*
* Copyright (C) 2012 Marek Vasut <marex@denx.de>
*
- * See file CREDITS for list of people who contributed to this
- * project.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of
- * the License, or (at your option) any later version.
+ * SPDX-License-Identifier: GPL-2.0+
*/
+
#ifndef __LINKER_LISTS_H__
#define __LINKER_LISTS_H__
+#include <linux/compiler.h>
+
+/*
+ * There is no use in including this from ASM files, but that happens
+ * anyway, e.g. PPC kgdb.S includes command.h which incluse us.
+ * So just don't define anything when included from ASM.
+ */
+
+#if !defined(__ASSEMBLY__)
+
+/**
+ * A linker list is constructed by grouping together linker input
+ * sections, each containning one entry of the list. Each input section
+ * contains a constant initialized variable which holds the entry's
+ * content. Linker list input sections are constructed from the list
+ * and entry names, plus a prefix which allows grouping all lists
+ * together. Assuming _list and _entry are the list and entry names,
+ * then the corresponding input section name is
+ *
+ * .u_boot_list_ + 2_ + @_list + _2_ + @_entry
+ *
+ * and the C variable name is
+ *
+ * _u_boot_list + _2_ + @_list + _2_ + @_entry
+ *
+ * This ensures uniqueness for both input section and C variable name.
+ *
+ * Note that the names differ only in the first character, "." for the
+ * setion and "_" for the variable, so that the linker cannot confuse
+ * section and symbol names. From now on, both names will be referred
+ * to as
+ *
+ * %u_boot_list_ + 2_ + @_list + _2_ + @_entry
+ *
+ * Entry variables need never be referred to directly.
+ *
+ * The naming scheme for input sections allows grouping all linker lists
+ * into a single linker output section and grouping all entries for a
+ * single list.
+ *
+ * Note the two '_2_' constant components in the names: their presence
+ * allows putting a start and end symbols around a list, by mapping
+ * these symbols to sections names with components "1" (before) and
+ * "3" (after) instead of "2" (within).
+ * Start and end symbols for a list can generally be defined as
+ *
+ * %u_boot_list_2_ + @_list + _1_...
+ * %u_boot_list_2_ + @_list + _3_...
+ *
+ * Start and end symbols for the whole of the linker lists area can be
+ * defined as
+ *
+ * %u_boot_list_1_...
+ * %u_boot_list_3_...
+ *
+ * Here is an example of the sorted sections which result from a list
+ * "array" made up of three entries : "first", "second" and "third",
+ * iterated at least once.
+ *
+ * .u_boot_list_2_array_1
+ * .u_boot_list_2_array_2_first
+ * .u_boot_list_2_array_2_second
+ * .u_boot_list_2_array_2_third
+ * .u_boot_list_2_array_3
+ *
+ * If lists must be divided into sublists (e.g. for iterating only on
+ * part of a list), one can simply give the list a name of the form
+ * 'outer_2_inner', where 'outer' is the global list name and 'inner'
+ * is the sub-list name. Iterators for the whole list should use the
+ * global list name ("outer"); iterators for only a sub-list should use
+ * the full sub-list name ("outer_2_inner").
+ *
+ * Here is an example of the sections generated from a global list
+ * named "drivers", two sub-lists named "i2c" and "pci", and iterators
+ * defined for the whole list and each sub-list:
+ *
+ * %u_boot_list_2_drivers_1
+ * %u_boot_list_2_drivers_2_i2c_1
+ * %u_boot_list_2_drivers_2_i2c_2_first
+ * %u_boot_list_2_drivers_2_i2c_2_first
+ * %u_boot_list_2_drivers_2_i2c_2_second
+ * %u_boot_list_2_drivers_2_i2c_2_third
+ * %u_boot_list_2_drivers_2_i2c_3
+ * %u_boot_list_2_drivers_2_pci_1
+ * %u_boot_list_2_drivers_2_pci_2_first
+ * %u_boot_list_2_drivers_2_pci_2_second
+ * %u_boot_list_2_drivers_2_pci_2_third
+ * %u_boot_list_2_drivers_2_pci_3
+ * %u_boot_list_2_drivers_3
+ */
+
/**
* ll_entry_declare() - Declare linker-generated array entry
* @_type: Data type of the entry
* @_name: Name of the entry
- * @_section_u: Subsection of u_boot_list in which this entry is placed
- * (with underscores instead of dots, for name concatenation)
- * @_section_d: Subsection of u_boot_list in which this entry is placed
- * (with dots, for section concatenation)
+ * @_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
- * and is as such placed into subsection of special section, .u_boot_list.
- * The subsection is specified by the _section_[u,d] parameter, see below.
- * The base name of the variable is _name, yet the actual variable is
- * declared as concatenation of
- *
- * %_u_boot_list_ + @_section_u + _ + @_name
- *
- * which ensures name uniqueness. This variable shall never be refered
- * directly though.
+ * 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 not generated.
*
- * 2) The @_section_u and @_section_d variables must match, the only difference
- * is that in @_section_u is every dot "." character present in @_section_d
- * replaced by a single underscore "_" character in @_section_u. The actual
- * purpose of these parameters is to select proper subsection in the global
- * .u_boot_list section.
+ * 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.
*
- * 3) 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.
+ * 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.
*
* 4) In case an outer section is declared that contains some array elements
- * AND am inner subsection of this section is declared and contains some
+ * 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.
*
* .y = 4,
* };
*/
-#define ll_entry_declare(_type, _name, _section_u, _section_d) \
- _type _u_boot_list_##_section_u##_##_name __attribute__(( \
- unused, aligned(4), \
- section(".u_boot_list."#_section_d"."#_name)))
+#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)))
+
+/**
+ * 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
- * @_section_u: Subsection of u_boot_list in which this entry is placed
- * (with underscores instead of dots)
+ * @_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 _section_u argument.
+ * 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, _section_u) \
- ({ \
- extern _type _u_boot_list_##_section_u##__start; \
- _type *_ll_result = &_u_boot_list_##_section_u##__start;\
- _ll_result; \
- })
+#define ll_entry_start(_type, _list) \
+({ \
+ static char start[0] __aligned(4) __attribute__((unused, \
+ section(".u_boot_list_2_"#_list"_1"))); \
+ (_type *)&start; \
+})
/**
- * ll_entry_count() - Return the number of elements in linker-generated array
+ * ll_entry_end() - Point after last entry of linker-generated array
* @_type: Data type of the entry
- * @_section_u: Subsection of u_boot_list in which this entry is placed
+ * @_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 *)&end; \
+})
+/**
+ * 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 _section_u
+ * placed into subsection of .u_boot_list section specified by _list
* argument. The result is of an unsigned int type.
*
* Example:
* 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, _section_u) \
+#define ll_entry_count(_type, _list) \
({ \
- extern _type _u_boot_list_##_section_u##__start; \
- extern _type _u_boot_list_##_section_u##__end; \
- unsigned int _ll_result = \
- &_u_boot_list_##_section_u##__end - \
- &_u_boot_list_##_section_u##__start; \
+ _type *start = ll_entry_start(_type, _list); \
+ _type *end = ll_entry_end(_type, _list); \
+ unsigned int _ll_result = end - start; \
_ll_result; \
})
-
/**
* ll_entry_get() - Retrieve entry from linker-generated array by name
* @_type: Data type of the entry
* @_name: Name of the entry
- * @_section_u: Subsection of u_boot_list in which this entry is placed
- * (with underscores instead of dots)
+ * @_list: Name of the list in which this entry is placed
*
* This function returns a pointer to a particular entry in LG-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, cmd.sub) = {
+ * 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, _section_u) \
+#define ll_entry_get(_type, _name, _list) \
({ \
- extern _type _u_boot_list_##_section_u##_##_name; \
- _type *_ll_result = &_u_boot_list_##_section_u##_##_name;\
+ extern _type _u_boot_list_2_##_list##_2_##_name; \
+ _type *_ll_result = \
+ &_u_boot_list_2_##_list##_2_##_name; \
_ll_result; \
})
+/**
+ * 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 *)&start; \
+})
+
+/**
+ * ll_entry_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 *)&end; \
+})
+
+#endif /* __ASSEMBLY__ */
+
#endif /* __LINKER_LISTS_H__ */
projects / karo-tx-uboot.git / blobdiff