1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright 2020, Heinrich Schuchardt <xypron.glpk@gmx.de>
4 *
5 * This driver emulates a real time clock based on timer ticks.
6 */
7
8#include <common.h>
9#include <div64.h>
10#include <dm.h>
11#include <env.h>
12#include <rtc.h>
13#include <timestamp.h>
14
15/**
16 * struct emul_rtc - private data for emulated RTC driver
17 */
18struct emul_rtc {
19	/**
20	 * @offset_us: microseconds from 1970-01-01 to timer_get_us() base
21	 */
22	u64 offset_us;
23	/**
24	 * @isdst: daylight saving time
25	 */
26	int isdst;
27};
28
29static int emul_rtc_get(struct udevice *dev, struct rtc_time *time)
30{
31	struct emul_rtc *priv = dev_get_priv(dev);
32	u64 now;
33
34	now = timer_get_us() + priv->offset_us;
35	do_div(now, 1000000);
36	rtc_to_tm(now, time);
37	time->tm_isdst = priv->isdst;
38
39	return 0;
40}
41
42static int emul_rtc_set(struct udevice *dev, const struct rtc_time *time)
43{
44	struct emul_rtc *priv = dev_get_priv(dev);
45
46	if (time->tm_year < 1970)
47		return -EINVAL;
48
49	priv->offset_us = rtc_mktime(time) * 1000000ULL - timer_get_us();
50
51	if (time->tm_isdst > 0)
52		priv->isdst = 1;
53	else if (time->tm_isdst < 0)
54		priv->isdst = -1;
55	else
56		priv->isdst = 0;
57
58	return 0;
59}
60
61int emul_rtc_probe(struct udevice *dev)
62{
63	struct emul_rtc *priv = dev_get_priv(dev);
64	const char *epoch_str;
65	u64 epoch;
66
67	epoch_str = env_get("rtc_emul_epoch");
68
69	if (epoch_str) {
70		epoch = simple_strtoull(epoch_str, NULL, 10);
71	} else {
72		/* Use the build date as initial time */
73		epoch = U_BOOT_EPOCH;
74	}
75	priv->offset_us = epoch * 1000000ULL - timer_get_us();
76	priv->isdst = -1;
77
78	return 0;
79}
80
81static const struct rtc_ops emul_rtc_ops = {
82	.get = emul_rtc_get,
83	.set = emul_rtc_set,
84};
85
86U_BOOT_DRIVER(rtc_emul) = {
87	.name	= "rtc_emul",
88	.id	= UCLASS_RTC,
89	.ops	= &emul_rtc_ops,
90	.probe	= emul_rtc_probe,
91	.priv_auto	= sizeof(struct emul_rtc),
92};
93
94U_BOOT_DRVINFO(rtc_emul) = {
95	.name	= "rtc_emul",
96};
97