0b3ce78e90
Create a cache of the nodes that contain a phandle property. Use this cache to find the node for a given phandle value instead of scanning the devicetree to find the node. If the phandle value is not found in the cache, of_find_node_by_phandle() will fall back to the tree scan algorithm. The cache is initialized in of_core_init(). The cache is freed via a late_initcall_sync() if modules are not enabled. If the devicetree is created by the dtc compiler, with all phandle property values auto generated, then the size required by the cache could be 4 * (1 + number of phandles) bytes. This results in an O(1) node lookup cost for a given phandle value. Due to a concern that the phandle property values might not be consistent with what is generated by the dtc compiler, a mask has been added to the cache lookup algorithm. To maintain the O(1) node lookup cost, the size of the cache has been increased by rounding the number of entries up to the next power of two. The overhead of finding the devicetree node containing a given phandle value has been noted by several people in the recent past, in some cases with a patch to add a hashed index of devicetree nodes, based on the phandle value of the node. One concern with this approach is the extra space added to each node. This patch takes advantage of the phandle property values auto generated by the dtc compiler, which begin with one and monotonically increase by one, resulting in a range of 1..n for n phandle values. This implementation should also provide a good reduction of overhead for any range of phandle values that are mostly in a monotonic range. Performance measurements by Chintan Pandya <cpandya@codeaurora.org> of several implementations of patches that are similar to this one suggest an expected reduction of boot time by ~400ms for his test system. If the cache size was decreased to 64 entries, the boot time was reduced by ~340 ms. The measurements were on a 4.9.73 kernel for arch/arm64/boot/dts/qcom/sda670-mtp.dts, contains 2371 nodes and 814 phandle values. Reported-by: Chintan Pandya <cpandya@codeaurora.org> Signed-off-by: Frank Rowand <frank.rowand@sony.com> Signed-off-by: Rob Herring <robh@kernel.org>
338 lines
8.4 KiB
C
338 lines
8.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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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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#define pr_fmt(fmt) "OF: resolver: " fmt
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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/slab.h>
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#include "of_private.h"
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static phandle live_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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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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static void adjust_overlay_phandles(struct device_node *overlay,
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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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/* adjust node's phandle in node */
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if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
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overlay->phandle += phandle_delta;
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/* copy adjusted phandle into *phandle properties */
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for_each_property_of_node(overlay, prop) {
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if (of_prop_cmp(prop->name, "phandle") &&
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of_prop_cmp(prop->name, "linux,phandle"))
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continue;
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if (prop->length < 4)
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continue;
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phandle = be32_to_cpup(prop->value);
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if (phandle == OF_PHANDLE_ILLEGAL)
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continue;
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*(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
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}
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for_each_child_of_node(overlay, child)
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adjust_overlay_phandles(child, phandle_delta);
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}
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static int update_usages_of_a_phandle_reference(struct device_node *overlay,
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struct property *prop_fixup, phandle phandle)
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{
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struct device_node *refnode;
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struct property *prop;
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char *value, *cur, *end, *node_path, *prop_name, *s;
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int offset, len;
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int err = 0;
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value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
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if (!value)
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return -ENOMEM;
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/* prop_fixup contains a list of tuples of path:property_name:offset */
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end = value + prop_fixup->length;
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for (cur = value; cur < end; cur += len + 1) {
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len = strlen(cur);
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node_path = cur;
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s = strchr(cur, ':');
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if (!s) {
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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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prop_name = s;
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s = strchr(s, ':');
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if (!s) {
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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)
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goto err_fail;
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refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
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if (!refnode)
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continue;
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for_each_property_of_node(refnode, prop) {
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if (!of_prop_cmp(prop->name, prop_name))
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break;
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}
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of_node_put(refnode);
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if (!prop) {
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err = -ENOENT;
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goto err_fail;
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}
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*(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
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}
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err_fail:
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kfree(value);
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return err;
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}
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/* compare nodes taking into account that 'name' strips out the @ part */
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static int node_name_cmp(const struct device_node *dn1,
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const struct device_node *dn2)
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{
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const char *n1 = kbasename(dn1->full_name);
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const char *n2 = kbasename(dn2->full_name);
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return of_node_cmp(n1, n2);
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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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*
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* Subtree @local_fixups, which is overlay node __local_fixups__,
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* mirrors the fragment node structure at the root of the overlay.
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*
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* For each property in the fragments that contains a phandle reference,
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* @local_fixups has a property of the same name that contains a list
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* of offsets of the phandle reference(s) within the respective property
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* value(s). The values at these offsets will be fixed up.
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*/
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static int adjust_local_phandle_references(struct device_node *local_fixups,
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struct device_node *overlay, int phandle_delta)
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{
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struct device_node *child, *overlay_child;
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struct property *prop_fix, *prop;
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int err, i, count;
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unsigned int off;
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if (!local_fixups)
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return 0;
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for_each_property_of_node(local_fixups, prop_fix) {
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/* skip properties added automatically */
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if (!of_prop_cmp(prop_fix->name, "name") ||
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!of_prop_cmp(prop_fix->name, "phandle") ||
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!of_prop_cmp(prop_fix->name, "linux,phandle"))
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continue;
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if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
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return -EINVAL;
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count = prop_fix->length / sizeof(__be32);
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for_each_property_of_node(overlay, prop) {
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if (!of_prop_cmp(prop->name, prop_fix->name))
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break;
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}
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if (!prop)
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return -EINVAL;
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for (i = 0; i < count; i++) {
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off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
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if ((off + 4) > prop->length)
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return -EINVAL;
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be32_add_cpu(prop->value + off, phandle_delta);
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}
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}
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/*
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* These nested loops recurse down two subtrees in parallel, where the
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* node names in the two subtrees match.
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*
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* The roots of the subtrees are the overlay's __local_fixups__ node
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* and the overlay's root node.
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*/
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for_each_child_of_node(local_fixups, child) {
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for_each_child_of_node(overlay, overlay_child)
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if (!node_name_cmp(child, overlay_child))
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break;
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if (!overlay_child)
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return -EINVAL;
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err = adjust_local_phandle_references(child, overlay_child,
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phandle_delta);
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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_phandles - Relocate and resolve overlay against live tree
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*
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* @overlay: Pointer to devicetree overlay to relocate and resolve
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*
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* Modify (relocate) values of local phandles in @overlay to a range that
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* does not conflict with the live expanded devicetree. Update references
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* to the local phandles in @overlay. Update (resolve) phandle references
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* in @overlay that refer to the live expanded devicetree.
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*
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* Phandle values in the live tree are in the range of
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* 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
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* also begin with at 1. Adjust the phandle values in the overlay to begin
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* at live_tree_max_phandle() + 1. Update references to the phandles to
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* the adjusted phandle values.
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*
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* The name of each property in the "__fixups__" node in the overlay matches
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* the name of a symbol (a label) in the live tree. The values of each
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* property in the "__fixups__" node is a list of the property values in the
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* overlay that need to be updated to contain the phandle reference
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* corresponding to that symbol in the live tree. Update the references in
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* the overlay with the phandle values in the live tree.
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*
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* @overlay must be detached.
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*
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* Resolving and applying @overlay to the live expanded devicetree must be
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* protected by a mechanism to ensure that multiple overlays are processed
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* in a single threaded manner so that multiple overlays will not relocate
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* phandles to overlapping ranges. The mechanism to enforce this is not
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* yet implemented.
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*
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* Return: %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 *overlay)
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{
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struct device_node *child, *local_fixups, *refnode;
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struct device_node *tree_symbols, *overlay_fixups;
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struct property *prop;
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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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tree_symbols = NULL;
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if (!overlay) {
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pr_err("null overlay\n");
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err = -EINVAL;
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goto out;
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}
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if (!of_node_check_flag(overlay, OF_DETACHED)) {
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pr_err("overlay not detached\n");
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err = -EINVAL;
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goto out;
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}
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phandle_delta = live_tree_max_phandle() + 1;
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adjust_overlay_phandles(overlay, phandle_delta);
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for_each_child_of_node(overlay, local_fixups)
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if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
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break;
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err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
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if (err)
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goto out;
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overlay_fixups = NULL;
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for_each_child_of_node(overlay, child) {
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if (!of_node_cmp(child->name, "__fixups__"))
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overlay_fixups = child;
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}
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if (!overlay_fixups) {
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err = 0;
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goto out;
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}
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tree_symbols = of_find_node_by_path("/__symbols__");
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if (!tree_symbols) {
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pr_err("no symbols in root of device tree.\n");
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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(overlay_fixups, prop) {
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/* skip properties added automatically */
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if (!of_prop_cmp(prop->name, "name"))
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continue;
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err = of_property_read_string(tree_symbols,
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prop->name, &refpath);
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if (err)
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goto out;
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refnode = of_find_node_by_path(refpath);
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if (!refnode) {
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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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err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
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if (err)
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break;
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}
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out:
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if (err)
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pr_err("overlay phandle fixup failed: %d\n", err);
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of_node_put(tree_symbols);
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return err;
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}
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EXPORT_SYMBOL_GPL(of_resolve_phandles);
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