1 /* $OpenBSD: bcm2711_rng.c,v 1.3 2022/04/06 18:59:28 naddy Exp $ */
2 /*
3 * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <sys/param.h>
19 #include <sys/systm.h>
20 #include <sys/device.h>
21 #include <sys/timeout.h>
22
23 #include <machine/bus.h>
24 #include <machine/fdt.h>
25
26 #include <dev/ofw/openfirm.h>
27 #include <dev/ofw/fdt.h>
28
29 /* Registers */
30 #define RNG_CTRL 0x0000
31 #define RNG_CTRL_RBGEN_MASK (0x1fff << 0)
32 #define RNG_CTRL_RBGEN_EN (1 << 0)
33 #define RNG_FIFO_DATA 0x0020
34 #define RNG_FIFO_COUNT 0x0024
35 #define RNG_FIFO_COUNT_MASK (0xff << 0)
36
37 #define HREAD4(sc, reg) \
38 (bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg)))
39 #define HWRITE4(sc, reg, val) \
40 bus_space_write_4((sc)->sc_iot, (sc)->sc_ioh, (reg), (val))
41
42 struct bcmirng_softc {
43 struct device sc_dev;
44 bus_space_tag_t sc_iot;
45 bus_space_handle_t sc_ioh;
46
47 struct timeout sc_to;
48 };
49
50 int bcmirng_match(struct device *, void *, void *);
51 void bcmirng_attach(struct device *, struct device *, void *);
52
53 const struct cfattach bcmirng_ca = {
54 sizeof (struct bcmirng_softc), bcmirng_match, bcmirng_attach
55 };
56
57 struct cfdriver bcmirng_cd = {
58 NULL, "bcmirng", DV_DULL
59 };
60
61 void bcmirng_rnd(void *);
62
63 int
bcmirng_match(struct device * parent,void * match,void * aux)64 bcmirng_match(struct device *parent, void *match, void *aux)
65 {
66 struct fdt_attach_args *faa = aux;
67
68 return (OF_is_compatible(faa->fa_node, "brcm,bcm2711-rng200") ||
69 OF_is_compatible(faa->fa_node, "brcm,bcm2838-rng200"));
70 }
71
72 void
bcmirng_attach(struct device * parent,struct device * self,void * aux)73 bcmirng_attach(struct device *parent, struct device *self, void *aux)
74 {
75 struct bcmirng_softc *sc = (struct bcmirng_softc *)self;
76 struct fdt_attach_args *faa = aux;
77
78 if (faa->fa_nreg < 1) {
79 printf(": no registers\n");
80 return;
81 }
82
83 sc->sc_iot = faa->fa_iot;
84 if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr,
85 faa->fa_reg[0].size, 0, &sc->sc_ioh)) {
86 printf(": can't map registers\n");
87 return;
88 }
89
90 printf("\n");
91
92 HWRITE4(sc, RNG_CTRL, RNG_CTRL_RBGEN_EN);
93
94 timeout_set(&sc->sc_to, bcmirng_rnd, sc);
95 bcmirng_rnd(sc);
96 }
97
98 void
bcmirng_rnd(void * arg)99 bcmirng_rnd(void *arg)
100 {
101 struct bcmirng_softc *sc = arg;
102 uint32_t data;
103 int count, i;
104
105 count = MAX(4, HREAD4(sc, RNG_FIFO_COUNT) & RNG_FIFO_COUNT_MASK);
106 for (i = 0; i < count; i++) {
107 data = HREAD4(sc, RNG_FIFO_DATA);
108 enqueue_randomness(data);
109 }
110
111 timeout_add_sec(&sc->sc_to, 1);
112 }
113