1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2020 The FreeBSD Foundation 5 * 6 * This software was developed by Björn Zeeb under sponsorship from 7 * the FreeBSD Foundation. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 * $FreeBSD$ 31 */ 32 33 #ifndef _LINUXKPI_LINUX_KCONFIG_H_ 34 #define _LINUXKPI_LINUX_KCONFIG_H_ 35 36 /* 37 * Checking if an option is defined would be easy if we could do CPP inside CPP. 38 * The defined case whether -Dxxx or -Dxxx=1 are easy to deal with. In either 39 * case the defined value is "1". A more general -Dxxx=<c> case will require 40 * more effort to deal with all possible "true" values. Hope we do not have 41 * to do this as well. 42 * The real problem is the undefined case. To avoid this problem we do the 43 * concat/varargs trick: "yyy" ## xxx can make two arguments if xxx is "1" 44 * by having a #define for yyy_1 which is "ignore,". 45 * Otherwise we will just get "yyy". 46 * Need to be careful about variable substitutions in macros though. 47 * This way we make a (true, false) problem a (don't care, true, false) or a 48 * (don't care true, false). Then we can use a variadic macro to only select 49 * the always well known and defined argument #2. And that seems to be 50 * exactly what we need. Use 1 for true and 0 for false to also allow 51 * #if IS_*() checks pre-compiler checks which do not like #if true. 52 */ 53 #define ___XAB_1 dontcare, 54 #define ___IS_XAB(_ignore, _x, ...) (_x) 55 #define __IS_XAB(_x) ___IS_XAB(_x 1, 0) 56 #define _IS_XAB(_x) __IS_XAB(__CONCAT(___XAB_, _x)) 57 58 /* This is if CONFIG_ccc=y. */ 59 #define IS_BUILTIN(_x) _IS_XAB(_x) 60 /* This is if CONFIG_ccc=m. */ 61 #define IS_MODULE(_x) _IS_XAB(_x ## _MODULE) 62 /* This is if CONFIG_ccc is compiled in(=y) or a module(=m). */ 63 #define IS_ENABLED(_x) (IS_BUILTIN(_x) || IS_MODULE(_x)) 64 /* 65 * This is weird case. If the CONFIG_ccc is builtin (=y) this returns true; 66 * or if the CONFIG_ccc is a module (=m) and the caller is built as a module 67 * (-DMODULE defined) this returns true, but if the callers is not a module 68 * (-DMODULE not defined, which means caller is BUILTIN) then it returns 69 * false. In other words, a module can reach the kernel, a module can reach 70 * a module, but the kernel cannot reach a module, and code never compiled 71 * cannot be reached either. 72 * XXX -- I'd hope the module-to-module case would be handled by a proper 73 * module dependency definition (MODULE_DEPEND() in FreeBSD). 74 */ 75 #define IS_REACHABLE(_x) (IS_BUILTIN(_x) || \ 76 (IS_MODULE(_x) && IS_BUILTIN(MODULE))) 77 78 #endif /* _LINUXKPI_LINUX_KCONFIG_H_ */ 79