cpufeature.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2017 Linaro Ltd. <[email protected]>
 */

#ifndef __ASM_CPUFEATURE_H
#define __ASM_CPUFEATURE_H

#include <linux/log2.h>
#include <asm/hwcap.h>

/*
 * Due to the fact that ELF_HWCAP is a 32-bit type on ARM, and given the number
 * of optional CPU features it defines, ARM's CPU hardware capability bits have
 * been distributed over separate elf_hwcap and elf_hwcap2 variables, each of
 * which covers a subset of the available CPU features.
 *
 * Currently, only a few of those are suitable for automatic module loading
 * (which is the primary use case of this facility) and those happen to be all
 * covered by HWCAP2. So let's only cover those via the cpu_feature()
 * convenience macro for now (which is used by module_cpu_feature_match()).
 * However, all capabilities are exposed via the modalias, and can be matched
 * using an explicit MODULE_DEVICE_TABLE() that uses __hwcap_feature() directly.
 */
#define MAX_CPU_FEATURES	64
#define __hwcap_feature(x)	ilog2(HWCAP_ ## x)
#define __hwcap2_feature(x)	(32 + ilog2(HWCAP2_ ## x))
#define cpu_feature(x)		__hwcap2_feature(x)

static inline bool cpu_have_feature(unsigned int num)
{
	return num < 32 ? elf_hwcap & BIT(num) : elf_hwcap2 & BIT(num - 32);
}

#endif