/*
 * 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.
 */

#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/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 of_node_get(node);

        for_each_child_of_node(node, child) {
                found = __of_find_node_by_full_name(child, full_name);
                if (found != NULL) {
                        of_node_put(child);
                        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;
                }
                of_node_put(refnode);

                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;

        if (!resolve)
                pr_err("%s: null node\n", __func__);
        if (resolve && !of_node_check_flag(resolve, OF_DETACHED))
                pr_err("%s: node %s not detached\n", __func__,
                         resolve->full_name);
        /* 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) {
                pr_err("%s: no symbols in root of device tree.\n", __func__);
                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);