// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2009 Benjamin Herrenschmidt, IBM Corp
 * benh@kernel.crashing.org
 *
 * Based on parts of drivers/of/fdt.c from Linux v4.9
 * Modifications for U-Boot
 * Copyright (c) 2017 Google, Inc
 */

#include <common.h>
#include <log.h>
#include <linux/libfdt.h>
#include <of_live.h>
#include <malloc.h>
#include <dm/of_access.h>
#include <linux/err.h>

static void *unflatten_dt_alloc(void **mem, unsigned long size,
                                unsigned long align)
{
        void *res;

        *mem = PTR_ALIGN(*mem, align);
        res = *mem;
        *mem += size;

        return res;
}

/**
 * unflatten_dt_node() - Alloc and populate a device_node from the flat tree
 * @blob: The parent device tree blob
 * @mem: Memory chunk to use for allocating device nodes and properties
 * @poffset: pointer to node in flat tree
 * @dad: Parent struct device_node
 * @nodepp: The device_node tree created by the call
 * @fpsize: Size of the node path up at t05he current depth.
 * @dryrun: If true, do not allocate device nodes but still calculate needed
 * memory size
 */
static void *unflatten_dt_node(const void *blob, void *mem, int *poffset,
                               struct device_node *dad,
                               struct device_node **nodepp,
                               unsigned long fpsize, bool dryrun)
{
        const __be32 *p;
        struct device_node *np;
        struct property *pp, **prev_pp = NULL;
        const char *pathp;
        int l;
        unsigned int allocl;
        static int depth;
        int old_depth;
        int offset;
        int has_name = 0;
        int new_format = 0;

        pathp = fdt_get_name(blob, *poffset, &l);
        if (!pathp)
                return mem;

        allocl = ++l;

        /*
         * version 0x10 has a more compact unit name here instead of the full
         * path. we accumulate the full path size using "fpsize", we'll rebuild
         * it later. We detect this because the first character of the name is
         * not '/'.
         */
        if ((*pathp) != '/') {
                new_format = 1;
                if (fpsize == 0) {
                        /*
                         * root node: special case. fpsize accounts for path
                         * plus terminating zero. root node only has '/', so
                         * fpsize should be 2, but we want to avoid the first
                         * level nodes to have two '/' so we use fpsize 1 here
                         */
                        fpsize = 1;
                        allocl = 2;
                        l = 1;
                        pathp = "";
                } else {
                        /*
                         * account for '/' and path size minus terminal 0
                         * already in 'l'
                         */
                        fpsize += l;
                        allocl = fpsize;
                }
        }

        np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
                                __alignof__(struct device_node));
        if (!dryrun) {
                char *fn;

                fn = (char *)np + sizeof(*np);
                np->full_name = fn;
                if (new_format) {
                        /* rebuild full path for new format */
                        if (dad && dad->parent) {
                                strcpy(fn, dad->full_name);
#ifdef DEBUG
                                if ((strlen(fn) + l + 1) != allocl) {
                                        debug("%s: p: %d, l: %d, a: %d\n",
                                              pathp, (int)strlen(fn), l,
                                              allocl);
                                }
#endif
                                fn += strlen(fn);
                        }
                        *(fn++) = '/';
                }
                memcpy(fn, pathp, l);

                prev_pp = &np->properties;
                if (dad != NULL) {
                        np->parent = dad;
                        np->sibling = dad->child;
                        dad->child = np;
                }
        }
        /* process properties */
        for (offset = fdt_first_property_offset(blob, *poffset);
             (offset >= 0);
             (offset = fdt_next_property_offset(blob, offset))) {
                const char *pname;
                int sz;

                p = fdt_getprop_by_offset(blob, offset, &pname, &sz);
                if (!p) {
                        offset = -FDT_ERR_INTERNAL;
                        break;
                }

                if (pname == NULL) {
                        debug("Can't find property name in list !\n");
                        break;
                }
                if (strcmp(pname, "name") == 0)
                        has_name = 1;
                pp = unflatten_dt_alloc(&mem, sizeof(struct property),
                                        __alignof__(struct property));
                if (!dryrun) {
                        /*
                         * We accept flattened tree phandles either in
                         * ePAPR-style "phandle" properties, or the
                         * legacy "linux,phandle" properties.  If both
                         * appear and have different values, things
                         * will get weird.  Don't do that. */
                        if ((strcmp(pname, "phandle") == 0) ||
                            (strcmp(pname, "linux,phandle") == 0)) {
                                if (np->phandle == 0)
                                        np->phandle = be32_to_cpup(p);
                        }
                        /*
                         * And we process the "ibm,phandle" property
                         * used in pSeries dynamic device tree
                         * stuff */
                        if (strcmp(pname, "ibm,phandle") == 0)
                                np->phandle = be32_to_cpup(p);
                        pp->name = (char *)pname;
                        pp->length = sz;
                        pp->value = (__be32 *)p;
                        *prev_pp = pp;
                        prev_pp = &pp->next;
                }
        }
        /*
         * with version 0x10 we may not have the name property, recreate
         * it here from the unit name if absent
         */
        if (!has_name) {
                const char *p1 = pathp, *ps = pathp, *pa = NULL;
                int sz;

                while (*p1) {
                        if ((*p1) == '@')
                                pa = p1;
                        if ((*p1) == '/')
                                ps = p1 + 1;
                        p1++;
                }
                if (pa < ps)
                        pa = p1;
                sz = (pa - ps) + 1;
                pp = unflatten_dt_alloc(&mem, sizeof(struct property) + sz,
                                        __alignof__(struct property));
                if (!dryrun) {
                        pp->name = "name";
                        pp->length = sz;
                        pp->value = pp + 1;
                        *prev_pp = pp;
                        prev_pp = &pp->next;
                        memcpy(pp->value, ps, sz - 1);
                        ((char *)pp->value)[sz - 1] = 0;
                        debug("fixed up name for %s -> %s\n", pathp,
                              (char *)pp->value);
                }
        }
        if (!dryrun) {
                *prev_pp = NULL;
                np->name = of_get_property(np, "name", NULL);
                np->type = of_get_property(np, "device_type", NULL);

                if (!np->name)
                        np->name = "<NULL>";
                if (!np->type)
                        np->type = "<NULL>";    }

        old_depth = depth;
        *poffset = fdt_next_node(blob, *poffset, &depth);
        if (depth < 0)
                depth = 0;
        while (*poffset > 0 && depth > old_depth) {
                mem = unflatten_dt_node(blob, mem, poffset, np, NULL,
                                        fpsize, dryrun);
                if (!mem)
                        return NULL;
        }

        if (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND) {
                debug("unflatten: error %d processing FDT\n", *poffset);
                return NULL;
        }

        /*
         * Reverse the child list. Some drivers assumes node order matches .dts
         * node order
         */
        if (!dryrun && np->child) {
                struct device_node *child = np->child;
                np->child = NULL;
                while (child) {
                        struct device_node *next = child->sibling;

                        child->sibling = np->child;
                        np->child = child;
                        child = next;
                }
        }

        if (nodepp)
                *nodepp = np;

        return mem;
}

/**
 * unflatten_device_tree() - create tree of device_nodes from flat blob
 *
 * unflattens a device-tree, creating the
 * tree of struct device_node. It also fills the "name" and "type"
 * pointers of the nodes so the normal device-tree walking functions
 * can be used.
 * @blob: The blob to expand
 * @mynodes: The device_node tree created by the call
 * @return 0 if OK, -ve on error
 */
static int unflatten_device_tree(const void *blob,
                                 struct device_node **mynodes)
{
        unsigned long size;
        int start;
        void *mem;

        debug(" -> unflatten_device_tree()\n");

        if (!blob) {
                debug("No device tree pointer\n");
                return -EINVAL;
        }

        debug("Unflattening device tree:\n");
        debug("magic: %08x\n", fdt_magic(blob));
        debug("size: %08x\n", fdt_totalsize(blob));
        debug("version: %08x\n", fdt_version(blob));

        if (fdt_check_header(blob)) {
                debug("Invalid device tree blob header\n");
                return -EINVAL;
        }

        /* First pass, scan for size */
        start = 0;
        size = (unsigned long)unflatten_dt_node(blob, NULL, &start, NULL, NULL,
                                                0, true);
        if (!size)
                return -EFAULT;
        size = ALIGN(size, 4);

        debug("  size is %lx, allocating...\n", size);

        /* Allocate memory for the expanded device tree */
        mem = malloc(size + 4);
        memset(mem, '\0', size);

        *(__be32 *)(mem + size) = cpu_to_be32(0xdeadbeef);

        debug("  unflattening %p...\n", mem);

        /* Second pass, do actual unflattening */
        start = 0;
        unflatten_dt_node(blob, mem, &start, NULL, mynodes, 0, false);
        if (be32_to_cpup(mem + size) != 0xdeadbeef) {
                debug("End of tree marker overwritten: %08x\n",
                      be32_to_cpup(mem + size));
                return -ENOSPC;
        }

        debug(" <- unflatten_device_tree()\n");

        return 0;
}

int of_live_build(const void *fdt_blob, struct device_node **rootp)
{
        int ret;

        debug("%s: start\n", __func__);
        ret = unflatten_device_tree(fdt_blob, rootp);
        if (ret) {
                debug("Failed to create live tree: err=%d\n", ret);
                return ret;
        }
        ret = of_alias_scan();
        if (ret) {
                debug("Failed to scan live tree aliases: err=%d\n", ret);
                return ret;
        }
        debug("%s: stop\n", __func__);

        return ret;
}