// 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/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/of_reserved_mem.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 <asm/setup.h>  /* for COMMAND_LINE_SIZE */

  #include <asm/page.h>

  #include "of_private.h"

  /*
   * 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 nr_address_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
  	int nr_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;

  	const __be32 *addr_prop;
  	const __be32 *size_prop;

  	int root_offset;
  	int cell_size;
  
  	root_offset = fdt_path_offset(initial_boot_params, "/");
  	if (root_offset < 0)
  		return;
  
  	addr_prop = fdt_getprop(initial_boot_params, root_offset,
  				"#address-cells", NULL);
  	if (addr_prop)
  		nr_address_cells = fdt32_to_cpu(*addr_prop);
  
  	size_prop = fdt_getprop(initial_boot_params, root_offset,
  				"#size-cells", NULL);
  	if (size_prop)
  		nr_size_cells = fdt32_to_cpu(*size_prop);
  
  	cell_size = sizeof(uint32_t)*(nr_address_cells + nr_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
  ", limit);
  			fdt_setprop(initial_boot_params, memory, "reg", val,
  					len);
  		}
  	}
  }

  static 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
  ", cur);

  			continue;
  		}
  
  		if (!pname) {

  			pr_warn("Cannot find property name at 0x%x
  ", 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;
  			pprev      = &pp->next;
  			memcpy(pp->value, ps, len - 1);
  			((char *)pp->value)[len - 1] = 0;
  			pr_debug("fixed up name for %s -> %s
  ",
  				 nodename, (char *)pp->value);
  		}
  	}
  
  	if (!dryrun)
  		*pprev = NULL;
  }

  static bool 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;

  	unsigned int l, allocl;

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

  		return false;

  	}

  	allocl = ++l;

  	np = unflatten_dt_alloc(mem, sizeof(struct device_node) + allocl,

  				__alignof__(struct device_node));

  	if (!dryrun) {

  		char *fn;

  		of_node_init(np);

  		np->full_name = fn = ((char *)np) + sizeof(*np);

  		memcpy(fn, pathp, l);

  		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 true;

  }

  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

   *
   * It returns 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;

  	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))
  			continue;

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

  		if (!populate_node(blob, offset, &mem, nps[depth],
  				   &nps[depth+1], dryrun))

  			return mem - base;
  
  		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
  ", 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
   *
   * 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

   * @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

   *
   * Returns 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;

  
  	pr_debug(" -> unflatten_device_tree()
  ");
  
  	if (!blob) {
  		pr_debug("No device tree pointer
  ");

  		return NULL;

  	}
  
  	pr_debug("Unflattening device tree:
  ");

  	pr_debug("magic: %08x
  ", fdt_magic(blob));
  	pr_debug("size: %08x
  ", fdt_totalsize(blob));
  	pr_debug("version: %08x
  ", fdt_version(blob));

  	if (fdt_check_header(blob)) {

  		pr_err("Invalid device tree blob header
  ");

  		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...
  ", 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...
  ", mem);

  
  	/* Second pass, do actual unflattening */

  	unflatten_dt_nodes(blob, mem, dad, mynodes);

  	if (be32_to_cpup(mem + size) != 0xdeadbeef)

  		pr_warning("End of tree marker overwritten: %08x
  ",

  			   be32_to_cpup(mem + size));

  	if (detached && mynodes) {

  		of_node_set_flag(*mynodes, OF_DETACHED);
  		pr_debug("unflattened tree is detached
  ");
  	}

  	pr_debug(" <- unflatten_device_tree()
  ");

  	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.

   *
   * Returns 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;

  
  #ifdef CONFIG_OF_EARLY_FLATTREE

  static u32 of_fdt_crc32;

  /**

   * res_mem_reserve_reg() - reserve all memory described in 'reg' property
   */
  static int __init __reserved_mem_reserve_reg(unsigned long node,
  					     const char *uname)
  {
  	int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
  	phys_addr_t base, size;

  	int len;
  	const __be32 *prop;

  	int first = 1;
  	bool nomap;

  
  	prop = of_get_flat_dt_prop(node, "reg", &len);
  	if (!prop)
  		return -ENOENT;
  
  	if (len && len % t_len != 0) {
  		pr_err("Reserved memory: invalid reg property in '%s', skipping node.
  ",
  		       uname);
  		return -EINVAL;
  	}
  
  	nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
  
  	while (len >= t_len) {
  		base = dt_mem_next_cell(dt_root_addr_cells, &prop);
  		size = dt_mem_next_cell(dt_root_size_cells, &prop);

  		if (size &&

  		    early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
  			pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB
  ",
  				uname, &base, (unsigned long)size / SZ_1M);
  		else
  			pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %ld MiB
  ",
  				uname, &base, (unsigned long)size / SZ_1M);
  
  		len -= t_len;

  		if (first) {
  			fdt_reserved_mem_save_node(node, uname, base, size);
  			first = 0;
  		}

  	}
  	return 0;
  }
  
  /**
   * __reserved_mem_check_root() - check if #size-cells, #address-cells provided
   * in /reserved-memory matches the values supported by the current implementation,
   * also check if ranges property has been provided
   */

  static int __init __reserved_mem_check_root(unsigned long node)

  {

  	const __be32 *prop;

  
  	prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
  	if (!prop || be32_to_cpup(prop) != dt_root_size_cells)
  		return -EINVAL;
  
  	prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
  	if (!prop || be32_to_cpup(prop) != dt_root_addr_cells)
  		return -EINVAL;
  
  	prop = of_get_flat_dt_prop(node, "ranges", NULL);
  	if (!prop)
  		return -EINVAL;
  	return 0;
  }
  
  /**
   * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
   */
  static int __init __fdt_scan_reserved_mem(unsigned long node, const char *uname,
  					  int depth, void *data)
  {
  	static int found;

  	int err;

  
  	if (!found && depth == 1 && strcmp(uname, "reserved-memory") == 0) {
  		if (__reserved_mem_check_root(node) != 0) {
  			pr_err("Reserved memory: unsupported node format, ignoring
  ");
  			/* break scan */
  			return 1;
  		}
  		found = 1;
  		/* scan next node */
  		return 0;
  	} else if (!found) {
  		/* scan next node */
  		return 0;
  	} else if (found && depth < 2) {
  		/* scanning of /reserved-memory has been finished */
  		return 1;
  	}

  	if (!of_fdt_device_is_available(initial_boot_params, node))

  		return 0;

  	err = __reserved_mem_reserve_reg(node, uname);
  	if (err == -ENOENT && of_get_flat_dt_prop(node, "size", NULL))
  		fdt_reserved_mem_save_node(node, uname, 0, 0);

  
  	/* scan next node */
  	return 0;
  }
  
  /**
   * 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;
  	u64 base, size;

  	if (!initial_boot_params)
  		return;

  	/* Process header /memreserve/ fields */
  	for (n = 0; ; n++) {
  		fdt_get_mem_rsv(initial_boot_params, n, &base, &size);
  		if (!size)
  			break;

  		early_init_dt_reserve_memory_arch(base, size, false);

  	}

  	of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);

  	fdt_init_reserved_mem();

  }
  
  /**

   * 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 */
  	early_init_dt_reserve_memory_arch(__pa(initial_boot_params),
  					  fdt_totalsize(initial_boot_params),

  					  false);

  }
  
  /**

   * 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);

  		if (*pathp == '/')
  			pathp = kbasename(pathp);

  		rc = it(offset, pathp, depth, data);
  	}

  	return rc;
  }
  
  /**

   * of_scan_flat_dt_subnodes - scan sub-nodes of a node call callback on each.
   * @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);
  		if (*pathp == '/')
  			pathp = kbasename(pathp);
  		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);

  }
  
  /**

   * 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.
   *
   * On match, returns a non-zero value 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_prop - 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);
  }

  struct fdt_scan_status {
  	const char *name;
  	int namelen;
  	int depth;
  	int found;
  	int (*iterator)(unsigned long node, const char *uname, int depth, void *data);
  	void *data;
  };

  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("
   unrecognized device tree list:
  [ ");
  
  		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("]
  
  ");
  		return NULL;
  	}
  
  	pr_info("Machine model: %s
  ", of_flat_dt_get_machine_name());
  
  	return best_data;
  }

  #ifdef CONFIG_BLK_DEV_INITRD

  static void __early_init_dt_declare_initrd(unsigned long start,
  					   unsigned long end)
  {

  	/* ARM64 would cause a BUG to occur here when CONFIG_DEBUG_VM is
  	 * enabled since __va() is called too early. ARM64 does make use
  	 * of phys_initrd_start/phys_initrd_size so we can skip this
  	 * conversion.
  	 */
  	if (!IS_ENABLED(CONFIG_ARM64)) {
  		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;

  
  	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);

  	__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
  ",
  		 (unsigned long long)start, (unsigned long long)end);

  }
  #else

  static inline void early_init_dt_check_for_initrd(unsigned long node)

  {
  }
  #endif /* CONFIG_BLK_DEV_INITRD */

  #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 **p_match;

  	const void *fdt = initial_boot_params;
  
  	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
  ", l, p);
  		return 0;
  	}

  	for (p_match = __earlycon_table; p_match < __earlycon_table_end;
  	     p_match++) {
  		const struct earlycon_id *match = *p_match;

  		if (!match->compatible[0])
  			continue;
  
  		if (fdt_node_check_compatible(fdt, offset, match->compatible))

  			continue;

  		of_setup_earlycon(match, offset, options);

  		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(unsigned long node, const char *uname,
  				   int depth, void *data)
  {

  	const __be32 *prop;

  
  	if (depth != 0)
  		return 0;

  	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 (prop)
  		dt_root_size_cells = be32_to_cpup(prop);

  	pr_debug("dt_root_size_cells = %x
  ", dt_root_size_cells);
  
  	prop = of_get_flat_dt_prop(node, "#address-cells", NULL);

  	if (prop)
  		dt_root_addr_cells = be32_to_cpup(prop);

  	pr_debug("dt_root_addr_cells = %x
  ", dt_root_addr_cells);
  
  	/* break now */
  	return 1;
  }

  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(unsigned long node, const char *uname,
  				     int depth, void *data)
  {

  	const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
  	const __be32 *reg, *endp;
  	int l;

  	bool hotpluggable;

  
  	/* We are scanning "memory" nodes only */

  	if (type == NULL || strcmp(type, "memory") != 0)

  		return 0;
  
  	reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
  	if (reg == NULL)
  		reg = of_get_flat_dt_prop(node, "reg", &l);
  	if (reg == NULL)
  		return 0;
  
  	endp = reg + (l / sizeof(__be32));

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

  	pr_debug("memory scan node %s, reg size %d,
  ", uname, l);

  
  	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
  		u64 base, size;
  
  		base = dt_mem_next_cell(dt_root_addr_cells, &reg);
  		size = dt_mem_next_cell(dt_root_size_cells, &reg);
  
  		if (size == 0)
  			continue;
  		pr_debug(" - %llx ,  %llx
  ", (unsigned long long)base,
  		    (unsigned long long)size);
  
  		early_init_dt_add_memory_arch(base, size);

  
  		if (!hotpluggable)
  			continue;
  
  		if (early_init_dt_mark_hotplug_memory_arch(base, size))
  			pr_warn("failed to mark hotplug range 0x%llx - 0x%llx
  ",
  				base, base + size);

  	}
  
  	return 0;
  }

  int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
  				     int depth, void *data)
  {

  	int l;
  	const char *p;

  	const void *rng_seed;

  
  	pr_debug("search \"chosen\", depth: %d, uname: %s
  ", depth, uname);

  	if (depth != 1 || !data ||

  	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
  		return 0;
  
  	early_init_dt_check_for_initrd(node);

  	/* Retrieve command line */

  	p = of_get_flat_dt_prop(node, "bootargs", &l);
  	if (p != NULL && l > 0)

  		strlcpy(data, p, min(l, COMMAND_LINE_SIZE));

  	/*
  	 * 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(data, " ", COMMAND_LINE_SIZE);
  	strlcat(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
  #elif defined(CONFIG_CMDLINE_FORCE)
  	strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
  #else
  	/* No arguments from boot loader, use kernel's  cmdl*/

  	if (!((char *)data)[0])

  		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);

  #endif

  #endif /* CONFIG_CMDLINE */

  	pr_debug("Command line is: %s
  ", (char*)data);

  	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));

  	}

  	/* break now */
  	return 1;
  }

  #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
  ",
  			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_warning("Ignoring memory block 0x%llx - 0x%llx
  ",
  				base, base + size);
  		return;
  	}

  	if (base + size - 1 > MAX_MEMBLOCK_ADDR) {

  		pr_warning("Ignoring memory range 0x%llx - 0x%llx
  ",

  				((u64)MAX_MEMBLOCK_ADDR) + 1, base + size);
  		size = MAX_MEMBLOCK_ADDR - base + 1;

  	}

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

  int __init __weak early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size)
  {
  	return memblock_mark_hotplug(base, size);
  }

  int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
  					phys_addr_t size, bool nomap)
  {

  	if (nomap)
  		return memblock_remove(base, size);
  	return memblock_reserve(base, size);
  }

  static void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)

  {

  	void *ptr = memblock_alloc(size, align);
  
  	if (!ptr)
  		panic("%s: Failed to allocate %llu bytes align=0x%llx
  ",
  		      __func__, size, align);
  
  	return ptr;

  }

  bool __init early_init_dt_verify(void *params)

  {
  	if (!params)
  		return false;

  	/* check device tree validity */

  	if (fdt_check_header(params))

  		return false;

  	/* Setup flat device-tree pointer */
  	initial_boot_params = params;

  	of_fdt_crc32 = crc32_be(~0, initial_boot_params,
  				fdt_totalsize(initial_boot_params));

  	return true;
  }
  
  
  void __init early_init_dt_scan_nodes(void)
  {

  	int rc = 0;

  	/* Retrieve various information from the /chosen node */

  	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
  	if (!rc)
  		pr_warn("No chosen node found, continuing without
  ");

  
  	/* Initialize {size,address}-cells info */
  	of_scan_flat_dt(early_init_dt_scan_root, NULL);
  
  	/* Setup memory, calling early_init_dt_add_memory_arch */
  	of_scan_flat_dt(early_init_dt_scan_memory, NULL);

  }
  
  bool __init early_init_dt_scan(void *params)
  {
  	bool status;
  
  	status = early_init_dt_verify(params);
  	if (!status)
  		return false;

  	early_init_dt_scan_nodes();

  	return true;
  }

  /**

   * 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)
  {

  	__unflatten_device_tree(initial_boot_params, 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)
  {

  	int size;
  	void *dt;
  
  	if (!initial_boot_params) {
  		pr_warn("No valid device tree found, continuing without
  ");
  		return;
  	}

  	size = fdt_totalsize(initial_boot_params);

  	dt = early_init_dt_alloc_memory_arch(size,

  					     roundup_pow_of_two(FDT_V17_SIZE));

  
  	if (dt) {
  		memcpy(dt, initial_boot_params, size);
  		initial_boot_params = dt;
  	}
  	unflatten_device_tree();
  }

  #ifdef CONFIG_SYSFS
  static ssize_t of_fdt_raw_read(struct file *filp, struct kobject *kobj,
  			       struct bin_attribute *bin_attr,
  			       char *buf, loff_t off, size_t count)

  {

  	memcpy(buf, initial_boot_params + off, count);
  	return count;
  }

  static int __init of_fdt_raw_init(void)
  {
  	static struct bin_attribute of_fdt_raw_attr =
  		__BIN_ATTR(fdt, S_IRUSR, of_fdt_raw_read, NULL, 0);

  	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
  ");

  		return 0;
  	}
  	of_fdt_raw_attr.size = fdt_totalsize(initial_boot_params);
  	return sysfs_create_bin_file(firmware_kobj, &of_fdt_raw_attr);

  }

  late_initcall(of_fdt_raw_init);

  #endif

  #endif /* CONFIG_OF_EARLY_FLATTREE */