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