Add apldog(4), a driver for the watchdog on Apple M1 SoCs.

This allows us to reboot the machine.

ok patrick@

1 files changed, 117 insertions, 0 deletions

diff --git a/sys/arch/arm64/dev/apldog.c b/sys/arch/arm64/dev/apldog.c
new file mode 100644
index 00000000000..9199df06e85
--- /dev/null
+++ b/sys/arch/arm64/dev/apldog.c
@@ -0,0 +1,117 @@
+/*	$OpenBSD: apldog.c,v 1.1 2021/02/22 21:30:54 kettenis Exp $	*/
+/*
+ * Copyright (c) 2021 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 <machine/bus.h>
+#include <machine/fdt.h>
+
+#include <dev/ofw/openfirm.h>
+#include <dev/ofw/fdt.h>
+
+extern void (*cpuresetfn)(void);
+
+/*
+ * This driver is based on preliminary device tree bindings and will
+ * almost certainly need changes once the official bindings land in
+ * mainline Linux.  Support for these preliminary bindings will be
+ * dropped as soon as official bindings are available.
+ */
+
+#define WDT_CHIP_CTL	0x000c
+#define WDT_SYS_TMR	0x0010
+#define WDT_SYS_RST	0x0014
+#define  WDT_SYS_RST_IMMEDIATE	(1 << 0)
+#define WDT_SYS_CTL	0x001c
+#define  WDT_SYS_CTL_ENABLE	(1 << 2)
+
+#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 apldog_softc {
+	struct device		sc_dev;
+	bus_space_tag_t		sc_iot;
+	bus_space_handle_t	sc_ioh;
+};
+
+struct apldog_softc *apldog_sc;
+
+int	apldog_match(struct device *, void *, void *);
+void	apldog_attach(struct device *, struct device *, void *);
+
+struct cfattach	apldog_ca = {
+	sizeof (struct apldog_softc), apldog_match, apldog_attach
+};
+
+struct cfdriver apldog_cd = {
+	NULL, "apldog", DV_DULL
+};
+
+void	apldog_reset(void);
+
+int
+apldog_match(struct device *parent, void *match, void *aux)
+{
+	struct fdt_attach_args *faa = aux;
+
+	return OF_is_compatible(faa->fa_node, "apple,reboot-v0");
+}
+
+void
+apldog_attach(struct device *parent, struct device *self, void *aux)
+{
+	struct apldog_softc *sc = (struct apldog_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");
+
+	/* Reset the watchdog timers. */
+	HWRITE4(sc, WDT_CHIP_CTL, 0);
+	HWRITE4(sc, WDT_SYS_CTL, 0);
+
+	apldog_sc = sc;
+	cpuresetfn = apldog_reset;
+}
+
+void
+apldog_reset(void)
+{
+	struct apldog_softc *sc = apldog_sc;
+
+	/* Trigger a system reset. */
+	HWRITE4(sc, WDT_SYS_RST, WDT_SYS_RST_IMMEDIATE);
+	HWRITE4(sc, WDT_SYS_CTL, WDT_SYS_CTL_ENABLE);
+	HWRITE4(sc, WDT_SYS_TMR, 0);
+
+	delay(1000000);
+}