arch/s390/crypto/arch_random.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * s390 arch random implementation.
   4  *
   5  * Copyright IBM Corp. 2017
   6  * Author(s): Harald Freudenberger <freude@de.ibm.com>
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/atomic.h>
  11 #include <linux/random.h>
  12 #include <linux/static_key.h>
  13 #include <asm/cpacf.h>
  14
  15 DEFINE_STATIC_KEY_FALSE(s390_arch_random_available);
  16
  17 atomic64_t s390_arch_random_counter = ATOMIC64_INIT(0);
  18 EXPORT_SYMBOL(s390_arch_random_counter);
  19
  20 static int __init s390_arch_random_init(void)
  21 {
  22         /* check if subfunction CPACF_PRNO_TRNG is available */
  23         if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
  24                 static_branch_enable(&s390_arch_random_available);
  25
  26         return 0;
  27 }
  28 arch_initcall(s390_arch_random_init);