Add a driver for the EFI RTC. This uses the EFI Runtime Services to query

the system time.

As we seem to only read this time on boot, and this is the only source of
time on many arm64 machines we need to enable this by default there. As
this is not always the case with U-Boot firmware, or when we have been
booted from a non-UEFI environment we only enable the device driver when
the Runtime Services are present and reading the time doesn't result in an
error.

PR:		212185
Reviewed by:	imp, kib
Tested by:	emaste
Relnotes:	yes
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D12650

sys/arm64/conf/GENERIC

@@ -226,6 +226,7 @@ device		md		# Memory "disks"
 device		gif		# IPv6 and IPv4 tunneling
 device		firmware	# firmware assist module
 device		psci		# Support for ARM PSCI
+options 	EFIRT		# EFI Runtime Services
 
 # EXT_RESOURCES pseudo devices
 options 	EXT_RESOURCES

sys/conf/files

@@ -1615,6 +1615,7 @@ dev/ed/if_ed_pccard.c		optional ed pccard
 dev/ed/if_ed_pci.c		optional ed pci
 dev/efidev/efidev.c		optional efirt
 dev/efidev/efirt.c		optional efirt
+dev/efidev/efirtc.c		optional efirt
 dev/e1000/if_em.c		optional em \
 	compile-with "${NORMAL_C} -I$S/dev/e1000"
 dev/e1000/em_txrx.c		optional em \

sys/dev/efidev/efirtc.c

@@ -0,0 +1,151 @@
+/*-
+ * Copyright (c) 2017 Andrew Turner
+ * All rights reserved.
+ *
+ * This software was developed by SRI International and the University of
+ * Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
+ * ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/clock.h>
+#include <sys/efi.h>
+#include <sys/kernel.h>
+#include <sys/module.h>
+
+#include "clock_if.h"
+
+static void
+efirtc_identify(driver_t *driver, device_t parent)
+{
+	struct efi_tm tm;
+	int error;
+
+	/*
+	 * Check if we can read the time. This will stop us attaching when
+	 * there is no EFI Runtime support, or the gettime function is
+	 * unimplemented, e.g. on some builds of U-Boot.
+	 */
+	error = efi_get_time(&tm);
+	if (error != 0)
+		return;
+
+	if (device_find_child(parent, "efirtc", -1) != NULL)
+		return;
+	if (BUS_ADD_CHILD(parent, 0, "efirtc", -1) == NULL)
+		device_printf(parent, "add child failed\n");
+}
+
+static int
+efirtc_probe(device_t dev)
+{
+
+	device_quiet(dev);
+	return (0);
+}
+
+static int
+efirtc_attach(device_t dev)
+{
+
+	clock_register(dev, 1000000);
+	return (0);
+}
+
+static int
+efirtc_detach(device_t dev)
+{
+
+	clock_unregister(dev);
+	return (0);
+}
+
+static int
+efirtc_gettime(device_t dev, struct timespec *ts)
+{
+	struct clocktime ct;
+	struct efi_tm tm;
+	int error;
+
+	error = efi_get_time(&tm);
+	if (error != 0)
+		return (error);
+
+	ct.sec = tm.tm_sec;
+	ct.min = tm.tm_min;
+	ct.hour = tm.tm_hour;
+	ct.day = tm.tm_mday;
+	ct.mon = tm.tm_mon;
+	ct.year = tm.tm_year;
+	ct.nsec = tm.tm_nsec;
+
+	return (clock_ct_to_ts(&ct, ts));
+}
+
+static int
+efirtc_settime(device_t dev, struct timespec *ts)
+{
+	struct clocktime ct;
+	struct efi_tm tm;
+
+	clock_ts_to_ct(ts, &ct);
+
+	tm.tm_sec = ct.sec;
+	tm.tm_min = ct.min;
+	tm.tm_hour = ct.hour;
+	tm.tm_mday = ct.day;
+	tm.tm_mon = ct.mon;
+	tm.tm_year = ct.year;
+	tm.tm_nsec = ct.nsec;
+
+	return (efi_set_time(&tm));
+}
+
+static device_method_t efirtc_methods[] = {
+	/* Device interface */
+	DEVMETHOD(device_identify,	efirtc_identify),
+	DEVMETHOD(device_probe,		efirtc_probe),
+	DEVMETHOD(device_attach,	efirtc_attach),
+	DEVMETHOD(device_detach,	efirtc_detach),
+
+	/* Clock interface */
+	DEVMETHOD(clock_gettime,	efirtc_gettime),
+	DEVMETHOD(clock_settime,	efirtc_settime),
+
+	DEVMETHOD_END
+};
+
+static devclass_t efirtc_devclass;
+static driver_t efirtc_driver = {
+	"efirtc",
+	efirtc_methods,
+	0
+};
+
+DRIVER_MODULE(efirtc, nexus, efirtc_driver, efirtc_devclass, 0, 0);

sys/modules/efirt/Makefile

@@ -5,6 +5,7 @@
 
 KMOD=	efirt
 SRCS=	efirt.c efirt_machdep.c efidev.c
-SRCS+=  device_if.h bus_if.h
+SRCS+=	efirtc.c
+SRCS+=  device_if.h bus_if.h clock_if.h
 
 .include <bsd.kmod.mk>