LXR uboot/env/callback.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * (C) Copyright 2012
   4 * Joe Hershberger, National Instruments, joe.hershberger@ni.com
   5 */
   6
   7#include <common.h>
   8#include <environment.h>
   9
  10#if defined(CONFIG_NEEDS_MANUAL_RELOC)
  11DECLARE_GLOBAL_DATA_PTR;
  12#endif
  13
  14/*
  15 * Look up a callback function pointer by name
  16 */
  17static struct env_clbk_tbl *find_env_callback(const char *name)
  18{
  19        struct env_clbk_tbl *clbkp;
  20        int i;
  21        int num_callbacks = ll_entry_count(struct env_clbk_tbl, env_clbk);
  22
  23        if (name == NULL)
  24                return NULL;
  25
  26        /* look up the callback in the linker-list */
  27        for (i = 0, clbkp = ll_entry_start(struct env_clbk_tbl, env_clbk);
  28             i < num_callbacks;
  29             i++, clbkp++) {
  30                if (strcmp(name, clbkp->name) == 0)
  31                        return clbkp;
  32        }
  33
  34        return NULL;
  35}
  36
  37static int first_call = 1;
  38static const char *callback_list;
  39
  40/*
  41 * Look for a possible callback for a newly added variable
  42 * This is called specifically when the variable did not exist in the hash
  43 * previously, so the blanket update did not find this variable.
  44 */
  45void env_callback_init(ENTRY *var_entry)
  46{
  47        const char *var_name = var_entry->key;
  48        char callback_name[256] = "";
  49        struct env_clbk_tbl *clbkp;
  50        int ret = 1;
  51
  52        if (first_call) {
  53                callback_list = env_get(ENV_CALLBACK_VAR);
  54                first_call = 0;
  55        }
  56
  57        /* look in the ".callbacks" var for a reference to this variable */
  58        if (callback_list != NULL)
  59                ret = env_attr_lookup(callback_list, var_name, callback_name);
  60
  61        /* only if not found there, look in the static list */
  62        if (ret)
  63                ret = env_attr_lookup(ENV_CALLBACK_LIST_STATIC, var_name,
  64                        callback_name);
  65
  66        /* if an association was found, set the callback pointer */
  67        if (!ret && strlen(callback_name)) {
  68                clbkp = find_env_callback(callback_name);
  69                if (clbkp != NULL)
  70#if defined(CONFIG_NEEDS_MANUAL_RELOC)
  71                        var_entry->callback = clbkp->callback + gd->reloc_off;
  72#else
  73                        var_entry->callback = clbkp->callback;
  74#endif
  75        }
  76}
  77
  78/*
  79 * Called on each existing env var prior to the blanket update since removing
  80 * a callback association should remove its callback.
  81 */
  82static int clear_callback(ENTRY *entry)
  83{
  84        entry->callback = NULL;
  85
  86        return 0;
  87}
  88
  89/*
  90 * Call for each element in the list that associates variables to callbacks
  91 */
  92static int set_callback(const char *name, const char *value, void *priv)
  93{
  94        ENTRY e, *ep;
  95        struct env_clbk_tbl *clbkp;
  96
  97        e.key   = name;
  98        e.data  = NULL;
  99        e.callback = NULL;
 100        hsearch_r(e, FIND, &ep, &env_htab, 0);
 101
 102        /* does the env variable actually exist? */
 103        if (ep != NULL) {
 104                /* the assocaition delares no callback, so remove the pointer */
 105                if (value == NULL || strlen(value) == 0)
 106                        ep->callback = NULL;
 107                else {
 108                        /* assign the requested callback */
 109                        clbkp = find_env_callback(value);
 110                        if (clbkp != NULL)
 111#if defined(CONFIG_NEEDS_MANUAL_RELOC)
 112                                ep->callback = clbkp->callback + gd->reloc_off;
 113#else
 114                                ep->callback = clbkp->callback;
 115#endif
 116                }
 117        }
 118
 119        return 0;
 120}
 121
 122static int on_callbacks(const char *name, const char *value, enum env_op op,
 123        int flags)
 124{
 125        /* remove all callbacks */
 126        hwalk_r(&env_htab, clear_callback);
 127
 128        /* configure any static callback bindings */
 129        env_attr_walk(ENV_CALLBACK_LIST_STATIC, set_callback, NULL);
 130        /* configure any dynamic callback bindings */
 131        env_attr_walk(value, set_callback, NULL);
 132
 133        return 0;
 134}
 135U_BOOT_ENV_CALLBACK(callbacks, on_callbacks);
 136