[J-u-boot.git] / include / linker_lists.h

/*
 * include/linker_lists.h
 *
 * Implementation of linker-generated arrays
 *
 * Copyright (C) 2012 Marek Vasut <[email protected]>
 *
 * 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.
 */

/*
 * 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
 */

#ifndef __LINKER_LISTS_H__
#define __LINKER_LISTS_H__

/**
 * 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.
 *
 * 4) 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, 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)))

/**
 * 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(4) __attribute__((unused,	\
		section(".u_boot_list_2_"#_list"_1")));			\
	(_type *)&start;						\
})

/**
 * 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 *)&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 _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;						\
	})

/**
 * 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 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) = {
 *         .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_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__ */
Commit	Line	Data
42ebaae3 MV	1	/*
	2	* include/linker_lists.h
	3	*
	4	* Implementation of linker-generated arrays
	5	*
	6	* Copyright (C) 2012 Marek Vasut <[email protected]>
	7	*
	8	* See file CREDITS for list of people who contributed to this
	9	* project.
	10	*
	11	* This program is free software; you can redistribute it and/or
	12	* modify it under the terms of the GNU General Public License as
	13	* published by the Free Software Foundation; either version 2 of
	14	* the License, or (at your option) any later version.
	15	*/
ef123c52 AA	16
	17	/*
	18	* There is no use in including this from ASM files, but that happens
	19	* anyway, e.g. PPC kgdb.S includes command.h which incluse us.
	20	* So just don't define anything when included from ASM.
	21	*/
	22
	23	#if !defined(__ASSEMBLY__)
	24
	25	/**
	26	* A linker list is constructed by grouping together linker input
	27	* sections, each containning one entry of the list. Each input section
	28	* contains a constant initialized variable which holds the entry's
	29	* content. Linker list input sections are constructed from the list
	30	* and entry names, plus a prefix which allows grouping all lists
	31	* together. Assuming _list and _entry are the list and entry names,
	32	* then the corresponding input section name is
	33	*
	34	* _u_boot_list + _2_ + @_list + _2_ + @_entry
	35	*
	36	* and the C variable name is
	37	*
	38	* .u_boot_list_ + 2_ + @_list + _2_ + @_entry
	39	*
	40	* This ensures uniqueness for both input section and C variable name.
	41	*
	42	* Note that the names differ only in the first character, "." for the
	43	* setion and "_" for the variable, so that the linker cannot confuse
	44	* section and symbol names. From now on, both names will be referred
	45	* to as
	46	*
	47	* %u_boot_list_ + 2_ + @_list + _2_ + @_entry
	48	*
	49	* Entry variables need never be referred to directly.
	50	*
	51	* The naming scheme for input sections allows grouping all linker lists
	52	* into a single linker output section and grouping all entries for a
	53	* single list.
	54	*
	55	* Note the two '_2_' constant components in the names: their presence
	56	* allows putting a start and end symbols around a list, by mapping
	57	* these symbols to sections names with components "1" (before) and
	58	* "3" (after) instead of "2" (within).
	59	* Start and end symbols for a list can generally be defined as
	60	*
	61	* %u_boot_list_2_ + @_list + _1_...
	62	* %u_boot_list_2_ + @_list + _3_...
	63	*
	64	* Start and end symbols for the whole of the linker lists area can be
	65	* defined as
	66	*
	67	* %u_boot_list_1_...
	68	* %u_boot_list_3_...
	69	*
	70	* Here is an example of the sorted sections which result from a list
	71	* "array" made up of three entries : "first", "second" and "third",
	72	* iterated at least once.
	73	*
	74	* .u_boot_list_2_array_1
	75	* .u_boot_list_2_array_2_first
	76	* .u_boot_list_2_array_2_second
	77	* .u_boot_list_2_array_2_third
	78	* .u_boot_list_2_array_3
	79	*
80	* If lists must be divided into sublists (e.g. for iterating only on
81	* part of a list), one can simply give the list a name of the form
82	* 'outer_2_inner', where 'outer' is the global list name and 'inner'
83	* is the sub-list name. Iterators for the whole list should use the
84	* global list name ("outer"); iterators for only a sub-list should use
85	* the full sub-list name ("outer_2_inner").
86	*
87	* Here is an example of the sections generated from a global list
88	* named "drivers", two sub-lists named "i2c" and "pci", and iterators
89	* defined for the whole list and each sub-list:
90	*
91	* %u_boot_list_2_drivers_1
92	* %u_boot_list_2_drivers_2_i2c_1
93	* %u_boot_list_2_drivers_2_i2c_2_first
94	* %u_boot_list_2_drivers_2_i2c_2_first
95	* %u_boot_list_2_drivers_2_i2c_2_second
96	* %u_boot_list_2_drivers_2_i2c_2_third
97	* %u_boot_list_2_drivers_2_i2c_3
98	* %u_boot_list_2_drivers_2_pci_1
99	* %u_boot_list_2_drivers_2_pci_2_first
100	* %u_boot_list_2_drivers_2_pci_2_second
101	* %u_boot_list_2_drivers_2_pci_2_third
102	* %u_boot_list_2_drivers_2_pci_3
103	* %u_boot_list_2_drivers_3
104	*/
105
42ebaae3 MV	106	#ifndef __LINKER_LISTS_H__
	107	#define __LINKER_LISTS_H__
	108
	109	/**
	110	* ll_entry_declare() - Declare linker-generated array entry
	111	* @_type: Data type of the entry
	112	* @_name: Name of the entry
ef123c52 AA	113	* @_list: name of the list. Should contain only characters allowed
ef123c52 AA	114	* in a C variable name!
42ebaae3 MV	115	*
	116	* This macro declares a variable that is placed into a linker-generated
	117	* array. This is a basic building block for more advanced use of linker-
	118	* generated arrays. The user is expected to build their own macro wrapper
	119	* around this one.
	120	*
ef123c52	121	* A variable declared using this macro must be compile-time initialized.
42ebaae3 MV	122	*
42ebaae3 MV	123	* Special precaution must be made when using this macro:
42ebaae3	124	*
ef123c52 AA	125	* 1) The _type must not contain the "static" keyword, otherwise the
	126	* entry is generated and can be iterated but is listed in the map
	127	* file and cannot be retrieved by name.
42ebaae3	128	*
ef123c52 AA	129	* 2) In case a section is declared that contains some array elements AND
	130	* a subsection of this section is declared and contains some elements,
	131	* it is imperative that the elements are of the same type.
42ebaae3 MV	132	*
42ebaae3 MV	133	* 4) In case an outer section is declared that contains some array elements
ef123c52	134	* AND an inner subsection of this section is declared and contains some
42ebaae3 MV	135	* elements, then when traversing the outer section, even the elements of
	136	* the inner sections are present in the array.
	137	*
	138	* Example:
	139	* ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub, cmd.sub) = {
	140	* .x = 3,
	141	* .y = 4,
	142	* };
	143	*/
ef123c52 AA	144	#define ll_entry_declare(_type, _name, _list) \
	145	_type _u_boot_list_2_##_list##_2_##_name __aligned(4) \
	146	__attribute__((unused, \
	147	section(".u_boot_list_2_"#_list"_2_"#_name)))
	148
	149	/**
	150	* We need a 0-byte-size type for iterator symbols, and the compiler
	151	* does not allow defining objects of C type 'void'. Using an empty
	152	* struct is allowed by the compiler, but causes gcc versions 4.4 and
	153	* below to complain about aliasing. Therefore we use the next best
	154	* thing: zero-sized arrays, which are both 0-byte-size and exempt from
	155	* aliasing warnings.
	156	*/
42ebaae3 MV	157
	158	/**
	159	* ll_entry_start() - Point to first entry of linker-generated array
	160	* @_type: Data type of the entry
ef123c52	161	* @_list: Name of the list in which this entry is placed
42ebaae3 MV	162	*
	163	* This function returns (_type *) pointer to the very first entry of a
	164	* linker-generated array placed into subsection of .u_boot_list section
ef123c52 AA	165	* specified by _list argument.
	166	*
	167	* Since this macro defines an array start symbol, its leftmost index
	168	* must be 2 and its rightmost index must be 1.
42ebaae3 MV	169	*
	170	* Example:
	171	* struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
	172	*/
ef123c52 AA	173	#define ll_entry_start(_type, _list) \
	174	({ \
	175	static char start[0] __aligned(4) __attribute__((unused, \
	176	section(".u_boot_list_2_"#_list"_1"))); \
	177	(_type *)&start; \
	178	})
42ebaae3 MV	179
42ebaae3 MV	180	/**
ef123c52	181	* ll_entry_end() - Point after last entry of linker-generated array
42ebaae3	182	* @_type: Data type of the entry
ef123c52	183	* @_list: Name of the list in which this entry is placed
42ebaae3 MV	184	* (with underscores instead of dots)
42ebaae3 MV	185	*
ef123c52 AA	186	* This function returns (_type *) pointer after the very last entry of
	187	* a linker-generated array placed into subsection of .u_boot_list
	188	* section specified by _list argument.
	189	*
	190	* Since this macro defines an array end symbol, its leftmost index
	191	* must be 2 and its rightmost index must be 3.
	192	*
	193	* Example:
	194	* struct my_sub_cmd *msc = ll_entry_end(struct my_sub_cmd, cmd_sub);
	195	*/
	196	#define ll_entry_end(_type, _list) \
	197	({ \
	198	static char end[0] __aligned(4) __attribute__((unused, \
	199	section(".u_boot_list_2_"#_list"_3"))); \
	200	(_type *)&end; \
	201	})
	202	/**
	203	* ll_entry_count() - Return the number of elements in linker-generated array
	204	* @_type: Data type of the entry
	205	* @_list: Name of the list of which the number of elements is computed
	206	*
42ebaae3	207	* This function returns the number of elements of a linker-generated array
ef123c52	208	* placed into subsection of .u_boot_list section specified by _list
42ebaae3 MV	209	* argument. The result is of an unsigned int type.
	210	*
	211	* Example:
	212	* int i;
	213	* const unsigned int count = ll_entry_count(struct my_sub_cmd, cmd_sub);
	214	* struct my_sub_cmd *msc = ll_entry_start(struct my_sub_cmd, cmd_sub);
	215	* for (i = 0; i < count; i++, msc++)
	216	* printf("Entry %i, x=%i y=%i\n", i, msc->x, msc->y);
	217	*/
ef123c52	218	#define ll_entry_count(_type, _list) \
42ebaae3	219	({ \
ef123c52 AA	220	_type *start = ll_entry_start(_type, _list); \
	221	_type *end = ll_entry_end(_type, _list); \
	222	unsigned int _ll_result = end - start; \
42ebaae3 MV	223	_ll_result; \
	224	})
	225
42ebaae3 MV	226	/**
	227	* ll_entry_get() - Retrieve entry from linker-generated array by name
	228	* @_type: Data type of the entry
	229	* @_name: Name of the entry
ef123c52	230	* @_list: Name of the list in which this entry is placed
42ebaae3 MV	231	*
	232	* This function returns a pointer to a particular entry in LG-array
	233	* identified by the subsection of u_boot_list where the entry resides
	234	* and it's name.
	235	*
	236	* Example:
	237	* ll_entry_declare(struct my_sub_cmd, my_sub_cmd, cmd_sub, cmd.sub) = {
	238	* .x = 3,
	239	* .y = 4,
	240	* };
	241	* ...
	242	* struct my_sub_cmd *c = ll_entry_get(struct my_sub_cmd, my_sub_cmd, cmd_sub);
	243	*/
ef123c52	244	#define ll_entry_get(_type, _name, _list) \
42ebaae3	245	({ \
ef123c52 AA	246	extern _type _u_boot_list_2_##_list##_2_##_name; \
	247	_type *_ll_result = \
	248	&_u_boot_list_2_##_list##_2_##_name; \
42ebaae3 MV	249	_ll_result; \
	250	})
	251
ef123c52 AA	252	/**
	253	* ll_start() - Point to first entry of first linker-generated array
	254	* @_type: Data type of the entry
	255	*
	256	* This function returns (_type *) pointer to the very first entry of
	257	* the very first linker-generated array.
	258	*
	259	* Since this macro defines the start of the linker-generated arrays,
	260	* its leftmost index must be 1.
	261	*
	262	* Example:
	263	* struct my_sub_cmd *msc = ll_start(struct my_sub_cmd);
	264	*/
	265	#define ll_start(_type) \
	266	({ \
	267	static char start[0] __aligned(4) __attribute__((unused, \
	268	section(".u_boot_list_1"))); \
	269	(_type *)&start; \
	270	})
	271
	272	/**
	273	* ll_entry_end() - Point after last entry of last linker-generated array
	274	* @_type: Data type of the entry
	275	*
	276	* This function returns (_type *) pointer after the very last entry of
	277	* the very last linker-generated array.
	278	*
	279	* Since this macro defines the end of the linker-generated arrays,
	280	* its leftmost index must be 3.
	281	*
	282	* Example:
	283	* struct my_sub_cmd *msc = ll_end(struct my_sub_cmd);
	284	*/
	285	#define ll_end(_type) \
	286	({ \
	287	static char end[0] __aligned(4) __attribute__((unused, \
	288	section(".u_boot_list_3"))); \
	289	(_type *)&end; \
	290	})
	291
	292	#endif /* __ASSEMBLY__ */
	293
42ebaae3	294	#endif /* __LINKER_LISTS_H__ */