Re: [PATCH 1/5] rtc: sun6i: Add sun6i RTC driver

On Wed, Jul 23, 2014 at 5:55 PM, Maxime Ripard
[off-list ref] wrote:

Hi,

On Mon, Jul 21, 2014 at 10:46:06PM +0800, Chen-Yu Tsai wrote:

quoted

Hi,

On Fri, Jul 18, 2014 at 4:07 PM, Maxime Ripard
[off-list ref] wrote:

quoted

Hi,

On Mon, Jul 14, 2014 at 03:32:13PM +0800, Chen-Yu Tsai wrote:

quoted

This patch introduces the driver for the RTC in the Allwinner A31 and
A23 SoCs.

Unlike the RTC found in A10/A20 SoCs, which was part of the timer, the
RTC in A31/A23 are a separate hardware block, which also contain a few
controls for the RTC block hardware (a regulator and RTC block GPIO pin
latches), while also having separate interrupts for the alarms.

Do you plan on supporting those at some point?

I haven't seen any devices use the regulator (which has an output pin).
I suppose we shouldn't add drivers for things we can't verify.
As for the GPIO pin latches, I'll have to experiment some more to figure
out what they do exactly.

Ok.

quoted

quoted

It's also worth noting that the first registers are supposed to
control the source of the low frequency oscillator in the SoC, which
will probably be the most troublesome, since we need these clocks very
early on.

That's true. I suppose the bootloader configures this. IIRC I've seen
code for this in boot0 or boot1 from Allwinner. I can't find the equivalent
for our sun4i u-boot though.

Do you know what was the bootloader configuring it to?

I checked this some time ago, when I started to look at the sunxi clock code.
For all the devices (sun6/7/8i) I've checked, the system is configured to use
the external 32.768k oscillator.

I don't really know how we can deal with this in a nice way, but I
guess it's not so urgent.

I agree. I will look at the BROM (for sun4/7i) and boot0 (sun6i) for signs of
when it is configured. Then we can determine if we need to implement it
somewhere.

[...]

ChenYu
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