1 /* $OpenBSD: bcm2835_rng.c,v 1.2 2018/04/28 15:44:59 jasper Exp $ */ 2 /* 3 * Copyright (c) 2018 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/rndvar.h> 27 #include <dev/ofw/openfirm.h> 28 #include <dev/ofw/fdt.h> 29 30 /* Registers */ 31 #define RNG_CTRL 0x0000 32 #define RNG_CTRL_EN (1 << 0) 33 #define RNG_STATUS 0x0004 34 #define RNG_STATUS_COUNT(x) ((x) >> 24) 35 #define RNG_DATA 0x0008 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 bcmrng_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 bcmrng_match(struct device *, void *, void *); 51 void bcmrng_attach(struct device *, struct device *, void *); 52 53 struct cfattach bcmrng_ca = { 54 sizeof (struct bcmrng_softc), bcmrng_match, bcmrng_attach 55 }; 56 57 struct cfdriver bcmrng_cd = { 58 NULL, "bcmrng", DV_DULL 59 }; 60 61 void bcmrng_rnd(void *); 62 63 int 64 bcmrng_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,bcm2835-rng"); 69 } 70 71 void 72 bcmrng_attach(struct device *parent, struct device *self, void *aux) 73 { 74 struct bcmrng_softc *sc = (struct bcmrng_softc *)self; 75 struct fdt_attach_args *faa = aux; 76 77 if (faa->fa_nreg < 1) { 78 printf(": no registers\n"); 79 return; 80 } 81 82 sc->sc_iot = faa->fa_iot; 83 if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr, 84 faa->fa_reg[0].size, 0, &sc->sc_ioh)) { 85 printf(": can't map registers\n"); 86 return; 87 } 88 89 printf("\n"); 90 91 /* Discard initial numbers which may be "less" random. */ 92 HWRITE4(sc, RNG_STATUS, 250000); 93 HWRITE4(sc, RNG_CTRL, RNG_CTRL_EN); 94 95 timeout_set(&sc->sc_to, bcmrng_rnd, sc); 96 bcmrng_rnd(sc); 97 } 98 99 void 100 bcmrng_rnd(void *arg) 101 { 102 struct bcmrng_softc *sc = arg; 103 uint32_t status, data; 104 int i, count; 105 106 status = HREAD4(sc, RNG_STATUS); 107 count = MIN(4, RNG_STATUS_COUNT(status)); 108 for (i = 0; i < count; i++) { 109 data = HREAD4(sc, RNG_DATA); 110 enqueue_randomness(data); 111 } 112 113 timeout_add_sec(&sc->sc_to, 1); 114 } 115