// SPDX-License-Identifier: GPL-2.0
/*
 * Functions for working with the Flattened Device Tree data format
 *
 * Copyright 2009 Benjamin Herrenschmidt, IBM Corp
 * benh@kernel.crashing.org
 */

#define pr_fmt(fmt)     "OF: fdt: " fmt

#include <linux/crash_dump.h>
#include <linux/crc32.h>
#include <linux/kernel.h>
#include <linux/initrd.h>
#include <linux/memblock.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/sizes.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/libfdt.h>
#include <linux/debugfs.h>
#include <linux/serial_core.h>
#include <linux/sysfs.h>
#include <linux/random.h>
#include <linux/kexec_handover.h>

#include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
#include <asm/page.h>

#include "of_private.h"

/*
 * __dtb_empty_root_begin[] and __dtb_empty_root_end[] magically created by
 * cmd_wrap_S_dtb in scripts/Makefile.dtbs
 */
extern uint8_t __dtb_empty_root_begin[];
extern uint8_t __dtb_empty_root_end[];

/*
 * of_fdt_limit_memory - limit the number of regions in the /memory node
 * @limit: maximum entries
 *
 * Adjust the flattened device tree to have at most 'limit' number of
 * memory entries in the /memory node. This function may be called
 * any time after initial_boot_param is set.
 */
void __init of_fdt_limit_memory(int limit)
{
        int memory;
        int len;
        const void *val;
        int cell_size = sizeof(uint32_t)*(dt_root_addr_cells + dt_root_size_cells);

        memory = fdt_path_offset(initial_boot_params, "/memory");
        if (memory > 0) {
                val = fdt_getprop(initial_boot_params, memory, "reg", &len);
                if (len > limit*cell_size) {
                        len = limit*cell_size;
                        pr_debug("Limiting number of entries to %d\n", limit);
                        fdt_setprop(initial_boot_params, memory, "reg", val,
                                        len);
                }
        }
}

bool of_fdt_device_is_available(const void *blob, unsigned long node)
{
        const char *status = fdt_getprop(blob, node, "status", NULL);

        if (!status)
                return true;

        if (!strcmp(status, "ok") || !strcmp(status, "okay"))
                return true;

        return false;
}

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;
}

static void populate_properties(const void *blob,
                                int offset,
                                void **mem,
                                struct device_node *np,
                                const char *nodename,
                                bool dryrun)
{
        struct property *pp, **pprev = NULL;
        int cur;
        bool has_name = false;

        pprev = &np->properties;
        for (cur = fdt_first_property_offset(blob, offset);
             cur >= 0;
             cur = fdt_next_property_offset(blob, cur)) {
                const __be32 *val;
                const char *pname;
                u32 sz;

                val = fdt_getprop_by_offset(blob, cur, &pname, &sz);
                if (!val) {
                        pr_warn("Cannot locate property at 0x%x\n", cur);
                        continue;
                }

                if (!pname) {
                        pr_warn("Cannot find property name at 0x%x\n", cur);
                        continue;
                }

                if (!strcmp(pname, "name"))
                        has_name = true;

                pp = unflatten_dt_alloc(mem, sizeof(struct property),
                                        __alignof__(struct property));
                if (dryrun)
                        continue;

                /* 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") ||
                    !strcmp(pname, "linux,phandle")) {
                        if (!np->phandle)
                                np->phandle = be32_to_cpup(val);
                }

                /* And we process the "ibm,phandle" property
                 * used in pSeries dynamic device tree
                 * stuff
                 */
                if (!strcmp(pname, "ibm,phandle"))
                        np->phandle = be32_to_cpup(val);

                pp->name   = (char *)pname;
                pp->length = sz;
                pp->value  = (__be32 *)val;
                *pprev     = pp;
                pprev      = &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 *p = nodename, *ps = p, *pa = NULL;
                int len;

                while (*p) {
                        if ((*p) == '@')
                                pa = p;
                        else if ((*p) == '/')
                                ps = p + 1;
                        p++;
                }

                if (pa < ps)
                        pa = p;
                len = (pa - ps) + 1;
                pp = unflatten_dt_alloc(mem, sizeof(struct property) + len,
                                        __alignof__(struct property));
                if (!dryrun) {
                        pp->name   = "name";
                        pp->length = len;
                        pp->value  = pp + 1;
                        *pprev     = pp;
                        memcpy(pp->value, ps, len - 1);
                        ((char *)pp->value)[len - 1] = 0;
                        pr_debug("fixed up name for %s -> %s\n",
                                 nodename, (char *)pp->value);
                }
        }
}

static int populate_node(const void *blob,
                          int offset,
                          void **mem,
                          struct device_node *dad,
                          struct device_node **pnp,
                          bool dryrun)
{
        struct device_node *np;
        const char *pathp;
        int len;

        pathp = fdt_get_name(blob, offset, &len);
        if (!pathp) {
                *pnp = NULL;
                return len;
        }

        len++;

        np = unflatten_dt_alloc(mem, sizeof(struct device_node) + len,
                                __alignof__(struct device_node));
        if (!dryrun) {
                char *fn;
                of_node_init(np);
                np->full_name = fn = ((char *)np) + sizeof(*np);

                memcpy(fn, pathp, len);

                if (dad != NULL) {
                        np->parent = dad;
                        np->sibling = dad->child;
                        dad->child = np;
                }
        }

        populate_properties(blob, offset, mem, np, pathp, dryrun);
        if (!dryrun) {
                np->name = of_get_property(np, "name", NULL);
                if (!np->name)
                        np->name = "<NULL>";
        }

        *pnp = np;
        return 0;
}

static void reverse_nodes(struct device_node *parent)
{
        struct device_node *child, *next;

        /* In-depth first */
        child = parent->child;
        while (child) {
                reverse_nodes(child);

                child = child->sibling;
        }

        /* Reverse the nodes in the child list */
        child = parent->child;
        parent->child = NULL;
        while (child) {
                next = child->sibling;

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

/**
 * unflatten_dt_nodes - 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
 * @dad: Parent struct device_node
 * @nodepp: The device_node tree created by the call
 *
 * Return: The size of unflattened device tree or error code
 */
static int unflatten_dt_nodes(const void *blob,
                              void *mem,
                              struct device_node *dad,
                              struct device_node **nodepp)
{
        struct device_node *root;
        int offset = 0, depth = 0, initial_depth = 0;
#define FDT_MAX_DEPTH   64
        struct device_node *nps[FDT_MAX_DEPTH];
        void *base = mem;
        bool dryrun = !base;
        int ret;

        if (nodepp)
                *nodepp = NULL;

        /*
         * We're unflattening device sub-tree if @dad is valid. There are
         * possibly multiple nodes in the first level of depth. We need
         * set @depth to 1 to make fdt_next_node() happy as it bails
         * immediately when negative @depth is found. Otherwise, the device
         * nodes except the first one won't be unflattened successfully.
         */
        if (dad)
                depth = initial_depth = 1;

        root = dad;
        nps[depth] = dad;

        for (offset = 0;
             offset >= 0 && depth >= initial_depth;
             offset = fdt_next_node(blob, offset, &depth)) {
                if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH - 1))
                        continue;

                if (!IS_ENABLED(CONFIG_OF_KOBJ) &&
                    !of_fdt_device_is_available(blob, offset))
                        continue;

                ret = populate_node(blob, offset, &mem, nps[depth],
                                   &nps[depth+1], dryrun);
                if (ret < 0)
                        return ret;

                if (!dryrun && nodepp && !*nodepp)
                        *nodepp = nps[depth+1];
                if (!dryrun && !root)
                        root = nps[depth+1];
        }

        if (offset < 0 && offset != -FDT_ERR_NOTFOUND) {
                pr_err("Error %d processing FDT\n", offset);
                return -EINVAL;
        }

        /*
         * Reverse the child list. Some drivers assumes node order matches .dts
         * node order
         */
        if (!dryrun)
                reverse_nodes(root);

        return mem - base;
}

/**
 * __unflatten_device_tree - create tree of device_nodes from flat blob
 * @blob: The blob to expand
 * @dad: Parent device node
 * @mynodes: The device_node tree created by the call
 * @dt_alloc: An allocator that provides a virtual address to memory
 * for the resulting tree
 * @detached: if true set OF_DETACHED on @mynodes
 *
 * 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.
 *
 * Return: NULL on failure or the memory chunk containing the unflattened
 * device tree on success.
 */
void *__unflatten_device_tree(const void *blob,
                              struct device_node *dad,
                              struct device_node **mynodes,
                              void *(*dt_alloc)(u64 size, u64 align),
                              bool detached)
{
        int size;
        void *mem;
        int ret;

        if (mynodes)
                *mynodes = NULL;

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

        if (!blob) {
                pr_debug("No device tree pointer\n");
                return NULL;
        }

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

        if (fdt_check_header(blob)) {
                pr_err("Invalid device tree blob header\n");
                return NULL;
        }

        /* First pass, scan for size */
        size = unflatten_dt_nodes(blob, NULL, dad, NULL);
        if (size <= 0)
                return NULL;

        size = ALIGN(size, 4);
        pr_debug("  size is %d, allocating...\n", size);

        /* Allocate memory for the expanded device tree */
        mem = dt_alloc(size + 4, __alignof__(struct device_node));
        if (!mem)
                return NULL;

        memset(mem, 0, size);

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

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

        /* Second pass, do actual unflattening */
        ret = unflatten_dt_nodes(blob, mem, dad, mynodes);

        if (be32_to_cpup(mem + size) != 0xdeadbeef)
                pr_warn("End of tree marker overwritten: %08x\n",
                        be32_to_cpup(mem + size));

        if (ret <= 0)
                return NULL;

        if (detached && mynodes && *mynodes) {
                of_node_set_flag(*mynodes, OF_DETACHED);
                pr_debug("unflattened tree is detached\n");
        }

        pr_debug(" <- unflatten_device_tree()\n");
        return mem;
}

static void *kernel_tree_alloc(u64 size, u64 align)
{
        return kzalloc(size, GFP_KERNEL);
}

static DEFINE_MUTEX(of_fdt_unflatten_mutex);

/**
 * of_fdt_unflatten_tree - create tree of device_nodes from flat blob
 * @blob: Flat device tree blob
 * @dad: Parent device node
 * @mynodes: The device tree created by the call
 *
 * unflattens the device-tree passed by the firmware, 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.
 *
 * Return: NULL on failure or the memory chunk containing the unflattened
 * device tree on success.
 */
void *of_fdt_unflatten_tree(const unsigned long *blob,
                            struct device_node *dad,
                            struct device_node **mynodes)
{
        void *mem;

        mutex_lock(&of_fdt_unflatten_mutex);
        mem = __unflatten_device_tree(blob, dad, mynodes, &kernel_tree_alloc,
                                      true);
        mutex_unlock(&of_fdt_unflatten_mutex);

        return mem;
}
EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);

/* Everything below here references initial_boot_params directly. */
int __initdata dt_root_addr_cells;
int __initdata dt_root_size_cells;

void *initial_boot_params __ro_after_init;
phys_addr_t initial_boot_params_pa __ro_after_init;

#ifdef CONFIG_OF_EARLY_FLATTREE

static u32 of_fdt_crc32;

/*
 * fdt_reserve_elfcorehdr() - reserves memory for elf core header
 *
 * This function reserves the memory occupied by an elf core header
 * described in the device tree. This region contains all the
 * information about primary kernel's core image and is used by a dump
 * capture kernel to access the system memory on primary kernel.
 */
static void __init fdt_reserve_elfcorehdr(void)
{
        if (!IS_ENABLED(CONFIG_CRASH_DUMP) || !elfcorehdr_size)
                return;

        if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
                pr_warn("elfcorehdr is overlapped\n");
                return;
        }

        memblock_reserve(elfcorehdr_addr, elfcorehdr_size);

        pr_info("Reserving %llu KiB of memory at 0x%llx for elfcorehdr\n",
                elfcorehdr_size >> 10, elfcorehdr_addr);
}

/**
 * early_init_fdt_scan_reserved_mem() - create reserved memory regions
 *
 * This function grabs memory from early allocator for device exclusive use
 * defined in device tree structures. It should be called by arch specific code
 * once the early allocator (i.e. memblock) has been fully activated.
 */
void __init early_init_fdt_scan_reserved_mem(void)
{
        int n;
        int res;
        u64 base, size;

        if (!initial_boot_params)
                return;

        fdt_reserve_elfcorehdr();
        fdt_scan_reserved_mem();

        /* Process header /memreserve/ fields */
        for (n = 0; ; n++) {
                res = fdt_get_mem_rsv(initial_boot_params, n, &base, &size);
                if (res) {
                        pr_err("Invalid memory reservation block index %d\n", n);
                        break;
                }
                if (!size)
                        break;
                memblock_reserve(base, size);
        }
}

/**
 * early_init_fdt_reserve_self() - reserve the memory used by the FDT blob
 */
void __init early_init_fdt_reserve_self(void)
{
        if (!initial_boot_params)
                return;

        /* Reserve the dtb region */
        memblock_reserve(__pa(initial_boot_params),
                         fdt_totalsize(initial_boot_params));
}

/**
 * of_scan_flat_dt - scan flattened tree blob and call callback on each.
 * @it: callback function
 * @data: context data pointer
 *
 * This function is used to scan the flattened device-tree, it is
 * used to extract the memory information at boot before we can
 * unflatten the tree
 */
int __init of_scan_flat_dt(int (*it)(unsigned long node,
                                     const char *uname, int depth,
                                     void *data),
                           void *data)
{
        const void *blob = initial_boot_params;
        const char *pathp;
        int offset, rc = 0, depth = -1;

        if (!blob)
                return 0;

        for (offset = fdt_next_node(blob, -1, &depth);
             offset >= 0 && depth >= 0 && !rc;
             offset = fdt_next_node(blob, offset, &depth)) {

                pathp = fdt_get_name(blob, offset, NULL);
                rc = it(offset, pathp, depth, data);
        }
        return rc;
}

/**
 * of_scan_flat_dt_subnodes - scan sub-nodes of a node call callback on each.
 * @parent: parent node
 * @it: callback function
 * @data: context data pointer
 *
 * This function is used to scan sub-nodes of a node.
 */
int __init of_scan_flat_dt_subnodes(unsigned long parent,
                                    int (*it)(unsigned long node,
                                              const char *uname,
                                              void *data),
                                    void *data)
{
        const void *blob = initial_boot_params;
        int node;

        fdt_for_each_subnode(node, blob, parent) {
                const char *pathp;
                int rc;

                pathp = fdt_get_name(blob, node, NULL);
                rc = it(node, pathp, data);
                if (rc)
                        return rc;
        }
        return 0;
}

/**
 * of_get_flat_dt_subnode_by_name - get the subnode by given name
 *
 * @node: the parent node
 * @uname: the name of subnode
 * @return offset of the subnode, or -FDT_ERR_NOTFOUND if there is none
 */

int __init of_get_flat_dt_subnode_by_name(unsigned long node, const char *uname)
{
        return fdt_subnode_offset(initial_boot_params, node, uname);
}

/*
 * of_get_flat_dt_root - find the root node in the flat blob
 */
unsigned long __init of_get_flat_dt_root(void)
{
        return 0;
}

/*
 * of_get_flat_dt_prop - Given a node in the flat blob, return the property ptr
 *
 * This function can be used within scan_flattened_dt callback to get
 * access to properties
 */
const void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
                                       int *size)
{
        return fdt_getprop(initial_boot_params, node, name, size);
}

const __be32 *__init of_flat_dt_get_addr_size_prop(unsigned long node,
                                                   const char *name,
                                                   int *entries)
{
        const __be32 *prop;
        int len, elen = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);

        prop = of_get_flat_dt_prop(node, name, &len);
        if (!prop || len % elen) {
                *entries = 0;
                return NULL;
        }

        *entries = len / elen;
        return prop;
}

bool __init of_flat_dt_get_addr_size(unsigned long node, const char *name,
                                     u64 *addr, u64 *size)
{
        const __be32 *prop;
        int entries;

        prop = of_flat_dt_get_addr_size_prop(node, name, &entries);
        if (!prop || entries != 1)
                return false;

        of_flat_dt_read_addr_size(prop, 0, addr, size);
        return true;
}

void __init of_flat_dt_read_addr_size(const __be32 *prop, int entry_index,
                                      u64 *addr, u64 *size)
{
        int entry_cells = dt_root_addr_cells + dt_root_size_cells;
        prop += entry_cells * entry_index;

        *addr = dt_mem_next_cell(dt_root_addr_cells, &prop);
        *size = dt_mem_next_cell(dt_root_size_cells, &prop);
}

/**
 * of_fdt_is_compatible - Return true if given node from the given blob has
 * compat in its compatible list
 * @blob: A device tree blob
 * @node: node to test
 * @compat: compatible string to compare with compatible list.
 *
 * Return: a non-zero value on match with smaller values returned for more
 * specific compatible values.
 */
static int of_fdt_is_compatible(const void *blob,
                      unsigned long node, const char *compat)
{
        const char *cp;
        int cplen;
        unsigned long l, score = 0;

        cp = fdt_getprop(blob, node, "compatible", &cplen);
        if (cp == NULL)
                return 0;
        while (cplen > 0) {
                score++;
                if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
                        return score;
                l = strlen(cp) + 1;
                cp += l;
                cplen -= l;
        }

        return 0;
}

/**
 * of_flat_dt_is_compatible - Return true if given node has compat in compatible list
 * @node: node to test
 * @compat: compatible string to compare with compatible list.
 */
int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
{
        return of_fdt_is_compatible(initial_boot_params, node, compat);
}

/*
 * of_flat_dt_match - Return true if node matches a list of compatible values
 */
static int __init of_flat_dt_match(unsigned long node, const char *const *compat)
{
        unsigned int tmp, score = 0;

        if (!compat)
                return 0;

        while (*compat) {
                tmp = of_fdt_is_compatible(initial_boot_params, node, *compat);
                if (tmp && (score == 0 || (tmp < score)))
                        score = tmp;
                compat++;
        }

        return score;
}

/*
 * of_get_flat_dt_phandle - Given a node in the flat blob, return the phandle
 */
uint32_t __init of_get_flat_dt_phandle(unsigned long node)
{
        return fdt_get_phandle(initial_boot_params, node);
}

const char * __init of_flat_dt_get_machine_name(void)
{
        const char *name;
        unsigned long dt_root = of_get_flat_dt_root();

        name = of_get_flat_dt_prop(dt_root, "model", NULL);
        if (!name)
                name = of_get_flat_dt_prop(dt_root, "compatible", NULL);
        return name;
}

/**
 * of_flat_dt_match_machine - Iterate match tables to find matching machine.
 *
 * @default_match: A machine specific ptr to return in case of no match.
 * @get_next_compat: callback function to return next compatible match table.
 *
 * Iterate through machine match tables to find the best match for the machine
 * compatible string in the FDT.
 */
const void * __init of_flat_dt_match_machine(const void *default_match,
                const void * (*get_next_compat)(const char * const**))
{
        const void *data = NULL;
        const void *best_data = default_match;
        const char *const *compat;
        unsigned long dt_root;
        unsigned int best_score = ~1, score = 0;

        dt_root = of_get_flat_dt_root();
        while ((data = get_next_compat(&compat))) {
                score = of_flat_dt_match(dt_root, compat);
                if (score > 0 && score < best_score) {
                        best_data = data;
                        best_score = score;
                }
        }
        if (!best_data) {
                const char *prop;
                int size;

                pr_err("\n unrecognized device tree list:\n[ ");

                prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
                if (prop) {
                        while (size > 0) {
                                printk("'%s' ", prop);
                                size -= strlen(prop) + 1;
                                prop += strlen(prop) + 1;
                        }
                }
                printk("]\n\n");
                return NULL;
        }

        pr_info("Machine model: %s\n", of_flat_dt_get_machine_name());

        return best_data;
}

static void __early_init_dt_declare_initrd(unsigned long start,
                                           unsigned long end)
{
        /*
         * __va() is not yet available this early on some platforms. In that
         * case, the platform uses phys_initrd_start/phys_initrd_size instead
         * and does the VA conversion itself.
         */
        if (!IS_ENABLED(CONFIG_ARM64) &&
            !(IS_ENABLED(CONFIG_RISCV) && IS_ENABLED(CONFIG_64BIT))) {
                initrd_start = (unsigned long)__va(start);
                initrd_end = (unsigned long)__va(end);
                initrd_below_start_ok = 1;
        }
}

/**
 * early_init_dt_check_for_initrd - Decode initrd location from flat tree
 * @node: reference to node containing initrd location ('chosen')
 */
static void __init early_init_dt_check_for_initrd(unsigned long node)
{
        u64 start, end;
        int len;
        const __be32 *prop;

        if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
                return;

        pr_debug("Looking for initrd properties... ");

        prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
        if (!prop)
                return;
        start = of_read_number(prop, len/4);

        prop = of_get_flat_dt_prop(node, "linux,initrd-end", &len);
        if (!prop)
                return;
        end = of_read_number(prop, len/4);
        if (start > end)
                return;

        __early_init_dt_declare_initrd(start, end);
        phys_initrd_start = start;
        phys_initrd_size = end - start;

        pr_debug("initrd_start=0x%llx  initrd_end=0x%llx\n", start, end);
}

/**
 * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat
 * tree
 * @node: reference to node containing elfcorehdr location ('chosen')
 */
static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
{
        if (!IS_ENABLED(CONFIG_CRASH_DUMP))
                return;

        pr_debug("Looking for elfcorehdr property... ");

        if (!of_flat_dt_get_addr_size(node, "linux,elfcorehdr",
                                      &elfcorehdr_addr, &elfcorehdr_size))
                return;

        pr_debug("elfcorehdr_start=0x%llx elfcorehdr_size=0x%llx\n",
                 elfcorehdr_addr, elfcorehdr_size);
}

static unsigned long chosen_node_offset = -FDT_ERR_NOTFOUND;

/*
 * The main usage of linux,usable-memory-range is for crash dump kernel.
 * Originally, the number of usable-memory regions is one. Now there may
 * be two regions, low region and high region.
 * To make compatibility with existing user-space and older kdump, the low
 * region is always the last range of linux,usable-memory-range if exist.
 */
#define MAX_USABLE_RANGES               2

/**
 * early_init_dt_check_for_usable_mem_range - Decode usable memory range
 * location from flat tree
 */
void __init early_init_dt_check_for_usable_mem_range(void)
{
        struct memblock_region rgn[MAX_USABLE_RANGES] = {0};
        const __be32 *prop;
        int len, i;
        u64 base, size;
        unsigned long node = chosen_node_offset;

        if ((long)node < 0)
                return;

        pr_debug("Looking for usable-memory-range property... ");

        prop = of_flat_dt_get_addr_size_prop(node, "linux,usable-memory-range",
                                             &len);
        if (!prop)
                return;

        len = min(len, MAX_USABLE_RANGES);

        for (i = 0; i < len; i++) {
                of_flat_dt_read_addr_size(prop, i, &base, &size);
                rgn[i].base = base;
                rgn[i].size = size;

                pr_debug("cap_mem_regions[%d]: base=%pa, size=%pa\n",
                         i, &rgn[i].base, &rgn[i].size);
        }

        memblock_cap_memory_range(rgn[0].base, rgn[0].size);
        for (i = 1; i < MAX_USABLE_RANGES && rgn[i].size; i++)
                memblock_add(rgn[i].base, rgn[i].size);
}

/**
 * early_init_dt_check_kho - Decode info required for kexec handover from DT
 */
static void __init early_init_dt_check_kho(void)
{
        unsigned long node = chosen_node_offset;
        u64 fdt_start, fdt_size, scratch_start, scratch_size;

        if (!IS_ENABLED(CONFIG_KEXEC_HANDOVER) || (long)node < 0)
                return;

        if (!of_flat_dt_get_addr_size(node, "linux,kho-fdt",
                                      &fdt_start, &fdt_size))
                return;

        if (!of_flat_dt_get_addr_size(node, "linux,kho-scratch",
                                      &scratch_start, &scratch_size))
                return;

        kho_populate(fdt_start, fdt_size, scratch_start, scratch_size);
}

#ifdef CONFIG_SERIAL_EARLYCON

int __init early_init_dt_scan_chosen_stdout(void)
{
        int offset;
        const char *p, *q, *options = NULL;
        int l;
        const struct earlycon_id *match;
        const void *fdt = initial_boot_params;
        int ret;

        offset = fdt_path_offset(fdt, "/chosen");
        if (offset < 0)
                offset = fdt_path_offset(fdt, "/chosen@0");
        if (offset < 0)
                return -ENOENT;

        p = fdt_getprop(fdt, offset, "stdout-path", &l);
        if (!p)
                p = fdt_getprop(fdt, offset, "linux,stdout-path", &l);
        if (!p || !l)
                return -ENOENT;

        q = strchrnul(p, ':');
        if (*q != '\0')
                options = q + 1;
        l = q - p;

        /* Get the node specified by stdout-path */
        offset = fdt_path_offset_namelen(fdt, p, l);
        if (offset < 0) {
                pr_warn("earlycon: stdout-path %.*s not found\n", l, p);
                return 0;
        }

        for (match = __earlycon_table; match < __earlycon_table_end; match++) {
                if (!match->compatible[0])
                        continue;

                if (fdt_node_check_compatible(fdt, offset, match->compatible))
                        continue;

                ret = of_setup_earlycon(match, offset, options);
                if (!ret || ret == -EALREADY)
                        return 0;
        }
        return -ENODEV;
}
#endif

/*
 * early_init_dt_scan_root - fetch the top level address and size cells
 */
int __init early_init_dt_scan_root(void)
{
        const __be32 *prop;
        const void *fdt = initial_boot_params;
        int node = fdt_path_offset(fdt, "/");

        if (node < 0)
                return -ENODEV;

        dt_root_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
        dt_root_addr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;

        prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
        if (!WARN(!prop, "No '#size-cells' in root node\n"))
                dt_root_size_cells = be32_to_cpup(prop);
        pr_debug("dt_root_size_cells = %x\n", dt_root_size_cells);

        prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
        if (!WARN(!prop, "No '#address-cells' in root node\n"))
                dt_root_addr_cells = be32_to_cpup(prop);
        pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);

        return 0;
}

u64 __init dt_mem_next_cell(int s, const __be32 **cellp)
{
        const __be32 *p = *cellp;

        *cellp = p + s;
        return of_read_number(p, s);
}

/*
 * early_init_dt_scan_memory - Look for and parse memory nodes
 */
int __init early_init_dt_scan_memory(void)
{
        int node, found_memory = 0;
        const void *fdt = initial_boot_params;

        fdt_for_each_subnode(node, fdt, 0) {
                const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
                const __be32 *reg;
                int i, l;
                bool hotpluggable;

                /* We are scanning "memory" nodes only */
                if (type == NULL || strcmp(type, "memory") != 0)
                        continue;

                if (!of_fdt_device_is_available(fdt, node))
                        continue;

                reg = of_flat_dt_get_addr_size_prop(node, "linux,usable-memory", &l);
                if (reg == NULL)
                        reg = of_flat_dt_get_addr_size_prop(node, "reg", &l);
                if (reg == NULL)
                        continue;

                hotpluggable = of_get_flat_dt_prop(node, "hotpluggable", NULL);

                pr_debug("memory scan node %s, reg {addr,size} entries %d,\n",
                         fdt_get_name(fdt, node, NULL), l);

                for (i = 0; i < l; i++) {
                        u64 base, size;

                        of_flat_dt_read_addr_size(reg, i, &base, &size);

                        if (size == 0)
                                continue;
                        pr_debug(" - %llx, %llx\n", base, size);

                        early_init_dt_add_memory_arch(base, size);

                        found_memory = 1;

                        if (!hotpluggable)
                                continue;

                        if (memblock_mark_hotplug(base, size))
                                pr_warn("failed to mark hotplug range 0x%llx - 0x%llx\n",
                                        base, base + size);
                }
        }
        return found_memory;
}

int __init early_init_dt_scan_chosen(char *cmdline)
{
        int l, node;
        const char *p;
        const void *rng_seed;
        const void *fdt = initial_boot_params;

        node = fdt_path_offset(fdt, "/chosen");
        if (node < 0)
                node = fdt_path_offset(fdt, "/chosen@0");
        if (node < 0)
                /* Handle the cmdline config options even if no /chosen node */
                goto handle_cmdline;

        chosen_node_offset = node;

        early_init_dt_check_for_initrd(node);
        early_init_dt_check_for_elfcorehdr(node);

        rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
        if (rng_seed && l > 0) {
                add_bootloader_randomness(rng_seed, l);

                /* try to clear seed so it won't be found. */
                fdt_nop_property(initial_boot_params, node, "rng-seed");

                /* update CRC check value */
                of_fdt_crc32 = crc32_be(~0, initial_boot_params,
                                fdt_totalsize(initial_boot_params));
        }

        /* Retrieve command line */
        p = of_get_flat_dt_prop(node, "bootargs", &l);
        if (p != NULL && l > 0)
                strscpy(cmdline, p, min(l, COMMAND_LINE_SIZE));

handle_cmdline:
        /*
         * CONFIG_CMDLINE is meant to be a default in case nothing else
         * managed to set the command line, unless CONFIG_CMDLINE_FORCE
         * is set in which case we override whatever was found earlier.
         */
#ifdef CONFIG_CMDLINE
#if defined(CONFIG_CMDLINE_EXTEND)
        strlcat(cmdline, " ", COMMAND_LINE_SIZE);
        strlcat(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#elif defined(CONFIG_CMDLINE_FORCE)
        strscpy(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#else
        /* No arguments from boot loader, use kernel's  cmdl*/
        if (!((char *)cmdline)[0])
                strscpy(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#endif
#endif /* CONFIG_CMDLINE */

        pr_debug("Command line is: %s\n", (char *)cmdline);

        return 0;
}

#ifndef MIN_MEMBLOCK_ADDR
#define MIN_MEMBLOCK_ADDR       __pa(PAGE_OFFSET)
#endif
#ifndef MAX_MEMBLOCK_ADDR
#define MAX_MEMBLOCK_ADDR       ((phys_addr_t)~0)
#endif

void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
{
        const u64 phys_offset = MIN_MEMBLOCK_ADDR;

        if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
                pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
                        base, base + size);
                return;
        }

        if (!PAGE_ALIGNED(base)) {
                size -= PAGE_SIZE - (base & ~PAGE_MASK);
                base = PAGE_ALIGN(base);
        }
        size &= PAGE_MASK;

        if (base > MAX_MEMBLOCK_ADDR) {
                pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
                        base, base + size);
                return;
        }

        if (base + size - 1 > MAX_MEMBLOCK_ADDR) {
                pr_warn("Ignoring memory range 0x%llx - 0x%llx\n",
                        ((u64)MAX_MEMBLOCK_ADDR) + 1, base + size);
                size = MAX_MEMBLOCK_ADDR - base + 1;
        }

        if (base + size < phys_offset) {
                pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
                        base, base + size);
                return;
        }
        if (base < phys_offset) {
                pr_warn("Ignoring memory range 0x%llx - 0x%llx\n",
                        base, phys_offset);
                size -= phys_offset - base;
                base = phys_offset;
        }
        memblock_add(base, size);
}

static void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
{
        return memblock_alloc_or_panic(size, align);
}

bool __init early_init_dt_verify(void *dt_virt, phys_addr_t dt_phys)
{
        if (!dt_virt)
                return false;

        /* check device tree validity */
        if (fdt_check_header(dt_virt))
                return false;

        /* Setup flat device-tree pointer */
        initial_boot_params = dt_virt;
        initial_boot_params_pa = dt_phys;
        of_fdt_crc32 = crc32_be(~0, initial_boot_params,
                                fdt_totalsize(initial_boot_params));

        /* Initialize {size,address}-cells info */
        early_init_dt_scan_root();

        return true;
}


void __init early_init_dt_scan_nodes(void)
{
        int rc;

        /* Retrieve various information from the /chosen node */
        rc = early_init_dt_scan_chosen(boot_command_line);
        if (rc)
                pr_warn("No chosen node found, continuing without\n");

        /* Setup memory, calling early_init_dt_add_memory_arch */
        early_init_dt_scan_memory();

        /* Handle linux,usable-memory-range property */
        early_init_dt_check_for_usable_mem_range();

        /* Handle kexec handover */
        early_init_dt_check_kho();
}

bool __init early_init_dt_scan(void *dt_virt, phys_addr_t dt_phys)
{
        bool status;

        status = early_init_dt_verify(dt_virt, dt_phys);
        if (!status)
                return false;

        early_init_dt_scan_nodes();
        return true;
}

static void *__init copy_device_tree(void *fdt)
{
        int size;
        void *dt;

        size = fdt_totalsize(fdt);
        dt = early_init_dt_alloc_memory_arch(size,
                                             roundup_pow_of_two(FDT_V17_SIZE));

        if (dt)
                memcpy(dt, fdt, size);

        return dt;
}

/**
 * unflatten_device_tree - create tree of device_nodes from flat blob
 *
 * unflattens the device-tree passed by the firmware, 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.
 */
void __init unflatten_device_tree(void)
{
        void *fdt = initial_boot_params;

        /* Save the statically-placed regions in the reserved_mem array */
        fdt_scan_reserved_mem_reg_nodes();

        /* Populate an empty root node when bootloader doesn't provide one */
        if (!fdt) {
                fdt = (void *) __dtb_empty_root_begin;
                /* fdt_totalsize() will be used for copy size */
                if (fdt_totalsize(fdt) >
                    __dtb_empty_root_end - __dtb_empty_root_begin) {
                        pr_err("invalid size in dtb_empty_root\n");
                        return;
                }
                of_fdt_crc32 = crc32_be(~0, fdt, fdt_totalsize(fdt));
                fdt = copy_device_tree(fdt);
        }

        __unflatten_device_tree(fdt, NULL, &of_root,
                                early_init_dt_alloc_memory_arch, false);

        /* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */
        of_alias_scan(early_init_dt_alloc_memory_arch);

        unittest_unflatten_overlay_base();
}

/**
 * unflatten_and_copy_device_tree - copy and create tree of device_nodes from flat blob
 *
 * Copies and unflattens the device-tree passed by the firmware, 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. This should only be used when the FDT memory has not been
 * reserved such is the case when the FDT is built-in to the kernel init
 * section. If the FDT memory is reserved already then unflatten_device_tree
 * should be used instead.
 */
void __init unflatten_and_copy_device_tree(void)
{
        if (initial_boot_params)
                initial_boot_params = copy_device_tree(initial_boot_params);

        unflatten_device_tree();
}

#ifdef CONFIG_SYSFS
static int __init of_fdt_raw_init(void)
{
        static __ro_after_init BIN_ATTR_SIMPLE_ADMIN_RO(fdt);

        if (!initial_boot_params)
                return 0;

        if (of_fdt_crc32 != crc32_be(~0, initial_boot_params,
                                     fdt_totalsize(initial_boot_params))) {
                pr_warn("not creating '/sys/firmware/fdt': CRC check failed\n");
                return 0;
        }
        bin_attr_fdt.private = initial_boot_params;
        bin_attr_fdt.size = fdt_totalsize(initial_boot_params);
        return sysfs_create_bin_file(firmware_kobj, &bin_attr_fdt);
}
late_initcall(of_fdt_raw_init);
#endif

#endif /* CONFIG_OF_EARLY_FLATTREE */