/*
   * (C) Copyright 2012
   * Joe Hershberger, National Instruments, joe.hershberger@ni.com
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  #include <common.h>
  #include <environment.h>
  
  #if defined(CONFIG_NEEDS_MANUAL_RELOC)
  DECLARE_GLOBAL_DATA_PTR;
  #endif
  
  /*
   * Look up a callback function pointer by name
   */
  static struct env_clbk_tbl *find_env_callback(const char *name)
  {
  	struct env_clbk_tbl *clbkp;
  	int i;
  	int num_callbacks = ll_entry_count(struct env_clbk_tbl, env_clbk);
  
  	if (name == NULL)
  		return NULL;
  
  	/* look up the callback in the linker-list */
  	for (i = 0, clbkp = ll_entry_start(struct env_clbk_tbl, env_clbk);
  	     i < num_callbacks;
  	     i++, clbkp++) {
  		if (strcmp(name, clbkp->name) == 0)
  			return clbkp;
  	}
  
  	return NULL;
  }
  
  static int first_call = 1;
  static const char *callback_list;
  
  /*
   * Look for a possible callback for a newly added variable
   * This is called specifically when the variable did not exist in the hash
   * previously, so the blanket update did not find this variable.
   */
  void env_callback_init(ENTRY *var_entry)
  {
  	const char *var_name = var_entry->key;
  	char callback_name[256] = "";
  	struct env_clbk_tbl *clbkp;
  	int ret = 1;
  
  	if (first_call) {
  		callback_list = getenv(ENV_CALLBACK_VAR);
  		first_call = 0;
  	}
  
  	/* look in the ".callbacks" var for a reference to this variable */
  	if (callback_list != NULL)
  		ret = env_attr_lookup(callback_list, var_name, callback_name);
  
  	/* only if not found there, look in the static list */
  	if (ret)
  		ret = env_attr_lookup(ENV_CALLBACK_LIST_STATIC, var_name,
  			callback_name);
  
  	/* if an association was found, set the callback pointer */
  	if (!ret && strlen(callback_name)) {
  		clbkp = find_env_callback(callback_name);
  		if (clbkp != NULL)
  #if defined(CONFIG_NEEDS_MANUAL_RELOC)
  			var_entry->callback = clbkp->callback + gd->reloc_off;
  #else
  			var_entry->callback = clbkp->callback;
  #endif
  	}
  }
  
  /*
   * Called on each existing env var prior to the blanket update since removing
   * a callback association should remove its callback.
   */
  static int clear_callback(ENTRY *entry)
  {
  	entry->callback = NULL;
  
  	return 0;
  }
  
  /*
   * Call for each element in the list that associates variables to callbacks
   */
  static int set_callback(const char *name, const char *value)
  {
  	ENTRY e, *ep;
  	struct env_clbk_tbl *clbkp;
  
  	e.key	= name;
  	e.data	= NULL;
  	hsearch_r(e, FIND, &ep, &env_htab, 0);
  
  	/* does the env variable actually exist? */
  	if (ep != NULL) {
  		/* the assocaition delares no callback, so remove the pointer */
  		if (value == NULL || strlen(value) == 0)
  			ep->callback = NULL;
  		else {
  			/* assign the requested callback */
  			clbkp = find_env_callback(value);
  			if (clbkp != NULL)
  #if defined(CONFIG_NEEDS_MANUAL_RELOC)
  				ep->callback = clbkp->callback + gd->reloc_off;
  #else
  				ep->callback = clbkp->callback;
  #endif
  		}
  	}
  
  	return 0;
  }
  
  static int on_callbacks(const char *name, const char *value, enum env_op op,
  	int flags)
  {
  	/* remove all callbacks */
  	hwalk_r(&env_htab, clear_callback);
  
  	/* configure any static callback bindings */
  	env_attr_walk(ENV_CALLBACK_LIST_STATIC, set_callback);
  	/* configure any dynamic callback bindings */
  	env_attr_walk(value, set_callback);
  
  	return 0;
  }
  U_BOOT_ENV_CALLBACK(callbacks, on_callbacks);