sys/mips/cavium/octeon_rnd.c

   1 /*-
   2  * Copyright (c) 2010 Juli Mallett <jmallett@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD$
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/systm.h>
  34 #include <sys/bus.h>
  35 #include <sys/clock.h>
  36 #include <sys/kernel.h>
  37 #include <sys/lock.h>
  38 #include <sys/module.h>
  39 #include <sys/random.h>
  40
  41 #include <contrib/octeon-sdk/cvmx.h>
  42 #include <contrib/octeon-sdk/cvmx-rng.h>
  43
  44 /*
  45  * XXX
  46  * random_harvest(9) says to call it with no more than 16 bytes, but at least
  47  * safe(4) seems to violate that rule.
  48  */
  49 #define OCTEON_RND_WORDS        2
  50
  51 struct octeon_rnd_softc {
  52         uint64_t sc_entropy[OCTEON_RND_WORDS];
  53         struct callout sc_callout;
  54 };
  55
  56 static void     octeon_rnd_identify(driver_t *drv, device_t parent);
  57 static int      octeon_rnd_attach(device_t dev);
  58 static int      octeon_rnd_probe(device_t dev);
  59 static int      octeon_rnd_detach(device_t dev);
  60
  61 static void     octeon_rnd_harvest(void *);
  62
  63 static device_method_t octeon_rnd_methods[] = {
  64         /* Device interface */
  65         DEVMETHOD(device_identify,      octeon_rnd_identify),
  66         DEVMETHOD(device_probe,         octeon_rnd_probe),
  67         DEVMETHOD(device_attach,        octeon_rnd_attach),
  68         DEVMETHOD(device_detach,        octeon_rnd_detach),
  69
  70         { 0, 0 }
  71 };
  72
  73 static driver_t octeon_rnd_driver = {
  74         "rnd",
  75         octeon_rnd_methods,
  76         sizeof (struct octeon_rnd_softc)
  77 };
  78 static devclass_t octeon_rnd_devclass;
  79 DRIVER_MODULE(rnd, nexus, octeon_rnd_driver, octeon_rnd_devclass, 0, 0);
  80
  81 static void
  82 octeon_rnd_identify(driver_t *drv, device_t parent)
  83 {
  84         BUS_ADD_CHILD(parent, 0, "rnd", 0);
  85 }
  86
  87 static int
  88 octeon_rnd_probe(device_t dev)
  89 {
  90         if (device_get_unit(dev) != 0)
  91                 return (ENXIO);
  92
  93         device_set_desc(dev, "Cavium Octeon Random Number Generator");
  94         return (0);
  95 }
  96
  97 static int
  98 octeon_rnd_attach(device_t dev)
  99 {
 100         struct octeon_rnd_softc *sc;
 101
 102         sc = device_get_softc(dev);
 103         callout_init(&sc->sc_callout, CALLOUT_MPSAFE);
 104         callout_reset(&sc->sc_callout, hz * 5, octeon_rnd_harvest, sc);
 105
 106         cvmx_rng_enable();
 107
 108         return (0);
 109 }
 110
 111 static int
 112 octeon_rnd_detach(device_t dev)
 113 {
 114         struct octeon_rnd_softc *sc;
 115
 116         sc = device_get_softc(dev);
 117
 118         callout_stop(&sc->sc_callout);
 119
 120         return (0);
 121 }
 122
 123 static void
 124 octeon_rnd_harvest(void *arg)
 125 {
 126         struct octeon_rnd_softc *sc;
 127         unsigned i;
 128
 129         sc = arg;
 130
 131         for (i = 0; i < OCTEON_RND_WORDS; i++)
 132                 sc->sc_entropy[i] = cvmx_rng_get_random64();
 133         random_harvest(sc->sc_entropy, sizeof sc->sc_entropy,
 134                        sizeof sc->sc_entropy * 8, 0, RANDOM_PURE);
 135
 136         callout_reset(&sc->sc_callout, hz * 5, octeon_rnd_harvest, sc);
 137 }