A limitation of most linker_list macros is that they cannot easily be used in data structures. This is because they include code inside their expressions.
Provide a way to support this, with new ll_start_decl() and ll_end_decl() macros.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v2: - Correct linker-list documentation
include/linker_lists.h | 57 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+)
diff --git a/include/linker_lists.h b/include/linker_lists.h index f9a2ee0c762..0f4a2d686e2 100644 --- a/include/linker_lists.h +++ b/include/linker_lists.h @@ -186,6 +186,63 @@ _ll_result; \ })
+/** + * Declares a symbol that points to the start/end of the list. + * + * @_sym: Arbitrary name for the symbol (to use later in the file) + * @_type: Data type of the entry + * @_list: Name of the list in which this entry is placed + * + * The name of the (new) symbol is arbitrary and can be anything that is not + * already declared in the file where it appears. It is provided in _sym and + * can then be used (later in the same file) within a data structure. + * The _type and _list arguments must match those passed to ll_entry_start/end() + * + * Example: + * + * Here we want to record the start of each sub-command in a list. We have two + * sub-commands, 'bob' and 'mary'. + * + * In bob.c:: + * + * ll_entry_declare(struct my_sub_cmd, bob_cmd, cmd_sub) = {...}; + * + * In mary.c:: + * + * ll_entry_declare(struct my_sub_cmd, mary_cmd, cmd_sub) = {...}; + * + * In a different file where we want a list the start of all sub-commands. + * It is not possible to use ll_entry_start() in a data structure, due to its + * use of code inside expressions - ({ ... }) - so this fails to compile: + * + * In sub_cmds.c:: + * + * struct cmd_sub *my_list[] = { + * ll_entry_start(cmd_sub, bob), + * ll_entry_start(cmd_sub, bob), + * }; + * + * Instead, we can use:: + * + * ll_start_decl(bob, struct my_sub_cmd, cmd_sub); + * ll_start_decl(mary, struct my_sub_cmd, cmd_sub); + * + * struct cmd_sub *my_list[] = { + * bob, + * mary, + * }; + * + * So 'bob' is declared as symbol, a struct my_list * which points to the + * start of the bob sub-commands. It is then used in my_list[] + */ +#define ll_start_decl(_sym, _type, _list) \ + static _type _sym[0] __aligned(CONFIG_LINKER_LIST_ALIGN) \ + __maybe_unused __section("__u_boot_list_2_" #_list "_1") + +#define ll_end_decl(_sym, _type, _list) \ + static _type _sym[0] __aligned(CONFIG_LINKER_LIST_ALIGN) \ + __maybe_unused __section("__u_boot_list_2_" #_list "_3") + /** * ll_entry_get() - Retrieve entry from linker-generated array by name * @_type: Data type of the entry