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// SPDX-License-Identifier: GPL-2.0
/*
* Extra Boot Config
* Masami Hiramatsu <mhiramat@kernel.org>
*/
#define pr_fmt(fmt) "bootconfig: " fmt
#include <linux/bootconfig.h>
#include <linux/bug.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/printk.h>
#include <linux/string.h>
/*
* Extra Boot Config (XBC) is given as tree-structured ascii text of
* key-value pairs on memory.
* xbc_parse() parses the text to build a simple tree. Each tree node is
* simply a key word or a value. A key node may have a next key node or/and
* a child node (both key and value). A value node may have a next value
* node (for array).
*/
static struct xbc_node *xbc_nodes __initdata;
static int xbc_node_num __initdata;
static char *xbc_data __initdata;
static size_t xbc_data_size __initdata;
static struct xbc_node *last_parent __initdata;
static int __init xbc_parse_error(const char *msg, const char *p)
{
int pos = p - xbc_data;
pr_err("Parse error at pos %d: %s\n", pos, msg);
return -EINVAL;
}
/**
* xbc_root_node() - Get the root node of extended boot config
*
* Return the address of root node of extended boot config. If the
* extended boot config is not initiized, return NULL.
*/
struct xbc_node * __init xbc_root_node(void)
{
if (unlikely(!xbc_data))
return NULL;
return xbc_nodes;
}
/**
* xbc_node_index() - Get the index of XBC node
* @node: A target node of getting index.
*
* Return the index number of @node in XBC node list.
*/
int __init xbc_node_index(struct xbc_node *node)
{
return node - &xbc_nodes[0];
}
/**
* xbc_node_get_parent() - Get the parent XBC node
* @node: An XBC node.
*
* Return the parent node of @node. If the node is top node of the tree,
* return NULL.
*/
struct xbc_node * __init xbc_node_get_parent(struct xbc_node *node)
{
return node->parent == XBC_NODE_MAX ? NULL : &xbc_nodes[node->parent];
}
/**
* xbc_node_get_child() - Get the child XBC node
* @node: An XBC node.
*
* Return the first child node of @node. If the node has no child, return
* NULL.
*/
struct xbc_node * __init xbc_node_get_child(struct xbc_node *node)
{
return node->child ? &xbc_nodes[node->child] : NULL;
}
/**
* xbc_node_get_next() - Get the next sibling XBC node
* @node: An XBC node.
*
* Return the NEXT sibling node of @node. If the node has no next sibling,
* return NULL. Note that even if this returns NULL, it doesn't mean @node
* has no siblings. (You also has to check whether the parent's child node
* is @node or not.)
*/
struct xbc_node * __init xbc_node_get_next(struct xbc_node *node)
{
return node->next ? &xbc_nodes[node->next] : NULL;
}
/**
* xbc_node_get_data() - Get the data of XBC node
* @node: An XBC node.
*
* Return the data (which is always a null terminated string) of @node.
* If the node has invalid data, warn and return NULL.
*/
const char * __init xbc_node_get_data(struct xbc_node *node)
{
int offset = node->data & ~XBC_VALUE;
if (WARN_ON(offset >= xbc_data_size))
return NULL;
return xbc_data + offset;
}
static bool __init
xbc_node_match_prefix(struct xbc_node *node, const char **prefix)
{
const char *p = xbc_node_get_data(node);
int len = strlen(p);
if (strncmp(*prefix, p, len))
return false;
p = *prefix + len;
if (*p == '.')
p++;
else if (*p != '\0')
return false;
*prefix = p;
return true;
}
/**
* xbc_node_find_child() - Find a child node which matches given key
* @parent: An XBC node.
* @key: A key string.
*
* Search a node under @parent which matches @key. The @key can contain
* several words jointed with '.'. If @parent is NULL, this searches the
* node from whole tree. Return NULL if no node is matched.
*/
struct xbc_node * __init
xbc_node_find_child(struct xbc_node *parent, const char *key)
{
struct xbc_node *node;
if (parent)
node = xbc_node_get_child(parent);
else
node = xbc_root_node();
while (node && xbc_node_is_key(node)) {
if (!xbc_node_match_prefix(node, &key))
node = xbc_node_get_next(node);
else if (*key != '\0')
node = xbc_node_get_child(node);
else
break;
}
return node;
}
/**
* xbc_node_find_value() - Find a value node which matches given key
* @parent: An XBC node.
* @key: A key string.
* @vnode: A container pointer of found XBC node.
*
* Search a value node under @parent whose (parent) key node matches @key,
* store it in *@vnode, and returns the value string.
* The @key can contain several words jointed with '.'. If @parent is NULL,
* this searches the node from whole tree. Return the value string if a
* matched key found, return NULL if no node is matched.
* Note that this returns 0-length string and stores NULL in *@vnode if the
* key has no value. And also it will return the value of the first entry if
* the value is an array.
*/
const char * __init
xbc_node_find_value(struct xbc_node *parent, const char *key,
struct xbc_node **vnode)
{
struct xbc_node *node = xbc_node_find_child(parent, key);
if (!node || !xbc_node_is_key(node))
return NULL;
node = xbc_node_get_child(node);
if (node && !xbc_node_is_value(node))
return NULL;
if (vnode)
*vnode = node;
return node ? xbc_node_get_data(node) : "";
}
/**
* xbc_node_compose_key_after() - Compose partial key string of the XBC node
* @root: Root XBC node
* @node: Target XBC node.
* @buf: A buffer to store the key.
* @size: The size of the @buf.
*
* Compose the partial key of the @node into @buf, which is starting right
* after @root (@root is not included.) If @root is NULL, this returns full
* key words of @node.
* Returns the total length of the key stored in @buf. Returns -EINVAL
* if @node is NULL or @root is not the ancestor of @node or @root is @node,
* or returns -ERANGE if the key depth is deeper than max depth.
* This is expected to be used with xbc_find_node() to list up all (child)
* keys under given key.
*/
int __init xbc_node_compose_key_after(struct xbc_node *root,
struct xbc_node *node,
char *buf, size_t size)
{
u16 keys[XBC_DEPTH_MAX];
int depth = 0, ret = 0, total = 0;
if (!node || node == root)
return -EINVAL;
if (xbc_node_is_value(node))
node = xbc_node_get_parent(node);
while (node && node != root) {
keys[depth++] = xbc_node_index(node);
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