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1a4596601f
Signed-off-by: Wolfgang Denk <wd@denx.de> [trini: Fixup common/cmd_io.c] Signed-off-by: Tom Rini <trini@ti.com>
289 lines
9.8 KiB
C
289 lines
9.8 KiB
C
/*
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* include/linker_lists.h
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*
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* Implementation of linker-generated arrays
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*
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* Copyright (C) 2012 Marek Vasut <marex@denx.de>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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/*
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* There is no use in including this from ASM files, but that happens
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* anyway, e.g. PPC kgdb.S includes command.h which incluse us.
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* So just don't define anything when included from ASM.
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*/
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#if !defined(__ASSEMBLY__)
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/**
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* A linker list is constructed by grouping together linker input
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* sections, each containning one entry of the list. Each input section
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* contains a constant initialized variable which holds the entry's
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* content. Linker list input sections are constructed from the list
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* and entry names, plus a prefix which allows grouping all lists
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* together. Assuming _list and _entry are the list and entry names,
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* then the corresponding input section name is
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*
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* _u_boot_list + _2_ + @_list + _2_ + @_entry
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*
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* and the C variable name is
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*
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* .u_boot_list_ + 2_ + @_list + _2_ + @_entry
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*
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* This ensures uniqueness for both input section and C variable name.
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*
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* Note that the names differ only in the first character, "." for the
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* setion and "_" for the variable, so that the linker cannot confuse
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* section and symbol names. From now on, both names will be referred
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* to as
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*
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* %u_boot_list_ + 2_ + @_list + _2_ + @_entry
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*
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* Entry variables need never be referred to directly.
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*
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* The naming scheme for input sections allows grouping all linker lists
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* into a single linker output section and grouping all entries for a
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* single list.
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*
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* Note the two '_2_' constant components in the names: their presence
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* allows putting a start and end symbols around a list, by mapping
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* these symbols to sections names with components "1" (before) and
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* "3" (after) instead of "2" (within).
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* Start and end symbols for a list can generally be defined as
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*
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* %u_boot_list_2_ + @_list + _1_...
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* %u_boot_list_2_ + @_list + _3_...
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*
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* Start and end symbols for the whole of the linker lists area can be
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* defined as
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*
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* %u_boot_list_1_...
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* %u_boot_list_3_...
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*
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* Here is an example of the sorted sections which result from a list
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* "array" made up of three entries : "first", "second" and "third",
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* iterated at least once.
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*
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* .u_boot_list_2_array_1
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* .u_boot_list_2_array_2_first
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* .u_boot_list_2_array_2_second
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* .u_boot_list_2_array_2_third
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* .u_boot_list_2_array_3
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*
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* If lists must be divided into sublists (e.g. for iterating only on
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* part of a list), one can simply give the list a name of the form
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* 'outer_2_inner', where 'outer' is the global list name and 'inner'
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* is the sub-list name. Iterators for the whole list should use the
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* global list name ("outer"); iterators for only a sub-list should use
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* the full sub-list name ("outer_2_inner").
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*
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* Here is an example of the sections generated from a global list
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* named "drivers", two sub-lists named "i2c" and "pci", and iterators
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* defined for the whole list and each sub-list:
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*
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* %u_boot_list_2_drivers_1
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* %u_boot_list_2_drivers_2_i2c_1
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* %u_boot_list_2_drivers_2_i2c_2_first
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* %u_boot_list_2_drivers_2_i2c_2_first
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* %u_boot_list_2_drivers_2_i2c_2_second
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* %u_boot_list_2_drivers_2_i2c_2_third
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* %u_boot_list_2_drivers_2_i2c_3
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* %u_boot_list_2_drivers_2_pci_1
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* %u_boot_list_2_drivers_2_pci_2_first
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* %u_boot_list_2_drivers_2_pci_2_second
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* %u_boot_list_2_drivers_2_pci_2_third
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* %u_boot_list_2_drivers_2_pci_3
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* %u_boot_list_2_drivers_3
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*/
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#ifndef __LINKER_LISTS_H__
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#define __LINKER_LISTS_H__
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/**
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* ll_entry_declare() - Declare linker-generated array entry
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* @_type: Data type of the entry
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* @_name: Name of the entry
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* @_list: name of the list. Should contain only characters allowed
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* in a C variable name!
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*
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* This macro declares a variable that is placed into a linker-generated
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* array. This is a basic building block for more advanced use of linker-
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* generated arrays. The user is expected to build their own macro wrapper
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* around this one.
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*
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* A variable declared using this macro must be compile-time initialized.
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*
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* Special precaution must be made when using this macro:
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*
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* 1) The _type must not contain the "static" keyword, otherwise the
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* entry is generated and can be iterated but is listed in the map
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* file and cannot be retrieved by name.
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*
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* 2) In case a section is declared that contains some array elements AND
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* a subsection of this section is declared and contains some elements,
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* it is imperative that the elements are of the same type.
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*
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* 4) In case an outer section is declared that contains some array elements
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* AND an inner subsection of this section is declared and contains some
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* elements, then when traversing the outer section, even the elements of
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* the inner sections are present in the array.
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*
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* Example:
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* ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub, cmd.sub) = {
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* .x = 3,
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* .y = 4,
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* };
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*/
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#define ll_entry_declare(_type, _name, _list) \
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_type _u_boot_list_2_##_list##_2_##_name __aligned(4) \
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__attribute__((unused, \
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section(".u_boot_list_2_"#_list"_2_"#_name)))
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/**
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* We need a 0-byte-size type for iterator symbols, and the compiler
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* does not allow defining objects of C type 'void'. Using an empty
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* struct is allowed by the compiler, but causes gcc versions 4.4 and
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* below to complain about aliasing. Therefore we use the next best
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* thing: zero-sized arrays, which are both 0-byte-size and exempt from
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* aliasing warnings.
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*/
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/**
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* ll_entry_start() - Point to first entry of linker-generated array
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* @_type: Data type of the entry
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* @_list: Name of the list in which this entry is placed
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*
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* This function returns (_type *) pointer to the very first entry of a
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* linker-generated array placed into subsection of .u_boot_list section
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* specified by _list argument.
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*
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* Since this macro defines an array start symbol, its leftmost index
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* must be 2 and its rightmost index must be 1.
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*
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* Example:
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* struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
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*/
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#define ll_entry_start(_type, _list) \
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({ \
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static char start[0] __aligned(4) __attribute__((unused, \
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section(".u_boot_list_2_"#_list"_1"))); \
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(_type *)&start; \
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})
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/**
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* ll_entry_end() - Point after last entry of linker-generated array
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* @_type: Data type of the entry
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* @_list: Name of the list in which this entry is placed
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* (with underscores instead of dots)
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*
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* This function returns (_type *) pointer after the very last entry of
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* a linker-generated array placed into subsection of .u_boot_list
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* section specified by _list argument.
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*
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* Since this macro defines an array end symbol, its leftmost index
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* must be 2 and its rightmost index must be 3.
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*
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* Example:
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* struct my_sub_cmd *msc = ll_entry_end(struct my_sub_cmd, cmd_sub);
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*/
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#define ll_entry_end(_type, _list) \
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({ \
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static char end[0] __aligned(4) __attribute__((unused, \
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section(".u_boot_list_2_"#_list"_3"))); \
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(_type *)&end; \
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})
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/**
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* ll_entry_count() - Return the number of elements in linker-generated array
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* @_type: Data type of the entry
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* @_list: Name of the list of which the number of elements is computed
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*
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* This function returns the number of elements of a linker-generated array
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* placed into subsection of .u_boot_list section specified by _list
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* argument. The result is of an unsigned int type.
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*
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* Example:
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* int i;
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* const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub);
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* struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
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* for (i = 0; i < count; i++, msc++)
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* printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y);
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*/
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#define ll_entry_count(_type, _list) \
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({ \
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_type *start = ll_entry_start(_type, _list); \
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_type *end = ll_entry_end(_type, _list); \
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unsigned int _ll_result = end - start; \
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_ll_result; \
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})
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/**
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* ll_entry_get() - Retrieve entry from linker-generated array by name
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* @_type: Data type of the entry
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* @_name: Name of the entry
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* @_list: Name of the list in which this entry is placed
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*
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* This function returns a pointer to a particular entry in LG-array
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* identified by the subsection of u_boot_list where the entry resides
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* and it's name.
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*
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* Example:
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* ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub, cmd.sub) = {
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* .x = 3,
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* .y = 4,
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* };
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* ...
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* struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub);
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*/
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#define ll_entry_get(_type, _name, _list) \
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({ \
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extern _type _u_boot_list_2_##_list##_2_##_name; \
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_type *_ll_result = \
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&_u_boot_list_2_##_list##_2_##_name; \
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_ll_result; \
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})
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/**
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* ll_start() - Point to first entry of first linker-generated array
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* @_type: Data type of the entry
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*
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* This function returns (_type *) pointer to the very first entry of
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* the very first linker-generated array.
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*
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* Since this macro defines the start of the linker-generated arrays,
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* its leftmost index must be 1.
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*
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* Example:
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* struct my_sub_cmd *msc = ll_start(struct my_sub_cmd);
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*/
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#define ll_start(_type) \
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({ \
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static char start[0] __aligned(4) __attribute__((unused, \
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section(".u_boot_list_1"))); \
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(_type *)&start; \
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})
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/**
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* ll_entry_end() - Point after last entry of last linker-generated array
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* @_type: Data type of the entry
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*
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* This function returns (_type *) pointer after the very last entry of
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* the very last linker-generated array.
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*
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* Since this macro defines the end of the linker-generated arrays,
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* its leftmost index must be 3.
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*
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* Example:
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* struct my_sub_cmd *msc = ll_end(struct my_sub_cmd);
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*/
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#define ll_end(_type) \
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({ \
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static char end[0] __aligned(4) __attribute__((unused, \
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section(".u_boot_list_3"))); \
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(_type *)&end; \
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})
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#endif /* __ASSEMBLY__ */
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#endif /* __LINKER_LISTS_H__ */
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