;
old_path = of_property_get_value(prop);
new_path = of_overlay_fix_path(root, overlay, old_path);
pr_debug("add symbol %s with new path %s\n",
prop->name, new_path);
of_property_write_string(root_symbols, prop->name, new_path);
}
return 0;
}
static int of_overlay_apply_fragment(struct device_node *root,
struct device_node *fragment)
{
struct device_node *target;
struct device_node *overlay;
overlay = of_get_child_by_name(fragment, "__overlay__");
if (!overlay)
return 0;
target = find_target(root, fragment);
if (!target)
return -EINVAL;
return of_overlay_apply(target, overlay);
}
/**
* Apply the overlay on the passed devicetree root
* @root: the devicetree onto which the overlay will be applied
* @overlay: the devicetree to apply as an overlay
*/
int of_overlay_apply_tree(struct device_node *root,
struct device_node *overlay)
{
struct device_node *resolved;
struct device_node *fragment;
int err;
resolved = of_resolve_phandles(root, overlay);
if (!resolved)
return -EINVAL;
/* Copy symbols from resolved overlay to base device tree */
err = of_overlay_apply_symbols(root, resolved);
if (err)
pr_warn("failed to copy symbols from overlay");
/* Copy nodes and properties from resolved overlay to root */
for_each_child_of_node(resolved, fragment) {
err = of_overlay_apply_fragment(root, fragment);
if (err)
pr_warn("failed to apply %s", fragment->name);
}
of_delete_node(resolved);
return err;
}
static int of_overlay_fixup(struct device_node *root, void *data)
{
struct device_node *overlay = data;
return of_overlay_apply_tree(root, overlay);
}
/**
* Iterate the overlay and call process for each fragment
*
* If process() fails for any fragment, the function will stop to process
* other fragments and return the error of the failed process() call.
*/
int of_process_overlay(struct device_node *root,
struct device_node *overlay,
int (*process)(struct device_node *target,
struct device_node *overlay, void *data),
void *data)
{
struct device_node *fragment;
int err = 0;
for_each_child_of_node(overlay, fragment) {
struct device_node *ovl;
struct device_node *target;
ovl = of_get_child_by_name(fragment, "__overlay__");
if (!ovl)
continue;
target = find_target(root, fragment);
if (!target)
continue;
err = process(target, ovl, data);
if (err) {
pr_warn("failed to process overlay for %s\n",
target->name);
break;
}
}
return err;
}
/**
* Register a devicetree overlay
*
* The overlay is not applied to the live device tree, but registered as fixup
* for the fixed up device tree. Therefore, drivers relying on the overlay
* must use the fixed device tree.
*
* The fixup takes ownership of the overlay.
*/
int of_register_overlay(struct device_node *overlay)
{
return of_register_fixup(of_overlay_fixup, overlay);
}
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