mirror of
https://github.com/AsahiLinux/u-boot
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fb71c3f490
Up to now the emulated RTC is initialized using the U-Boot build time.
With this patch the environment variable 'rtc_emul_epoch' can be used to
provide a better initial time. The variable is a decimal string with
the number of seconds since 1970-01-01. Here is an example where the RTC
had not been probed yet:
=> setenv rtc_emul_epoch 1610109000
=> date
Date: 2021-01-08 (Friday) Time: 12:30:00
If the variable does not exist, the U-Boot build time is used as fallback.
The environment variable may be set when shutting down the operating system
if the U-Boot environment is exposed to the OS (cf. ENV_IS_IN_FAT and
ENV_IS_IN_EXT4).
Suggested-by: Pablo Sebastián Greco <pgreco@centosproject.org>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
96 lines
1.8 KiB
C
96 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright 2020, Heinrich Schuchardt <xypron.glpk@gmx.de>
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*
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* This driver emulates a real time clock based on timer ticks.
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*/
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#include <common.h>
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#include <div64.h>
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#include <dm.h>
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#include <env.h>
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#include <generated/timestamp_autogenerated.h>
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#include <rtc.h>
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/**
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* struct emul_rtc - private data for emulated RTC driver
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*/
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struct emul_rtc {
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/**
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* @offset_us: microseconds from 1970-01-01 to timer_get_us() base
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*/
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u64 offset_us;
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/**
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* @isdst: daylight saving time
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*/
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int isdst;
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};
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static int emul_rtc_get(struct udevice *dev, struct rtc_time *time)
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{
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struct emul_rtc *priv = dev_get_priv(dev);
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u64 now;
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now = timer_get_us() + priv->offset_us;
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do_div(now, 1000000);
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rtc_to_tm(now, time);
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time->tm_isdst = priv->isdst;
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return 0;
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}
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static int emul_rtc_set(struct udevice *dev, const struct rtc_time *time)
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{
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struct emul_rtc *priv = dev_get_priv(dev);
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if (time->tm_year < 1970)
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return -EINVAL;
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priv->offset_us = rtc_mktime(time) * 1000000ULL - timer_get_us();
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if (time->tm_isdst > 0)
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priv->isdst = 1;
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else if (time->tm_isdst < 0)
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priv->isdst = -1;
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else
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priv->isdst = 0;
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return 0;
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}
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int emul_rtc_probe(struct udevice *dev)
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{
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struct emul_rtc *priv = dev_get_priv(dev);
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const char *epoch_str;
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u64 epoch;
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epoch_str = env_get("rtc_emul_epoch");
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if (epoch_str) {
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epoch = simple_strtoull(epoch_str, NULL, 10);
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} else {
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/* Use the build date as initial time */
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epoch = U_BOOT_EPOCH;
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}
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priv->offset_us = epoch * 1000000ULL - timer_get_us();
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priv->isdst = -1;
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return 0;
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}
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static const struct rtc_ops emul_rtc_ops = {
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.get = emul_rtc_get,
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.set = emul_rtc_set,
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};
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U_BOOT_DRIVER(rtc_emul) = {
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.name = "rtc_emul",
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.id = UCLASS_RTC,
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.ops = &emul_rtc_ops,
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.probe = emul_rtc_probe,
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.priv_auto_alloc_size = sizeof(struct emul_rtc),
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};
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U_BOOT_DEVICE(rtc_emul) = {
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.name = "rtc_emul",
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};
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