Add bcmrng(4), a driver for the random number generator on the Raspberry Pi.

diff --git a/sys/dev/fdt/bcm2835_rng.c b/sys/dev/fdt/bcm2835_rng.c
new file mode 100644 (file)
index 0000000..4712e83
--- /dev/null
+++ b/sys/dev/fdt/bcm2835_rng.c
@@ -0,0 +1,114 @@
+/*     $OpenBSD: bcm2835_rng.c,v 1.1 2018/02/24 13:46:22 kettenis Exp $        */
+/*
+ * Copyright (c) 2018 Mark Kettenis <kettenis@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/device.h>
+#include <sys/timeout.h>
+
+#include <machine/bus.h>
+#include <machine/fdt.h>
+
+#include <dev/rndvar.h>
+#include <dev/ofw/openfirm.h>
+#include <dev/ofw/fdt.h>
+
+/* Registers */
+#define RNG_CTRL               0x0000
+#define  RNG_CTRL_EN           (1 << 0)
+#define RNG_STATUS             0x0004
+#define  RNG_STATUS_COUNT(x)   ((x) >> 24)
+#define RNG_DATA               0x0008
+
+#define HREAD4(sc, reg)                                                        \
+       (bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg)))
+#define HWRITE4(sc, reg, val)                                          \
+       bus_space_write_4((sc)->sc_iot, (sc)->sc_ioh, (reg), (val))
+
+struct bcmrng_softc {
+       struct device           sc_dev;
+       bus_space_tag_t         sc_iot;
+       bus_space_handle_t      sc_ioh;
+
+       struct timeout          sc_to;
+};
+
+int    bcmrng_match(struct device *, void *, void *);
+void   bcmrng_attach(struct device *, struct device *, void *);
+
+struct cfattach        bcmrng_ca = {
+       sizeof (struct bcmrng_softc), bcmrng_match, bcmrng_attach
+};
+
+struct cfdriver bcmrng_cd = {
+       NULL, "bcmrng", DV_DULL
+};
+
+void   bcmrng_rnd(void *);
+
+int
+bcmrng_match(struct device *parent, void *match, void *aux)
+{
+       struct fdt_attach_args *faa = aux;
+
+       return OF_is_compatible(faa->fa_node, "brcm,bcm2835-rng");
+}
+
+void
+bcmrng_attach(struct device *parent, struct device *self, void *aux)
+{
+       struct bcmrng_softc *sc = (struct bcmrng_softc *)self;
+       struct fdt_attach_args *faa = aux;
+
+       if (faa->fa_nreg < 1) {
+               printf(": no registers\n");
+               return;
+       }
+
+       sc->sc_iot = faa->fa_iot;
+       if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr,
+           faa->fa_reg[0].size, 0, &sc->sc_ioh)) {
+               printf(": can't map registers\n");
+               return;
+       }
+
+       printf("\n");
+
+       /* Discard initial numbers which may be "less" random. */
+       HWRITE4(sc, RNG_STATUS, 250000);
+       HWRITE4(sc, RNG_CTRL, RNG_CTRL_EN);
+
+       timeout_set(&sc->sc_to, bcmrng_rnd, sc);
+       bcmrng_rnd(sc);
+}
+
+void
+bcmrng_rnd(void *arg)
+{
+       struct bcmrng_softc *sc = arg;
+       uint32_t status, data;
+       int i, count;
+
+       status = HREAD4(sc, RNG_STATUS);
+       count = MIN(4, RNG_STATUS_COUNT(status));
+       for (i = 0; i < count; i++) {
+               data = HREAD4(sc, RNG_DATA);
+               add_true_randomness(data);
+       }
+
+       timeout_add_sec(&sc->sc_to, 1);
+}

diff --git a/sys/dev/fdt/files.fdt b/sys/dev/fdt/files.fdt
index 5ab9386..e17ff35 100644 (file)
--- a/sys/dev/fdt/files.fdt
+++ b/sys/dev/fdt/files.fdt
@@ -1,4 +1,4 @@
-#      $OpenBSD: files.fdt,v 1.39 2018/02/24 13:23:21 kettenis Exp $
+#      $OpenBSD: files.fdt,v 1.40 2018/02/24 13:46:22 kettenis Exp $
 #
 # Config file and device description for machine-independent FDT code.
 # Included by ports that need it.
@@ -57,6 +57,10 @@ device       bcmdog
 attach bcmdog at fdt
 file   dev/fdt/bcm2835_dog.c           bcmdog
 
+device bcmrng
+attach bcmrng at fdt
+file   dev/fdt/bcm2835_rng.c           bcmrng
+
 device bcmtemp
 attach bcmtemp at fdt
 file   dev/fdt/bcm2835_temp.c          bcmtemp