include/linux/cpufeature.h

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