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cdf7545a | 1 | // SPDX-License-Identifier: GPL-2.0 |
023f333a JG |
2 | #include <linux/rtc.h> |
3 | #include <linux/time.h> | |
4 | ||
5 | /** | |
6 | * rtc_set_ntp_time - Save NTP synchronized time to the RTC | |
7 | * @now: Current time of day | |
0f295b06 | 8 | * @target_nsec: pointer for desired now->tv_nsec value |
023f333a | 9 | * |
3c00a1fe | 10 | * Replacement for the NTP platform function update_persistent_clock64 |
023f333a JG |
11 | * that stores time for later retrieval by rtc_hctosys. |
12 | * | |
13 | * Returns 0 on successful RTC update, -ENODEV if a RTC update is not | |
14 | * possible at all, and various other -errno for specific temporary failure | |
15 | * cases. | |
16 | * | |
0f295b06 | 17 | * -EPROTO is returned if now.tv_nsec is not close enough to *target_nsec. |
c7d50d2b | 18 | * |
023f333a JG |
19 | * If temporary failure is indicated the caller should try again 'soon' |
20 | */ | |
0f295b06 | 21 | int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec) |
023f333a JG |
22 | { |
23 | struct rtc_device *rtc; | |
24 | struct rtc_time tm; | |
0f295b06 | 25 | struct timespec64 to_set; |
023f333a | 26 | int err = -ENODEV; |
0f295b06 | 27 | bool ok; |
023f333a | 28 | |
9c5150b3 | 29 | rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE); |
0f295b06 JG |
30 | if (!rtc) |
31 | goto out_err; | |
32 | ||
a01ab066 | 33 | if (!rtc->ops || !rtc->ops->set_time) |
0f295b06 JG |
34 | goto out_close; |
35 | ||
36 | /* Compute the value of tv_nsec we require the caller to supply in | |
37 | * now.tv_nsec. This is the value such that (now + | |
38 | * set_offset_nsec).tv_nsec == 0. | |
39 | */ | |
40 | set_normalized_timespec64(&to_set, 0, -rtc->set_offset_nsec); | |
41 | *target_nsec = to_set.tv_nsec; | |
42 | ||
43 | /* The ntp code must call this with the correct value in tv_nsec, if | |
44 | * it does not we update target_nsec and return EPROTO to make the ntp | |
45 | * code try again later. | |
46 | */ | |
47 | ok = rtc_tv_nsec_ok(rtc->set_offset_nsec, &to_set, &now); | |
48 | if (!ok) { | |
49 | err = -EPROTO; | |
50 | goto out_close; | |
023f333a JG |
51 | } |
52 | ||
0f295b06 JG |
53 | rtc_time64_to_tm(to_set.tv_sec, &tm); |
54 | ||
0f295b06 JG |
55 | err = rtc_set_time(rtc, &tm); |
56 | ||
57 | out_close: | |
58 | rtc_class_close(rtc); | |
59 | out_err: | |
023f333a JG |
60 | return err; |
61 | } |