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 <env.h>
9 #include <env_internal.h>
10 #include <asm/global_data.h>
11
12 #if defined(CONFIG_NEEDS_MANUAL_RELOC)
13 DECLARE_GLOBAL_DATA_PTR;
14 #endif
15
16 /*
17 * Look up a callback function pointer by name
18 */
find_env_callback(const char * name)19 static struct env_clbk_tbl *find_env_callback(const char *name)
20 {
21 struct env_clbk_tbl *clbkp;
22 int i;
23 int num_callbacks = ll_entry_count(struct env_clbk_tbl, env_clbk);
24
25 if (name == NULL)
26 return NULL;
27
28 /* look up the callback in the linker-list */
29 for (i = 0, clbkp = ll_entry_start(struct env_clbk_tbl, env_clbk);
30 i < num_callbacks;
31 i++, clbkp++) {
32 if (strcmp(name, clbkp->name) == 0)
33 return clbkp;
34 }
35
36 return NULL;
37 }
38
39 static int first_call = 1;
40 static const char *callback_list;
41
42 /*
43 * Look for a possible callback for a newly added variable
44 * This is called specifically when the variable did not exist in the hash
45 * previously, so the blanket update did not find this variable.
46 */
env_callback_init(struct env_entry * var_entry)47 void env_callback_init(struct env_entry *var_entry)
48 {
49 const char *var_name = var_entry->key;
50 char callback_name[256] = "";
51 struct env_clbk_tbl *clbkp;
52 int ret = 1;
53
54 if (first_call) {
55 callback_list = env_get(ENV_CALLBACK_VAR);
56 first_call = 0;
57 }
58
59 var_entry->callback = NULL;
60
61 /* look in the ".callbacks" var for a reference to this variable */
62 if (callback_list != NULL)
63 ret = env_attr_lookup(callback_list, var_name, callback_name);
64
65 /* only if not found there, look in the static list */
66 if (ret)
67 ret = env_attr_lookup(ENV_CALLBACK_LIST_STATIC, var_name,
68 callback_name);
69
70 /* if an association was found, set the callback pointer */
71 if (!ret && strlen(callback_name)) {
72 clbkp = find_env_callback(callback_name);
73 if (clbkp != NULL)
74 #if defined(CONFIG_NEEDS_MANUAL_RELOC)
75 var_entry->callback = clbkp->callback + gd->reloc_off;
76 #else
77 var_entry->callback = clbkp->callback;
78 #endif
79 }
80 }
81
82 /*
83 * Called on each existing env var prior to the blanket update since removing
84 * a callback association should remove its callback.
85 */
clear_callback(struct env_entry * entry)86 static int clear_callback(struct env_entry *entry)
87 {
88 entry->callback = NULL;
89
90 return 0;
91 }
92
93 /*
94 * Call for each element in the list that associates variables to callbacks
95 */
set_callback(const char * name,const char * value,void * priv)96 static int set_callback(const char *name, const char *value, void *priv)
97 {
98 struct env_entry e, *ep;
99 struct env_clbk_tbl *clbkp;
100
101 e.key = name;
102 e.data = NULL;
103 e.callback = NULL;
104 hsearch_r(e, ENV_FIND, &ep, &env_htab, 0);
105
106 /* does the env variable actually exist? */
107 if (ep != NULL) {
108 /* the assocaition delares no callback, so remove the pointer */
109 if (value == NULL || strlen(value) == 0)
110 ep->callback = NULL;
111 else {
112 /* assign the requested callback */
113 clbkp = find_env_callback(value);
114 if (clbkp != NULL)
115 #if defined(CONFIG_NEEDS_MANUAL_RELOC)
116 ep->callback = clbkp->callback + gd->reloc_off;
117 #else
118 ep->callback = clbkp->callback;
119 #endif
120 }
121 }
122
123 return 0;
124 }
125
on_callbacks(const char * name,const char * value,enum env_op op,int flags)126 static int on_callbacks(const char *name, const char *value, enum env_op op,
127 int flags)
128 {
129 /* remove all callbacks */
130 hwalk_r(&env_htab, clear_callback);
131
132 /* configure any static callback bindings */
133 env_attr_walk(ENV_CALLBACK_LIST_STATIC, set_callback, NULL);
134 /* configure any dynamic callback bindings */
135 env_attr_walk(value, set_callback, NULL);
136
137 return 0;
138 }
139 U_BOOT_ENV_CALLBACK(callbacks, on_callbacks);
140