of: Introduce Device Tree resolve support.
Introduce support for dynamic device tree resolution. Using it, it is possible to prepare a device tree that's been loaded on runtime to be modified and inserted at the kernel live tree. Export of of_resolve and bug fix of double free by Guenter Roeck <groeck@juniper.net> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com> [grant.likely: Don't need to select CONFIG_OF_DYNAMIC and CONFIG_OF_DEVICE] [grant.likely: Don't need to depend on OF or !SPARC] [grant.likely: Factor out duplicate code blocks into single function] Signed-off-by: Grant Likely <grant.likely@linaro.org>
This commit is contained in:
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Коммит
7941b27b16
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@ -0,0 +1,25 @@
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Device Tree Dynamic Resolver Notes
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----------------------------------
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This document describes the implementation of the in-kernel
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Device Tree resolver, residing in drivers/of/resolver.c and is a
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companion document to Documentation/devicetree/dt-object-internal.txt[1]
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How the resolver works
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----------------------
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The resolver is given as an input an arbitrary tree compiled with the
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proper dtc option and having a /plugin/ tag. This generates the
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appropriate __fixups__ & __local_fixups__ nodes as described in [1].
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In sequence the resolver works by the following steps:
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1. Get the maximum device tree phandle value from the live tree + 1.
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2. Adjust all the local phandles of the tree to resolve by that amount.
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3. Using the __local__fixups__ node information adjust all local references
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by the same amount.
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4. For each property in the __fixups__ node locate the node it references
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in the live tree. This is the label used to tag the node.
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5. Retrieve the phandle of the target of the fixup.
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6. For each fixup in the property locate the node:property:offset location
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and replace it with the phandle value.
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@ -79,4 +79,7 @@ config OF_RESERVED_MEM
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help
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Helpers to allow for reservation of memory regions
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config OF_RESOLVE
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bool
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endmenu # OF
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@ -13,6 +13,7 @@ obj-$(CONFIG_OF_PCI) += of_pci.o
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obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o
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obj-$(CONFIG_OF_MTD) += of_mtd.o
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obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
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obj-$(CONFIG_OF_RESOLVE) += resolver.o
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CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
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CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt
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@ -0,0 +1,336 @@
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/*
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* Functions for dealing with DT resolution
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*
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* Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
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* Copyright (C) 2012 Texas Instruments Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/string.h>
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#include <linux/ctype.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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/* illegal phandle value (set when unresolved) */
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#define OF_PHANDLE_ILLEGAL 0xdeadbeef
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/**
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* Find a node with the give full name by recursively following any of
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* the child node links.
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*/
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static struct device_node *__of_find_node_by_full_name(struct device_node *node,
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const char *full_name)
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{
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struct device_node *child, *found;
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if (node == NULL)
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return NULL;
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/* check */
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if (of_node_cmp(node->full_name, full_name) == 0)
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return node;
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for_each_child_of_node(node, child) {
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found = __of_find_node_by_full_name(child, full_name);
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if (found != NULL)
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return found;
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}
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return NULL;
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}
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/*
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* Find live tree's maximum phandle value.
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*/
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static phandle of_get_tree_max_phandle(void)
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{
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struct device_node *node;
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phandle phandle;
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unsigned long flags;
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/* now search recursively */
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raw_spin_lock_irqsave(&devtree_lock, flags);
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phandle = 0;
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for_each_of_allnodes(node) {
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if (node->phandle != OF_PHANDLE_ILLEGAL &&
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node->phandle > phandle)
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phandle = node->phandle;
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}
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raw_spin_unlock_irqrestore(&devtree_lock, flags);
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return phandle;
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}
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/*
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* Adjust a subtree's phandle values by a given delta.
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* Makes sure not to just adjust the device node's phandle value,
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* but modify the phandle properties values as well.
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*/
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static void __of_adjust_tree_phandles(struct device_node *node,
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int phandle_delta)
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{
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struct device_node *child;
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struct property *prop;
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phandle phandle;
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/* first adjust the node's phandle direct value */
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if (node->phandle != 0 && node->phandle != OF_PHANDLE_ILLEGAL)
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node->phandle += phandle_delta;
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/* now adjust phandle & linux,phandle values */
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for_each_property_of_node(node, prop) {
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/* only look for these two */
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if (of_prop_cmp(prop->name, "phandle") != 0 &&
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of_prop_cmp(prop->name, "linux,phandle") != 0)
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continue;
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/* must be big enough */
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if (prop->length < 4)
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continue;
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/* read phandle value */
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phandle = be32_to_cpup(prop->value);
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if (phandle == OF_PHANDLE_ILLEGAL) /* unresolved */
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continue;
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/* adjust */
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*(uint32_t *)prop->value = cpu_to_be32(node->phandle);
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}
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/* now do the children recursively */
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for_each_child_of_node(node, child)
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__of_adjust_tree_phandles(child, phandle_delta);
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}
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static int __of_adjust_phandle_ref(struct device_node *node, struct property *rprop, int value, bool is_delta)
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{
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phandle phandle;
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struct device_node *refnode;
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struct property *sprop;
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char *propval, *propcur, *propend, *nodestr, *propstr, *s;
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int offset, propcurlen;
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int err = 0;
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/* make a copy */
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propval = kmalloc(rprop->length, GFP_KERNEL);
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if (!propval) {
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pr_err("%s: Could not copy value of '%s'\n",
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__func__, rprop->name);
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return -ENOMEM;
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}
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memcpy(propval, rprop->value, rprop->length);
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propend = propval + rprop->length;
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for (propcur = propval; propcur < propend; propcur += propcurlen + 1) {
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propcurlen = strlen(propcur);
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nodestr = propcur;
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s = strchr(propcur, ':');
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if (!s) {
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pr_err("%s: Illegal symbol entry '%s' (1)\n",
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__func__, propcur);
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err = -EINVAL;
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goto err_fail;
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}
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*s++ = '\0';
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propstr = s;
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s = strchr(s, ':');
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if (!s) {
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pr_err("%s: Illegal symbol entry '%s' (2)\n",
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__func__, (char *)rprop->value);
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err = -EINVAL;
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goto err_fail;
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}
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*s++ = '\0';
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err = kstrtoint(s, 10, &offset);
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if (err != 0) {
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pr_err("%s: Could get offset '%s'\n",
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__func__, (char *)rprop->value);
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goto err_fail;
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}
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/* look into the resolve node for the full path */
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refnode = __of_find_node_by_full_name(node, nodestr);
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if (!refnode) {
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pr_warn("%s: Could not find refnode '%s'\n",
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__func__, (char *)rprop->value);
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continue;
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}
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/* now find the property */
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for_each_property_of_node(refnode, sprop) {
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if (of_prop_cmp(sprop->name, propstr) == 0)
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break;
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}
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if (!sprop) {
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pr_err("%s: Could not find property '%s'\n",
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__func__, (char *)rprop->value);
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err = -ENOENT;
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goto err_fail;
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}
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phandle = is_delta ? be32_to_cpup(sprop->value + offset) + value : value;
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*(__be32 *)(sprop->value + offset) = cpu_to_be32(phandle);
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}
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err_fail:
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kfree(propval);
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return err;
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}
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/*
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* Adjust the local phandle references by the given phandle delta.
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* Assumes the existances of a __local_fixups__ node at the root
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* of the tree. Does not take any devtree locks so make sure you
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* call this on a tree which is at the detached state.
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*/
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static int __of_adjust_tree_phandle_references(struct device_node *node,
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int phandle_delta)
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{
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struct device_node *child;
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struct property *rprop;
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int err;
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/* locate the symbols & fixups nodes on resolve */
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for_each_child_of_node(node, child)
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if (of_node_cmp(child->name, "__local_fixups__") == 0)
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break;
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/* no local fixups */
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if (!child)
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return 0;
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/* find the local fixups property */
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for_each_property_of_node(child, rprop) {
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/* skip properties added automatically */
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if (of_prop_cmp(rprop->name, "name") == 0)
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continue;
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err = __of_adjust_phandle_ref(node, rprop, phandle_delta, true);
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if (err)
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return err;
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}
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return 0;
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}
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/**
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* of_resolve - Resolve the given node against the live tree.
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*
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* @resolve: Node to resolve
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*
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* Perform dynamic Device Tree resolution against the live tree
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* to the given node to resolve. This depends on the live tree
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* having a __symbols__ node, and the resolve node the __fixups__ &
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* __local_fixups__ nodes (if needed).
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* The result of the operation is a resolve node that it's contents
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* are fit to be inserted or operate upon the live tree.
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* Returns 0 on success or a negative error value on error.
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*/
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int of_resolve_phandles(struct device_node *resolve)
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{
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struct device_node *child, *refnode;
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struct device_node *root_sym, *resolve_sym, *resolve_fix;
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struct property *rprop;
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const char *refpath;
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phandle phandle, phandle_delta;
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int err;
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/* the resolve node must exist, and be detached */
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if (!resolve || !of_node_check_flag(resolve, OF_DETACHED))
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return -EINVAL;
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/* first we need to adjust the phandles */
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phandle_delta = of_get_tree_max_phandle() + 1;
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__of_adjust_tree_phandles(resolve, phandle_delta);
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err = __of_adjust_tree_phandle_references(resolve, phandle_delta);
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if (err != 0)
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return err;
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root_sym = NULL;
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resolve_sym = NULL;
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resolve_fix = NULL;
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/* this may fail (if no fixups are required) */
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root_sym = of_find_node_by_path("/__symbols__");
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/* locate the symbols & fixups nodes on resolve */
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for_each_child_of_node(resolve, child) {
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if (!resolve_sym &&
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of_node_cmp(child->name, "__symbols__") == 0)
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resolve_sym = child;
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if (!resolve_fix &&
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of_node_cmp(child->name, "__fixups__") == 0)
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resolve_fix = child;
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/* both found, don't bother anymore */
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if (resolve_sym && resolve_fix)
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break;
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}
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/* we do allow for the case where no fixups are needed */
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if (!resolve_fix) {
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err = 0; /* no error */
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goto out;
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}
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/* we need to fixup, but no root symbols... */
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if (!root_sym) {
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err = -EINVAL;
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goto out;
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}
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for_each_property_of_node(resolve_fix, rprop) {
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/* skip properties added automatically */
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if (of_prop_cmp(rprop->name, "name") == 0)
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continue;
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err = of_property_read_string(root_sym,
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rprop->name, &refpath);
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if (err != 0) {
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pr_err("%s: Could not find symbol '%s'\n",
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__func__, rprop->name);
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goto out;
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}
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refnode = of_find_node_by_path(refpath);
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if (!refnode) {
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pr_err("%s: Could not find node by path '%s'\n",
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__func__, refpath);
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err = -ENOENT;
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goto out;
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}
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phandle = refnode->phandle;
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of_node_put(refnode);
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pr_debug("%s: %s phandle is 0x%08x\n",
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__func__, rprop->name, phandle);
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err = __of_adjust_phandle_ref(resolve, rprop, phandle, false);
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if (err)
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break;
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}
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out:
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/* NULL is handled by of_node_put as NOP */
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of_node_put(root_sym);
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return err;
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}
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EXPORT_SYMBOL_GPL(of_resolve_phandles);
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@ -863,4 +863,7 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
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}
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#endif
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/* CONFIG_OF_RESOLVE api */
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extern int of_resolve_phandles(struct device_node *tree);
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#endif /* _LINUX_OF_H */
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