text: // SPDX-License-Identifier: GPL-2.0
  #include <linux/string.h>
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/of.h>
  #include <asm/prom.h>
  
  #include "of_helpers.h"
  
  /**
   * pseries_of_derive_parent - basically like dirname(1)
   * @path:  the full_name of a node to be added to the tree
   *
   * Returns the node which should be the parent of the node
   * described by path.  E.g., for path = "/foo/bar", returns
   * the node with full_name = "/foo".
   */
  struct device_node *pseries_of_derive_parent(const char *path)
  {
  	struct device_node *parent;
  	char *parent_path = "/";
  	const char *tail;
  
  	/* We do not want the trailing '/' character */
  	tail = kbasename(path) - 1;
  
  	/* reject if path is "/" */
  	if (!strcmp(path, "/"))
  		return ERR_PTR(-EINVAL);
  
  	if (tail > path) {
  		parent_path = kstrndup(path, tail - path, GFP_KERNEL);
  		if (!parent_path)
  			return ERR_PTR(-ENOMEM);
  	}
  	parent = of_find_node_by_path(parent_path);
  	if (strcmp(parent_path, "/"))
  		kfree(parent_path);
  	return parent ? parent : ERR_PTR(-EINVAL);
  }
  
  
  /* Helper Routines to convert between drc_index to cpu numbers */
  
  int of_read_drc_info_cell(struct property **prop, const __be32 **curval,
  			struct of_drc_info *data)
  {
  	const char *p = (char *)(*curval);
  	const __be32 *p2;
  
  	if (!data)
  		return -EINVAL;
  
  	/* Get drc-type:encode-string */
  	data->drc_type = (char *)p;
  	p = of_prop_next_string(*prop, p);
  	if (!p)
  		return -EINVAL;
  
  	/* Get drc-name-prefix:encode-string */
  	data->drc_name_prefix = (char *)p;
  	p = of_prop_next_string(*prop, p);
  	if (!p)
  		return -EINVAL;
  
  	/* Get drc-index-start:encode-int */
  	p2 = (const __be32 *)p;
  	data->drc_index_start = be32_to_cpu(*p2);
  
  	/* Get drc-name-suffix-start:encode-int */
  	p2 = of_prop_next_u32(*prop, p2, &data->drc_name_suffix_start);
  	if (!p2)
  		return -EINVAL;
  
  	/* Get number-sequential-elements:encode-int */
  	p2 = of_prop_next_u32(*prop, p2, &data->num_sequential_elems);
  	if (!p2)
  		return -EINVAL;
  
  	/* Get sequential-increment:encode-int */
  	p2 = of_prop_next_u32(*prop, p2, &data->sequential_inc);
  	if (!p2)
  		return -EINVAL;
  
  	/* Get drc-power-domain:encode-int */
  	p2 = of_prop_next_u32(*prop, p2, &data->drc_power_domain);
  	if (!p2)
  		return -EINVAL;
  
  	/* Should now know end of current entry */
  	(*curval) = (void *)p2;
  	data->last_drc_index = data->drc_index_start +
  		((data->num_sequential_elems - 1) * data->sequential_inc);
  
  	return 0;
  }
  EXPORT_SYMBOL(of_read_drc_info_cell);
  