arch/s390/crypto/arch_random.c

   1 /*
   2  * s390 arch random implementation.
   3  *
   4  * Copyright IBM Corp. 2017
   5  * Author(s): Harald Freudenberger <freude@de.ibm.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License (version 2 only)
   9  * as published by the Free Software Foundation.
  10  *
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/atomic.h>
  15 #include <linux/random.h>
  16 #include <linux/static_key.h>
  17 #include <asm/cpacf.h>
  18
  19 DEFINE_STATIC_KEY_FALSE(s390_arch_random_available);
  20
  21 atomic64_t s390_arch_random_counter = ATOMIC64_INIT(0);
  22 EXPORT_SYMBOL(s390_arch_random_counter);
  23
  24 static int __init s390_arch_random_init(void)
  25 {
  26         /* check if subfunction CPACF_PRNO_TRNG is available */
  27         if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
  28                 static_branch_enable(&s390_arch_random_available);
  29
  30         return 0;
  31 }
  32 arch_initcall(s390_arch_random_init);