include/linux/cpufeature.h

0001 /* SPDX-License-Identifier: GPL-2.0-only */
0002 /*
0003  * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
0004  */
0005
0006 #ifndef __LINUX_CPUFEATURE_H
0007 #define __LINUX_CPUFEATURE_H
0008
0009 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
0010
0011 #include <linux/init.h>
0012 #include <linux/mod_devicetable.h>
0013 #include <asm/cpufeature.h>
0014
0015 /*
0016  * Macros imported from <asm/cpufeature.h>:
0017  * - cpu_feature(x)     ordinal value of feature called 'x'
0018  * - cpu_have_feature(u32 n)    whether feature #n is available
0019  * - MAX_CPU_FEATURES       upper bound for feature ordinal values
0020  * Optional:
0021  * - CPU_FEATURE_TYPEFMT    format string fragment for printing the cpu type
0022  * - CPU_FEATURE_TYPEVAL    set of values matching the format string above
0023  */
0024
0025 #ifndef CPU_FEATURE_TYPEFMT
0026 #define CPU_FEATURE_TYPEFMT "%s"
0027 #endif
0028
0029 #ifndef CPU_FEATURE_TYPEVAL
0030 #define CPU_FEATURE_TYPEVAL ELF_PLATFORM
0031 #endif
0032
0033 /*
0034  * Use module_cpu_feature_match(feature, module_init_function) to
0035  * declare that
0036  * a) the module shall be probed upon discovery of CPU feature 'feature'
0037  *    (typically at boot time using udev)
0038  * b) the module must not be loaded if CPU feature 'feature' is not present
0039  *    (not even by manual insmod).
0040  *
0041  * For a list of legal values for 'feature', please consult the file
0042  * 'asm/cpufeature.h' of your favorite architecture.
0043  */
0044 #define module_cpu_feature_match(x, __initfunc)         \
0045 static struct cpu_feature const __maybe_unused cpu_feature_match_ ## x[] = \
0046     { { .feature = cpu_feature(x) }, { } };         \
0047 MODULE_DEVICE_TABLE(cpu, cpu_feature_match_ ## x);      \
0048                                 \
0049 static int __init cpu_feature_match_ ## x ## _init(void)    \
0050 {                               \
0051     if (!cpu_have_feature(cpu_feature(x)))          \
0052         return -ENODEV;                 \
0053     return __initfunc();                    \
0054 }                               \
0055 module_init(cpu_feature_match_ ## x ## _init)
0056
0057 #endif
0058 #endif