public inbox for devel@edk2.groups.io
 help / color / mirror / Atom feed
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Masahisa Kojima <masahisa.kojima@linaro.org>
Cc: "edk2-devel@lists.01.org" <edk2-devel@lists.01.org>,
	Leif Lindholm <leif.lindholm@linaro.org>,
	 Yoshitoyo Osaki <osaki.yoshitoyo@socionext.com>
Subject: Re: [PATCH v3] Silicon/NXP/Pcf8563RealTimeClockLib: add Voltage-low handling
Date: Wed, 20 Jun 2018 12:51:18 +0200	[thread overview]
Message-ID: <CAKv+Gu9PO4S0fE1AH=4yZ31oGgDNxpN7JLO8hWb=HOZSPWydXA@mail.gmail.com> (raw)
In-Reply-To: <20180620071549.2295-1-masahisa.kojima@linaro.org>

On 20 June 2018 at 09:15,  <masahisa.kojima@linaro.org> wrote:
> From: Masahisa Kojima <masahisa.kojima@linaro.org>
>
> BcdToDecimal8() in LibGetTime() asserts with the
> following condition.
>  1) RTC device has not been initialized yet, RTC device
>     returns indeterminate value with VL bit(1)
>  2) DEBUG build
>
> UEFI boot fails with assertion when it satisfies above conditions.
>
> Aside form boot failure, UEFI shell commands "date/time" expect
> that getting time from RTC should success when user sets the time.
> ShellCommandRunTime() performs GetTime()->update time->SetTime(),
> if the first GetTime() fails, user can not set time.
> With that, simply returning EFI_DEVICE_ERROR in LibGetTime()
> is not applicable to VL bit handling.
>
> To avoid this situation, even if it only occurs in DEBUG build,
> RTC driver should check the VL bit in the VL_seconds register.
> This VL bit is voltage-low detector, it means integrity of the
> clock information is not guaranteed if it sets to 1. In this
> case, driver return dummy date/time(01/01/2000 00:00:00) to
> proceed succeeding process.
>
> linux driver also checks this bit when driver gets the time
> from RTC. If VL bit is 1, linux driver discard the retreived
> time data.
>
> Note that if VL bit is 1, GetTime() returns always
> 01/01/2000 00:00:00 until user sets date/time.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
> Signed-off-by: Yoshitoyo Osaki <osaki.yoshitoyo@socionext.com>

Thanks

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Pushed as 070938aa96aa91d822de57897e39c747c56eb4de

> ---
>  .../Pcf8563RealTimeClockLib.c                      | 28 +++++++++++++++-------
>  1 file changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c b/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c
> index fb58e1feb4..77d8998cfd 100644
> --- a/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c
> +++ b/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c
> @@ -24,6 +24,7 @@
>  #define SLAVE_ADDRESS             (FixedPcdGet8 (PcdI2cSlaveAddress))
>  #define PCF8563_DATA_REG_OFFSET   0x2
>
> +#define PCF8563_CLOCK_INVALID     0x80
>  #define PCF8563_SECONDS_MASK      0x7f
>  #define PCF8563_MINUTES_MASK      0x7f
>  #define PCF8563_HOURS_MASK        0x3f
> @@ -122,15 +123,24 @@ LibGetTime (
>      return EFI_DEVICE_ERROR;
>    }
>
> -  Time->Second  = BcdToDecimal8 (DateTime.VL_seconds & PCF8563_SECONDS_MASK);
> -  Time->Minute  = BcdToDecimal8 (DateTime.Minutes & PCF8563_MINUTES_MASK);
> -  Time->Hour    = BcdToDecimal8 (DateTime.Hours & PCF8563_HOURS_MASK);
> -  Time->Day     = BcdToDecimal8 (DateTime.Days & PCF8563_DAYS_MASK);
> -  Time->Month   = BcdToDecimal8 (DateTime.Century_months & PCF8563_MONTHS_MASK);
> -  Time->Year    = BcdToDecimal8 (DateTime.Years) + EPOCH_BASE;
> -
> -  if (DateTime.Century_months & PCF8563_CENTURY_MASK) {
> -    Time->Year += 100;
> +  if ((DateTime.VL_seconds & PCF8563_CLOCK_INVALID) != 0) {
> +      Time->Second  = 0;
> +      Time->Minute  = 0;
> +      Time->Hour    = 0;
> +      Time->Day     = 1;
> +      Time->Month   = 1;
> +      Time->Year    = EPOCH_BASE;
> +  } else {
> +      Time->Second  = BcdToDecimal8 (DateTime.VL_seconds & PCF8563_SECONDS_MASK);
> +      Time->Minute  = BcdToDecimal8 (DateTime.Minutes & PCF8563_MINUTES_MASK);
> +      Time->Hour    = BcdToDecimal8 (DateTime.Hours & PCF8563_HOURS_MASK);
> +      Time->Day     = BcdToDecimal8 (DateTime.Days & PCF8563_DAYS_MASK);
> +      Time->Month   = BcdToDecimal8 (DateTime.Century_months & PCF8563_MONTHS_MASK);
> +      Time->Year    = BcdToDecimal8 (DateTime.Years) + EPOCH_BASE;
> +
> +      if (DateTime.Century_months & PCF8563_CENTURY_MASK) {
> +          Time->Year += 100;
> +      }
>    }
>
>    if (Capabilities != NULL) {
> --
> 2.14.2
>


      reply	other threads:[~2018-06-20 10:51 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-20  7:15 [PATCH v3] Silicon/NXP/Pcf8563RealTimeClockLib: add Voltage-low handling masahisa.kojima
2018-06-20 10:51 ` Ard Biesheuvel [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-list from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAKv+Gu9PO4S0fE1AH=4yZ31oGgDNxpN7JLO8hWb=HOZSPWydXA@mail.gmail.com' \
    --to=devel@edk2.groups.io \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox