0b145f91d8
In order to support setting the system time from modular RTC drivers via the hctosys mechanism, check at the end of RTC device registration for whether the time should be synced, rather than once at late init. Bug: 144103362 Bug: 143046457 Change-Id: I65d2fd14e075a65f2a23e1268b02c907c5245fb8 Signed-off-by: Steve Muckle <smuckle@google.com>
76 lines
1.9 KiB
C
76 lines
1.9 KiB
C
/*
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* RTC subsystem, initialize system time on startup
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*
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* Copyright (C) 2005 Tower Technologies
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* Author: Alessandro Zummo <a.zummo@towertech.it>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/rtc.h>
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/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
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* whether it stores the most close value or the value with partial
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* seconds truncated. However, it is important that we use it to store
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* the truncated value. This is because otherwise it is necessary,
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* in an rtc sync function, to read both xtime.tv_sec and
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* xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
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* of >32bits is not possible. So storing the most close value would
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* slow down the sync API. So here we have the truncated value and
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* the best guess is to add 0.5s.
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*/
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int rtc_hctosys(void)
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{
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int err = -ENODEV;
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struct rtc_time tm;
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struct timespec64 tv64 = {
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.tv_nsec = NSEC_PER_SEC >> 1,
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};
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struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
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if (rtc == NULL) {
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pr_info("unable to open rtc device (%s)\n",
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CONFIG_RTC_HCTOSYS_DEVICE);
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goto err_open;
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}
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err = rtc_read_time(rtc, &tm);
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if (err) {
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dev_err(rtc->dev.parent,
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"hctosys: unable to read the hardware clock\n");
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goto err_read;
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}
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tv64.tv_sec = rtc_tm_to_time64(&tm);
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#if BITS_PER_LONG == 32
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if (tv64.tv_sec > INT_MAX) {
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err = -ERANGE;
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goto err_read;
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}
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#endif
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err = do_settimeofday64(&tv64);
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dev_info(rtc->dev.parent,
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"setting system clock to "
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"%d-%02d-%02d %02d:%02d:%02d UTC (%lld)\n",
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tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
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tm.tm_hour, tm.tm_min, tm.tm_sec,
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(long long) tv64.tv_sec);
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err_read:
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rtc_class_close(rtc);
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err_open:
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rtc_hctosys_ret = err;
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return err;
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}
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