linux-kernel - Re: [RFC PATCH 1/3] efi-rtc: Remove wakeup functionality

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Message-ID: <aHSu1WVYXZ2N5X8X@U-2FWC9VHC-2323.local>
Date: Mon, 14 Jul 2025 15:16:37 +0800
From: Feng Tang <feng.tang@...ux.alibaba.com>
To: Ard Biesheuvel <ardb+git@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Ard Biesheuvel <ardb@...nel.org>,
	Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Juergen Gross <jgross@...e.com>,
	Stefano Stabellini <sstabellini@...nel.org>,
	Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
	Sunil V L <sunilvl@...tanamicro.com>,
	Bibo Mao <maobibo@...ngson.cn>, linux-rtc@...r.kernel.org,
	linux-efi@...r.kernel.org, xen-devel@...ts.xenproject.org,
	x86@...nel.org, linux-riscv@...ts.infradead.org,
	loongarch@...ts.linux.dev
Subject: Re: [RFC PATCH 1/3] efi-rtc: Remove wakeup functionality

On Mon, Jul 14, 2025 at 08:08:45AM +0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@...nel.org>
> 
> The EFI rtc driver is used by non-x86 architectures only, and exposes
> the get/set wakeup time functionality provided by the underlying
> platform. This is usually broken on most platforms, and not widely used
> to begin with [if at all], so let's just remove it.

This solves the problem reported in 
https://lore.kernel.org/all/20250710084151.55003-1-feng.tang@linux.alibaba.com/T/#u

Tested-by: Feng Tang <feng.tang@...ux.alibaba.com>

Thanks!

- Feng

> 
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> ---
>  drivers/rtc/rtc-efi.c | 76 +-------------------
>  1 file changed, 2 insertions(+), 74 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c
> index fa8bf82df948..b4f44999ef0f 100644
> --- a/drivers/rtc/rtc-efi.c
> +++ b/drivers/rtc/rtc-efi.c
> @@ -112,48 +112,6 @@ 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;
> -
> -	/*
> -	 * As of EFI v1.10, this call always returns an unsupported status
> -	 */
> -	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);
> -
> -	/*
> -	 * XXX Fixme:
> -	 * As of EFI 0.92 with the firmware I have on my
> -	 * machine this call does not seem to work quite
> -	 * right
> -	 *
> -	 * As of v1.10, this call always returns an unsupported status
> -	 */
> -	status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
> -
> -	dev_warn(dev, "write status is %d\n", (int)status);
> -
> -	return status == EFI_SUCCESS ? 0 : -EINVAL;
> -}
> -
>  static int efi_read_time(struct device *dev, struct rtc_time *tm)
>  {
>  	efi_status_t status;
> @@ -188,17 +146,13 @@ 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, alm;
> +	efi_time_t        eft;
>  	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);
> -	efi.get_wakeup_time(&enabled, &pending, &alm);
>  
>  	seq_printf(seq,
>  		   "Time\t\t: %u:%u:%u.%09u\n"
> @@ -214,26 +168,6 @@ 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, "Timezone\t: unspecified\n");
> -		else
> -			/* XXX fixme: convert to string? */
> -			seq_printf(seq, "Timezone\t: %u\n", alm.timezone);
> -	}
> -
>  	/*
>  	 * now prints the capabilities
>  	 */
> @@ -249,8 +183,6 @@ 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,
>  };
>  
> @@ -271,11 +203,7 @@ static int __init efi_rtc_probe(struct platform_device *dev)
>  	platform_set_drvdata(dev, rtc);
>  
>  	rtc->ops = &efi_rtc_ops;
> -	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
> -	if (efi_rt_services_supported(EFI_RT_SUPPORTED_WAKEUP_SERVICES))
> -		set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, rtc->features);
> -	else
> -		clear_bit(RTC_FEATURE_ALARM, rtc->features);
> +	clear_bit(RTC_FEATURE_ALARM, rtc->features);
>  
>  	device_init_wakeup(&dev->dev, true);
>  
> -- 
> 2.50.0.727.gbf7dc18ff4-goog