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