[0/3] Meson8b: add support for the RTC on EC-100 and Odroid-C1
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Message ID 20190413163423.15149-1-martin.blumenstingl@googlemail.com
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  • Meson8b: add support for the RTC on EC-100 and Odroid-C1
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Martin Blumenstingl April 13, 2019, 4:34 p.m. UTC
This adds support for the RTC on the Meson8b EC-100 and Odroid-C1
boards. Example kernel log snippet while booting my EC-100:
  [    5.713750] meson-rtc c8100740.rtc: setting system clock to 2019-04-13T16:21:48 UTC (1555172508)

I am only 99% sure about the naming of the clock in patch 2 and 3.
The public S805 datasheet from Hardkernel shows (on page 24 for example)
that clk81 can use "XTAL/32khz" as clock input. That "XTAL/32khz" clock
is described as a mux between 24MHz (our main XTAL) and 32kHz ("that
other XTAL").
I believe that this other 32kHz XTAL is NOT the RTC32K crystal because:
- schematics of the EC-100 and Odroid-C1 clearly show that the SoC input
  for the RTC32K clock is labeled RTC32K_XI / RTC32K_XO
- GPIOAO_6 has a CLK_32KIN function (shows in EC-100 and Odroid-C1
  schematics as well as the public S805 datasheet)
- Always On domain PWR_CNTL0[11:10] (public S805 datasheet page 19)
  describes it as "Alternate 32khz input clock select from GPIO pad"

Thus I believe that the naming of the RTC32K clock is correct, but I
wanted to point out that I'm only 99% (instead of 100%) sure.
Jianxin, please let me know if you disagree with my findings.


Martin Blumenstingl (3):
  ARM: dts: meson: add support for the RTC
  ARM: dts: meson8b: ec100: enable the RTC
  ARM: dts: meson8b: odroid-c1: prepare support for the RTC

 arch/arm/boot/dts/meson.dtsi           |  9 +++++++++
 arch/arm/boot/dts/meson8.dtsi          |  5 +++++
 arch/arm/boot/dts/meson8b-ec100.dts    | 14 ++++++++++++++
 arch/arm/boot/dts/meson8b-odroidc1.dts | 14 ++++++++++++++
 arch/arm/boot/dts/meson8b.dtsi         |  5 +++++
 5 files changed, 47 insertions(+)

Comments

Kevin Hilman April 16, 2019, 7:01 p.m. UTC | #1
Martin Blumenstingl <martin.blumenstingl@googlemail.com> writes:

> This adds support for the RTC on the Meson8b EC-100 and Odroid-C1
> boards. Example kernel log snippet while booting my EC-100:
>   [    5.713750] meson-rtc c8100740.rtc: setting system clock to 2019-04-13T16:21:48 UTC (1555172508)
>
> I am only 99% sure about the naming of the clock in patch 2 and 3.
> The public S805 datasheet from Hardkernel shows (on page 24 for example)
> that clk81 can use "XTAL/32khz" as clock input. That "XTAL/32khz" clock
> is described as a mux between 24MHz (our main XTAL) and 32kHz ("that
> other XTAL").
> I believe that this other 32kHz XTAL is NOT the RTC32K crystal because:
> - schematics of the EC-100 and Odroid-C1 clearly show that the SoC input
>   for the RTC32K clock is labeled RTC32K_XI / RTC32K_XO
> - GPIOAO_6 has a CLK_32KIN function (shows in EC-100 and Odroid-C1
>   schematics as well as the public S805 datasheet)
> - Always On domain PWR_CNTL0[11:10] (public S805 datasheet page 19)
>   describes it as "Alternate 32khz input clock select from GPIO pad"
>
> Thus I believe that the naming of the RTC32K clock is correct, but I
> wanted to point out that I'm only 99% (instead of 100%) sure.
> Jianxin, please let me know if you disagree with my findings.

99% confidence is higher than we normally have, so that's fine by me. :)
And, we can fix if we get any updated info from Jianxin.

Thanks for the detailed description.

Queuing for v5.2,

Kevin