net/net_rand.h

   1 /*
   2  *      Copied from LiMon - BOOTP.
   3  *
   4  *      Copyright 1994, 1995, 2000 Neil Russell.
   5  *      (See License)
   6  *      Copyright 2000 Paolo Scaffardi
   7  */
   8
   9 #ifndef __NET_RAND_H__
  10 #define __NET_RAND_H__
  11
  12 #include <common.h>
  13 #include <dm/uclass.h>
  14 #include <rng.h>
  15
  16 /*
  17  * Return a seed for the PRNG derived from the eth0 MAC address.
  18  */
  19 static inline unsigned int seed_mac(void)
  20 {
  21         unsigned char enetaddr[ARP_HLEN];
  22         unsigned int seed;
  23
  24         /* get our mac */
  25         memcpy(enetaddr, eth_get_ethaddr(), ARP_HLEN);
  26
  27         seed = enetaddr[5];
  28         seed ^= enetaddr[4] << 8;
  29         seed ^= enetaddr[3] << 16;
  30         seed ^= enetaddr[2] << 24;
  31         seed ^= enetaddr[1];
  32         seed ^= enetaddr[0] << 8;
  33
  34         return seed;
  35 }
  36
  37 /*
  38  * Seed the random number generator using the eth0 MAC address.
  39  */
  40 static inline void srand_mac(void)
  41 {
  42         int ret;
  43         struct udevice *devp;
  44         u32 randv = 0;
  45
  46         if (IS_ENABLED(CONFIG_DM_RNG)) {
  47                 ret = uclass_get_device(UCLASS_RNG, 0, &devp);
  48                 if (ret) {
  49                         ret = dm_rng_read(devp, &randv, sizeof(randv));
  50                         if (ret < 0)
  51                                 randv = 0;
  52                 }
  53         }
  54         if (randv)
  55                 srand(randv);
  56         else
  57                 srand(seed_mac());
  58 }
  59
  60 #endif /* __NET_RAND_H__ */