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:
Pantelis Antoniou 2014-07-04 19:59:20 +03:00 коммит произвёл Grant Likely
Родитель 841ec21357
Коммит 7941b27b16
5 изменённых файлов: 368 добавлений и 0 удалений

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@ -0,0 +1,25 @@
Device Tree Dynamic Resolver Notes
----------------------------------
This document describes the implementation of the in-kernel
Device Tree resolver, residing in drivers/of/resolver.c and is a
companion document to Documentation/devicetree/dt-object-internal.txt[1]
How the resolver works
----------------------
The resolver is given as an input an arbitrary tree compiled with the
proper dtc option and having a /plugin/ tag. This generates the
appropriate __fixups__ & __local_fixups__ nodes as described in [1].
In sequence the resolver works by the following steps:
1. Get the maximum device tree phandle value from the live tree + 1.
2. Adjust all the local phandles of the tree to resolve by that amount.
3. Using the __local__fixups__ node information adjust all local references
by the same amount.
4. For each property in the __fixups__ node locate the node it references
in the live tree. This is the label used to tag the node.
5. Retrieve the phandle of the target of the fixup.
6. For each fixup in the property locate the node:property:offset location
and replace it with the phandle value.

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@ -79,4 +79,7 @@ config OF_RESERVED_MEM
help
Helpers to allow for reservation of memory regions
config OF_RESOLVE
bool
endmenu # OF

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@ -13,6 +13,7 @@ obj-$(CONFIG_OF_PCI) += of_pci.o
obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o
obj-$(CONFIG_OF_MTD) += of_mtd.o
obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
obj-$(CONFIG_OF_RESOLVE) += resolver.o
CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
CFLAGS_fdt_address.o = -I$(src)/../../scripts/dtc/libfdt

336
drivers/of/resolver.c Normal file
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@ -0,0 +1,336 @@
/*
* Functions for dealing with DT resolution
*
* Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
* Copyright (C) 2012 Texas Instruments Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*/
#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/string.h>
#include <linux/slab.h>
/* illegal phandle value (set when unresolved) */
#define OF_PHANDLE_ILLEGAL 0xdeadbeef
/**
* Find a node with the give full name by recursively following any of
* the child node links.
*/
static struct device_node *__of_find_node_by_full_name(struct device_node *node,
const char *full_name)
{
struct device_node *child, *found;
if (node == NULL)
return NULL;
/* check */
if (of_node_cmp(node->full_name, full_name) == 0)
return node;
for_each_child_of_node(node, child) {
found = __of_find_node_by_full_name(child, full_name);
if (found != NULL)
return found;
}
return NULL;
}
/*
* Find live tree's maximum phandle value.
*/
static phandle of_get_tree_max_phandle(void)
{
struct device_node *node;
phandle phandle;
unsigned long flags;
/* now search recursively */
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;
}
/*
* Adjust a subtree's phandle values by a given delta.
* Makes sure not to just adjust the device node's phandle value,
* but modify the phandle properties values as well.
*/
static void __of_adjust_tree_phandles(struct device_node *node,
int phandle_delta)
{
struct device_node *child;
struct property *prop;
phandle phandle;
/* first adjust the node's phandle direct value */
if (node->phandle != 0 && node->phandle != OF_PHANDLE_ILLEGAL)
node->phandle += phandle_delta;
/* now adjust phandle & linux,phandle values */
for_each_property_of_node(node, prop) {
/* only look for these two */
if (of_prop_cmp(prop->name, "phandle") != 0 &&
of_prop_cmp(prop->name, "linux,phandle") != 0)
continue;
/* must be big enough */
if (prop->length < 4)
continue;
/* read phandle value */
phandle = be32_to_cpup(prop->value);
if (phandle == OF_PHANDLE_ILLEGAL) /* unresolved */
continue;
/* adjust */
*(uint32_t *)prop->value = cpu_to_be32(node->phandle);
}
/* now do the children recursively */
for_each_child_of_node(node, child)
__of_adjust_tree_phandles(child, phandle_delta);
}
static int __of_adjust_phandle_ref(struct device_node *node, struct property *rprop, int value, bool is_delta)
{
phandle phandle;
struct device_node *refnode;
struct property *sprop;
char *propval, *propcur, *propend, *nodestr, *propstr, *s;
int offset, propcurlen;
int err = 0;
/* make a copy */
propval = kmalloc(rprop->length, GFP_KERNEL);
if (!propval) {
pr_err("%s: Could not copy value of '%s'\n",
__func__, rprop->name);
return -ENOMEM;
}
memcpy(propval, rprop->value, rprop->length);
propend = propval + rprop->length;
for (propcur = propval; propcur < propend; propcur += propcurlen + 1) {
propcurlen = strlen(propcur);
nodestr = propcur;
s = strchr(propcur, ':');
if (!s) {
pr_err("%s: Illegal symbol entry '%s' (1)\n",
__func__, propcur);
err = -EINVAL;
goto err_fail;
}
*s++ = '\0';
propstr = s;
s = strchr(s, ':');
if (!s) {
pr_err("%s: Illegal symbol entry '%s' (2)\n",
__func__, (char *)rprop->value);
err = -EINVAL;
goto err_fail;
}
*s++ = '\0';
err = kstrtoint(s, 10, &offset);
if (err != 0) {
pr_err("%s: Could get offset '%s'\n",
__func__, (char *)rprop->value);
goto err_fail;
}
/* look into the resolve node for the full path */
refnode = __of_find_node_by_full_name(node, nodestr);
if (!refnode) {
pr_warn("%s: Could not find refnode '%s'\n",
__func__, (char *)rprop->value);
continue;
}
/* now find the property */
for_each_property_of_node(refnode, sprop) {
if (of_prop_cmp(sprop->name, propstr) == 0)
break;
}
if (!sprop) {
pr_err("%s: Could not find property '%s'\n",
__func__, (char *)rprop->value);
err = -ENOENT;
goto err_fail;
}
phandle = is_delta ? be32_to_cpup(sprop->value + offset) + value : value;
*(__be32 *)(sprop->value + offset) = cpu_to_be32(phandle);
}
err_fail:
kfree(propval);
return err;
}
/*
* Adjust the local phandle references by the given phandle delta.
* Assumes the existances of a __local_fixups__ node at the root
* of the tree. Does not take any devtree locks so make sure you
* call this on a tree which is at the detached state.
*/
static int __of_adjust_tree_phandle_references(struct device_node *node,
int phandle_delta)
{
struct device_node *child;
struct property *rprop;
int err;
/* locate the symbols & fixups nodes on resolve */
for_each_child_of_node(node, child)
if (of_node_cmp(child->name, "__local_fixups__") == 0)
break;
/* no local fixups */
if (!child)
return 0;
/* find the local fixups property */
for_each_property_of_node(child, rprop) {
/* skip properties added automatically */
if (of_prop_cmp(rprop->name, "name") == 0)
continue;
err = __of_adjust_phandle_ref(node, rprop, phandle_delta, true);
if (err)
return err;
}
return 0;
}
/**
* of_resolve - Resolve the given node against the live tree.
*
* @resolve: Node to resolve
*
* 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.
*/
int of_resolve_phandles(struct device_node *resolve)
{
struct device_node *child, *refnode;
struct device_node *root_sym, *resolve_sym, *resolve_fix;
struct property *rprop;
const char *refpath;
phandle phandle, phandle_delta;
int err;
/* the resolve node must exist, and be detached */
if (!resolve || !of_node_check_flag(resolve, OF_DETACHED))
return -EINVAL;
/* first we need to adjust the phandles */
phandle_delta = of_get_tree_max_phandle() + 1;
__of_adjust_tree_phandles(resolve, phandle_delta);
err = __of_adjust_tree_phandle_references(resolve, phandle_delta);
if (err != 0)
return err;
root_sym = NULL;
resolve_sym = NULL;
resolve_fix = NULL;
/* this may fail (if no fixups are required) */
root_sym = of_find_node_by_path("/__symbols__");
/* locate the symbols & fixups nodes on resolve */
for_each_child_of_node(resolve, child) {
if (!resolve_sym &&
of_node_cmp(child->name, "__symbols__") == 0)
resolve_sym = child;
if (!resolve_fix &&
of_node_cmp(child->name, "__fixups__") == 0)
resolve_fix = child;
/* both found, don't bother anymore */
if (resolve_sym && resolve_fix)
break;
}
/* we do allow for the case where no fixups are needed */
if (!resolve_fix) {
err = 0; /* no error */
goto out;
}
/* we need to fixup, but no root symbols... */
if (!root_sym) {
err = -EINVAL;
goto out;
}
for_each_property_of_node(resolve_fix, rprop) {
/* skip properties added automatically */
if (of_prop_cmp(rprop->name, "name") == 0)
continue;
err = of_property_read_string(root_sym,
rprop->name, &refpath);
if (err != 0) {
pr_err("%s: Could not find symbol '%s'\n",
__func__, rprop->name);
goto out;
}
refnode = of_find_node_by_path(refpath);
if (!refnode) {
pr_err("%s: Could not find node by path '%s'\n",
__func__, refpath);
err = -ENOENT;
goto out;
}
phandle = refnode->phandle;
of_node_put(refnode);
pr_debug("%s: %s phandle is 0x%08x\n",
__func__, rprop->name, phandle);
err = __of_adjust_phandle_ref(resolve, rprop, phandle, false);
if (err)
break;
}
out:
/* NULL is handled by of_node_put as NOP */
of_node_put(root_sym);
return err;
}
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,
}
#endif
/* CONFIG_OF_RESOLVE api */
extern int of_resolve_phandles(struct device_node *tree);
#endif /* _LINUX_OF_H */