1 /* $OpenBSD: omrng.c,v 1.3 2022/04/06 18:59:26 naddy Exp $ */
2 /*
3 * Copyright (c) 2018, 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 #include <armv7/omap/prcmvar.h>
30
31 /* Registers */
32 #define RNG_OUTPUT0 0x0000
33 #define RNG_OUTPUT1 0x0004
34 #define RNG_STATUS 0x0008
35 #define RNG_STATUS_READY (1 << 0)
36 #define RNG_STATUS_SHUTDOWN (1 << 1)
37 #define RNG_INTACK 0x0010
38 #define RNG_INTACK_READY (1 << 0)
39 #define RNG_INTACK_SHUTDOWN (1 << 1)
40 #define RNG_CONTROL 0x0014
41 #define RNG_CONTROL_START_CYCLES_SHIFT 16
42 #define RNG_CONTROL_TRNG_EN (1 << 10)
43 #define RNG_CONFIG 0x0018
44 #define RNG_CONFIG_MIN_CYCLES_SHIFT 0
45 #define RNG_CONFIG_MAX_CYCLES_SHIFT 16
46 #define RNG_ALARMCNT 0x001c
47 #define RNG_ALARMCNT_ALARM_TH_SHIFT 0
48 #define RNG_ALARMCNT_SHUTDOWN_TH_SHIFT 16
49 #define RNG_FROENABLE 0x0020
50 #define RNG_FROENABLE_MASK 0xffffff
51 #define RNG_FRODETUNE 0x0024
52 #define RNG_ALARMMASK 0x0028
53 #define RNG_ALARMSTOP 0x002c
54
55 #define HREAD4(sc, reg) \
56 (bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg)))
57 #define HWRITE4(sc, reg, val) \
58 bus_space_write_4((sc)->sc_iot, (sc)->sc_ioh, (reg), (val))
59 #define HSET4(sc, reg, bits) \
60 HWRITE4((sc), (reg), HREAD4((sc), (reg)) | (bits))
61 #define HCLR4(sc, reg, bits) \
62 HWRITE4((sc), (reg), HREAD4((sc), (reg)) & ~(bits))
63
64 struct omrng_softc {
65 struct device sc_dev;
66 bus_space_tag_t sc_iot;
67 bus_space_handle_t sc_ioh;
68
69 struct timeout sc_to;
70 };
71
72 int omrng_match(struct device *, void *, void *);
73 void omrng_attach(struct device *, struct device *, void *);
74
75 const struct cfattach omrng_ca = {
76 sizeof (struct omrng_softc), omrng_match, omrng_attach
77 };
78
79 struct cfdriver omrng_cd = {
80 NULL, "omrng", DV_DULL
81 };
82
83 void omrng_rnd(void *);
84
85 int
omrng_match(struct device * parent,void * match,void * aux)86 omrng_match(struct device *parent, void *match, void *aux)
87 {
88 struct fdt_attach_args *faa = aux;
89
90 return OF_is_compatible(faa->fa_node, "ti,omap4-rng");
91 }
92
93 void
omrng_attach(struct device * parent,struct device * self,void * aux)94 omrng_attach(struct device *parent, struct device *self, void *aux)
95 {
96 struct omrng_softc *sc = (struct omrng_softc *)self;
97 struct fdt_attach_args *faa = aux;
98
99 if (faa->fa_nreg < 1) {
100 printf(": no registers\n");
101 return;
102 }
103
104 sc->sc_iot = faa->fa_iot;
105 if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr,
106 faa->fa_reg[0].size, 0, &sc->sc_ioh)) {
107 printf(": can't map registers\n");
108 return;
109 }
110
111 printf("\n");
112
113 if (OF_getproplen(faa->fa_node, "ti,hwmods") > 0)
114 prcm_enablemodule(PRCM_RNG);
115
116 /* Configure and enable the RNG. */
117 HWRITE4(sc, RNG_CONFIG, 0x21 << RNG_CONFIG_MIN_CYCLES_SHIFT |
118 0x22 << RNG_CONFIG_MAX_CYCLES_SHIFT);
119 HWRITE4(sc, RNG_FRODETUNE, 0);
120 HWRITE4(sc, RNG_FROENABLE, RNG_FROENABLE_MASK);
121 HWRITE4(sc, RNG_ALARMCNT, 0xff << RNG_ALARMCNT_ALARM_TH_SHIFT |
122 0x4 << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT);
123 HWRITE4(sc, RNG_CONTROL, 0xff << RNG_CONTROL_START_CYCLES_SHIFT |
124 RNG_CONTROL_TRNG_EN);
125
126 timeout_set(&sc->sc_to, omrng_rnd, sc);
127 omrng_rnd(sc);
128 }
129
130 void
omrng_rnd(void * arg)131 omrng_rnd(void *arg)
132 {
133 struct omrng_softc *sc = arg;
134 uint32_t status, detune;
135
136 status = HREAD4(sc, RNG_STATUS);
137 if (status & RNG_STATUS_SHUTDOWN) {
138 /* Clear alarms. */
139 HWRITE4(sc, RNG_ALARMMASK, 0);
140 HWRITE4(sc, RNG_ALARMSTOP, 0);
141
142 /* Detune FROs that are shutdown. */
143 detune = ~HREAD4(sc, RNG_FROENABLE) & RNG_FROENABLE_MASK;
144 HSET4(sc, RNG_FRODETUNE, detune);
145
146 /* Re-enable them. */
147 HWRITE4(sc, RNG_FROENABLE, RNG_FROENABLE_MASK);
148 HWRITE4(sc, RNG_INTACK, RNG_INTACK_SHUTDOWN);
149 }
150 if (status & RNG_STATUS_READY) {
151 enqueue_randomness(HREAD4(sc, RNG_OUTPUT0));
152 enqueue_randomness(HREAD4(sc, RNG_OUTPUT1));
153 HWRITE4(sc, RNG_INTACK, RNG_INTACK_READY);
154 }
155
156 timeout_add_sec(&sc->sc_to, 1);
157 }
158