Add bcmirng(4), a driver for the RNG200 random number generator found on

the Raspberry Pi 4.

ok deraadt@

1 files changed, 113 insertions, 0 deletions

diff --git a/sys/dev/fdt/bcm2711_rng.c b/sys/dev/fdt/bcm2711_rng.c
new file mode 100644
index 00000000000..72ddb39a4c3
--- /dev/null
+++ b/sys/dev/fdt/bcm2711_rng.c
@@ -0,0 +1,113 @@
+/*	$OpenBSD: bcm2711_rng.c,v 1.1 2020/04/19 16:00:00 kettenis Exp $	*/
+/*
+ * Copyright (c) 2020 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_RBGEN_MASK	(0x1fff << 0)
+#define  RNG_CTRL_RBGEN_EN	(1 << 0)
+#define RNG_FIFO_DATA		0x0020
+#define RNG_FIFO_COUNT		0x0024
+#define  RNG_FIFO_COUNT_MASK	(0xff << 0)
+
+#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 bcmirng_softc {
+	struct device		sc_dev;
+	bus_space_tag_t		sc_iot;
+	bus_space_handle_t	sc_ioh;
+
+	struct timeout		sc_to;
+};
+
+int	bcmirng_match(struct device *, void *, void *);
+void	bcmirng_attach(struct device *, struct device *, void *);
+
+struct cfattach	bcmirng_ca = {
+	sizeof (struct bcmirng_softc), bcmirng_match, bcmirng_attach
+};
+
+struct cfdriver bcmirng_cd = {
+	NULL, "bcmirng", DV_DULL
+};
+
+void	bcmirng_rnd(void *);
+
+int
+bcmirng_match(struct device *parent, void *match, void *aux)
+{
+	struct fdt_attach_args *faa = aux;
+
+	return (OF_is_compatible(faa->fa_node, "brcm,bcm2711-rng200") ||
+	    OF_is_compatible(faa->fa_node, "brcm,bcm2838-rng200"));
+}
+
+void
+bcmirng_attach(struct device *parent, struct device *self, void *aux)
+{
+	struct bcmirng_softc *sc = (struct bcmirng_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");
+
+	HWRITE4(sc, RNG_CTRL, RNG_CTRL_RBGEN_EN);
+
+	timeout_set(&sc->sc_to, bcmirng_rnd, sc);
+	bcmirng_rnd(sc);
+}
+
+void
+bcmirng_rnd(void *arg)
+{
+	struct bcmirng_softc *sc = arg;
+	uint32_t data;
+	int count, i;
+
+	count = MAX(4, HREAD4(sc, RNG_FIFO_COUNT) & RNG_FIFO_COUNT_MASK);
+	for (i = 0; i < count; i++) {
+		data = HREAD4(sc, RNG_FIFO_DATA);
+		enqueue_randomness(data);
+	}
+
+	timeout_add_sec(&sc->sc_to, 1);
+}