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+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * include/linker_lists.h
+ *
+ * Implementation of linker-generated arrays
+ *
+ * Copyright (C) 2012 Marek Vasut <marex@denx.de>
+ */
+
+#ifndef __LINKER_LISTS_H__
+#define __LINKER_LISTS_H__
+
+#include <linux/compiler.h>
+
+/*
+ * There is no use in including this from ASM files.
+ * So just don't define anything when included from ASM.
+ */
+
+#if !defined(__ASSEMBLY__)
+
+/**
+ * llsym() - Access a linker-generated array entry
+ * @_type: Data type of the entry
+ * @_name: Name of the entry
+ * @_list: name of the list. Should contain only characters allowed
+ * in a C variable name!
+ */
+#define llsym(_type, _name, _list) \
+ ((_type *)&_u_boot_list_2_##_list##_2_##_name)
+
+/**
+ * ll_entry_declare() - Declare linker-generated array entry
+ * @_type: Data type of the entry
+ * @_name: Name of the entry
+ * @_list: name of the list. Should contain only characters allowed
+ * in a C variable name!
+ *
+ * This macro declares a variable that is placed into a linker-generated
+ * array. This is a basic building block for more advanced use of linker-
+ * generated arrays. The user is expected to build their own macro wrapper
+ * around this one.
+ *
+ * A variable declared using this macro must be compile-time initialized.
+ *
+ * Special precaution must be made when using this macro:
+ *
+ * 1) The _type must not contain the "static" keyword, otherwise the
+ * entry is generated and can be iterated but is listed in the map
+ * file and cannot be retrieved by name.
+ *
+ * 2) In case a section is declared that contains some array elements AND
+ * a subsection of this section is declared and contains some elements,
+ * it is imperative that the elements are of the same type.
+ *
+ * 3) In case an outer section is declared that contains some array elements
+ * AND an inner subsection of this section is declared and contains some
+ * elements, then when traversing the outer section, even the elements of
+ * the inner sections are present in the array.
+ *
+ * Example:
+ *
+ * ::
+ *
+ * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
+ * .x = 3,
+ * .y = 4,
+ * };
+ */
+#define ll_entry_declare(_type, _name, _list) \
+ _type _u_boot_list_2_##_list##_2_##_name __aligned(4) \
+ __attribute__((unused)) \
+ __section("__u_boot_list_2_"#_list"_2_"#_name)
+
+/**
+ * ll_entry_declare_list() - Declare a list of link-generated array entries
+ * @_type: Data type of each entry
+ * @_name: Name of the entry
+ * @_list: name of the list. Should contain only characters allowed
+ * in a C variable name!
+ *
+ * This is like ll_entry_declare() but creates multiple entries. It should
+ * be assigned to an array.
+ *
+ * ::
+ *
+ * ll_entry_declare_list(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
+ * { .x = 3, .y = 4 },
+ * { .x = 8, .y = 2 },
+ * { .x = 1, .y = 7 }
+ * };
+ */
+#define ll_entry_declare_list(_type, _name, _list) \
+ _type _u_boot_list_2_##_list##_2_##_name[] __aligned(4) \
+ __attribute__((unused)) \
+ __section("__u_boot_list_2_"#_list"_2_"#_name)
+
+/*
+ * We need a 0-byte-size type for iterator symbols, and the compiler
+ * does not allow defining objects of C type 'void'. Using an empty
+ * struct is allowed by the compiler, but causes gcc versions 4.4 and
+ * below to complain about aliasing. Therefore we use the next best
+ * thing: zero-sized arrays, which are both 0-byte-size and exempt from
+ * aliasing warnings.
+ */
+
+/**
+ * ll_entry_start() - Point to first entry of linker-generated array
+ * @_type: Data type of the entry
+ * @_list: Name of the list in which this entry is placed
+ *
+ * This function returns ``(_type *)`` pointer to the very first entry of a
+ * linker-generated array placed into subsection of __u_boot_list section
+ * specified by _list argument.
+ *
+ * Since this macro defines an array start symbol, its leftmost index
+ * must be 2 and its rightmost index must be 1.
+ *
+ * Example:
+ *
+ * ::
+ *
+ * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
+ */
+#define ll_entry_start(_type, _list) \
+({ \
+ static char start[0] __aligned(CONFIG_LINKER_LIST_ALIGN) \
+ __attribute__((unused)) \
+ __section("__u_boot_list_2_"#_list"_1"); \
+ _type * tmp = (_type *)&start; \
+ asm("":"+r"(tmp)); \
+ tmp; \
+})
+
+/**
+ * ll_entry_end() - Point after last entry of linker-generated array
+ * @_type: Data type of the entry
+ * @_list: Name of the list in which this entry is placed
+ * (with underscores instead of dots)
+ *
+ * This function returns ``(_type *)`` pointer after the very last entry of
+ * a linker-generated array placed into subsection of __u_boot_list
+ * section specified by _list argument.
+ *
+ * Since this macro defines an array end symbol, its leftmost index
+ * must be 2 and its rightmost index must be 3.
+ *
+ * Example:
+ *
+ * ::
+ *
+ * struct my_sub_cmd *msc = ll_entry_end(struct my_sub_cmd, cmd_sub);
+ */
+#define ll_entry_end(_type, _list) \
+({ \
+ static char end[0] __aligned(4) __attribute__((unused)) \
+ __section("__u_boot_list_2_"#_list"_3"); \
+ _type * tmp = (_type *)&end; \
+ asm("":"+r"(tmp)); \
+ tmp; \
+})
+/**
+ * ll_entry_count() - Return the number of elements in linker-generated array
+ * @_type: Data type of the entry
+ * @_list: Name of the list of which the number of elements is computed
+ *
+ * This function returns the number of elements of a linker-generated array
+ * placed into subsection of __u_boot_list section specified by _list
+ * argument. The result is of an unsigned int type.
+ *
+ * Example:
+ *
+ * ::
+ *
+ * int i;
+ * const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub);
+ * struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
+ * for (i = 0; i < count; i++, msc++)
+ * printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y);
+ */
+#define ll_entry_count(_type, _list) \
+ ({ \
+ _type *start = ll_entry_start(_type, _list); \
+ _type *end = ll_entry_end(_type, _list); \
+ unsigned int _ll_result = end - start; \
+ _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
+ * @_name: Name of the entry
+ * @_list: Name of the list in which this entry is placed
+ *
+ * This function returns a pointer to a particular entry in linker-generated
+ * array identified by the subsection of u_boot_list where the entry resides
+ * and it's name.
+ *
+ * Example:
+ *
+ * ::
+ *
+ * ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub) = {
+ * .x = 3,
+ * .y = 4,
+ * };
+ * ...
+ * struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub);
+ */
+#define ll_entry_get(_type, _name, _list) \
+ ({ \
+ extern _type _u_boot_list_2_##_list##_2_##_name; \
+ _type *_ll_result = \
+ &_u_boot_list_2_##_list##_2_##_name; \
+ _ll_result; \
+ })
+
+/**
+ * ll_entry_ref() - Get a reference to a linker-generated array entry
+ *
+ * Once an extern ll_entry_declare() has been used to declare the reference,
+ * this macro allows the entry to be accessed.
+ *
+ * This is like ll_entry_get(), but without the extra code, so it is suitable
+ * for putting into data structures.
+ *
+ * @_type: C type of the list entry, e.g. 'struct foo'
+ * @_name: name of the entry
+ * @_list: name of the list
+ */
+#define ll_entry_ref(_type, _name, _list) \
+ ((_type *)&_u_boot_list_2_##_list##_2_##_name)
+
+/**
+ * ll_start() - Point to first entry of first linker-generated array
+ * @_type: Data type of the entry
+ *
+ * This function returns ``(_type *)`` pointer to the very first entry of
+ * the very first linker-generated array.
+ *
+ * Since this macro defines the start of the linker-generated arrays,
+ * its leftmost index must be 1.
+ *
+ * Example:
+ *
+ * ::
+ *
+ * struct my_sub_cmd *msc = ll_start(struct my_sub_cmd);
+ */
+#define ll_start(_type) \
+({ \
+ static char start[0] __aligned(4) __attribute__((unused)) \
+ __section("__u_boot_list_1"); \
+ _type * tmp = (_type *)&start; \
+ asm("":"+r"(tmp)); \
+ tmp; \
+})
+
+/**
+ * ll_end() - Point after last entry of last linker-generated array
+ * @_type: Data type of the entry
+ *
+ * This function returns ``(_type *)`` pointer after the very last entry of
+ * the very last linker-generated array.
+ *
+ * Since this macro defines the end of the linker-generated arrays,
+ * its leftmost index must be 3.
+ *
+ * Example:
+ *
+ * ::
+ *
+ * struct my_sub_cmd *msc = ll_end(struct my_sub_cmd);
+ */
+#define ll_end(_type) \
+({ \
+ static char end[0] __aligned(4) __attribute__((unused)) \
+ __section("__u_boot_list_3"); \
+ _type * tmp = (_type *)&end; \
+ asm("":"+r"(tmp)); \
+ tmp; \
+})
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __LINKER_LISTS_H__ */