1 /* 2 * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9 #ifndef __ASM_CPUFEATURE_H 10 #define __ASM_CPUFEATURE_H 11 12 #include <linux/log2.h> 13 #include <asm/hwcap.h> 14 15 /* 16 * Due to the fact that ELF_HWCAP is a 32-bit type on ARM, and given the number 17 * of optional CPU features it defines, ARM's CPU hardware capability bits have 18 * been distributed over separate elf_hwcap and elf_hwcap2 variables, each of 19 * which covers a subset of the available CPU features. 20 * 21 * Currently, only a few of those are suitable for automatic module loading 22 * (which is the primary use case of this facility) and those happen to be all 23 * covered by HWCAP2. So let's only cover those via the cpu_feature() 24 * convenience macro for now (which is used by module_cpu_feature_match()). 25 * However, all capabilities are exposed via the modalias, and can be matched 26 * using an explicit MODULE_DEVICE_TABLE() that uses __hwcap_feature() directly. 27 */ 28 #define MAX_CPU_FEATURES 64 29 #define __hwcap_feature(x) ilog2(HWCAP_ ## x) 30 #define __hwcap2_feature(x) (32 + ilog2(HWCAP2_ ## x)) 31 #define cpu_feature(x) __hwcap2_feature(x) 32 33 static inline bool cpu_have_feature(unsigned int num) 34 { 35 return num < 32 ? elf_hwcap & BIT(num) : elf_hwcap2 & BIT(num - 32); 36 } 37 38 #endif 39