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)
11 DECLARE_GLOBAL_DATA_PTR;
12 #endif
13
14 /*
15 * Look up a callback function pointer by name
16 */
find_env_callback(const char * name)17 static 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
37 static int first_call = 1;
38 static 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 */
env_callback_init(ENTRY * var_entry)45 void 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 */
clear_callback(ENTRY * entry)82 static 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 */
set_callback(const char * name,const char * value,void * priv)92 static 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
on_callbacks(const char * name,const char * value,enum env_op op,int flags)122 static 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 }
135 U_BOOT_ENV_CALLBACK(callbacks, on_callbacks);
136