rtc_kern.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2020 Intel Corporation
  4 * Author: Johannes Berg <johannes@sipsolutions.net>
  5 */
  6#include <linux/platform_device.h>
  7#include <linux/time-internal.h>
  8#include <linux/suspend.h>
  9#include <linux/err.h>
 10#include <linux/rtc.h>
 11#include <kern_util.h>
 12#include <irq_kern.h>
 13#include <os.h>
 14#include "rtc.h"
 15
 16static time64_t uml_rtc_alarm_time;
 17static bool uml_rtc_alarm_enabled;
 18static struct rtc_device *uml_rtc;
 19static int uml_rtc_irq_fd, uml_rtc_irq;
 20
 21#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
 22
 23static void uml_rtc_time_travel_alarm(struct time_travel_event *ev)
 24{
 25	uml_rtc_send_timetravel_alarm();
 26}
 27
 28static struct time_travel_event uml_rtc_alarm_event = {
 29	.fn = uml_rtc_time_travel_alarm,
 30};
 31#endif
 32
 33static int uml_rtc_read_time(struct device *dev, struct rtc_time *tm)
 34{
 35	struct timespec64 ts;
 36
 37	/* Use this to get correct time in time-travel mode */
 38	read_persistent_clock64(&ts);
 39	rtc_time64_to_tm(timespec64_to_ktime(ts) / NSEC_PER_SEC, tm);
 40
 41	return 0;
 42}
 43
 44static int uml_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 45{
 46	rtc_time64_to_tm(uml_rtc_alarm_time, &alrm->time);
 47	alrm->enabled = uml_rtc_alarm_enabled;
 48
 49	return 0;
 50}
 51
 52static int uml_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
 53{
 54	struct timespec64 ts;
 55	unsigned long long secs;
 56
 57	if (!enable && !uml_rtc_alarm_enabled)
 58		return 0;
 59
 60	uml_rtc_alarm_enabled = enable;
 61
 62	read_persistent_clock64(&ts);
 63	secs = uml_rtc_alarm_time - ts.tv_sec;
 64
 65	if (time_travel_mode == TT_MODE_OFF) {
 66		if (!enable) {
 67			uml_rtc_disable_alarm();
 68			return 0;
 69		}
 70
 71		/* enable or update */
 72		return uml_rtc_enable_alarm(secs);
 73	} else {
 74		time_travel_del_event(&uml_rtc_alarm_event);
 75
 76		if (enable)
 77			time_travel_add_event_rel(&uml_rtc_alarm_event,
 78						  secs * NSEC_PER_SEC -
 79						  ts.tv_nsec);
 80	}
 81
 82	return 0;
 83}
 84
 85static int uml_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 86{
 87	uml_rtc_alarm_irq_enable(dev, 0);
 88	uml_rtc_alarm_time = rtc_tm_to_time64(&alrm->time);
 89	uml_rtc_alarm_irq_enable(dev, alrm->enabled);
 90
 91	return 0;
 92}
 93
 94static const struct rtc_class_ops uml_rtc_ops = {
 95	.read_time = uml_rtc_read_time,
 96	.read_alarm = uml_rtc_read_alarm,
 97	.alarm_irq_enable = uml_rtc_alarm_irq_enable,
 98	.set_alarm = uml_rtc_set_alarm,
 99};
100
101static irqreturn_t uml_rtc_interrupt(int irq, void *data)
102{
103	unsigned long long c = 0;
104
105	/* alarm triggered, it's now off */
106	uml_rtc_alarm_enabled = false;
107
108	os_read_file(uml_rtc_irq_fd, &c, sizeof(c));
109	WARN_ON(c == 0);
110
111	pm_system_wakeup();
112	rtc_update_irq(uml_rtc, 1, RTC_IRQF | RTC_AF);
113
114	return IRQ_HANDLED;
115}
116
117static int uml_rtc_setup(void)
118{
119	int err;
120
121	err = uml_rtc_start(time_travel_mode != TT_MODE_OFF);
122	if (WARN(err < 0, "err = %d\n", err))
123		return err;
124
125	uml_rtc_irq_fd = err;
126
127	err = um_request_irq(UM_IRQ_ALLOC, uml_rtc_irq_fd, IRQ_READ,
128			     uml_rtc_interrupt, 0, "rtc", NULL);
129	if (err < 0) {
130		uml_rtc_stop(time_travel_mode != TT_MODE_OFF);
131		return err;
132	}
133
134	irq_set_irq_wake(err, 1);
135
136	uml_rtc_irq = err;
137	return 0;
138}
139
140static void uml_rtc_cleanup(void)
141{
142	um_free_irq(uml_rtc_irq, NULL);
143	uml_rtc_stop(time_travel_mode != TT_MODE_OFF);
144}
145
146static int uml_rtc_probe(struct platform_device *pdev)
147{
148	int err;
149
150	err = uml_rtc_setup();
151	if (err)
152		return err;
153
154	uml_rtc = devm_rtc_allocate_device(&pdev->dev);
155	if (IS_ERR(uml_rtc)) {
156		err = PTR_ERR(uml_rtc);
157		goto cleanup;
158	}
159
160	uml_rtc->ops = &uml_rtc_ops;
161
162	device_init_wakeup(&pdev->dev, 1);
163
164	err = devm_rtc_register_device(uml_rtc);
165	if (err)
166		goto cleanup;
167
168	return 0;
169cleanup:
170	uml_rtc_cleanup();
171	return err;
172}
173
174static void uml_rtc_remove(struct platform_device *pdev)
175{
176	device_init_wakeup(&pdev->dev, 0);
177	uml_rtc_cleanup();
178}
179
180static struct platform_driver uml_rtc_driver = {
181	.probe = uml_rtc_probe,
182	.remove = uml_rtc_remove,
183	.driver = {
184		.name = "uml-rtc",
185	},
186};
187
188static int __init uml_rtc_init(void)
189{
190	struct platform_device *pdev;
191	int err;
192
193	err = platform_driver_register(&uml_rtc_driver);
194	if (err)
195		return err;
196
197	pdev = platform_device_alloc("uml-rtc", 0);
198	if (!pdev) {
199		err = -ENOMEM;
200		goto unregister;
201	}
202
203	err = platform_device_add(pdev);
204	if (err)
205		goto unregister;
206	return 0;
207
208unregister:
209	platform_device_put(pdev);
210	platform_driver_unregister(&uml_rtc_driver);
211	return err;
212}
213device_initcall(uml_rtc_init);