Re: [linux-sunxi] Re: [PATCH] nvmem: sunxi-sid: add support for A64/H5's SID controller

From: icenowy
Date: Tue Sep 19 2017 - 08:19:07 EST

å 2017-09-19 19:55ïMaxime Ripard åéï
On Tue, Sep 19, 2017 at 04:23:14PM +0800, Icenowy Zheng wrote:

ä 2017å9æ19æ GMT+08:00 äå4:20:19, Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> åå:
>On Mon, Sep 18, 2017 at 11:42:04PM +0800, Icenowy Zheng wrote:
>> Allwinner A64/H5 SoCs come with a SID controller like the one in H3,
>> without the silicon bug that makes the initial value at 0x200 wrong,
>> the value at 0x200 can be directly read.
>> Add support for this kind of SID controller.
>> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>
>> ---
>> Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt | 1
>> drivers/nvmem/sunxi_sid.c | 6
>> 2 files changed, 7 insertions(+)
>> diff --git
>> index ef06d061913c..6ea0836939ee 100644
>> --- a/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
>> +++ b/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
>> @@ -5,6 +5,7 @@ Required properties:
>> "allwinner,sun4i-a10-sid"
>> "allwinner,sun7i-a20-sid"
>> "allwinner,sun8i-h3-sid"
>> + "allwinner,sun50i-a64-sid"
>> - reg: Should contain registers location and length
>> diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c
>> index 0d6648be93b8..3c9fd4fb9207 100644
>> --- a/drivers/nvmem/sunxi_sid.c
>> +++ b/drivers/nvmem/sunxi_sid.c
>> @@ -199,10 +199,16 @@ static const struct sunxi_sid_cfg sun8i_h3_cfg
>= {
>> .need_register_readout = true,
>> };
>> +static const struct sunxi_sid_cfg sun50i_a64_cfg = {
>> + .value_offset = 0x200,
>> + .size = 0x100,
>> +};
>> +
>How did you get those values?

In the BSP U-Boot headers.

This should be mentionned in your commit log then.

P.S. the 0x200 offset is not in the header, but as a proven experience
on new generation SID controllers.

>Also, it's reported that the SID can only be accessed in secure
>mode, did you test it?

Yes, however the secure is broken again, and this only
happen if Secure Boot bit is burned.

Is broken again, meaning?

As far as I know, the only breakage we've had is on the A80 / A83T,
but we don't have anything like it on the A64, do we?

A80/A83T is not the *only* breakage, but the *most serious* breakage,
which affected correctly using SMP in non-secure.

Newer Allwinner SoCs doesn't have the GIC broken, but the TZPC still
doesn't work when not Secure Boot, which means that all peripherals
set to secure-only can still be accessed. Affected SoCs are at least
H3, H5, A64.

It seems that the registers marked as secure-only inside PRCM still
works -- however this still has no meaningful secure/non-secure
seperation, as the secure setting register in PRCM is not
secure-only at least on SoCs without SB enabled.

If it's really burned, we will have no clean way to access SID.

Well, in such a case we shouldn't access it either, so..

We will need the THS calibration data.

Maybe a custom call to ATF can be created, but I consider it dirty.