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 
16 static time64_t uml_rtc_alarm_time;
17 static bool uml_rtc_alarm_enabled;
18 static struct rtc_device *uml_rtc;
19 static int uml_rtc_irq_fd, uml_rtc_irq;
20 
21 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
22 
23 static void uml_rtc_time_travel_alarm(struct time_travel_event *ev)
24 {
25 	uml_rtc_send_timetravel_alarm();
26 }
27 
28 static struct time_travel_event uml_rtc_alarm_event = {
29 	.fn = uml_rtc_time_travel_alarm,
30 };
31 #endif
32 
33 static 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 
44 static 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 
52 static 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 
85 static 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 
94 static 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 
101 static 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 
117 static 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 
140 static 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 
146 static 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;
169 cleanup:
170 	uml_rtc_cleanup();
171 	return err;
172 }
173 
174 static void uml_rtc_remove(struct platform_device *pdev)
175 {
176 	device_init_wakeup(&pdev->dev, 0);
177 	uml_rtc_cleanup();
178 }
179 
180 static 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 
188 static 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 
208 unregister:
209 	platform_device_put(pdev);
210 	platform_driver_unregister(&uml_rtc_driver);
211 	return err;
212 }
213 device_initcall(uml_rtc_init);
214