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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