1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
4 */
5
6 #ifndef __ASM_CPUFEATURE_H
7 #define __ASM_CPUFEATURE_H
8
9 #include <linux/log2.h>
10 #include <asm/hwcap.h>
11
12 /*
13 * Due to the fact that ELF_HWCAP is a 32-bit type on ARM, and given the number
14 * of optional CPU features it defines, ARM's CPU hardware capability bits have
15 * been distributed over separate elf_hwcap and elf_hwcap2 variables, each of
16 * which covers a subset of the available CPU features.
17 *
18 * Currently, only a few of those are suitable for automatic module loading
19 * (which is the primary use case of this facility) and those happen to be all
20 * covered by HWCAP2. So let's only cover those via the cpu_feature()
21 * convenience macro for now (which is used by module_cpu_feature_match()).
22 * However, all capabilities are exposed via the modalias, and can be matched
23 * using an explicit MODULE_DEVICE_TABLE() that uses __hwcap_feature() directly.
24 */
25 #define MAX_CPU_FEATURES 64
26 #define __hwcap_feature(x) ilog2(HWCAP_ ## x)
27 #define __hwcap2_feature(x) (32 + ilog2(HWCAP2_ ## x))
28 #define cpu_feature(x) __hwcap2_feature(x)
29
30 static inline bool cpu_have_feature(unsigned int num)
31 {
32 return num < 32 ? elf_hwcap & BIT(num) : elf_hwcap2 & BIT(num - 32);
33 }
34
35 #endif