7 files changed, 339 insertions, 1 deletions

diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
index 58e3ffc17b7d..03ba34b61115 100644
--- a/arch/um/drivers/Kconfig
+++ b/arch/um/drivers/Kconfig
@@ -346,3 +346,14 @@ config VIRTIO_UML
 	help
 	  This driver provides support for virtio based paravirtual device
 	  drivers over vhost-user sockets.
+
+config UML_RTC
+	bool "UML RTC driver"
+	depends on RTC_CLASS
+	# there's no use in this if PM_SLEEP isn't enabled ...
+	depends on PM_SLEEP
+	help
+	  When PM_SLEEP is configured, it may be desirable to wake up using
+	  rtcwake, especially in time-travel mode. This driver enables that
+	  by providing a fake RTC clock that causes a wakeup at the right
+	  time.
diff --git a/arch/um/drivers/Makefile b/arch/um/drivers/Makefile
index 2a249f619467..dcc64a02f81f 100644
--- a/arch/um/drivers/Makefile
+++ b/arch/um/drivers/Makefile
@@ -17,6 +17,7 @@ hostaudio-objs := hostaudio_kern.o
 ubd-objs := ubd_kern.o ubd_user.o
 port-objs := port_kern.o port_user.o
 harddog-objs := harddog_kern.o harddog_user.o
+rtc-objs := rtc_kern.o rtc_user.o
 
 LDFLAGS_pcap.o = $(shell $(CC) $(KBUILD_CFLAGS) -print-file-name=libpcap.a)
 
@@ -62,6 +63,7 @@ obj-$(CONFIG_UML_WATCHDOG) += harddog.o
 obj-$(CONFIG_BLK_DEV_COW_COMMON) += cow_user.o
 obj-$(CONFIG_UML_RANDOM) += random.o
 obj-$(CONFIG_VIRTIO_UML) += virtio_uml.o
+obj-$(CONFIG_UML_RTC) += rtc.o
 
 # pcap_user.o must be added explicitly.
 USER_OBJS := fd.o null.o pty.o tty.o xterm.o slip_common.o pcap_user.o vde_user.o vector_user.o
diff --git a/arch/um/drivers/rtc.h b/arch/um/drivers/rtc.h
new file mode 100644
index 000000000000..95e41c7d35c4
--- /dev/null
+++ b/arch/um/drivers/rtc.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Intel Corporation
+ * Author: Johannes Berg <johannes@sipsolutions.net>
+ */
+#ifndef __UM_RTC_H__
+#define __UM_RTC_H__
+
+int uml_rtc_start(bool timetravel);
+int uml_rtc_enable_alarm(unsigned long long delta_seconds);
+void uml_rtc_disable_alarm(void);
+void uml_rtc_stop(bool timetravel);
+void uml_rtc_send_timetravel_alarm(void);
+
+#endif /* __UM_RTC_H__ */
diff --git a/arch/um/drivers/rtc_kern.c b/arch/um/drivers/rtc_kern.c
new file mode 100644
index 000000000000..97ceb205cfe6
--- /dev/null
+++ b/arch/um/drivers/rtc_kern.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Intel Corporation
+ * Author: Johannes Berg <johannes@sipsolutions.net>
+ */
+#include <linux/platform_device.h>
+#include <linux/time-internal.h>
+#include <linux/suspend.h>
+#include <linux/err.h>
+#include <linux/rtc.h>
+#include <kern_util.h>
+#include <irq_kern.h>
+#include <os.h>
+#include "rtc.h"
+
+static time64_t uml_rtc_alarm_time;
+static bool uml_rtc_alarm_enabled;
+static struct rtc_device *uml_rtc;
+static int uml_rtc_irq_fd, uml_rtc_irq;
+
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+
+static void uml_rtc_time_travel_alarm(struct time_travel_event *ev)
+{
+	uml_rtc_send_timetravel_alarm();
+}
+
+static struct time_travel_event uml_rtc_alarm_event = {
+	.fn = uml_rtc_time_travel_alarm,
+};
+#endif
+
+static int uml_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct timespec64 ts;
+
+	/* Use this to get correct time in time-travel mode */
+	read_persistent_clock64(&ts);
+	rtc_time64_to_tm(timespec64_to_ktime(ts) / NSEC_PER_SEC, tm);
+
+	return 0;
+}
+
+static int uml_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	rtc_time64_to_tm(uml_rtc_alarm_time, &alrm->time);
+	alrm->enabled = uml_rtc_alarm_enabled;
+
+	return 0;
+}
+
+static int uml_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	unsigned long long secs;
+
+	if (!enable && !uml_rtc_alarm_enabled)
+		return 0;
+
+	uml_rtc_alarm_enabled = enable;
+
+	secs = uml_rtc_alarm_time - ktime_get_real_seconds();
+
+	if (time_travel_mode == TT_MODE_OFF) {
+		if (!enable) {
+			uml_rtc_disable_alarm();
+			return 0;
+		}
+
+		/* enable or update */
+		return uml_rtc_enable_alarm(secs);
+	} else {
+		time_travel_del_event(&uml_rtc_alarm_event);
+
+		if (enable)
+			time_travel_add_event_rel(&uml_rtc_alarm_event,
+						  secs * NSEC_PER_SEC);
+	}
+
+	return 0;
+}
+
+static int uml_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	uml_rtc_alarm_irq_enable(dev, 0);
+	uml_rtc_alarm_time = rtc_tm_to_time64(&alrm->time);
+	uml_rtc_alarm_irq_enable(dev, alrm->enabled);
+
+	return 0;
+}
+
+static const struct rtc_class_ops uml_rtc_ops = {
+	.read_time = uml_rtc_read_time,
+	.read_alarm = uml_rtc_read_alarm,
+	.alarm_irq_enable = uml_rtc_alarm_irq_enable,
+	.set_alarm = uml_rtc_set_alarm,
+};
+
+static irqreturn_t uml_rtc_interrupt(int irq, void *data)
+{
+	unsigned long long c = 0;
+
+	/* alarm triggered, it's now off */
+	uml_rtc_alarm_enabled = false;
+
+	os_read_file(uml_rtc_irq_fd, &c, sizeof(c));
+	WARN_ON(c == 0);
+
+	pm_system_wakeup();
+	rtc_update_irq(uml_rtc, 1, RTC_IRQF | RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static int uml_rtc_setup(void)
+{
+	int err;
+
+	err = uml_rtc_start(time_travel_mode != TT_MODE_OFF);
+	if (WARN(err < 0, "err = %d\n", err))
+		return err;
+
+	uml_rtc_irq_fd = err;
+
+	err = um_request_irq(UM_IRQ_ALLOC, uml_rtc_irq_fd, IRQ_READ,
+			     uml_rtc_interrupt, 0, "rtc", NULL);
+	if (err < 0) {
+		uml_rtc_stop(time_travel_mode != TT_MODE_OFF);
+		return err;
+	}
+
+	irq_set_irq_wake(err, 1);
+
+	uml_rtc_irq = err;
+	return 0;
+}
+
+static void uml_rtc_cleanup(void)
+{
+	um_free_irq(uml_rtc_irq, NULL);
+	uml_rtc_stop(time_travel_mode != TT_MODE_OFF);
+}
+
+static int uml_rtc_probe(struct platform_device *pdev)
+{
+	int err;
+
+	err = uml_rtc_setup();
+	if (err)
+		return err;
+
+	uml_rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(uml_rtc)) {
+		err = PTR_ERR(uml_rtc);
+		goto cleanup;
+	}
+
+	uml_rtc->ops = &uml_rtc_ops;
+
+	device_init_wakeup(&pdev->dev, 1);
+
+	err = devm_rtc_register_device(uml_rtc);
+	if (err)
+		goto cleanup;
+
+	return 0;
+cleanup:
+	uml_rtc_cleanup();
+	return err;
+}
+
+static int uml_rtc_remove(struct platform_device *pdev)
+{
+	device_init_wakeup(&pdev->dev, 0);
+	uml_rtc_cleanup();
+	return 0;
+}
+
+static struct platform_driver uml_rtc_driver = {
+	.probe = uml_rtc_probe,
+	.remove = uml_rtc_remove,
+	.driver = {
+		.name = "uml-rtc",
+	},
+};
+
+static int __init uml_rtc_init(void)
+{
+	struct platform_device *pdev;
+	int err;
+
+	err = platform_driver_register(&uml_rtc_driver);
+	if (err)
+		return err;
+
+	pdev = platform_device_alloc("uml-rtc", 0);
+	if (!pdev) {
+		err = -ENOMEM;
+		goto unregister;
+	}
+
+	err = platform_device_add(pdev);
+	if (err)
+		goto unregister;
+	return 0;
+
+unregister:
+	platform_device_put(pdev);
+	platform_driver_unregister(&uml_rtc_driver);
+	return err;
+}
+device_initcall(uml_rtc_init);
diff --git a/arch/um/drivers/rtc_user.c b/arch/um/drivers/rtc_user.c
new file mode 100644
index 000000000000..4016bc1d577e
--- /dev/null
+++ b/arch/um/drivers/rtc_user.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Intel Corporation
+ * Author: Johannes Berg <johannes@sipsolutions.net>
+ */
+#include <os.h>
+#include <errno.h>
+#include <sched.h>
+#include <unistd.h>
+#include <kern_util.h>
+#include <sys/select.h>
+#include <stdio.h>
+#include <sys/timerfd.h>
+#include "rtc.h"
+
+static int uml_rtc_irq_fds[2];
+
+void uml_rtc_send_timetravel_alarm(void)
+{
+	unsigned long long c = 1;
+
+	CATCH_EINTR(write(uml_rtc_irq_fds[1], &c, sizeof(c)));
+}
+
+int uml_rtc_start(bool timetravel)
+{
+	int err;
+
+	if (timetravel) {
+		int err = os_pipe(uml_rtc_irq_fds, 1, 1);
+		if (err)
+			goto fail;
+	} else {
+		uml_rtc_irq_fds[0] = timerfd_create(CLOCK_REALTIME, TFD_CLOEXEC);
+		if (uml_rtc_irq_fds[0] < 0) {
+			err = -errno;
+			goto fail;
+		}
+
+		/* apparently timerfd won't send SIGIO, use workaround */
+		sigio_broken(uml_rtc_irq_fds[0]);
+		err = add_sigio_fd(uml_rtc_irq_fds[0]);
+		if (err < 0) {
+			close(uml_rtc_irq_fds[0]);
+			goto fail;
+		}
+	}
+
+	return uml_rtc_irq_fds[0];
+fail:
+	uml_rtc_stop(timetravel);
+	return err;
+}
+
+int uml_rtc_enable_alarm(unsigned long long delta_seconds)
+{
+	struct itimerspec it = {
+		.it_value = {
+			.tv_sec = delta_seconds,
+		},
+	};
+
+	if (timerfd_settime(uml_rtc_irq_fds[0], 0, &it, NULL))
+		return -errno;
+	return 0;
+}
+
+void uml_rtc_disable_alarm(void)
+{
+	uml_rtc_enable_alarm(0);
+}
+
+void uml_rtc_stop(bool timetravel)
+{
+	if (timetravel)
+		os_close_file(uml_rtc_irq_fds[1]);
+	else
+		ignore_sigio_fd(uml_rtc_irq_fds[0]);
+	os_close_file(uml_rtc_irq_fds[0]);
+}
diff --git a/arch/um/include/linux/time-internal.h b/arch/um/include/linux/time-internal.h
index 8688e16e832b..759956ab0108 100644
--- a/arch/um/include/linux/time-internal.h
+++ b/arch/um/include/linux/time-internal.h
@@ -55,6 +55,9 @@ static inline void time_travel_wait_readable(int fd)
 }
 
 void time_travel_add_irq_event(struct time_travel_event *e);
+void time_travel_add_event_rel(struct time_travel_event *e,
+			       unsigned long long delay_ns);
+bool time_travel_del_event(struct time_travel_event *e);
 #else
 struct time_travel_event {
 };
@@ -80,6 +83,14 @@ static inline void time_travel_add_irq_event(struct time_travel_event *e)
 {
 	WARN_ON(1);
 }
+
+/*
+ * not inlines so the data structure need not exist,
+ * cause linker failures
+ */
+extern void time_travel_not_configured(void);
+#define time_travel_add_event_rel(...) time_travel_not_configured()
+#define time_travel_del_event(...) time_travel_not_configured()
 #endif /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
 
 /*
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 8144406b6ea3..e0cdb9694fb8 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -321,6 +321,12 @@ static void time_travel_add_event(struct time_travel_event *e,
 	__time_travel_add_event(e, time);
 }
 
+void time_travel_add_event_rel(struct time_travel_event *e,
+			       unsigned long long delay_ns)
+{
+	time_travel_add_event(e, time_travel_time + delay_ns);
+}
+
 void time_travel_periodic_timer(struct time_travel_event *e)
 {
 	time_travel_add_event(&time_travel_timer_event,
@@ -384,7 +390,7 @@ static void time_travel_deliver_event(struct time_travel_event *e)
 	}
 }
 
-static bool time_travel_del_event(struct time_travel_event *e)
+bool time_travel_del_event(struct time_travel_event *e)
 {
 	unsigned long flags;
 
@@ -594,6 +600,8 @@ extern u64 time_travel_ext_req(u32 op, u64 time);
 
 /* these are empty macros so the struct/fn need not exist */
 #define time_travel_add_event(e, time) do { } while (0)
+/* externally not usable - redefine here so we can */
+#undef time_travel_del_event
 #define time_travel_del_event(e) do { } while (0)
 #endif