text: /*
   * Functions for working with the Flattened Device Tree data format
   *
   * Copyright 2009 Benjamin Herrenschmidt, IBM Corp
   * benh@kernel.crashing.org
   *
   * 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.
   */
  
  #include <linux/crc32.h>
  #include <linux/kernel.h>
  #include <linux/initrd.h>
  #include <linux/memblock.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 <asm/setup.h>  /* for COMMAND_LINE_SIZE */
  #include <asm/page.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 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 uint32_t *addr_prop;
  	const uint32_t *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\n", limit);
  			fdt_setprop(initial_boot_params, memory, "reg", val,
  					len);
  		}
  	}
  }
  
  /**
   * 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.
   */
  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_fdt_is_big_endian - Return true if given node needs BE MMIO accesses
   * @blob: A device tree blob
   * @node: node to test
   *
   * Returns true if the node has a "big-endian" property, or if the kernel
   * was compiled for BE *and* the node has a "native-endian" property.
   * Returns false otherwise.
   */
  bool of_fdt_is_big_endian(const void *blob, unsigned long node)
  {
  	if (fdt_getprop(blob, node, "big-endian", NULL))
  		return true;
  	if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
  	    fdt_getprop(blob, node, "native-endian", NULL))
  		return true;
  	return false;
  }
  
  /**
   * of_fdt_match - Return true if node matches a list of compatible values
   */
  int of_fdt_match(const void *blob, unsigned long node,
                   const char *const *compat)
  {
  	unsigned int tmp, score = 0;
  
  	if (!compat)
  		return 0;
  
  	while (*compat) {
  		tmp = of_fdt_is_compatible(blob, node, *compat);
  		if (tmp && (score == 0 || (tmp < score)))
  			score = tmp;
  		compat++;
  	}
  
  	return score;
  }
  
  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 the 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;
  	unsigned int l, allocl;
  	static int depth = 0;
  	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;
  		of_node_init(np);
  		np->full_name = fn = ((char *)np) + sizeof(*np);
  		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) {
  					pr_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;
  		u32 sz;
  
  		if (!(p = fdt_getprop_by_offset(blob, offset, &pname, &sz))) {
  			offset = -FDT_ERR_INTERNAL;
  			break;
  		}
  
  		if (pname == NULL) {
  			pr_info("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;
  			pr_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 (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND)
  		pr_err("unflatten: error %d processing FDT\n", *poffset);
  
  	/*
  	 * 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
   * @dt_alloc: An allocator that provides a virtual address to memory
   * for the resulting tree
   */
  static void __unflatten_device_tree(const void *blob,
  			     struct device_node **mynodes,
  			     void * (*dt_alloc)(u64 size, u64 align))
  {
  	unsigned long size;
  	int start;
  	void *mem;
  
  	pr_debug(" -> unflatten_device_tree()\n");
  
  	if (!blob) {
  		pr_debug("No device tree pointer\n");
  		return;
  	}
  
  	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;
  	}
  
  	/* First pass, scan for size */
  	start = 0;
  	size = (unsigned long)unflatten_dt_node(blob, NULL, &start, NULL, NULL, 0, true);
  	size = ALIGN(size, 4);
  
  	pr_debug("  size is %lx, allocating...\n", size);
  
  	/* Allocate memory for the expanded device tree */
  	mem = dt_alloc(size + 4, __alignof__(struct device_node));
  	memset(mem, 0, size);
  
  	*(__be32 *)(mem + size) = cpu_to_be32(0xdeadbeef);
  
  	pr_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)
  		pr_warning("End of tree marker overwritten: %08x\n",
  			   be32_to_cpup(mem + size));
  
  	pr_debug(" <- unflatten_device_tree()\n");
  }
  
  static void *kernel_tree_alloc(u64 size, u64 align)
  {
  	return kzalloc(size, GFP_KERNEL);
  }
  
  /**
   * of_fdt_unflatten_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 of_fdt_unflatten_tree(const unsigned long *blob,
  			struct device_node **mynodes)
  {
  	__unflatten_device_tree(blob, mynodes, &kernel_tree_alloc);
  }
  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;
  
  #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 nomap, first = 1;
  
  	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.\n",
  		       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\n",
  				uname, &base, (unsigned long)size / SZ_1M);
  		else
  			pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %ld MiB\n",
  				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;
  	const char *status;
  	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\n");
  			/* 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;
  	}
  
  	status = of_get_flat_dt_prop(node, "status", NULL);
  	if (status && strcmp(status, "okay") != 0 && strcmp(status, "ok") != 0)
  		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, 0);
  	}
  
  	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),
  					  0);
  }
  
  /**
   * 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;
  
          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_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_size - Return the total size of the FDT
   */
  int __init of_get_flat_dt_size(void)
  {
  	return fdt_totalsize(initial_boot_params);
  }
  
  /**
   * 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_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
   */
  int __init of_flat_dt_match(unsigned long node, const char *const *compat)
  {
  	return of_fdt_match(initial_boot_params, node, compat);
  }
  
  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("\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;
  }
  
  #ifdef CONFIG_BLK_DEV_INITRD
  /**
   * 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);
  
  	initrd_start = (unsigned long)__va(start);
  	initrd_end = (unsigned long)__va(end);
  	initrd_below_start_ok = 1;
  
  	pr_debug("initrd_start=0x%llx  initrd_end=0x%llx\n",
  		 (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
  extern struct of_device_id __earlycon_of_table[];
  
  static int __init early_init_dt_scan_chosen_serial(void)
  {
  	int offset;
  	const char *p;
  	int l;
  	const struct of_device_id *match = __earlycon_of_table;
  	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;
  
  	/* Get the node specified by stdout-path */
  	offset = fdt_path_offset(fdt, p);
  	if (offset < 0)
  		return -ENODEV;
  
  	while (match->compatible[0]) {
  		u64 addr;
  
  		if (fdt_node_check_compatible(fdt, offset, match->compatible)) {
  			match++;
  			continue;
  		}
  
  		addr = fdt_translate_address(fdt, offset);
  		if (addr == OF_BAD_ADDR)
  			return -ENXIO;
  
  		of_setup_earlycon(addr, match->data);
  		return 0;
  	}
  	return -ENODEV;
  }
  
  static int __init setup_of_earlycon(char *buf)
  {
  	if (buf)
  		return 0;
  
  	return early_init_dt_scan_chosen_serial();
  }
  early_param("earlycon", setup_of_earlycon);
  #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\n", 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\n", 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 an 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;
  
  	/* We are scanning "memory" nodes only */
  	if (type == NULL) {
  		/*
  		 * The longtrail doesn't have a device_type on the
  		 * /memory node, so look for the node called /memory@0.
  		 */
  		if (!IS_ENABLED(CONFIG_PPC32) || depth != 1 || strcmp(uname, "memory@0") != 0)
  			return 0;
  	} else if (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));
  
  	pr_debug("memory scan node %s, reg size %d,\n", 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\n", (unsigned long long)base,
  		    (unsigned long long)size);
  
  		early_init_dt_add_memory_arch(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;
  
  	pr_debug("search \"chosen\", depth: %d, uname: %s\n", 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((int)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
  #ifndef CONFIG_CMDLINE_FORCE
  	if (!((char *)data)[0])
  #endif
  		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
  #endif /* CONFIG_CMDLINE */
  
  	pr_debug("Command line is: %s\n", (char*)data);
  
  	/* break now */
  	return 1;
  }
  
  #ifdef CONFIG_HAVE_MEMBLOCK
  #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 = __pa(PAGE_OFFSET);
  
  	if (!PAGE_ALIGNED(base)) {
  		if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
  			pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
  				base, base + size);
  			return;
  		}
  		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\n",
  				base, base + size);
  		return;
  	}
  
  	if (base + size - 1 > MAX_MEMBLOCK_ADDR) {
  		pr_warning("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_warning("Ignoring memory block 0x%llx - 0x%llx\n",
  			   base, base + size);
  		return;
  	}
  	if (base < phys_offset) {
  		pr_warning("Ignoring memory range 0x%llx - 0x%llx\n",
  			   base, phys_offset);
  		size -= phys_offset - base;
  		base = phys_offset;
  	}
  	memblock_add(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);
  }
  
  /*
   * called from unflatten_device_tree() to bootstrap devicetree itself
   * Architectures can override this definition if memblock isn't used
   */
  void * __init __weak early_init_dt_alloc_memory_arch(u64 size, u64 align)
  {
  	return __va(memblock_alloc(size, align));
  }
  #else
  void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
  {
  	WARN_ON(1);
  }
  
  int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
  					phys_addr_t size, bool nomap)
  {
  	pr_err("Reserved memory not supported, ignoring range 0x%pa - 0x%pa%s\n",
  		  &base, &size, nomap ? " (nomap)" : "");
  	return -ENOSYS;
  }
  
  void * __init __weak early_init_dt_alloc_memory_arch(u64 size, u64 align)
  {
  	WARN_ON(1);
  	return NULL;
  }
  #endif
  
  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)
  {
  	/* Retrieve various information from the /chosen node */
  	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
  
  	/* 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, &of_root,
  				early_init_dt_alloc_memory_arch);
  
  	/* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */
  	of_alias_scan(early_init_dt_alloc_memory_arch);
  }
  
  /**
   * 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\n");
  		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("fdt: not creating '/sys/firmware/fdt': CRC check failed\n");
  		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 */
  