arch/powerpc/platforms/pseries/rng.c

   1 /*
   2  * Copyright 2013, Michael Ellerman, IBM Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9
  10 #define pr_fmt(fmt)     "pseries-rng: " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/of.h>
  14 #include <asm/archrandom.h>
  15 #include <asm/machdep.h>
  16 #include <asm/plpar_wrappers.h>
  17
  18
  19 static int pseries_get_random_long(unsigned long *v)
  20 {
  21         unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
  22
  23         if (plpar_hcall(H_RANDOM, retbuf) == H_SUCCESS) {
  24                 *v = retbuf[0];
  25                 return 1;
  26         }
  27
  28         return 0;
  29 }
  30
  31 static __init int rng_init(void)
  32 {
  33         struct device_node *dn;
  34
  35         dn = of_find_compatible_node(NULL, NULL, "ibm,random");
  36         if (!dn)
  37                 return -ENODEV;
  38
  39         pr_info("Registering arch random hook.\n");
  40
  41         ppc_md.get_random_long = pseries_get_random_long;
  42
  43         return 0;
  44 }
  45 machine_subsys_initcall(pseries, rng_init);