// SPDX-License-Identifier: GPL-2.0 /* * Functions for dealing with DT resolution * * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com> * Copyright (C) 2012 Texas Instruments Inc. */ #define pr_fmt(fmt) "OF: resolver: " fmt #include <linux/kernel.h> #include <linux/module.h> #include <linux/of.h> #include <linux/of_device.h> #include <linux/string.h> #include <linux/ctype.h> #include <linux/errno.h> #include <linux/slab.h> #include "of_private.h" static phandle live_tree_max_phandle(void) { struct device_node *node; phandle phandle; unsigned long flags; raw_spin_lock_irqsave(&devtree_lock, flags); phandle = 0; for_each_of_allnodes(node) { if (node->phandle != OF_PHANDLE_ILLEGAL && node->phandle > phandle) phandle = node->phandle; } raw_spin_unlock_irqrestore(&devtree_lock, flags); return phandle; } static void adjust_overlay_phandles(struct device_node *overlay, int phandle_delta) { struct device_node *child; 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") && of_prop_cmp(prop->name, "linux,phandle")) continue; if (prop->length < 4) continue; phandle = be32_to_cpup(prop->value); if (phandle == OF_PHANDLE_ILLEGAL) continue; *(__be32 *)prop->value = cpu_to_be32(overlay->phandle); } for_each_child_of_node(overlay, child) adjust_overlay_phandles(child, phandle_delta); } static int update_usages_of_a_phandle_reference(struct device_node *overlay, struct property *prop_fixup, phandle phandle) { struct device_node *refnode; struct property *prop; char *value, *cur, *end, *node_path, *prop_name, *s; int offset, len; int err = 0; value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL); if (!value) return -ENOMEM; /* 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); node_path = cur; s = strchr(cur, ':'); if (!s) { err = -EINVAL; goto err_fail; } *s++ = '\0'; prop_name = s; s = strchr(s, ':'); if (!s) { err = -EINVAL; goto err_fail; } *s++ = '\0'; err = kstrtoint(s, 10, &offset); if (err) goto err_fail; refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path); if (!refnode) continue; for_each_property_of_node(refnode, prop) { if (!of_prop_cmp(prop->name, prop_name)) break; } of_node_put(refnode); if (!prop) { err = -ENOENT; goto err_fail; } if (offset < 0 || offset + sizeof(__be32) > prop->length) { err = -EINVAL; goto err_fail; } *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle); } err_fail: kfree(value); return err; } /* compare nodes taking into account that 'name' strips out the @ part */ static int node_name_cmp(const struct device_node *dn1, const struct device_node *dn2) { const char *n1 = kbasename(dn1->full_name); const char *n2 = kbasename(dn2->full_name); return of_node_cmp(n1, n2); } /* * Adjust the local phandle references by the given phandle delta. * * 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) { struct device_node *child, *overlay_child; struct property *prop_fix, *prop; int err, i, count; unsigned int off; if (!local_fixups) return 0; for_each_property_of_node(local_fixups, prop_fix) { /* skip properties added automatically */ if (!of_prop_cmp(prop_fix->name, "name") || !of_prop_cmp(prop_fix->name, "phandle") || !of_prop_cmp(prop_fix->name, "linux,phandle")) continue; if ((prop_fix->length % 4) != 0 || prop_fix->length == 0) return -EINVAL; count = prop_fix->length / sizeof(__be32); for_each_property_of_node(overlay, prop) { if (!of_prop_cmp(prop->name, prop_fix->name)) break; } if (!prop) return -EINVAL; for (i = 0; i < count; i++) { off = be32_to_cpu(((__be32 *)prop_fix->value)[i]); if ((off + 4) > prop->length) return -EINVAL; be32_add_cpu(prop->value + off, phandle_delta); } } /* * 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) if (!node_name_cmp(child, overlay_child)) break; if (!overlay_child) return -EINVAL; err = adjust_local_phandle_references(child, overlay_child, phandle_delta); if (err) return err; } return 0; } /** * 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. * * 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. * * Return: %0 on success or a negative error value on error. */ int of_resolve_phandles(struct device_node *overlay) { struct device_node *child, *local_fixups, *refnode; struct device_node *tree_symbols, *overlay_fixups; struct property *prop; const char *refpath; phandle phandle, phandle_delta; int err; tree_symbols = NULL; if (!overlay) { pr_err("null overlay\n"); err = -EINVAL; goto out; } if (!of_node_check_flag(overlay, OF_DETACHED)) { pr_err("overlay not detached\n"); err = -EINVAL; goto out; } phandle_delta = live_tree_max_phandle() + 1; adjust_overlay_phandles(overlay, phandle_delta); for_each_child_of_node(overlay, local_fixups) if (of_node_name_eq(local_fixups, "__local_fixups__")) break; err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta); if (err) goto out; overlay_fixups = NULL; for_each_child_of_node(overlay, child) { if (of_node_name_eq(child, "__fixups__")) overlay_fixups = child; } if (!overlay_fixups) { err = 0; goto out; } tree_symbols = of_find_node_by_path("/__symbols__"); if (!tree_symbols) { pr_err("no symbols in root of device tree.\n"); err = -EINVAL; goto out; } for_each_property_of_node(overlay_fixups, prop) { /* skip properties added automatically */ if (!of_prop_cmp(prop->name, "name")) continue; err = of_property_read_string(tree_symbols, prop->name, &refpath); if (err) goto out; refnode = of_find_node_by_path(refpath); if (!refnode) { err = -ENOENT; goto out; } phandle = refnode->phandle; of_node_put(refnode); err = update_usages_of_a_phandle_reference(overlay, prop, phandle); if (err) break; } out: if (err) pr_err("overlay phandle fixup failed: %d\n", err); of_node_put(tree_symbols); return err; } EXPORT_SYMBOL_GPL(of_resolve_phandles);