From b430d1f6d80c005b486f028910e1ac3c91812710 Mon Sep 17 00:00:00 2001 From: "Johnny.Fan" Date: Mon, 31 Aug 2026 22:00:14 +0800 Subject: [PATCH] rtc: efi: restore alarm support with runtime capability probe Restore the EFI RTC alarm functionality (read_alarm/set_alarm and procfs output) that was removed by commit 18a3510bc87d ("rtc: efi: Remove wakeup functionality"). The removal was motivated by the observation that many EFI platforms lack RTC wakeup support while also omitting the RT_PROP table, causing the wakeup capability to be incorrectly advertised. While that is true, removing the feature entirely also breaks platforms where the wakeup runtime service actually works. On CIX SoCs, the RTC is an I2C device owned by firmware, and in the ACPI boot configuration the I2C bus it sits on is not exposed to the OS, so the EFI runtime services are the only way Linux can access the RTC at all. Both Linux and Windows use this same interface by design, so the RTC state is consistent across the operating systems installed on the machine, and Windows relies on the EFI wakeup services for its own RTC alarm support. With the alarm support removed from rtc-efi, Linux loses the equivalent capability entirely on these platforms: rtcwake fails for both suspend-to-RAM and power-off wakeup, as there is no other path to program the RTC alarm. This is a real product requirement that CIX customers have explicitly requested, not a hypothetical use case. To avoid exposing a broken alarm on firmware that does not implement the wakeup runtime services, probe the capability at ->probe() time by actually calling GetWakeupTime() -- if it fails, clear RTC_FEATURE_ALARM and the device behaves as before the removal. Also set RTC_FEATURE_ALARM_WAKEUP_ONLY since EFI wakeup time is a wakeup-only alarm, not a periodic/update interrupt source. Acked-by: Ard Biesheuvel Reviewed-by: Feng Tang Reviewed-by: Fugang Duan Signed-off-by: Johnny.Fan Link: https://patch.msgid.link/20260831140014.839222-1-johnny.fan@cixtech.com Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-efi.c | 80 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 78 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c index b4f44999ef0f..a8c18ebc5599 100644 --- a/drivers/rtc/rtc-efi.c +++ b/drivers/rtc/rtc-efi.c @@ -52,6 +52,7 @@ compute_wday(efi_time_t *eft, int yday) static void convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft) { + memset(eft, 0, sizeof(*eft)); eft->year = wtime->tm_year + 1900; eft->month = wtime->tm_mon + 1; eft->day = wtime->tm_mday; @@ -112,6 +113,35 @@ convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime) return true; } +static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm) +{ + efi_time_t eft; + efi_status_t status; + + memset(&eft, 0, sizeof(eft)); + status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled, + (efi_bool_t *)&wkalrm->pending, &eft); + if (status != EFI_SUCCESS) + return -EINVAL; + + if (!convert_from_efi_time(&eft, &wkalrm->time)) + return -EIO; + + return rtc_valid_tm(&wkalrm->time); +} + +static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm) +{ + efi_time_t eft; + efi_status_t status; + + convert_to_efi_time(&wkalrm->time, &eft); + + status = efi.set_wakeup_time((efi_bool_t)!!wkalrm->enabled, &eft); + + return status == EFI_SUCCESS ? 0 : -EINVAL; +} + static int efi_read_time(struct device *dev, struct rtc_time *tm) { efi_status_t status; @@ -146,13 +176,21 @@ static int efi_set_time(struct device *dev, struct rtc_time *tm) static int efi_procfs(struct device *dev, struct seq_file *seq) { - efi_time_t eft; + efi_time_t eft, alm; efi_time_cap_t cap; + efi_bool_t enabled, pending; + struct rtc_device *rtc = dev_get_drvdata(dev); memset(&eft, 0, sizeof(eft)); + memset(&alm, 0, sizeof(alm)); memset(&cap, 0, sizeof(cap)); efi.get_time(&eft, &cap); + if (test_bit(RTC_FEATURE_ALARM, rtc->features) && + efi.get_wakeup_time(&enabled, &pending, &alm) != EFI_SUCCESS) { + enabled = 0; + pending = 0; + } seq_printf(seq, "Time\t\t: %u:%u:%u.%09u\n" @@ -168,6 +206,25 @@ static int efi_procfs(struct device *dev, struct seq_file *seq) /* XXX fixme: convert to string? */ seq_printf(seq, "Timezone\t: %u\n", eft.timezone); + if (test_bit(RTC_FEATURE_ALARM, rtc->features)) { + seq_printf(seq, + "Alarm Time\t: %u:%u:%u.%09u\n" + "Alarm Date\t: %u-%u-%u\n" + "Alarm Daylight\t: %u\n" + "Enabled\t\t: %s\n" + "Pending\t\t: %s\n", + alm.hour, alm.minute, alm.second, alm.nanosecond, + alm.year, alm.month, alm.day, + alm.daylight, + enabled == 1 ? "yes" : "no", + pending == 1 ? "yes" : "no"); + + if (alm.timezone == EFI_UNSPECIFIED_TIMEZONE) + seq_puts(seq, "Alarm Timezone\t: unspecified\n"); + else + seq_printf(seq, "Alarm Timezone\t: %d\n", alm.timezone); + } + /* * now prints the capabilities */ @@ -183,6 +240,8 @@ static int efi_procfs(struct device *dev, struct seq_file *seq) static const struct rtc_class_ops efi_rtc_ops = { .read_time = efi_read_time, .set_time = efi_set_time, + .read_alarm = efi_read_alarm, + .set_alarm = efi_set_alarm, .proc = efi_procfs, }; @@ -191,6 +250,7 @@ static int __init efi_rtc_probe(struct platform_device *dev) struct rtc_device *rtc; efi_time_t eft; efi_time_cap_t cap; + efi_bool_t enabled, pending; /* First check if the RTC is usable */ if (efi.get_time(&eft, &cap) != EFI_SUCCESS) @@ -203,7 +263,23 @@ static int __init efi_rtc_probe(struct platform_device *dev) platform_set_drvdata(dev, rtc); rtc->ops = &efi_rtc_ops; - clear_bit(RTC_FEATURE_ALARM, rtc->features); + clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features); + + /* + * The EFI_RT_SUPPORTED_WAKEUP_SERVICES bit defaults to enabled + * and only gets cleared when the RT_PROP table explicitly says + * wakeup is unsupported. Many platforms lack an RT_PROP table + * even though they don't implement the wakeup runtime service, + * so probe by actually calling GetWakeupTime() to avoid exposing + * a broken alarm to userspace. + */ + if (efi_rt_services_supported(EFI_RT_SUPPORTED_WAKEUP_SERVICES) && + efi.get_wakeup_time(&enabled, &pending, &eft) == EFI_SUCCESS) { + set_bit(RTC_FEATURE_ALARM, rtc->features); + set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, rtc->features); + } else { + clear_bit(RTC_FEATURE_ALARM, rtc->features); + } device_init_wakeup(&dev->dev, true);