LXR linux/include/linux/cpufeature.h

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
   4 */
   5
   6#ifndef __LINUX_CPUFEATURE_H
   7#define __LINUX_CPUFEATURE_H
   8
   9#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
  10
  11#include <linux/init.h>
  12#include <linux/mod_devicetable.h>
  13#include <asm/cpufeature.h>
  14
  15/*
  16 * Macros imported from <asm/cpufeature.h>:
  17 * - cpu_feature(x)             ordinal value of feature called 'x'
  18 * - cpu_have_feature(u32 n)    whether feature #n is available
  19 * - MAX_CPU_FEATURES           upper bound for feature ordinal values
  20 * Optional:
  21 * - CPU_FEATURE_TYPEFMT        format string fragment for printing the cpu type
  22 * - CPU_FEATURE_TYPEVAL        set of values matching the format string above
  23 */
  24
  25#ifndef CPU_FEATURE_TYPEFMT
  26#define CPU_FEATURE_TYPEFMT     "%s"
  27#endif
  28
  29#ifndef CPU_FEATURE_TYPEVAL
  30#define CPU_FEATURE_TYPEVAL     ELF_PLATFORM
  31#endif
  32
  33/*
  34 * Use module_cpu_feature_match(feature, module_init_function) to
  35 * declare that
  36 * a) the module shall be probed upon discovery of CPU feature 'feature'
  37 *    (typically at boot time using udev)
  38 * b) the module must not be loaded if CPU feature 'feature' is not present
  39 *    (not even by manual insmod).
  40 *
  41 * For a list of legal values for 'feature', please consult the file
  42 * 'asm/cpufeature.h' of your favorite architecture.
  43 */
  44#define module_cpu_feature_match(x, __initfunc)                 \
  45static struct cpu_feature const __maybe_unused cpu_feature_match_ ## x[] = \
  46        { { .feature = cpu_feature(x) }, { } };                 \
  47MODULE_DEVICE_TABLE(cpu, cpu_feature_match_ ## x);              \
  48                                                                \
  49static int __init cpu_feature_match_ ## x ## _init(void)        \
  50{                                                               \
  51        if (!cpu_have_feature(cpu_feature(x)))                  \
  52                return -ENODEV;                                 \
  53        return __initfunc();                                    \
  54}                                                               \
  55module_init(cpu_feature_match_ ## x ## _init)
  56
  57#endif
  58#endif
  59